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in the biblical story of the tower of babel , all of humanity once spoke a single language until they suddenly split into many groups unable to understand each other . we do n't really know if such an original language ever existed , but we do know that the thousands of languages existing today can be traced back to a much smaller number . so how did we end up with so many ? in the early days of human migration , the world was much less populated . groups of people that shared a single language and culture often split into smaller tribes , going separate ways in search of fresh game and fertile land . as they migrated and settled in new places , they became isolated from one another and developed in different ways . centuries of living in different conditions , eating different food and encountering different neighbors turned similar dialects with varied pronunciation and vocabulary into radically different languages , continuing to divide as populations grew and spread out further . like genealogists , modern linguists try to map this process by tracing multiple languages back as far as they can to their common ancestor , or protolanguage . a group of all languages related in this way is called a language family , which can contain many branches and sub-families . so how do we determine whether languages are related in the first place ? similar sounding words do n't tell us much . they could be false cognates or just directly borrowed terms rather than derived from a common root . grammar and syntax are a more reliable guide , as well as basic vocabulary , such as pronouns , numbers or kinship terms , that 's less likely to be borrowed . by systematically comparing these features and looking for regular patterns of sound changes and correspondences between languages , linguists can determine relationships , trace specific steps in their evolution and even reconstruct earlier languages with no written records . linguistics can even reveal other important historical clues , such as determining the geographic origins and lifestyles of ancient peoples based on which of their words were native , and which were borrowed . there are two main problems linguists face when constructing these language family trees . one is that there is no clear way of deciding where the branches at the bottom should end , that is , which dialects should be considered separate languages or vice versa . chinese is classified as a single language , but its dialects vary to the point of being mutually unintelligible , while speakers of spanish and portuguese can often understand each other . languages actually spoken by living people do not exist in neatly divided categories , but tend to transition gradually , crossing borders and classifications . often the difference between languages and dialects is a matter of changing political and national considerations , rather than any linguistic features . this is why the answer to , `` how many languages are there ? '' can be anywhere between 3,000 and 8,000 , depending on who 's counting . the other problem is that the farther we move back in time towards the top of the tree , the less evidence we have about the languages there . the current division of major language families represents the limit at which relationships can be established with reasonable certainty , meaning that languages of different families are presumed not to be related on any level . but this may change . while many proposals for higher level relationships -- or super families -- are speculative , some have been widely accepted and others are being considered , especially for native languages with small speaker populations that have not been extensively studied . we may never be able to determine how language came about , or whether all human languages did in fact have a common ancestor scattered through the babel of migration . but the next time you hear a foreign language , pay attention . it may not be as foreign as you think .

languages actually spoken by living people do not exist in neatly divided categories , but tend to transition gradually , crossing borders and classifications . often the difference between languages and dialects is a matter of changing political and national considerations , rather than any linguistic features . this is why the answer to , `` how many languages are there ? ''

which is not a reason for linguistic divergence ?

translator : andrea mcdonough reviewer : bedirhan cinar you might have heard that we 're running out of fresh water . this might sound strange to you because , if you live in a place where water flows freely from the tap or shower at any time , it sure does n't seem like a big deal . it 's just there , right ? wrong ! the only obvious thing about fresh water is how much we need it . because it 's essential to life , we need to think about it carefully . right now , at this very moment , some people , women and girls in particular , walk hours and miles per day to get fresh water , and even then , it may not be clean . every 15 seconds , a child dies due to water-born diseases . this is tragic ! the most compelling reasons to think about fresh water , therefore , have to do with what we might call the global common good . this is not something we normally think about , but it means recognizing how much fresh water matters for the flourishing of human and non-human life on earth now and in the future . how do we think about something as local as our faucets and as global as fresh water ? is there a connection between them ? many people assume that fresh water shortages are due to individual wastefulness : running the water while you brush your teeth , for example , or taking really long showers . most of us assume , therefore , that water shortages can be fixed by improving our personal habits : taking shorter showers or turning off the water while we brush our teeth . but , global fresh water scarcity neither starts nor ends in your shower . globally , domestic use of fresh water accounts for only 8 % of consumption , 8 % ! ! compare that to the 70 % that goes to agriculture and the 22 % that goes to industrial uses . now , hold up - you 're not off the hook ! individual habits are still part of the puzzle . you should still cultivate water virtue in your daily life , turn off the tap when you brush your teeth . but still , it 's true . taking shorter showers wo n't solve global problems , which is too bad . it would be much more straightforward and easier if virtuous , individual actions could do the trick . you 'd just stand there for 30 seconds less , and you 'd be done with that irksome , planet-saving task for the day . well , that 's not so much the case . agricultural and industrial patterns of water use need serious attention . how do our societies value water ? distribute it ? subsidize its use in agriculture ? incentivize its consumption or pollution ? these are all questions that stem from how we think about fresh water 's value . is it an economic commodity ? a human right ? a public good ? nobel prize winners , global water justice activists , transnational institutions like the united nations , and even the catholic church are at work on the issue . but , it 's tricky , too , because the business of water became very profitable in the 20th century . and profit is not the same thing as the common good . we need to figure out how to value fresh water as a public good , something that 's vital for human and non-human life , now and in the future . now that 's a virtuous , collective task that goes far beyond your shower .

right now , at this very moment , some people , women and girls in particular , walk hours and miles per day to get fresh water , and even then , it may not be clean . every 15 seconds , a child dies due to water-born diseases . this is tragic !

every 15 seconds , a child dies due to water borne illness .

there 's a job out there with a great deal of power , pay , prestige , and near-perfect job security . and there 's only one way to be hired : get appointed to the us supreme court . if you want to become a justice on the supreme court , the highest federal court in the united states , three things have to happen . you have to be nominated by the president of the united states , your nomination needs to be approved by the senate , and finally , the president must formally appoint you to the court . because the constitution does n't specify any qualifications , in other words , that there 's no age , education , profession , or even native-born citizenship requirement , a president can nominate any individual to serve . so far , six justices have been foreign-born , at least one never graduated from high school , and another was only 32 years old when he joined the bench . most presidents nominate individuals who broadly share their ideological view , so a president with a liberal ideology will tend to appoint liberals to the court . of course , a justice 's leanings are not always so predictable . for example , when president eisenhower , a republican , nominated earl warren for chief justice , eisenhower expected him to make conservative decisions . instead , warren 's judgements have gone down as some of the most liberal in the court 's history . eisenhower later remarked on that appointment as `` the biggest damned-fool mistake '' he ever made . many other factors come up for consideration , as well , including experience , personal loyalties , ethnicity , and gender . the candidates are then thoroughly vetted down to their tax records and payments to domestic help . once the president interviews the candidate and makes a formal nomination announcement , the senate leadership traditionally turns the nomination over to hearings by the senate judiciary committee . depending on the contentiousness of the choice , that can stretch over many days . since the nixon administration , these hearings have averaged 60 days . the nominee is interviewed about their law record , if applicable , and where they stand on key issues to discern how they might vote . and especially in more recent history , the committee tries to unearth any dark secrets or past indiscretions . the judiciary committee votes to send the nomination to the full senate with a positive or negative recommendation , often reflective of political leanings , or no recommendation at all . most rejections have happened when the senate majority has been a different political party than the president . when the senate does approve , it 's by a simple majority vote , with ties broken by the vice president . with the senate 's consent , the president issues a written appointment , allowing the nominee to complete the final steps to take the constitutional and judicial oaths . in doing so , they solemnly swear to administer justice without respect to persons and do equal right to the poor and the rich and faithfully and impartially discharge and perform all the duties incumbent upon a us supreme court justice . this job is for life , barring resignation , retirement , or removal from the court by impeachment . and of the 112 justices who have held the position , not one has yet been removed from office as a result of an impeachment . one of their roles is to protect the fundamental rights of all americans , even as different parties take power . with the tremendous impact of this responsibility , it 's no wonder that a us supreme court justice is expected to be , in the words of irving r. kaufman , `` a paragon of virtue , an intellectual titan , and an administrative wizard . '' of course , not every member of the court turns out to be an exemplar of justice . each leaves behind a legacy of decisions and opinions to be debated and dissected by the ultimate judges , time and history .

one of their roles is to protect the fundamental rights of all americans , even as different parties take power . with the tremendous impact of this responsibility , it 's no wonder that a us supreme court justice is expected to be , in the words of irving r. kaufman , `` a paragon of virtue , an intellectual titan , and an administrative wizard . '' of course , not every member of the court turns out to be an exemplar of justice .

what us supreme court justice today , if any , would you describe as a paragon of virtue , an intellectual titan , and an administrative wizard ?

europium is an element which , when you excite the atoms or excite the electrons in the atoms , gives out very nice red coloured light . ok , so europium is pretty much in the middle of the lanthanide series . perhaps its most famous use is in television screens . in fact , most or many of the rare earths can fluoresce in this way and give out light , but europium is particularly good at giving a very nice red colour , and so europium salts are used in television screens , not lcd screens like you have on the laptop , but the old-fashioned cathode ray televisions . so it ’ s very good at phosphorescence , for example , so we use it in the tubes in tv screens to get different colours . the screen on the inside of the screen you have dots of europium and when the electrons from the electron beam in the cathode ray tube hit the europium you get a very intense emission of red light which gives you the red colour to form the colour television pictures .

europium is an element which , when you excite the atoms or excite the electrons in the atoms , gives out very nice red coloured light . ok , so europium is pretty much in the middle of the lanthanide series .

which color does europium emit when you excite the electrons in its atoms ?

translator : tom carter reviewer : bedirhan cinar she 's only a few feet away . the closer he gets , the more nervous he becomes , the budding zit on his nose growing bigger and bigger until it practically eclipses his face . she looks at him hovering nearby , sees the massive zit , and giggles . he slumps away , feeling sick . stress can sure make a mess , and it happens to both teens and adults . but how does it happen ? let 's rewind to before the zit , to before justin even sees his crush . already late for school , justin got to class just in time to hear the teacher say `` pop quiz . '' he had n't done his homework the night before , and felt more unprepared than the ambushed world war ii soldiers he was supposed to write about . a sudden rush of panic swept over his body , leaving him with sweaty palms , a foggy mind and a racing heart . he stumbled out of class in a daze , and ran straight into his all-time crush , spiking up his stress . stress is a general biological response to a potential danger . in primitive caveman terms , stress can make you fight for your life , or run for your life , if , for example , you 're confronted by a hungry saber-tooth tiger . special chemicals called stress hormones run through your body , giving you more oxygen and power to run away from danger or to face it and fight for your life , hence the term `` fight or flight . '' but when you do n't fight , or take flight , you face the plight . when we 're taking final exams , sitting in traffic or pondering pollution , we internalize stress . it all begins in the brain . the hypothalamus , the master controller of your hormones , releases something called corticotropin-releasing hormone . this triggers the pituitary gland , a pea-sized gland found at the base of the brain , to release adrenocorticotropic hormone which then stimulates the adrenal gland sitting on top of the kidneys to release cortisol , the major stress hormone . these natural chemicals are a great help when you need to run away quickly , or do superhuman feats of courage , but when you 're simply sitting , these stress hormones collect in the body and affect your overall health . stress hormones increase inflammation in the body , suppress the immune system , which makes you more susceptible to infection by acne-causing bacteria , and can even increase oil production in the skin . and this is the perfect storm for forming a pimple . cortisol is a major stress hormone involved in making skin cells churn out oily lipids from special glands called sebaceous glands . but when there 's too much of these oily lipids , called sebum , they can plug up the swollen , inflamed pores and trap the pesky , acne-causing bacteria inside , where they set up house and thrive . add a dash of inflammatory neuropeptides released by the nervous system when you 're -- well , nervous -- and angry zits follow . to make matters worse , justin is a boy , meaning he 's got more testosterone than girls . testosterone is another hormone that increases oil production in the skin . so , his already oily skin , together with a boost in oil and inflammation from stress , is the perfect environment for bacteria to swell , swell , swell up into a major zit . so what could 've justin done to avoid the big pimple ? stressful situations are unavoidable . but we can try to change our responses so that we 're not so stressed in the end . and had he been confident in approaching her , she might not have noticed the pimple , or he might not have had one .

in primitive caveman terms , stress can make you fight for your life , or run for your life , if , for example , you 're confronted by a hungry saber-tooth tiger . special chemicals called stress hormones run through your body , giving you more oxygen and power to run away from danger or to face it and fight for your life , hence the term `` fight or flight . '' but when you do n't fight , or take flight , you face the plight .

what are the fight-or-flight chemicals called ?

translator : tom carter reviewer : bedirhan cinar ( zombie noises ) doctor 1 : so , here we are again . you know , i 've been thinking . why is this thing so angry ? doctor 2 : maybe he 's just hungry . d1 : ( laughs ) i 'm not going in there to feed it . no , this seems like something very primal . d2 : this is kind of a hard one , because we do n't really have any biological definitions for emotions like anger . sure , brain imaging studies have shown that some brain regions are more active when people are angry , but these are almost always correlational . when it 's warmer outside , people wear less clothing , but if i strip down to my birthday suit , it does n't make it sunny . d1 : ( laughs ) it 's like having someone run on a treadmill and saying `` look at how much more his arms move when he runs faster ! the arms must be where running happens . '' d2 : that 's why working with people with brain lesions is so important to neuroscience . it adds some causal evidence that a brain area might be required for a behavior . same with brain simulation studies . if stimulating a brain area causes a behavior , then that 's good evidence that the brain region is involved in that behavior . so like studies with cats in the 1950s showed that stimulating a small almond-shaped area deep in the brain called the amygdala leads to aggressive or predatory behaviors . these things look pretty aggressive to me . d1 : right . but other studies have shown that stimulating different parts of the amygdala can actually suppress predatory behaviors . so it 's kind of a complicated little brain structure . d2 : yeah . and fmri studies have found that the amygdala is active in violent criminals . d1 : whoa , whoa , whoa . careful there . just because criminals have the same active brain regions as people who are angry , does n't mean that they 're inherently aggressive . that 's like saying because i kiss with the same face hole that i use to burp , then these two things are related . it 's a false equivalence . d2 : huh ! never thought of it like that . that 's a good point . d1 : you know , the amygdala is part of the papez circuit . this system was discovered by james papez , who used the rabies virus to lesion different areas in the cat 's brain . he found that the amygdala was physically connected to another region called the hippocampus -- a little seahorse-shaped area that is needed to turn short-term memories into long-term memories . it 's thought that this connection between the amygdala and hippocampus links emotion and memory together , so that you remember really emotional stuff better than boring everyday things . d2 : yeah , like patient h.m . in the 1950s , surgeons removed both his left and right hippocampuses to treat his epilepsy . but after the surgery , he could n't remember any new information for longer than a few minutes . zombies appear to be pretty forgetful , would n't you agree ? d1 : ( laughs ) absolutely . between the amygdala-related aggression , and memory deficits from the hippocampus , papez may have actually accidentally created the first zombie cat . d2 : aw , come on now , let 's not get carried away . but now we do have some testable hypotheses . i 'd put money on its aggression and memory problems being linked to abnormalities in its amygdala and hippocampus , respectively . d1 : great ! so all we need to do now is figure out how to experimentally test this . do you think it 'll let us examine its brain to verify our hypothesis ? d2 : uh , you know , i think i might be more comfortable not knowing the answer to this one . d1 : hmm . maybe we could get a graduate student to do it for us ?

d2 : this is kind of a hard one , because we do n't really have any biological definitions for emotions like anger . sure , brain imaging studies have shown that some brain regions are more active when people are angry , but these are almost always correlational . when it 's warmer outside , people wear less clothing , but if i strip down to my birthday suit , it does n't make it sunny .

when trying to understand brain-behavior links what are the advantages and disadvantages of correlational ( e.g. , brain imaging ) and causal ( e.g. , brain lesion ) methods respectively ? what does it really mean for a brain area to be active during a particular task ? what might we miss when trying to characterize behavioral changes in patient populations ?

hi , i 'm medium invader from the classic video game space invaders , and i want to tell you a little bit about where video games came from . a video game is an electronic game that has an interface designed for human interaction on a video device . simple . video games are used by scientists , the military , and people like you , and their evolution has spread across arcades , consoles , computers , smart phones , and all kinds of other electronics . these days video games are everywhere , but they were actually made in science labs . in fact , the earliest u.s. video game patent on record was in 1948 , and at the time it was referred to as a cathode-ray tube amusement device . that 's a mouthful ! some of the earliest video games include the nimrod computer , oxo , tennis for two , and my personal favorite , spacewar ! but none of these early video games were ever sold to the public because they were either too huge or too expensive to get out of the lab . this all changed when a man named ralph baer looked at his television screen and wondered how else it might be used . in 1972 , baer 's idea to get video games out of the science lab and into the living room led to the release of a game console called odyssey . odyssey allowed you to play a game on your tv . at about the same time , two other people , nolan bushnell and ted dabney , were working on something similar in a little company called atari . you might have heard of it , and even if you have n't , i 'm sure that your dad has . atari 's first major game release was in 1972 , an arcade game called pong . it was an immediate hit , and it 's credited as the first commercially successful video game . atari then released a home version of pong in 1974 . by 1978 , competition between atari and another game company called midway was heating up . midway had licensed an arcade game for the japanese company , taito , that put them on the map . the game : space invaders . it featured iconic actors , like me , and it went on to become the second highest selling arcade game of all time . space invaders also helped kick off what is known as the golden age of arcade games . in response , atari followed with the release of the arcade game asteroids , which ranked sixth on the list of highest selling arcade games . it was a good game , but it 's no space invaders . by 1980 , color came to arcade games , and this was also the year that another video gaming milestone was born . pac-man , created by the japanese company namco , was brought to the u.s. by midway . important to the spread of video games into popular culture , pac-man was a character that could be licensed . it was n't long before it had a song on the charts , a saturday morning television show , and all sorts of other products . in just a year , pac-man arcade games made over one billion dollars in quarters . then , in 1981 , a company called nintendo started making waves in the u.s. video game market with their release of donkey kong . it was the earliest video game to have a story line . the story went a bit like this : donkey kong is the pet of a carpenter named jumpman . jumpman mistreats his pet ape , so the ape steals his girlfriend , leaving the game player to assume the role of jumpman and rescue the girl . jumpman was eventually renamed to mario . other iconic arcade games from the early 80s include frogger , dragon 's lair , and mario brothers . perhaps the last iconic game considered to be part of the golden age of arcade games is double dragon . it was the first really successful example of the beat-them-up genre . it was released in 1987 , and , like donkey kong , it featured a damsel in distress storyline , a storyline common in many video games . by the mid-90s , the golden age of arcade games was coming to an end , and the home game console was gaining in popularity . while arcade games continued to decline in sales over the years , the popularity of video games was merely beginning , and we 'll talk about that and a lot more in part two of a brief history of video games .

by the mid-90s , the golden age of arcade games was coming to an end , and the home game console was gaining in popularity . while arcade games continued to decline in sales over the years , the popularity of video games was merely beginning , and we 'll talk about that and a lot more in part two of a brief history of video games .

who uses video games ?

the human brain is one of the most sophisticated organs in the world , a supercomputer made of billions of neurons that processes and controls all of our senses , thoughts , and actions . but there was something charles darwin found even more impressive : the brain of an ant , which he called one of the most marvelous atoms of matter in the world . if you find it hard to believe that something so tiny could have a complex brain , you 're not alone . in his project to classify and describe all living things , swedish naturalist carl linnaeus assumed insects had no brains at all . he was wrong , but understandably so . insect brains are not only miniscule , but in many respects , they function differently than our own . one of the most noticeable differences is that an insect that loses its head can still walk , scratch itself , breathe , and even fly . this is because while our nervous system works like a monarchy , with the brain calling the shots , the insect nervous system works more like a decentralized federation . many insect activities , like walking or breathing , are coordinated by clusters of neurons , also known as ganglia , along their bodies . together with the brain , these local ganglia form the insect nervous system . while an insect can do a lot with just its local ganglia , the brain is still crucial for its survival . an insect 's brain lets it perceive the world through sight and smell . it also chooses suitable mates , remembers locations of food sources and hives , regulates communication , and even coordinates navigation over huge distances . and this vast diversity of behaviors is controlled by an organ the size of the head of a pin , with less than one million neurons , compared to our 86 billion . but even though the insect brain is organized very differently from ours , there are some striking similarities . for example , most insects have smell detectors on their antennae , similar to those found in human noses . and our primary olfactory brain regions look and function rather similarly , with clusters of neurons activated and deactivated in precise timing to code for specific scents . scientists have been astonished by these similarities because insects and humans are not very closely related . in fact , our last common ancestor was a simple worm-like creature that lived more than 500 million years ago . so how did we end up with such similar brain structures when our evolution took almost entirely different paths ? scientists call this phenomenon convergent evolution . it 's the same principle behind birds , bats , and bees separately evolving wings . similar selective pressures can cause natural selection to favor the same evolutionary strategy in species with vastly different evolutionary pasts . by studying the comparison between insect and human brains , scientists can thus understand which of our brain functions are unique , and which are general solutions to evolutionary problems . but this is not the only reason scientists are fascinated by insect brains . their small size and simplicity makes it easier to understand exactly how neurons work together in the brain . this is also valuable for engineers , who study the insect brain to help design control systems for everything from self-flying airplanes to tiny search-and-rescue roach bots . so , size and complexity are not always the most impressive things . the next time you try to swat a fly , take a moment to marvel at the efficiency of its tiny nervous system as it outsmarts your fancy brain .

in fact , our last common ancestor was a simple worm-like creature that lived more than 500 million years ago . so how did we end up with such similar brain structures when our evolution took almost entirely different paths ? scientists call this phenomenon convergent evolution .

the sense of smell in insects and humans has evolved via different paths from different origins , and yet the brain structures dedicated to it are very similar . this is a prime example of convergent evolution . can you think of other examples of convergent evolution in the animal kingdom ?

in the 16th century , the mathematician robert recorde wrote a book called `` the whetstone of witte '' to teach english students algebra . but he was getting tired of writing the words `` is equal to '' over and over . his solution ? he replaced those words with two parallel horizontal line segments because the way he saw it , no two things can be more equal . could he have used four line segments instead of two ? of course . could he have used vertical line segments ? in fact , some people did . there 's no reason why the equals sign had to look the way it does today . at some point , it just caught on , sort of like a meme . more and more mathematicians began to use it , and eventually , it became a standard symbol for equality . math is full of symbols . lines , dots , arrows , english letters , greek letters , superscripts , subscripts . it can look like an illegible jumble . it 's normal to find this wealth of symbols a little intimidating and to wonder where they all came from . sometimes , as recorde himself noted about his equals sign , there 's an apt conformity between the symbol and what it represents . another example of that is the plus sign for addition , which originated from a condensing of the latin word et meaning and . sometimes , however , the choice of symbol is more arbitrary , such as when a mathematician named christian kramp introduced the exclamation mark for factorials just because he needed a shorthand for expressions like this . in fact , all of these symbols were invented or adopted by mathematicians who wanted to avoid repeating themselves or having to use a lot of words to write out mathematical ideas . many of the symbols used in mathematics are letters , usually from the latin alphabet or greek . characters are often found representing quantities that are unknown , and the relationships between variables . they also stand in for specific numbers that show up frequently but would be cumbersome or impossible to fully write out in decimal form . sets of numbers and whole equations can be represented with letters , too . other symbols are used to represent operations . some of these are especially valuable as shorthand because they condense repeated operations into a single expression . the repeated addition of the same number is abbreviated with a multiplication sign so it does n't take up more space than it has to . a number multiplied by itself is indicated with an exponent that tells you how many times to repeat the operation . and a long string of sequential terms added together is collapsed into a capital sigma . these symbols shorten lengthy calculations to smaller terms that are much easier to manipulate . symbols can also provide succinct instructions about how to perform calculations . consider the following set of operations on a number . take some number that you 're thinking of , multiply it by two , subtract one from the result , multiply the result of that by itself , divide the result of that by three , and then add one to get the final output . without our symbols and conventions , we 'd be faced with this block of text . with them , we have a compact , elegant expression . sometimes , as with equals , these symbols communicate meaning through form . many , however , are arbitrary . understanding them is a matter of memorizing what they mean and applying them in different contexts until they stick , as with any language . if we were to encounter an alien civilization , they 'd probably have a totally different set of symbols . but if they think anything like us , they 'd probably have symbols . and their symbols may even correspond directly to ours . they 'd have their own multiplication sign , symbol for pi , and , of course , equals .

consider the following set of operations on a number . take some number that you 're thinking of , multiply it by two , subtract one from the result , multiply the result of that by itself , divide the result of that by three , and then add one to get the final output . without our symbols and conventions , we 'd be faced with this block of text .

what is one of the main reasons mathematicians give for introducing new notation ?

when you think about the brain , it 's difficult to understand , because if i were to ask you right now , how does the heart work , you would instantly tell me it 's a pump . it pumps blood . if i were to ask about your lungs , you would say it exchanges oxygen for carbon dioxide . that 's easy . if i were to ask you how the brain works , it 's hard to understand because you ca n't just look at a brain and understand what it is . it 's not a mechanical object , not a pump , not an airbag . it 's just like , if you held it in your hand when it was dead , it 's just a piece of fat . to understand how the brain works , you have to go inside a living brain . because the brain 's not mechanical , the brain is electrical and it 's chemical . your brain is made out of 100 billion cells , called neurons . and these neurons communicate with each other with electricity . and we 're going to eavesdrop in on a conversation between two cells , and we 're going to listen to something called a spike . but we 're not going to record my brain or your brain or your teachers ' brains , we 're going to use our good friend the cockroach . not just because i think they 're cool , but because they have brains very similar to ours . so if you learn a little bit about how their brains work , we 're going to learn a lot about how our brains work . i 'm going to put them in some ice water here and then -- audience : ew ! greg gabe : yeah ... right now they 're becoming anesthetized . because they 're cold blooded , they become the temperature of the water and they ca n't control it so they just basically `` chillax , '' right ? they 're not going to feel anything , which may tell you a little about what we 're going to do , a scientific experiment to understand the brain . so ... this is the leg of a cockroach . and a cockroach has all these beautiful hairs and pricklies all over it . underneath each one of those is a cell , and this cell 's a neuron that is going to send information about wind or vibration . if you ever try to catch a cockroach , it 's hard because they can feel you coming before you 're even there , they start running . these cells are zipping up this information up to the brain using those little axons with electronic messages in there . we 're going to record by sticking a pin right in there . we need to take off the leg of a cockroach -- do n't worry , they 'll grow back -- then we 're going to put two pins in there . these are metal pins . one will pick up this electronic message , this electric message is going by . so , we 're now going to do the surgery , let 's see if you guys can see this . yeah , it 's gross ... all right . so there we go . you guys can see his leg right there . now i 'm going to take this leg , i 'm going to put it in this invention that we came up with called the spikerbox -- and this replaces lots of expensive equipment in a research lab , so you guys can do this in your own high schools , or in your own basements if it 's me . ( audience : laughter ) so , there . can you guys see that ? alright , so i 'm going to go ahead and turn this on . i 'm going to plug it in . ( tuning sound ) to me , this is the most beautiful sound in the world . this is what your brain is doing right now . you have 100 billion cells making these raindrop-type noises . let 's take a look at what it looks like , let 's pull it up on the ipad screen . i plugged my ipad into here as well . so remember we said the axon looks like a spike . so we 're going to take a look at what one of them looks like in just a brief second . we 're going to tap here , so we can sort of average this guy . so there we see it . that 's an action potential . you 've got 100 billion cells in your brain doing this right now , sending all this information back about what you 're seeing , hearing . we also said this is a cell that 's going to be taking up information about vibrations in the wind . so what if we do an experiment ? we can actually blow on this and hear if we see a change . are you guys going to be ready ? if i blow on it you tell me if you hear anything . ( blowing ) ( sound changes ) let me just touch this with a little pen here . ( noise ) that was the neural firing rate . that actually took a while in neuroscience to understand this . this is called rate coding : the harder you press on something , the more spikes there are , and all that information is coming up to your brain . that 's how you perceive things . so that 's one way of doing an experiment with electricity . the other way is that your brain is not only taking in electrical impulses , you 're also sending out . that 's how you move your muscles around . let 's see what happens if i 've plugged in something that 's electric into the cockroach leg here . i 'm going to take two pins , i 'm going to plug them onto the cockroach . i 'm going to take the other end , i 'm going to plug in into my ipod . it 's my iphone actually . do you guys know how your earbuds work in your ears ? you have a battery in your phone , or ipod , right ? it 's sending electrical current into these magnets in your earbuds which shake back and forth and allow you to hear things . but that current 's the same currency that our brain uses , so we can send that to our cockroach leg and hopefully if this works , we can actually see what happens when we play music into the cockroach . let 's take a look . ( music beat ) can we turn it up ? there we go . ( audience reacts and gasps ) gg : so what 's happening ? audience : wow ! ( laughter ) so you see what 's moving . it 's moving on the bass . all those audiophiles out there , if you have awesome , kicking car stereos , you know , the bass speakers are the biggest speakers . the biggest speakers have the longest waves , which have the most current , and the current is what 's causing these things to move . so it 's not just speakers that are causing electricity . microphones also cause electricity . ( beat ) so i 'm going to go ahead and invite another person out on the stage here to help me out with this . so there we go . ( beatboxing ) this is the first time this has ever happened in the history of mankind . human beatbox to a cockroach leg . when you guys go back to your high school , think about neuroscience and how you guys can begin the neuro-revolution . thank you very much . bye bye . ( applause )

when you guys go back to your high school , think about neuroscience and how you guys can begin the neuro-revolution . thank you very much . bye bye .

according to gage , we have a much easier time understanding and explaining organs like the heart and lungs than we do with the brain . why is that ?

consider throwing a ball straight into the air . can you predict the motion of the ball after it leaves your hand ? sure , that 's easy . the ball will move upward until it gets to some highest point , then it will come back down and land in your hand again . of course , that 's what happens , and you know this because you have witnessed events like this countless times . you 've been observing the physics of everyday phenomena your entire life . but suppose we explore a question about the physics of atoms , like what does the motion of an electron around the nucleus of a hydrogen atom look like ? could we answer that question based on our experience with everyday physics ? definietly not . why ? because the physics that governs the behavior of systems at such small scales is much different than the physics of the macroscopic objects you see around you all the time . the everyday world you know and love behaves according to the laws of classical mechanics . but systems on the scale of atoms behave according to the laws of quantum mechanics . this quantum world turns out to be a very strange place . an illustration of quantum strangeness is given by a famous thought experiment : schrödinger 's cat . a physicist , who does n't particularly like cats , puts a cat in a box , along with a bomb that has a 50 % chance of blowing up after the lid is closed . until we reopen the lid , there is no way of knowing whether the bomb exploded or not , and thus , no way of knowing if the cat is alive or dead . in quantum physics , we could say that before our observation the cat was in a superposition state . it was neither alive nor dead but rather in a mixture of both possibilities , with a 50 % chance for each . the same sort of thing happens to physical systems at quantum scales , like an electron orbiting in a hydrogen atom . the electron is n't really orbiting at all . it 's sort of everywhere in space , all at once , with more of a probability of being at some places than others , and it 's only after we measure its position that we can pinpoint where it is at that moment . a lot like how we did n't know whether the cat was alive or dead until we opened the box . this brings us to the strange and beautiful phenomenon of quantum entanglement . suppose that instead of one cat in a box , we have two cats in two different boxes . if we repeat the schrödinger 's cat experiment with this pair of cats , the outcome of the experiment can be one of four possibilities . either both cats will be alive , or both will be dead , or one will be alive and the other dead , or vice versa . the system of both cats is again in a superposition state , with each outcome having a 25 % chance rather than 50 % . but here 's the cool thing : quantum mechanics tells us it 's possible to erase the both cats alive and both cats dead outcomes from the superposition state . in other words , there can be a two cat system , such that the outcome will always be one cat alive and the other cat dead . the technical term for this is that the states of the cats are entangled . but there 's something truly mindblowing about quantum entanglement . if you prepare the system of two cats in boxes in this entangled state , then move the boxes to opposite ends of the universe , the outcome of the experiment will still always be the same . one cat will always come out alive , and the other cat will always end up dead , even though which particular cat lives or dies is completely undetermined before we measure the outcome . how is this possible ? how is it that the states of cats on opposite sides of the universe can be entangled in this way ? they 're too far away to communicate with each other in time , so how do the two bombs always conspire such that one blows up and the other does n't ? you might be thinking , `` this is just some theoretical mumbo jumbo . this sort of thing ca n't happen in the real world . '' but it turns out that quantum entanglement has been confirmed in real world lab experiments . two subatomic particles entangled in a superposition state , where if one spins one way then the other must spin the other way , will do just that , even when there 's no way for information to pass from one particle to the other indicating which way to spin to obey the rules of entanglement . it 's not surprising then that entanglement is at the core of quantum information science , a growing field studying how to use the laws of the strange quantum world in our macroscopic world , like in quantum cryptography , so spies can send secure messages to each other , or quantum computing , for cracking secret codes . everyday physics may start to look a bit more like the strange quantum world . quantum teleportation may even progress so far , that one day your cat will escape to a safer galaxy , where there are no physicists and no boxes .

the everyday world you know and love behaves according to the laws of classical mechanics . but systems on the scale of atoms behave according to the laws of quantum mechanics . this quantum world turns out to be a very strange place .

systems on atomic scales behave according to the laws of :

you know , i had a real rough time in school with add , and i have a phd . i earned a phd , but ... tough to pay attention -- biology , geology , physics , chemistry -- really tough for me . only one thing grabbed my attention , and it 's that planet called earth . but in this picture here , you 'll see that earth is mostly water . that 's the pacific . seventy percent of earth is covered with water . you can say , `` hey , i know earth . i live here . '' you do n't know earth . you do n't know this planet , because most of it 's covered with that -- average depth , two miles . and when you go outside and look up at the empire state building , chrysler building , the average depth of the ocean is 15 of those on top of one another . we 've explored about five percent of what 's in that water . `` explored , '' meaning , for the first time , go peek and see what 's there . so what i want to do today is show you some things about this planet , about the oceans . i want to take you from shallow water down to the deep water , and hopefully , like me , you 'll see some things that get you hooked on exploring planet earth . you know things like corals ; you 've seen plenty of corals , those of you who 've been to the beach , snorkeling , know corals are an amazing place to go -- full of life , some big animals , small animals , some nice , some dangerous , sharks , whales , all that stuff . they need to be protected from humanity . they 're great places . but what you probably do n't know is in the very deep part of the ocean , we have volcanic eruptions . most volcanoes on earth are at the bottom of the sea -- more than 80 percent . and we actually have fire , fire deep inside the ocean , going on right now . all over the world -- in the pacific , the atlantic , the indian ocean . in this place , the ocean floor , the rocks actually turn to liquid . so you actually have waves on the ocean floor . you 'd say nothing could live there , but when we look in detail , even there , in the deepest , darkest places on earth , we find life , which tells us that life really wants to happen . so , pretty amazing stuff . every time we go to the bottom of the sea , we explore with our submarines , with our robots , we see something that 's usually surprising , sometimes it 's startling and sometimes revolutionary . you see that puddle of water sitting there . and all around the water there 's a little cliff , there 's a little white sandy beach . we 'll get closer , you 'll see the beach a little bit better , some of the waves in that water , down there . the thing that 's special about this water is that it 's at the bottom of the gulf of mexico . so you 're sitting inside a submarine , looking out the window at a little pond of water beneath the sea . we see ponds , we see lakes , we see rivers -- in fact , right here is a river at the bottom of the ocean going from the lower left to the upper right . water is actually flowing through there . this totally blew our minds . how can you have this at the bottom ? you 're in the ocean looking at more water . and there 's animals that only live in that water . so , the bottom of the ocean -- i love this map , because it shows in the middle of the ocean , there 's a mountain range . it 's the greatest mountain range on earth , called the mid-ocean ridge -- 50,000 miles long , and we 've hardly had a peek at it . hardly had a peek at it . we find valleys , many thousands of valleys , larger , wider , deeper than the grand canyon . we find , as i said , underwater lakes , rivers , waterfalls . the largest waterfall on the planet is actually under the ocean , up near iceland . all that stuff is in that five percent that we 've explored . so the deal about the ocean is that to explore it , you 've got to have technology . not only technology , but it 's not just dave gallo or one person exploring , it 's a team of people . you 've got to have the talent , the team . you 've got to have the technology . in this case , it 's our ship , atlantis , and the submarine , alvin . inside that submarine -- this is an alvin launch -- there 's three people . they 're being wheeled out onto deck . there 's 47 other people , the teamwork on that ship , making sure that these people are okay . everybody in that submarine is thinking one thing right now : should i have gone to the bathroom one more time ? because you 're in there for 10 hours -- 10 hours in that little sphere . three of you together and nobody is going to be around you . you go into the water and once you hit the water , it 's amazing . there 's a lovely color blue that penetrates right inside you . you do n't hear the surface ship anymore , you hear that pinging of a sonar . if you 've got an iphone you 've got sonar on there -- it 's that same pinging that goes down to the bottom and comes back up . divers check out the sub to make sure the outside is okay , and then they say `` go , '' and down you go to the bottom of the ocean and it 's an amazing trip . so for two and a half hours , you sink down to the bottom . and two hours of it is totally pitch black . we thought that nothing could live inside that world at the bottom of the ocean . and when we look , we find some amazing things . all the way down -- we call it the mid-water -- from the top of the ocean down to the bottom , we find life . whenever we stop and look , we find life . i 'm going to show you some jellies . they 're absolutely some of the coolest creatures on earth . look at that thing , just flailing his arms around . that 's like a little lobster . that one is like all these animals with their mouths hooked together , the colonial animals . some animals are tiny , some can be longer than this stage . just amazing animals . and you ca n't collect them with a net -- we have to go with our cameras and take a look at them . so every time we go , new species of life . the ocean is full of life . and yet the deepest part of the ocean -- when we go to that mountain range , we find hot springs . now we were sure -- because this is poisonous water , because it 's so deep it would crush the titanic the same way you crush an empty cup in your hand -- we were sure there would be no life there at all . instead , we find more life and diversity and density than in the tropical rainforest . so , in one instance , in one peek out the window of the sub , we discover something that revolutionizes the way we think about life on earth ; and that is , you do n't always have to have sunlight to get life going . there 's big animals down there too , some that look familiar . that guy 's called dumbo . i love him . dumbo 's great . this guy -- oh man , i wish i had more footage of this . we 're trying to get an expedition together to go look at this and maybe in a year we 'll have that . go online and look . vampyroteuthis infernalis . the vampire squid . incredibly cool . in the darkness of the deep sea , he 's got glowing tentacles , so if i 'm coming at you like him , i put my arms out in the darkness so all you see are little glowing things over here . meanwhile , i 'm coming at you . when he wants to escape , he 's got these glowing pods on his butt that look like eyes . glowing eyes on his butt . how cool is that ? just an amazing animal . ( laughter ) `` vampire '' squid , because when it gets protective , it pulls this black cape over its whole body , and curls up into a ball . outrageous animal . this ship , `` the ship of dreams '' -- a hundred years ago this coming april , this ship was supposed to show up in new york . it 's the titanic . i co-led an expedition out there last year . we are learning so much about that ship . the titanic is an interesting place for biology , because animals are moving in to live on the titanic . microbes are actually eating the hull of the titanic . that 's where jack was king of the world there on the bow of the titanic . so we 're doing real good . and what 's exciting to me is that we 're making a virtual titanic , so you can sit there at home with your joystick and your headset on , and you can actually explore the titanic for yourself . that 's what we want to do , make these virtual worlds , so it 's not dave gallo or someone else exploring the world ; it 's you . you explore it for yourself . so here 's the bottom line : the oceans are unexplored and i ca n't begin to tell you how important that is , because they 're important to us . seven billion people live on this planet and all of us are impacted by the sea , because the oceans control the air you breathe , the water you drink , the food you eat . all those are controlled in some way by the ocean , and this is a thing that we have n't even explored -- five percent . the thing i want to leave you with is , in that five percent , i showed you some cool stuff . there 's a lot more cool stuff -- every dive we go on in the ocean , we find something new about the sea . so what 's in that other 95 percent ? did we get the exciting stuff or is there more out there ? and i 'm here to tell you that the ocean is full of surprises . there 's a quote i love by marcel proust : `` the true voyage of exploration is not so much in seeking new landscapes , '' which we do , `` but in having new eyes . '' and so i hope today , by showing you some of this , it 's given you some new eyes about this planet , and for the first time , i want you to think about it differently . thank you very much . thank you . ( applause )

so the deal about the ocean is that to explore it , you 've got to have technology . not only technology , but it 's not just dave gallo or one person exploring , it 's a team of people . you 've got to have the talent , the team .

gallo notes that deep-sea exploration is a team effort , even if only one or two people actually travel in a submersible . what other kinds of personnel do you think you ’ d need to carry out an expedition like the ones gallo describes ? which role ( s ) are most appealing to you , and why ?

translator : andrea mcdonough reviewer : bedirhan cinar every cell in your body is separated from those around it by its outermost layer , its membrane . a cell membrane must be both sturdy and flexible . imagine a membrane made of metal - great at keeping the cell 's guts inside , but horrible at letting materials flow in and out . but a membrane made of fishnet stocking would go too far in the opposite direction - leaky , but easily torn . so , the ideal membrane falls somewhere in the middle . over the past few centuries , we 've learned a lot about the way membranes work . the tale starts in the late 1800 's when , according to legend , a german woman named agnes pockels was doing dishes . her observation , that not all detergents dissolve grease in the same way , piqued her curiosity , so she made careful measurements of the size of soapy films that formed on the surface of a metal tray filled with water . later , in the 1920 's , ge scientists irving langmuir and katharine blodgett reexamined the problem with a more elaborate contraption and found that those tiny slicks were in fact a single layer of oil molecules . each oil molecule has one side that loves water and floats on the surface , and one side that loathes water and protrudes into the air . so what does it have to do with cell membranes ? well , at the turn of the 20th century , chemists charles overton and hans meyer demonstrated that the cell membrane is composed of substances that , like oil , have a water-loving part and a water-loathing part . we now call these substances lipids . in 1925 , two scientists , evert gorter and francois grendel , pushed our understanding further . they designed an experiment meant to test whether cell membranes are made of only one layer of lipids , a monolayer , or two layers stacked on top of one another , called a bilayer . gorter and grendel drew blood from a dog , a sheep , a rabbit , a goat , a guinea pig , and human volunteers . from each of these samples , they extracted all the lipids from all the red blood cells and placed a few drops of this extract on a tray of water . true to form , the lipids , like oil , spread out into a monolayer , whose size gorter and grendel could measure . if they compared the surface area of that monolayer to the surface area to the intact red blood cells , they 'd be able to tell whether the red blood cell membrane is one or two layers thick . to understand the design of their experiment , imagine looking down at a sandwich . if you measure the surface area of what you see , you 'll get the dimensions of a single slice of bread even though there are two slices , one stacked perfectly atop the other . but , if you open the sandwich and place the two slices side by side , you get twice the surface area . the gorter and grendel experiment is basically the same idea . the open sandwich is the monolayer formed by extracted cellular lipids spreading out into a sheet . the closed sandwich is the intact red blood cell membrane . low and behold , they observed a two-to-one ratio , proving beyond the shadow of a doubt that a cell membrane is a bilayer , which when unstacked , yields a monolayer twice its size . so almost 30 years before the double-helix structure of dna was elucidated , a single experiment involving fancy versions of household materials enabled deep insight into the basic architecture of the cell .

but , if you open the sandwich and place the two slices side by side , you get twice the surface area . the gorter and grendel experiment is basically the same idea . the open sandwich is the monolayer formed by extracted cellular lipids spreading out into a sheet .

what were gorter and grendel trying to prove ?

as 1905 dawned , the soon-to-be 26-year-old albert einstein faced life as a failed academic . most physicists of the time would have scoffed at the idea that this minor civil servant could have much to contribute to science . yet within the following year , einstein would publish not one , not two , not three , but four extraordinary papers , each on a different topic , that were destined to radically transform our understanding of the universe . the myth that einstein had failed math is just that . he had mastered calculus on his own by the age of 15 and done well at both his munich secondary school and at the swiss polytechnic , where he studied for a math and physics teaching diploma . but skipping classes to spend more time in the lab and neglecting to show proper deference to his professors had derailed his intended career path . passed over even for a lab assistant position , he had to settle for a job at the swiss patent office , obtained with the help of a friend 's father . working six days a week as a patent clerk , einstein still managed to make some time for physics , discussing the latest work with a few close friends , and publishing a couple of minor papers . it came as a major surprise when in march 1905 he submitted a paper with a shocking hypothesis . despite decades of evidence that light was a wave , einstein proposed that it could , in fact , be a particle , showing that mysterious phenomena , such as the photoelectric effect , could be explained by his hypothesis . the idea was derided for years to come , but einstein was simply twenty years ahead of his time . wave-particle duality was slated to become a cornerstone of the quantum revolution . two months later in may , einstein submitted a second paper , this time tackling the centuries old question of whether atoms actually exist . though certain theories were built on the idea of invisible atoms , some prominent scientists still believed them to be a useful fiction , rather than actual physical objects . but einstein used an ingenious argument , showing that the behavior of small particles randomly moving around in a liquid , known as brownian motion , could be precisely predicted by the collisions of millions of invisible atoms . experiments soon confirmed einstein 's model , and atomic skeptics threw in the towel . the third paper came in june . for a long time , einstein had been troubled by an inconsistency between two fundamental principles of physics . the well established principle of relativity , going all the way back to galileo , stated that absolute motion could not be defined . yet electromagnetic theory , also well established , asserted that absolute motion did exist . the discrepancy , and his inability to resolve it , left einstein in what he described as a state of psychic tension . but one day in may , after he had mulled over the puzzle with his friend michele besso , the clouds parted . einstein realized that the contradiction could be resolved if it was the speed of light that remained constant , regardless of reference frame , while both time and space were relative to the observer . it took einstein only a few weeks to work out the details and formulate what came to be known as special relativity . the theory not only shattered our previous understanding of reality but would also pave the way for technologies , ranging from particle accelerators , to the global positioning system . one might think that this was enough , but in september , a fourth paper arrived as a `` by the way '' follow-up to the special relativity paper . einstein had thought a little bit more about his theory , and realized it also implied that mass and energy , one apparently solid and the other supposedly ethereal , were actually equivalent . and their relationship could be expressed in what was to become the most famous and consequential equation in history : e=mc^2 . einstein would not become a world famous icon for nearly another fifteen years . it was only after his later general theory of relativity was confirmed in 1919 by measuring the bending of starlight during a solar eclipse that the press would turn him into a celebrity . but even if he had disappeared back into the patent office and accomplished nothing else after 1905 , those four papers of his miracle year would have remained the gold standard of startling unexpected genius .

though certain theories were built on the idea of invisible atoms , some prominent scientists still believed them to be a useful fiction , rather than actual physical objects . but einstein used an ingenious argument , showing that the behavior of small particles randomly moving around in a liquid , known as brownian motion , could be precisely predicted by the collisions of millions of invisible atoms . experiments soon confirmed einstein 's model , and atomic skeptics threw in the towel .

einstein 's second `` miracle year '' paper , in may 1905 , showed that _____ could explain the so-called `` brownian motion '' behavior of small particles randomly moving around in a liquid .

the dead coming back to life sounds scary . but for scientists , it can be a wonderful opportunity . of course , we 're not talking about zombies . rather , this particular opportunity came in the unlikely form of large , slow-moving fish called the coelacanth . this oddity dates back 360 million years , and was believed to have died out during the same mass extinction event that wiped out the dinosaurs 65 million years ago . to biologists and paleontologists , this creature was a very old and fascinating but entirely extinct fish , forever fossilized . that is , until 1938 when marjorie courtenay-latimer , a curator at a south african museum , came across a prehistoric looking , gleaming blue fish hauled up at the nearby docks . she had a hunch that this strange , 1.5 meter long specimen was important but could n't preserve it in time to be studied and had it taxidermied . when she finally was able to reach j.l.b . smith , a local fish expert , he was able to confirm , at first site , that the creature was indeed a coelacanth . but it was another 14 years before a live specimen was found in the comoros islands , allowing scientists to closely study a creature that had barely evolved in 300 million years . a living fossil . decades later , a second species was found near indonesia . the survival of creatures thought extinct for so long proved to be one of the biggest discoveries of the century . but the fact that the coelacanth came back from the dead is n't all that makes this fish so astounding . even more intriguing is the fact that genetically and morphologically , the coelacanth has more in common with four-limbed vertebrates than almost any other fish , and its smaller genome is ideal for study . this makes the coelacanth a powerful link between aquatic and land vertebrates , a living record of their transition from water to land millions of years ago . the secret to this transition is in the fins . while the majority of ocean fish fall into the category of ray-finned fishes , coelacanths are part of a much smaller , evolutionarily distinct group with thicker fins known as lobe-finned fish . six of the coelacanth 's fins contain bones organized much like our limbs , with one bone connecting the fin to the body , another two connecting the bone to the tip of the fin , and several small , finger-like bones at the tip . not only are those fins structured in pairs to move in a synchronized way , the coelacanth even shares the same genetic sequence that promotes limb development in land vertebrates . so although the coelacanth itself is n't a land-walker , its fins do resemble those of its close relatives who first hauled their bodies onto land with the help of these sturdy , flexible appendages , acting as an evolutionary bridge to the land lovers that followed . so that 's how this prehistoric fish helps explain the evolutionary movement of vertebrates from water to land . over millions of years , that transition led to the spread of all four-limbed animals , called tetrapods , like amphibians , birds , and even the mammals that are our ancestors . there 's even another powerful clue in that unlike most fish , coelacanths do n't lay eggs , instead giving birth to live , young pups , just like mammals . and this prehistoric fish will continue to provide us with fascinating information about the migration of vertebrates out of the ocean over 300 million years ago . a journey that ultimately drove our own evolution , survival and existence . today the coelacanth remains the symbol of the wondrous mysteries that remain to be uncovered by science . with so much left to learn about this fish , the ocean depths and evolution itself , who knows what other well-kept secrets our future discoveries may bring to life !

so although the coelacanth itself is n't a land-walker , its fins do resemble those of its close relatives who first hauled their bodies onto land with the help of these sturdy , flexible appendages , acting as an evolutionary bridge to the land lovers that followed . so that 's how this prehistoric fish helps explain the evolutionary movement of vertebrates from water to land . over millions of years , that transition led to the spread of all four-limbed animals , called tetrapods , like amphibians , birds , and even the mammals that are our ancestors .

what other animals represent a significant link to our evolutionary past ? briefly explain the link of at least two other animals .

it starts with a tickle in your throat that becomes a cough . your muscles begin to ache , you grow irritable , and you lose your appetite . it 's official : you 've got the flu . it 's logical to assume that this miserable medley of symptoms is the result of the infection coursing through your body , but is that really the case ? what 's actually making you feel sick ? what if your body itself was driving this vicious onslaught ? you first get ill when a pathogen like the flu virus gets into your system , infecting and killing your cells . but this unwelcome intrusion has another effect : it alerts your body 's immune system to your plight . as soon as it becomes aware of infection , your body leaps to your defense . cells called macrophages charge in as the first line of attack , searching for and destroying the viruses and infected cells . afterwards , the macrophages release protein molecules called cytokines whose job is to recruit and organize more virus-busting cells from your immune system . if this coordinated effort is strong enough , it 'll wipe out the infection before you even notice it . but that 's just your body setting the scene for some real action . in some cases , viruses spread further , even into the blood and vital organs . to avoid this sometimes dangerous fate , your immune system must launch a stronger attack , coordinating its activity with the brain . that 's where those unpleasant symptoms come in , starting with the surging temperature , aches and pains , and sleepiness . so why do we experience this ? when the immune system is under serious attack , it secretes more cytokines , which trigger two responses . first , the vagus nerve , which runs through the body into the brain , quickly transmits the information to the brain stem , passing near an important area of pain processing . second , cytokines travel through the body to the hypothalamus , the part of the brain responsible for controlling temperature , thirst , hunger , and sleep , among other things . when it receives this message , the hypothalamus produces another molecule called prostaglandin e2 , which gears it up for war . the hypothalamus sends signals that instruct your muscles to contract and causes a rise in body temperature . it also makes you sleepy , and you lose your appetite and thirst . but what 's the point of all of these unpleasant symptoms ? well , we 're not yet sure , but some theorize that they aid in recovery . the rise in temperature can slow bacteria and help your immune system destroy pathogens . sleep lets your body channel more energy towards fighting infection . when you stop eating , your liver can take up much of the iron in your blood , and since iron is essential for bacterial survival , that effectively starves them . your reduced thirst makes you mildly dehydrated , diminishing transmission through sneezes , coughs , vomit , or diarrhea . though it 's worth noting that if you do n't drink enough water , that dehydration can become dangerous . even the body 's aches make you more sensitive , drawing attention to infected cuts that might be worsening , or even causing your condition . in addition to physical symptoms , sickness can also make you irritable , sad , and confused . that 's because cytokines and prostaglandin can reach even higher structures in your brain , disrupting the activity of neurotransmitters , like glutamate , endorphins , serotonin , and dopamine . this affects areas like the limbic system , which oversees emotions , and your cerebral cortex , which is involved in reasoning . so it 's actually the body 's own immune response that causes much of the discomfort you feel every time you get ill . unfortunately , it does n't always work perfectly . most notably , millions of people worldwide suffer from autoimmune diseases , in which the immune system treats normal bodily cues as threats , so the body attacks itself . but for the majority of the human race , millions of years of evolution have fine-tuned the immune system so that it works for , rather than against us . the symptoms of our illnesses are annoying , but collectively , they signify an ancient process that will continue barricading our bodies against the outside world for centuries to come .

in some cases , viruses spread further , even into the blood and vital organs . to avoid this sometimes dangerous fate , your immune system must launch a stronger attack , coordinating its activity with the brain . that 's where those unpleasant symptoms come in , starting with the surging temperature , aches and pains , and sleepiness .

one of the first sites for the relay of immune-brain communication is the :

far beneath the palace of the treacherous king minos , in the damp darkness of an inescapable labryinth , a horrific beast stalks the endless corridors of its prison , enraged with a bloodlust so intense that its deafening roar shakes the earth . it is easy to see why the minotaur myth has a long history of being disregarded as pure fiction . however , there 's a good chance that the minotaur and other monsters and gods were created by our early ancestors to rationalize the terrifying things that they saw in the natural world but did not understand . and while we ca n't explain every aspect of their stories , there may be some actual science that reveals itself when we dissect them for clues . so , as far as we know , there have never been human-bull hybrids . but the earliest material written about the minotaur does n't even mention its physical form . so that 's probably not the key part of the story . what the different tellings do agree upon , however , is that the beast lives underground , and when it bellows , it causes tremendous problems . the various myths are also specific in stating that genius inventor daedalus , carved out the labyrinth beneath the island of crete . archeological attempts to find the fabled maze have come up empty handed . but crete itself has yielded the most valuable clue of all in the form of seismic activity . crete sits on a piece of continental crust called the aegean block , and has a bit of oceanic crust known as the nubian block sliding right beneath it . this sort of geologic feature , called a subduction zone , is common all over the world and results in lots of earthquakes . however , in crete the situation is particularly volatile as the nubian block is attached to the massive buoyant continental crust that is africa . when the nubian block moves , it does not go down nearly as easily or as steeply as oceanic crust does in most other subduction zones . instead , it violently and abruptly forces sections of the mediterranean upwards in an event called uplift , and crete is in uplift central . in the year 2014 , crete had more than 1300 earthquakes of magnitude 2.0 or higher . by comparison , in the same period of time , southern california , a much larger area , experienced a mere 255 earthquakes . of course , we do n't have detailed seismic records from the days of king minos , but we do know from fossil records and geologic evidence that crete has experienced serious uplift events that sometimes exceeded 30 feet in a single moment . contrast this for a moment with the island of hawaii , where earthquakes and volcanic activity were tightly woven to legends surrounding pele , a goddess both fiery and fair . like the minotaur , her myths included tales of destruction , but they also contained elements of dance and creation . so why did hawaii end up with pele and crete end up with the minotaur ? the difference likely comes down to the lava that followed many of hawaii 's worst earthquakes . the lava on hawaii is made of basalt , which once cooled , is highly fertile . within a couple of decades of terrible eruptions , islanders would have seen vibrant green life thriving on new peninsulas made of lava . so it makes sense that the mythology captured this by portraying pele as creator as well as a destroyer . as for the people of crete , their earthquakes brought only destruction and barren lands , so perhaps for them the unnatural and deadly minotaur was born . the connections between mythical stories and the geology of the regions where they originated teach us that mythology and science are actually two sides of the same coin . both are rooted in explaining and understanding the world . the key difference is that where mythology uses gods , monsters and magic , science uses measurements , records and experiments .

the connections between mythical stories and the geology of the regions where they originated teach us that mythology and science are actually two sides of the same coin . both are rooted in explaining and understanding the world . the key difference is that where mythology uses gods , monsters and magic , science uses measurements , records and experiments .

describe how the practice of creating myths is similar to the practice of studying the natural world in a scientific manner .

have you ever seen a big , red `` no running '' sign at a public pool ? for the most part , the pace on the deck reflects this statement . but while the sign accurately describes the patrons ' movements , is n't it true that people are walking because the sign tells them no running ? so , is this sign portraying the pool 's environment , or is it doing something else , something more powerful ? the difference between a statement that describes and one that commands is an idea developed by british linguist j. l. austin . he defines this distinction as two separate parts of speech : constatives and performatives . constatives are sentences that describe something as true or false , and performatives are sentences that denote an action . in other words , a constative is , and a performative does . to help us distinguish these two parts of speech , let 's start by examining constatives around the park outside the pool . the first sign we encounter says , `` the park closes at 6 p.m. '' after checking with a friendly park official that the park does , indeed , close at 6 , we can confirm that this statement is a true constative . nearby , there 's a man on a bench with a newspaper , and the headline reads , `` heatwave ! '' however , the sky is cloudy and it feels quite chilly . today 's headline is a false constative as it has proven to be incorrect . before the rain starts to fall , let 's throw away our can of soda at the blue trash bin that says , `` recycle . '' it 's a performative . performatives are sentences that are meant to inspire actions . rather than conveying a message , it acts upon the world , it does something . in this case , the performative of `` recycle '' is requesting people to put their trash into the proper receptacle . words not only bring about actions , sometimes words themselves are actions . this is what is known as speech acts . these actions include , but are not limited to , ordering , promising , apologizing , warning , sentencing , christening , and even marrying . take a look at the wedding near the gazebo . the couple says the words , `` i do . '' the speech act here are the words , `` i do . '' these words cause them to marry one another . `` i do '' has acted upon them and profoundly changed their world . however , performatives depend on context and reception . these are known as felicity conditions . imagine if the mayor showed up to the wedding and said , `` by the power vested in me as mayor of the city , i name this gazebo 'the mayor 's pizza palace . ' '' his words would be a speech act by which he named the gazebo . and because he 's the mayor , the gazebo would be known by its new name . but if someone who is n't the mayor , just a normal passerby , decides to name the gazebo after her favorite cat , the chances are the name would not change . felicity conditions are the rules under which the performative can be enacted . these are fairly logical . the performative should have proper authority , it should be understood , it should be clear , and it should be able to be executed . if the performative does n't meet these conditions , then it does n't have the power to denote action . but just because a performative meets its conditions and is clearly stated , does n't mean that it 's implicitly followed . back at the pool , a rowdy group of teenagers races to the high dive . `` no running '' does not seem to have power over them , and they 'll have to face the consequences of breaking this performative . they may even have to force out some performatives of their own , such as apologizing to the life guard and promising to never run again . maybe the life guard will respond with another performative , sentencing them to be banished from the pool for the rest of the day . after all , these teenagers must learn to respect the power of words .

they may even have to force out some performatives of their own , such as apologizing to the life guard and promising to never run again . maybe the life guard will respond with another performative , sentencing them to be banished from the pool for the rest of the day . after all , these teenagers must learn to respect the power of words .

describe a time when you disregarded a performative that resulted in another performative ( for example , you ignored the no running sign and were banished from the pool for the rest of the day ) .

in 1898 , marie and pierre curie discovered radium . claimed to have restorative properties , radium was added to toothpaste , medicine , water , and food . a glowing , luminous green , it was also used in beauty products and jewelry . it was n't until the mid-20th century we realized that radium 's harmful effects as a radioactive element outweighed its visual benefits . unfortunately , radium is n't the only pigment that historically seemed harmless or useful but turned out to be deadly . that lamentable distinction includes a trio of colors and pigments that we 've long used to decorate ourselves and the things we make : white , green , and orange . our story begins with white . as far back as the 4th century bce , the ancient greeks treated lead to make the brilliant white pigment we know today . the problem ? in humans , lead is directly absorbed into the body and distributed to the blood , soft tissues , and mineralized tissues . once in the nervous system , lead mimics and disrupts the normal functions of calcium , causing damages ranging from learning disabilities to high blood pressure . yet the practice of using this toxic pigment continued across time and cultures . lead white was the only practical choice for white oil or tempera paint until the 19th century . to make their paint , artists would grind a block of lead into powder , exposing highly toxic dust particles . the pigment 's liberal use resulted in what was known as painter 's colic , or what we 'd now call lead poisoning . artists who worked with lead complained of palseys , melancholy , coughing , enlarged retinas , and even blindness . but lead white 's density , opacity , and warm tone were irresistible to artists like vermeer , and later , the impressionists . its glow could n't be matched , and the pigment continued to be widely used until it was banned in the 1970s . as bad as all that sounds , white 's dangerous effects pale in comparison to another , more wide-spread pigment , green . two synthetic greens called scheele 's green and paris green were first introduced in the 18th century . they were far more vibrant and flashy than the relatively dull greens made from natural pigments , so they quickly became popular choices for paint as well as dye for textiles , wallpaper , soaps , cake decorations , toys , candy , and clothing . these green pigments were made from a compound called cupric hydrogen arsenic . in humans , exposure to arsenic can damage the way cells communicate and function . and high levels of arsenic have been directly linked to cancer and heart disease . as a result , 18th century fabric factory workers were often poisoned , and women in green dresses reportedly collapsed from exposure to arsenic on their skin . bed bugs were rumored not to live in green rooms , and it 's even been speculated that napoleon died from slow arsenic poisoning from sleeping in his green wallpapered bedroom . the intense toxicity of these green stayed under wraps until the arsenic recipe was published in 1822 . and a century later , it was repurposed as an insecticide . synthetic green was probably the most dangerous color in widespread use , but at least it did n't share radium 's property of radioactivity . another color did , though - orange . before world war ii , it was common for manufacturers of ceramic dinnerware to use uranium oxide in colored glazes . the compound produced brilliant reds and oranges , which were appealing attributes , if not for the radiation they emitted . of course , radiation was something we were unaware of until the late 1800s , let alone the associated cancer risks , which we discovered much later . during world war ii , the u.s. government confiscated all uranium for use in bomb development . however , the atomic energy commission relaxed these restrictions in 1959 , and depleted uranium returned to ceramics and glass factory floors . orange dishes made during the next decade may still have some hazardous qualities on their surfaces to this day . most notably , vintage fiestaware reads positive for radioactivity . and while the levels are low enough that they do n't officially pose a health risk if they 're on a shelf , the u.s. epa warns against eating food off of them . though we still occasionally run into issues with synthetic food dyes , our scientific understanding has helped us prune hazardous colors out of our lives .

in 1898 , marie and pierre curie discovered radium . claimed to have restorative properties , radium was added to toothpaste , medicine , water , and food . a glowing , luminous green , it was also used in beauty products and jewelry .

when first discovered , radium was added to toothpaste , medicine , beauty products , jewelry , water , and food because of claimed ____________ and its _____________ .

hey , vsauce . michael here . the earth is spinning and we are spinning along with it . but what if the earth suddenly stopped spinning ? well , first of all , you would gain weight . but that would be the least of your worries . the spin of our planet is important and literally giving you the time of your life . at the equator , the surface of earth , and everything on it , is spinning around at 465 meters per second . as you move closer to the poles you do n't have to move as quickly to complete earths daily rotation . here in san francisco , the earth is driving me east at 368 meters per second . if i could float above the surface independent of the earth 's rotation , the earth would spin underneath me this quickly . pretty cool . but , of course , when i jump straight up into the air , the earth does n't move underneath me because i continued to spin with it . we are all spinning with the earth and that is why slamming on a set of magical planetary breaks that caused everything classically called earth to stop spinning would be catastrophic . immediately everything that was n't earth , and was n't safely at the poles , would continue moving , as it had been , and be flung due east at more than a thousand miles an hour . you would n't be flung into space because escape velocity is 24,800 mph but your body would instantly become a 9.5 inch caliber bullet . well , really more of a supersonic tumbleweed . because the atmosphere would more gradually slow down , people in airplanes , assuming they could navigate the resulting storms , might have a better chance of surviving . astronauts aboard the iss would fare even better . but it is unlikely that anyone would be waiting for them down on the ground . runways would just be entrances to the new planet-sized graveyard , created by the no longer spinning earth . people really really near the poles might be okay but only at first . gusts of wind , as fast as those near an atomic bomb detonation , would blast , pass the surface and up into the sky forming worldwide storms of unprecedented magnitude . the friction alone , caused by the now stopped earth colliding with these winds , would be enough to cause massive fires , unparalleled erosion and damage to anything strong enough to stay put after the initial braking . the sun would seem to freeze in the sky as days became not 24 hours long but 365 days long . without spinning innards , earth 's protective magnetic field would cease to exist and we would be dosed with deadly amounts of ionising radiation from the sun . the oceans would surge onto land in tsunamis kilometers high and wash over nearly all dry land , before migrating to the poles , where gravity is stronger , no longer held to the ocean basins by the inertia earth 's spin gave them , until earth itself , no longer bulging an extra 42 kilometers around its equator , because of its rotation slowly compressed into a more perfect sphere than it is now . possibly allowing the oceans to eventually return somewhat . that is what would occur if it actually happened . it wo n't actually happen but woah , its rotation is slowing down . more on that later . first , if the earth really is spinning so quickly , why ca n't we feel it ? why does n't the earth 's rotation make us dizzy ? well , lucky for us , the change in velocity is just too gradual . the earth is too huge . it 's like driving in a car that takes 6 hours and six thousand miles to make one left turn . it 's not sudden enough to register with our senses . but that change in velocity is real and it makes us way less , because of inertia . on our spinning planet your velocity is constantly changing but always tangential to the circular path you were being dragged along . now , because inertia is a property of matter , which includes your body , without a force acting upon us we would slowly leave the surface of earth . luckily , the earth is exerting a force on us . a center-seeking , centripetal force , delivered by gravity . the centripetal force required to keep you along a circular path with earth is subtracted from earth 's total gravitational pull on you . the remaining force simply pushes you down , toward the centre of the earth - it gives you weight . at the equator , if the earth did n't spin , and no centripetal force was required to keep you with the earth , you would weigh 0.3 percent more than you currently do . if earth spun you around 17 times faster than it currently does , all of its gravitational force would go toward centripetal force fighting against your inertia and you would be weightless . so here 's a diet idea . hope that the earth starts spinning faster and go back for guilt-free seconds . seconds . we know exactly how long a second is . the outermost electron of an atom of cesium 133 is alone . when the atom is undisturbed , only the nucleus interacts with this outermost electron , tickling it regularly and rapidly between two levels . after 9,192,631,770 oscillations between those two levels , one second has passed . exactly . that is literally the definition of a second . we can measure and count those oscillations . it 's how atomic clocks work . making atomic clocks , the most accurate measurement device ever built by humans , to measure anything . we ca n't define a second more simply , as say , 1/60th of 1/60th of 1/24th of a day because of earth 's spin . it 's too irregular . little changes in the distribution of mass on earth , caused by earthquakes or melting ice or man-made dams or technically even you walking up stairs or downstairs , cause earth 's rotational speed to change . like a figure skater moving their arms further away from or closer to their bodies . now add on top of that the fact that tides , caused by the moon , drag against earth 's rotation and you wind up with an unstable rotation speed that is predominately slowing down . now , these changes are incredibly incredibly slight , but over time they add up . in 140 million years , a day on earth will not be 24 hours long , it will be 25 . that might not sound like much but in order to do important things , like deliver accurate gps information , we need a more accurate timekeeping device than that . so , as a solution scientists keep the pace of seconds using atomic clocks , tai time . and other scientists measure the changing speed of earth 's rotation by observing distant stars and quasars . now , every few months they find out just how behind or ahead earth is running , and if it 's getting too close to being a second off , they decide to add or subtract the second from the current year . the result is the time used almost everywhere , including your phone : utc . since this system began in 1972 25 leap seconds have been added . what this means is that clock time is , and has to be , a manufactured product with upgrades and tune ups administered periodically , after defects are noticed . the time we give to now and the future is only ever approximate . that 's weird but it 's also entirely not weird . as demetrios matsakis , the chief scientist of time services for the us naval observatory puts it , `` we save lives and we end lives . we add time and we can take time away , but in both cases we do so without completely understanding exactly what life is , or what time is . '' regardless , thank you for spending some of yours with me ... and as always , thanks for watching .

we can measure and count those oscillations . it 's how atomic clocks work . making atomic clocks , the most accurate measurement device ever built by humans , to measure anything .

why are atomic clocks the most precise way of telling time ?

translator : andrea mcdonough reviewer : bedirhan cinar my name is tom chi . i spent two years of my life building the user experience team for the google x division of google , and it 's a place i affectionately call the department of science fiction because of the futuristic nature of the types of projects we took on : self-driving cars , google glass , and other things that you 'll see soon enough . so , for those who have n't heard of this project , this is what google glass looks like . it allows you to overlay digital things into your eye sight while still maintaining being part of the world . so , if i , you know , were to pull out my cell phone and look into it , i 'm basically out of this world now , like , i 'm in my own little cell phone-tablet world , what have you . but , google glass has the vision of allowing us to continue to be in the world but also have access to the digital things that we need and love . now , i am going to ask you a real simple question about google glass : how would you prototype this experience ? how long do you think it would take you to make the first working version of the headset display ? okay , a little bit on the long side . the answer is one day . and here 's what it looked like . so , basically the magic piece is the coat hanger . the coat hanger , i bent it in a specific shape and the top loop goes around your neck and then the bottom loop rests against your chest and it allows me to carry a piece of plexiglass on with a little sheet protector . so these are the things you put your book reports in so they do n't get wet , i literally got at the drug store . you know , have it out at the end of the plexiglass and then it gets projected onto with the pico projector that 's connected to a netbook . and using this set-up , within one day we 're already able to start having the experience of what it looks like to have digital things overlaid on your physical world , be able to move around with it , and also use the netbook to try out tons and tons of different ideas around software . now , after you start getting something like that working , you know , a really important problem comes up , like you 're wearing this thing on your head , it 's like a pair of glasses , so you do n't have a mouse or a keyboard or a touchscreen , all the ways you are used to interacting with a machine . so , we thought for a second , well , maybe we could do something like , you know , what was shown in < i > minority report < /i > . so , for folks who have n't seen that , basically tom cruise is manipulating software with his hands in front of his face and photos are flying over here and his email is over here and so on and so forth . so i 'll ask the the same question again , how long do you think it would take to have the real experience of doing something like that ? two years , ok. somebody said one day . 45 minutes . so here 's how it looks . so you wear the thing that we saw that first time because you need some way to go project things , but what happens is we got two hairbands , which i think was the hardest part we had to do , ask people for their hairbands . but you put one hand in each hairband and attach that hairband , we tied a fishing line . and the fishing line goes over the top of a whiteboard and then goes down to this little assembly that 's taped to the floor . and what this means is every time i move my hand in any direction , it adds tension to the line and it does the following with the assembly on the floor . so , the other end of the fishing wire is attached to a chopstick and it 's not because i 'm asian , there 's just a cafeteria nearby , i do n't just carry chopsticks on me . but , i tied it to the end of a chopstick , i clipped it into a binder clip , and then put it over a pen , and basically what happens then is when you move your arm and it produces tension on the wire , the chopstick comes down like a lever and clicks a presentation clicker , one hand moves the presentation forward , the other hand moves the presentation backwards . so this was built in 45 minutes and that meant shortly afterwards , we were having experiences like looking at an image gallery and saying , `` next image , next image , previous image , '' or looking at our emails and saying , `` let me click into this email , let me click reply now . '' and this was exactly the experience of what it was like to go control software with your hands . and ultimately , what it taught us is we probably should n't have this in the product . we learned a lot of things about the social awkwardness of it and some of the ergonomic aspects of it that you could n't have figured out ahead of just thinking about it . and , ergo the second prototyping rule , which is `` doing is the best kind of thinking . '' they teach you to think a lot in school , but i think it is a little bit overrated . now last example , you know , actually google is not the first team that 's tried to go make something like this and if you search for headset display , you get tons of images of teams that have built various systems like this , but i can tell you at a glance that none of these pieces of hardware are comfortable to wear for more than 15 minutes except for maybe the helmet over there , but then you got to wear a helmet . so , you know , how would you go figure out a way to go wear something like this comfortably ? the answer is really basic materials : modeling wire , paper , clay , and using something like this is able to make something look like a pair of glasses really quickly . i cut out pieces of clay that weighed exactly the same amount as the electronic components that we were talking about putting on the device , wrapped it in paper so you did n't get clay on your face , and then taped it to the modeling wire in various places to go experiment with how a pair of glasses could fit on you . and , we discovered something really important then . like , if you look at this drawing on the bottom , it turns out that the weight of a pair of glasses is actually mostly perceived through how much weight is on your nose . and , it also turns out that your ears can carry a lot more weight than your nose , and that is a totally different experiment , you can ask me about that . but , because of that fact , if you put weight behind your ears , it allows your ear to go act like the fulcrum of a lever and it then takes weight off of your nose on the front . and , actually , you can try this now , anybody with glasses , if you push very gently on the back of your glasses , you 'll find , actually your glasses feel tremendously lighter . now , this meant that we not only discovered something interesting about how to go , you know , that 's useful for developing a device like this , we actually discovered something pretty fundamental that never been discovered about glasses , period . so , if you have really heavy glasses , you could do this and you would be more comfortable . now , the last point i want to make is about two types of learning because through the process of rapid prototyping , you are able to learn very quickly . it 's a very specific type of learning . the type of learning that you usually learn in school i call book learning . it comes from what humanity already knows and it 's a necessary foundation for you guys to go and explore the world . but there is a totally different type of learning , which i call expansive learning , and this is the learning you do on behalf of humanity . right ? you are creating something new , you are expanding into the possibilities , and you 're building the sphere of human knowledge in that process . and , we think about these things and as soon as you hear like , ok , the infinite realm of possibilities beyond the sphere of human knowledge , you might be thinking there 's the scientists at the large hadron collider who have these amazing instruments , like that 's their job , right ? but the truth is that this action is available to all of us , you know , it 's not just for the scientists , it 's also for the poet or the songwriter that expresses an emotion for the first time in a unique way . it 's also for the person that has an amazing business idea that they 're certain could help millions of lives . and , it 's the realm of using paper , clay , and tape in order to go find a new insight in an ancient technology . so now that you know a lot about rapid prototyping , i 'm excited to see what you do with it . thank you .

and this was exactly the experience of what it was like to go control software with your hands . and ultimately , what it taught us is we probably should n't have this in the product . we learned a lot of things about the social awkwardness of it and some of the ergonomic aspects of it that you could n't have figured out ahead of just thinking about it .

describe a product that you can prototype . what is it 's purpose and why do we need it ?

today lots of girls play sports . but , for a long time , girls were not encouraged to kick , throw , run , jump , shoot , slide , or hit like boys . so , why did things change ? and how much have they changed ? are girls and boys treated equally when it comes to sports ? to begin to answer these questions , we have to look back . in 1972 , congress passed a law called title ix , which protected girls and women from discrimination in schools , colleges , and universities . this included discrimination in school-sponsored sports . at that time , only 15 % of college athletes were women , and in high schools , only 7 % of athletes were girls . female athletes did n't get a lot of support either and often had to provide their own uniforms and equipment . it was title ix that forced school administrators to make sports more equal . but what does equal mean in sports ? the government developed rules to measure equality under two general categories : participation and treatment . in the early days of title ix , the number of girls playing sports was so low that it would have been very difficult for schools to suddenly provide exactly the same number of opportunities for girls and boys . instead , the government wrote rules that gave schools three options , or tests , to demonstrate fairness in opportunities for girls . the three tests are proportionality , progress , and satisfied interests . a school can pick which test to follow . proportionality means that girls should receive the same percentage of athletic opportunities as the percentage of girls in the student body . so , if 51 % of students are girls , then girls should have approximately 51 % of the opportunities to play sports . the second test , progress , requires schools to make up for the days when girls had fewer opportunities by adding new sports for girls on a regular basis . the third test asks if girls interested in athletics are satisfied . under this test , a school must regularly ask female students what sports they are interested in and also take into consideration the popularity of certain sports in the area where the school is located . it must , then , add teams according to the girls ' interests . another important part of title ix is that it does n't just look at how many athletic opportunities are available to each sex but whether those opportunities are of equal quality . specifically , title ix requires equality between boys and girls teams for things like equipment and supplies , publicity , the scheduling of games and practice times , and the quality and number of coaches . girls should also have equal access to locker rooms , practice spaces , and competitive facilities , as well as medical services . so , if the best time to play basketball is on friday nights because that 's when most parents and fans can come , then the girls and boys teams should take turns playing on friday night . if boys teams play in a stadium with lights , scoreboards , and concession stands , then girls teams must have the same opportunity , either by sharing those facilities or getting their own of equal quality . but , as we all know , just because a law exists does n't mean that everybody follows it . school officials are responsible for making sure there is fairness in sports , but you can help , too , by keeping an eye on your own school . look around . are there a lot more boys than girls who play sports ? is the boys ' soccer field better than the girls ' ? are athletic trainers available to all teams equally ? does the baseball team get new uniforms every year , while the softball team gets them every three years ? if you think there might be inequality in your schools , you can approach a school administrator , a parent , or the office of civil rights , a government agency that makes sure schools comply with title ix because equality is important for everyone , both on the field and off .

female athletes did n't get a lot of support either and often had to provide their own uniforms and equipment . it was title ix that forced school administrators to make sports more equal . but what does equal mean in sports ?

which government agency is responsible for responding to title ix complaints ?

if i say , `` venice , '' do you imagine yourself gliding down the grand canal , serenaded by a gondolier ? there 's no doubt that the gondola is a symbol of venice , italy , but how did this curious banana-shaped black boat get its distinctive look ? the origins of the venetian gondola are lost to history , but by the 1500s , some 10,000 gondolas transported dignitaries , merchants and goods through the city 's canals . in fact , venice teemed with many types of handmade boats , from utilitarian rafts to the doge 's own ostentatious gilded barge . like a modern day taxi system , gondolas were leased to boatmen who made the rounds of the city 's ferry stations . passengers paid a fare to be carried from one side of the grand canal to the other , as well as to other points around the city . but gondoliers soon developed a bad rap . historical documents describe numerous infractions involving boatmen , including cursing , gambling , extorting passengers -- even occasional acts of violence . to minimize the unpredictability of canal travel , venetian citizens who could afford it purchased their own gondolas , just as a celebirty might use a private car and driver today . these wealthy venetians hired two private gondoliers to ferry them around the city and maintain their boats . the gondolas soon became a status symbol , much like an expensive car , with custom fittings , carved and gilded ornamentation , and seasonal fabrics , like silk and velvet . however , the majority of gondolas seen today are black because in 1562 , venetian authorities decreed that all but ceremonial gondolas be painted black in order to avoid sinfully extravagant displays . apparently , venetian authorities did not believe in `` pimping their rides . '' still , some wealthy venetians chose to pay the fines in order to maintain their ornamental gondolas , a small price to keep up appearances . the distinctive look of the gondola developed over many centuries . each gondola was constructed in a family boatyard called a squero . > from their fathers and grandfathers , sons learned how to select and season pieces of beech , cherry , elm , fir , larch , lime , mahogany , oak and walnut . the gondola makers began with a wooden template that may have been hammered into the workshop floor generations earlier . > from this basic form , they attached fore and aft sterns , then formed the longitudinal planks and ribs that made up the frame of a boat designed to glide through shallow , narrow canals . a gondola has no straight lines or edges . its familiar profile was achieved through an impressive fire and water process that involved warping the boards with torches made of marsh reeds set ablaze . however , the majority of the 500 hours that went into building a gondola involved the final stages : preparing surfaces and applying successive coats of waterproof varnish . the varnish was a family recipe , as closely guarded as one for risotto or a homemade sauce . yet even with the woodwork finished , the gondola was still not complete . specialized artisans supplied their gondola-making colleagues with elaborate covered passenger compartments , upholstery and ornaments of steel and brass . oar makers became integral partners to the gondola makers . the venetian oarlock , or fórcola , began as a simple wooden fork , but evolved into a high-precision tool that allowed a gondolier to guide the oar into many positions . by the late 1800s , gondola makers began to make the left side of the gondola wider than the right as a counter balance to the force created by a single gondolier . this modification allowed rowers to steer from the right side only , and without lifting the oar from the water . while these modifications improved gondola travel , they were not enough to keep pace with motorized boats . today , only about 400 gondolas glide through the waterways of venice , and each year , fewer authentic gondolas are turned out by hand . but along the alleys , street signs contain words in venetian dialect for the locations of old boatyards , oar makers and ferry stations , imprinting the memory of the boat-building trades that once kept life in the most serene republic gliding along at a steady clip .

passengers paid a fare to be carried from one side of the grand canal to the other , as well as to other points around the city . but gondoliers soon developed a bad rap . historical documents describe numerous infractions involving boatmen , including cursing , gambling , extorting passengers -- even occasional acts of violence .

oarlocks became more intricately carved over the centuries in order to allow gondoliers to have :

85 % of the matter in our universe is a mystery . we do n't know what it 's made of , which is why we call it dark matter . but we know it 's out there because we can observe its gravitational attraction on galaxies and other celestial objects . we 've yet to directly observe dark matter , but scientists theorize that we may actually be able to create it in the most powerful particle collider in the world . that 's the 27 kilometer-long large hadron collider , or lhc , in geneva , switzerland . so how would that work ? in the lhc , two proton beams move in opposite directions and are accelerated to near the speed of light . at four collision points , the beams cross and protons smash into each other . protons are made of much smaller components called quarks and gluons in most ordinary collisions , the two protons pass through each other without any significant outcome . however , in about one in a million collisions , two components hit each other so violently , that most of the collision energy is set free producing thousands of new particles . it 's only in these collisions that very massive particles , like the theorized dark matter , can be produced . the collision points are surrounded by detectors containing about 100 million sensors . like huge three-dimensional cameras , they gather information on those new particles , including their trajectory , electrical charge , and energy . once processed , the computers can depict a collision as an image . each line is the path of a different particle , and different types of particles are color-coded . data from the detectors allows scientists to determine what each of these particles is , things like photons and electrons . now , the detectors take snapshots of about a billion of these collisions per second to find signs of extremely rare massive particles . to add to the difficulty , the particles we 're looking for may be unstable and decay into more familiar particles before reaching the sensors . take , for example , the higgs boson , a long-theorized particle that was n't observed until 2012 . the odds of a given collision producing a higgs boson are about one in 10 billion , and it only lasts for a tiny fraction of a second before decaying . but scientists developed theoretical models to tell them what to look for . for the higgs , they thought it would sometimes decay into two photons . so they first examined only the high-energy events that included two photons . but there 's a problem here . there are innumerable particle interactions that can produce two random photons . so how do you separate out the higgs from everything else ? the answer is mass . the information gathered by the detectors allows the scientists to go a step back and determine the mass of whatever it was that produced two photons . they put that mass value into a graph and then repeat the process for all events with two photons . the vast majority of these events are just random photon observations , what scientists call background events . but when a higgs boson is produced and decays into two photons , the mass always comes out to be the same . therefore , the tell-tale sign of the higgs boson would be a little bump sitting on top of the background . it takes billions of observations before a bump like this can appear , and it 's only considered a meaningful result if that bump becomes significantly higher than the background . in the case of the higgs boson , the scientists at the lhc announced their groundbreaking result when there was only a one in 3 million chance this bump could have appeared by a statistical fluke . so back to the dark matter . if the lhc 's proton beams have enough energy to produce it , that 's probably an even rarer occurrence than the higgs boson . so it takes quadrillions of collisions combined with theoretical models to even start to look . that 's what the lhc is currently doing . by generating a mountain of data , we 're hoping to find more tiny bumps in graphs that will provide evidence for yet unknown particles , like dark matter . or maybe what we 'll find wo n't be dark matter , but something else that would reshape our understanding of how the universe works entirely . that 's part of the fun at this point . we have no idea what we 're going to find .

so back to the dark matter . if the lhc 's proton beams have enough energy to produce it , that 's probably an even rarer occurrence than the higgs boson . so it takes quadrillions of collisions combined with theoretical models to even start to look .

scientists at the lhc are analyzing the results of billions of proton-proton collisions . why is it not possible to identify the higgs boson by looking just at few proton-proton collision ?

in 479 bc , when persian soldiers besieged the greek city of potidaea , the tide retreated much farther than usual , leaving a convenient invasion route . but this was n't a stroke of luck . before they had crossed halfway , the water returned in a wave higher than anyone had ever seen , drowning the attackers . the potiidaeans believed they had been saved by the wrath of poseidon . but what really saved them was likely the same phenomenon that has destroyed countless others : a tsunami . although tsunamis are commonly known as tidal waves , they 're actually unrelated to the tidal activity caused by the gravitational forces of the sun and moon . in many ways , tsunamis are just larger versions of regular waves . they have a trough and a crest , and consist not of moving water , but the movement of energy through water . the difference is in where this energy comes from . for normal ocean waves , it comes from wind . because this only affects the surface , the waves are limited in size and speed . but tsunamis are caused by energy originating underwater , from a volcanic eruption , a submarine landslide , or most commonly , an earthquake on the ocean floor caused when the tectonic plates of the earth 's surface slip , releasing a massive amount of energy into the water . this energy travels up to the surface , displacing water and raising it above the normal sea level , but gravity pulls it back down , which makes the energy ripple outwards horizontally . thus , the tsunami is born , moving at over 500 miles per hour . when it 's far from shore , a tsunami can be barely detectable since it moves through the entire depth of the water . but when it reaches shallow water , something called wave shoaling occurs . because there is less water to move through , this still massive amount of energy is compressed . the wave 's speed slows down , while its height rises to as much as 100 feet . the word tsunami , japanese for `` harbor wave , '' comes from the fact that it only seems to appear near the coast . if the trough of a tsunami reaches shore first , the water will withdraw farther than normal before the wave hits , which can be misleadingly dangerous . a tsunami will not only drown people near the coast , but level buildings and trees for a mile inland or more , especially in low-lying areas . as if that were n't enough , the water then retreats , dragging with it the newly created debris , and anything , or anyone , unfortunate enough to be caught in its path . the 2004 indian ocean tsunami was one of the deadliest natural disasters in history , killing over 200,000 people throughout south asia . so how can we protect ourselves against this destructive force of nature ? people in some areas have attempted to stop tsunamis with sea walls , flood gates , and channels to divert the water . but these are not always effective . in 2011 , a tsunami surpassed the flood wall protecting japan 's fukushima power plant , causing a nuclear disaster in addition to claiming over 18,000 lives . many scientists and policy makers are instead focusing on early detection , monitoring underwater pressure and seismic activity , and establishing global communication networks for quickly distributing alerts . when nature is too powerful to stop , the safest course is to get out of its way .

this energy travels up to the surface , displacing water and raising it above the normal sea level , but gravity pulls it back down , which makes the energy ripple outwards horizontally . thus , the tsunami is born , moving at over 500 miles per hour . when it 's far from shore , a tsunami can be barely detectable since it moves through the entire depth of the water .

how high can a tsunami reach ?

do you have a friend or a sibling that 's always competing with you to see who 's the fastest ? our alien friends bleebop and mark are having the same debate with their custom-built rockets , and they 've asked us to be the judge of a space race to their moon . the only problem is that they are starting from different asteroids . bleebop is on an asteroid 240 miles from the moon , and mark is on one 150 miles away . do n't worry , it 's not rocket science . solving this equation is as simple as dirt . we can decide who the winner is using the d=rt formula , or dirt . this stands for distance equals rate times time . in the case of bleebop and mark , we will only know the distance they traveled and the time it took for them to get to the finish line . it 'll be up to us to find the rate and who is faster . let 's turn to the race now and see what information we get . three , two , one , blast off ! bleebop and mark 's rockets go zipping across the galaxy towards their moon , dodging clunky meteorites and loopy space buggies . after a few close calls with a wandering satellite , mark arrives first in two hours , and bleebop gets there one hour later . looks like mark has the faster rocket , but let 's check out the results with our dirt equation . begin by setting up a chart . make four columns and three rows . use dirt to remember what to fill in . each rocket will have information for distance , rate , and time . mark 's rocket went 150 miles , we do n't know the rate , and he got there in 2 hours . bleebop 's rocket went 240 miles , we do n't know the rate , and the time is 1 hour after mark , or 3 hours . because we do n't know mark or bleebop 's rate , that number is going to be a variable in each equation , which we 'll represent with x . we 'll solve the equation for the variable to find its value . mark finished first , so start with his rocket . remembering dirt , write down d=rt . 150 miles equals x times 2 hours . divide both sides by 2 hours . this will leave x isolated on the right side of the equation . 150 miles divided by 2 hours is 75 miles over 1 hour . mark 's rate is 75 miles per hour . that 's what mph means . it 's the amount of miles over one hour . still think mark is faster ? let 's set up the same equation for bleebop and see . d=rt 240 miles equals x times 3 hours . divide both sides by 3 hours . this will leave x isolated on the right side of the equation . 240 miles divided by 3 hours is 80 miles over 1 hour . bleebop 's rate is 80 miles per hour . wow , even though bleebop got there one hour later , it turns out he had the faster rocket . mark seems pretty upset , but with aliens , you can never really tell . thanks to dirt , you now know how to calculate distance , rate , and time . in what other situations can you use the distance formula ? you do n't even need to be watching a space race . as long as you know two pieces of information for the formula d=rt , you can calculate any moving vehicle or object . now , the next time you 're in a car , you can let your friends know exactly when you 'll be arriving , how fast you 're going , or the distance you 'll travel . it 's as simple as dirt .

we can decide who the winner is using the d=rt formula , or dirt . this stands for distance equals rate times time . in the case of bleebop and mark , we will only know the distance they traveled and the time it took for them to get to the finish line .

how do you solve for rate when you know the distance and the time ?

in 1879 , amateur archaeologist marcelino sanz de sautuola and his young daughter maria explored a dark cave in northern spain . when maria wondered off by herself , she made an amazing discovery . they were standing inside a site of ancient art , the walls and roofs decorated with prehistoric paintings and engravings , ranging from 19,000 to 35,000 years old . similar marks of our ancestors have been preserved in caves all over the world . the oldest we 've found were made up to 40,000 years ago . what do these images tell us about the ancient human mind and the lives of their creators ? these early artists mixed minerals , clay , charcoal , and ochre with spit or animal fat to create paint . they drew with their hands and tools , like pads of moss , twigs , bones , and hair . in many instances , their images follow the contours of the cave to create depth and shade . the most common depictions are of geometric shapes , followed by large mammals , like bison , horses , mammoths , deer , and boars . human figures appear rarely , as well as occasional hand prints . some have theorized that these artworks are the creation of hunters , or of holy men in trance-like states . and we 've found examples created by men , women , and even children . and why did they create this art ? perhaps they were documenting what they knew about the natural world , like modern scientists , or marking their tribal territory . maybe the images were the culmination of sacred hunting rituals or spiritual journeys . or could they be art for art 's sake , the sheer joy and fulfillment of creation ? as with many unsolved mysteries of the ancient world , we may never know for sure , barring the invention of a time machine , that is . but while the answers remain elusive , these images are our earliest proof of human communication , testifying to the human capacity for creativity thousands of years before writing . they are a distinct visual language that imagines the world outside the self , just like modern art forms , from graffiti and painting to animated virtual-reality caves .

in 1879 , amateur archaeologist marcelino sanz de sautuola and his young daughter maria explored a dark cave in northern spain . when maria wondered off by herself , she made an amazing discovery .

marcelino and maria sanz de sautola discovered cave painting :

in this short video , we 're going to show you how we used animation to make custom playing cards to do magical tricks in ted-ed 's lesson on synesthesia . synesthesia is a neurological condition in which two or more senses are paired together to create a completely new experience . for example , many synesthetes see letters and numbers in colors , even when they are printed in black . or they can taste certain words . for instance , jail tastes like bacon . because synesthesia generally involves the brain pairing up two or more senses , we paired up playing cards with unique , colorful , and visceral symbols . we then used an animation technique called stop motion to manipulate the cards in ways that would be otherwise physically impossible . and as the cards were flipping , shuffling , and sliding , we used a mixture of animation and reality to ensure that the symbols on the cards did their part to explain the nuances of synesthesia . this type of animation is very difficult to pull off without some planning first . a storyboard is a series of still images that basically serve as a road map for an animation from beginning to end . an animatic is a storyboard in motion . by making the animatic , we were able to review the digital motion for each shot , which allowed us to progressively work out timing , camera positioning , and , most importantly , any challenges we anticipated in the final animation process . how many hands do you need to shuffle a deck of cards ? here , we wanted to emphasize each nucleotide in the dna sequence and stop motion allows for more control . by shuffling between individual frames , we could ensure that each card had a controlled amount of screen time , in this case , three frames , and that the card 's placement was consistent . but sometimes four hands just is n't enough . we use this trick a lot in this lesson , all thanks to one secret ingredient : play-doh ! by molding the play-doh into different sized pyramids , the cards can be held in different positions , always keeping the pyramid big enough to support the card , but small enough to not be seen and to not cast its own revealing shadow . making an animated movie is like making a delicious layer cake . it 's up to the animators to create the many planes , or layers . the use of green screen enables us to shoot individual elements moving , and to later assemble those layers one on top of the other . using software , we key out the green color , both on the background and play-doh . layer the cards , add the hands , insert a background , and if you planned your ingredients carefully , everything should come together just right . so , grab some fishing wire , glue , masking tape , chopsticks , and whatever else you can find . we 'd love to see you make some of your own animated illusions .

it 's up to the animators to create the many planes , or layers . the use of green screen enables us to shoot individual elements moving , and to later assemble those layers one on top of the other . using software , we key out the green color , both on the background and play-doh . layer the cards , add the hands , insert a background , and if you planned your ingredients carefully , everything should come together just right .

what 's the wildest thing you would animate using a green screen ?

the naming of clouds on a cold december evening in 1802 , a nervous young man named luke howard stood before the assembled members of a london science club about to give a lecture that would change his life and go on to change humanity 's understanding of the skies . luke howard was a pharmacist by profession , but he was a meteorologist by inclination , having been obsessed by clouds and weather since childhood . as a school boy , he spent hours staring out of the classroom window , gazing at the passing clouds . like everyone else at the time , he had no idea how clouds formed , or how they stayed aloft . but he enjoyed observing their endless transformations . by his own admission , luke paid little attention to his lessons , but fortunately for the future of meteorology , he managed to pick up a good knowledge of latin . compared to the other natural sciences , meteorology , the study of weather , was a late developer , mainly because weather is elusive . you ca n't snap off a piece of rainbow or a section of cloud for convenient study . you can , of course , collect rain water in calibrated containers , but all you really end up with are buckets of water . understanding clouds required a different approach , which is where luke howard 's idea came in . his simple insight based on years of observation was that clouds have many individual shapes but they have few basic forms . in fact , all clouds belong to one of three principle types to which howard gave the names : cirrus , latin for tendril or hair , cumulus , heap or pile , and stratus , layer or sheet . but that was n't the clever part . clouds are constantly changing , merging , rising , falling , and spreading throughout the atmosphere , rarely maintaining the same shapes for more than a few minutes . any successful naming system had to accommodate this essential instability , as howard realized . so , in addition to the three main cloud types , he introduced a series of intermediate and compound types as a way of including the regular transitions that occur among clouds . a high , whispy cirrus cloud that descended and spread into a sheet was named cirrostratus , while groups of fluffy cumulus clouds that joined up and spread were named stratocumulus . howard identified seven cloud types , but these have since been expanded to ten , cloud nine being the towering cumulonimbus thunder cloud , which is probably why being on cloud nine means to be on top of the world . howard 's classification had an immediate international impact . the german poet and scientist j.w . von goethe wrote a series of poems in praise of howard 's clouds , which ended with the memorable lines , `` as clouds ascend , are folded , scatter , fall , let the world think of thee who taught it all , '' while percy shelley also wrote a poem `` the cloud , '' in which each of howard 's seven cloud types was characterized in turn . but perhaps the most impressive response to the naming of clouds was by the painter john constable , who spent two summers on hampstead heath painting clouds in the open air . once they had been named and classified , clouds became easier to understand as the visible signs of otherwise invisible atmospheric processes . clouds write a kind of journal on the sky that allows us to understand the circulating patterns of weather and climate . perhaps the most important breakthrough in understanding clouds was realizing that they are subject to the same physical laws as everything else on earth . clouds , for example , do not float , but fall slowly under the influence of gravity . some of them stay aloft due to upward convection from the sun-heated ground , but most are in a state of slow , balletic descent . `` clouds are the patron goddesses of idle fellows , '' as the greek dramatist aristophanes wrote in 420 b.c . and nephology , the study of clouds , remains a daydreamer 's science , aptly founded by a thoughtful young man whose favorite activity was staring out of the window at the sky .

by his own admission , luke paid little attention to his lessons , but fortunately for the future of meteorology , he managed to pick up a good knowledge of latin . compared to the other natural sciences , meteorology , the study of weather , was a late developer , mainly because weather is elusive . you ca n't snap off a piece of rainbow or a section of cloud for convenient study .

why was meteorology such a late developer compared to other branches of science ? can you think of ways in which weather might have been studied in the centuries before computers appeared ?

thinking of getting a tattoo ? decorating your birthday suit would add another personal story to a history of tattoos stretching back at least 8000 years . tattooed mummies from around the world attest to the universality of body modification across the millennia , and to the fact that you really were stuck with it forever if your civilization never got around to inventing laser removal . a mummy from the chinchorro culture in pre-incan peru has a mustache tattooed on his upper lip . ötzi , mummified iceman of the alps , has patterned charcoal tats along his spine , behind his knee and around his ankles , which might be from an early sort of acupuncture . the mummy of amunet , a priestess in middle kingdom egypt , features tattoos thought to symbolize sexuality and fertility . even older than the mummies , figurines of seemingly tattooed people , and tools possibly used for tattooing date back tens of thousands of years . tattoos do n't have one historical origin point that we know of , but why do we english speakers call them all tattoos ? the word is an anglophonic modification of `` tatao , '' a polynesian word used in tahiti , where english captain james cook landed in 1769 and encountered heavily tattooed men and women . stories of cook 's findings and the tattoos his crew acquired cemented our usage of `` tattoo '' over previous words like `` scarring , '' `` painting , '' and `` staining , '' and sparked a craze in victorian english high society . we might think of victorians having victorian attitudes about such a risque thing , and you can find such sentiments , and even bans , on tattooing throughout history . but while publicly some brits looked down their noses at tattoos , behind closed doors and away from their noses , lots of people had them . reputedly , queen victoria had a tiger fighting a python , and tattoos became very popular among cook 's fellow soldiers , who used them to note their travels . you crossed the atlantic ? get an anchor . been south of the equator ? time for your turtle tat . but westerners sported tattoos long before meeting the samoans and maori of the south pacific . crusaders got the jerusalem cross so if they died in battle , they 'd get a christian burial . roman soldiers on hadrian 's wall had military tattoos and called the picts beyond it `` picts , '' for the pictures painted on them . there 's also a long tradition of people being tattooed unwillingly . greeks and romans tattooed slaves and mercenaries to discourage escape and desertion . criminals in japan were tattooed as such as far back as the 7th century . most infamously , the nazis tattooed numbers on the chest or arms of jews and other prisoners at the auschwitz concentration camp in order to identify stripped corpses . but tattoos forced on prisoners and outcasts can be redefined as people take ownership of that status or history . primo levi survived auschwitz and wore short sleeves to germany after the war to remind people of the crime his number represented . today , some holocaust survivors ' descendants have their relatives numbers ' tattooed on their arms . the torah has rules against tattoos , but what if you want to make indelible what you feel should never be forgotten ? and those criminals and outcasts of japan , where tattooing was eventually outlawed from the mid-19th century to just after world war ii , added decoration to their penal tattoos , with designs borrowed from woodblock prints , popular literature and mythical spirtual iconography . yakuza gangs viewed their outsider tattoos as signs of lifelong loyalty and courage . after all , they lasted forever and it really hurt to get them . for the maori , those tattoos were an accepted mainstream tradition . if you shied away from the excruciating chiseling in of your moko design , your unfinished tattoo marked your cowardice . today , unless you go the traditional route , your tattoo artist will probably use a tattoo machine based on the one patented by samuel o'reilly in 1891 , itself based on thomas edison 's stencil machine from 1876 . but with the incredibly broad history of tattoos giving you so many options , what are you going to get ? this is a bold-lined expression of who you are , or you want to appear to be . as the naturalist aboard cook 's ship said of the tataoed tahitians , `` everyone is marked , thus in different parts of his body , according maybe to his humor or different circumstances of his life . '' maybe your particular humor and circumstances suggest getting a symbol of cultural heritage , a sign of spirituality , sexual energy , or good old-fashioned avant-garde defiance . a reminder of a great accomplishment , or of how you think it would look cool if hulk hogan rode a rhino . it 's your expression , your body , so it 's your call . just two rules : you have to find a tattooist who wo n't be ashamed to draw your idea , and when in doubt , you can never go wrong with `` mom . ''

you crossed the atlantic ? get an anchor . been south of the equator ?

what would an english sailor ’ s anchor tattoo most likely symbolize or refer to ?

translator : tom carter reviewer : bedirhan cinar the periodic table is instantly recognizable . it 's not just in every chemistry lab worldwide , it 's found on t-shirts , coffee mugs , and shower curtains . but the periodic table is n't just another trendy icon . it 's a massive slab of human genius , up there with the taj mahal , the mona lisa , and the ice cream sandwich -- and the table 's creator , dmitri mendeleev , is a bonafide science hall-of-famer . but why ? what 's so great about him and his table ? is it because he made a comprehensive list of the known elements ? nah , you do n't earn a spot in science valhalla just for making a list . besides , mendeleev was far from the first person to do that . is it because mendeleev arranged elements with similar properties together ? not really , that had already been done too . so what was mendeleev 's genius ? let 's look at one of the first versions of the periodic table from around 1870 . here we see elements designated by their two-letter symbols arranged in a table . check out the entry of the third column , fifth row . there 's a dash there . from that unassuming placeholder springs the raw brilliance of mendeleev . that dash is science . by putting that dash there , dmitri was making a bold statement . he said -- and i 'm paraphrasing here -- y'all have n't discovered this element yet . in the meantime , i 'm going to give it a name . it 's one step away from aluminum , so we 'll call it eka-aluminum , `` eka '' being sanskrit for one . nobody 's found eka-aluminum yet , so we do n't know anything about it , right ? wrong ! based on where it 's located , i can tell you all about it . first of all , an atom of eka-aluminum has an atomic weight of 68 , about 68 times heavier than a hydrogen atom . when eka-aluminum is isolated , you 'll see it 's a solid metal at room temperature . it 's shiny , it conducts heat really well , it can be flattened into a sheet , stretched into a wire , but its melting point is low . like , freakishly low . oh , and a cubic centimeter of it will weigh six grams . mendeleev could predict all of these things simply from where the blank spot was , and his understanding of how the elements surrounding it behave . a few years after this prediction , a french guy named paul emile lecoq de boisbaudran discovered a new element in ore samples and named it gallium after gaul , the historical name for france . gallium is one step away from aluminum on the periodic table . it 's eka-aluminum . so were mendeleev 's predictions right ? gallium 's atomic weight is 69.72 . a cubic centimeter of it weighs 5.9 grams . it 's a solid metal at room temperature , but it melts at a paltry 30 degrees celcius , 85 degrees fahrenheit . it melts in your mouth and in your hand . not only did mendeleev completely nail gallium , he predicted other elements that were unknown at the time : scandium , germanium , rhenium . the element he called eka-manganese is now called technetium . technetium is so rare it could n't be isolated until it was synthesized in a cyclotron in 1937 , almost 70 years after dmitri predicted its existence , 30 years after he died . dmitri died without a nobel prize in 1907 , but he wound up receiving a much more exclusive honor . in 1955 , scientists at uc berkeley successfully created 17 atoms of a previously undiscovered element . this element filled an empty spot in the perodic table at number 101 , and was officially named mendelevium in 1963 . there have been well over 800 nobel prize winners , but only 15 scientists have an element named after them . so the next time you stare at a periodic table , whether it 's on the wall of a university classroom or on a five-dollar coffee mug , dmitri mendeleev , the architect of the periodic table , will be staring back .

besides , mendeleev was far from the first person to do that . is it because mendeleev arranged elements with similar properties together ? not really , that had already been done too .

how do you think mendeleev was able to so accurately estimate the properties of undiscovered elements ?

this just in : `` thief robs town with world 's largest chocolate bunny . '' wait , so are we talking about this , or this ? that 's a classic case of a misplaced modifier , a common grammatical mistake that can dramatically change the meaning of a sentence . and lest you think this is a bit far-fetched , confusing headlines like this appear all the time . modifiers are words , phrases , and clauses that add information about other parts of a sentence , which is usually helpful . but when modifiers are n't linked clearly enough to the words they 're actually referring to , they can create unintentional ambiguity . that happens because the modifying words , in this case , `` with world 's largest chocolate bunny , '' modify the wrong thing , the robber 's actions instead of the town . to correct this particular sentence , we simply rephrase to make it clearer what the modifying phrase is talking about . `` town with world 's largest chocolate bunny robbed by thief . '' now , at least it 's clear that the thief was n't armed with a giant chocolate animal . sometimes , modifying words , phrases , or clauses do n't appear to be modifying anything at all . that 's called a dangling modifier . `` having robbed the bank in record time , it was possible to make off with the town 's chocolate rabbit as well . '' the modifying phrase in this sentence seems unrelated to anything else , and so we 're clueless about who the chocolate-loving criminal could possibly be . giving the modifier something to modify will solve the problem . then there 's another group called the squinting modifiers because they 're stuck between two things and could feasibly refer to either . often , these modifiers are adverbs , like the one in this sentence : `` robbers who steal chocolate bunnies rapidly attract the outrage of onlookers . '' `` rapidly '' is the modifier , here , but what 's not clear is whether it 's referring to the speed of the chocolate thievery , or how quickly it alerts the furious onlookers . to clarify , we can either put the modifier closer to its intended phrase , which works in some cases , or we can entirely reword the sentence so that the modifier no longer squints , but clearly applies to only one part . `` chocolate bunny-thieving robbers rapidly attract the outrage of onlookers . '' justice will eventually come to the chocolate thief , but in the meantime , our task is to avoid verbal ambiguity by making it clear which parts of the sentences modifiers belong to . that way , we can at least maintain grammatical law and order .

sometimes , modifying words , phrases , or clauses do n't appear to be modifying anything at all . that 's called a dangling modifier . `` having robbed the bank in record time , it was possible to make off with the town 's chocolate rabbit as well . ''

what is a modifier ?

if i were to distill the 20 years of elephant research that i 've done into one sentence , what would it be ? what could i tell you ? i would say that elephants are just like us ! and what do i mean by that ? it takes a lot of patience to be out there in the field and trying to figure out patterns of these very slow and intelligent animals . but over time , it is true they are very similar to us . and you think , `` well , how can i say that ? look , they have huge ears , they have really long noses . what do you mean they 're like us ? '' well , in fact , their families are very similar to ours . and family is extremely important to elephants . they grow up in very tight-knit families and they have extended families . and it 's just like our family reunions where you have all the aunts gathering around with all the food they 're going to bring and plan , and all the boys are thinking , `` are we going to play our video games together ? are we going to spar ? '' it 's very , very similar , and it 's jubilant , and screaming , yelling , it 's really amazing to see . but , as soon as you get that family gathering , it 's just like a wedding or anything else , all of the sudden the family politics come out , and the lower-ranking individuals in this scene , you see the arrow off to the back , the lower-ranking individuals already know their station , they 're going to drink at the muddiest part of the pan because the whole family 's here and we ca n't drink at the best water because that 's reserved for the top-ranking family . what 's also very similar is that you have elders in the group that everyone reveres . this is the matriarch , and the other female is reaching over and doing what 's called a trunk to mouth placing her trunk in the mouth , and it 's a sign of respect , it 's kind of like a handshake , but it 's also like a salute . and this salute is learned at a very young age . now , ritual and bonding within the family also facilitates coordinated activities . so , here 's a young female whose calf has fallen into the trough and she does n't know what to do and she panics . well , the older female , that 's the matriarch , she says , `` no problem here , '' she just scoops the baby out . now , that 's not true for a lot of different families , they ca n't coordinate very well , the younger females do n't really know what to do , but the older ones will just get down , kneel down together and pick the baby out . another thing that 's very similar is the coming of age of teenage boys . male elephants at the age of about 12 to 15 . the biggest elephant in this photograph here is an elephant who 's about the leave the family . he gets too big , he gets a little fresh , the adult females had enough of him , but he also is independent , he wants to go out and play with the guys . so what happens then is that you have this all male society , very ritual male society . greg is our main dominant bull here , you can see him in the middle . he 's got a huge posse , his following reveres him . and it 's very interesting how very good leaders , very good dominant individuals know how to titrate the carrot and the stick . this guy 's a master at it , and there 's other bullies out there that want to kind of want to create their own little following , but they ca n't do it because they 're too agressive . and so when he 's not around they try and sweet talk the underlings to come into their fold , and they actually become less agressive . so it 's very interesting to see how politics play out in these male and female societies . now back to the ladies here . in a core family group you 'll have a mother , maybe even a grandmother , her daughters and all of their offspring , the male and female calves . and what 's very interesting here is that how character makes a difference . so each matriarch has a very different character . these two characters are kind of curious , they 're uncertain , whereas these other two characters are really agressive . `` we 're going to charge first , ask questions later . '' but then there are also matriarchs that say , `` forget it ! i 'm going to run first and then figure it out when we 're in the bush and it 's safe . '' but the wisest matriarch , the matriarchs that succeed best in all of the studies that have been done , is the one that assesses the danger and decides is this worth running away from or is this not a big deal at all . now being social is super important for elephants and of course right at the beginning , just like early childhood development , socialization is very important . bathing together , eating together , playing together , rough housing , this is all very important for social development . and who has n't tried to beat their sibling to the head of the line coming into the water hole ? and these relationships from the beginning is just like best friends forever for real . these females are going to live together for life . now if it 's a male , female they might know each other for life , but it 's really important to develop those bonds early on . those are the relationships that are going to save you later . i 'll show you a little schoolyard scenario here . where , i think if you just focus on what 's happening here you can see that we have the bully , he 's pulling on the trunk of this baby calf , and then we have the diplomat who 's reaching over and saying , `` no , do n't do that ! stop doing that ! '' and then , of course , we have the bystander . and how do you get these three different characters within the family ? it 's kind of fascinating to think that elephants really are just like us . and so i got curious about this and i thought , `` well , what if you measure the difference in character of a dominant female 's calf versus a lower-ranking female 's calf , and see what happens in their growing up . '' and so we started doing this . and you can see this little guy with his ears out , really charging at you . the difference between that character and the character who holds back , wants to touch mom , is n't so certain about what 's going on here . but the other one 's charging ahead all confident . well , we started measuring how far away a calf will stray from mom , how often do they touch others , how often do they initiate play , and then look at the dominance of the females , of their mothers . and what we found is that socializing with the dominant calves actually socialize more significantly more than the lower-ranking calves . and what it looks like is it 's not that the lower-ranking calves do n't want to play , they 're actually not allowed to interact with the higher-ranking calves . they get swatted away from the dominant females . and so this is kind of the downside of , okay we are very much like elephants , elephants are as much like us , but it 's kind of for better or for worse because i can also see this happening in humans and maybe we should take a lesson from that . one last thing that we found is that the males will be the risk-takers , they 're more independent and they 're more likely to spend more time away from mom . and that 's very true in human societies and with other social animals . so i hope i 've convinced you that we have very similar lives to elephants and that elephants have very individual , durable characters that we 've measured across years . the bully always tends to be the bully unless there 's some kind of social upset , and he decides he better be a softy or else he 's not going to gain favor at all . and then you have the gentle giants that are always going to be gentle . the young males really need mentoring from the elders , and those gentle giants are very good at doing that , soliciting them . leaving family is a really hard things for the males , but they survive and they figure out who to hang out with . so , just to end here , i just wanted to say that since they are so similar to us , and have these characters , i hope when you see them on tv or you go out and you 're lucky enough to see them in the wild , that maybe you 'll think of them as individual characters deserving of our attention , and also deserving of our protection . thank you .

another thing that 's very similar is the coming of age of teenage boys . male elephants at the age of about 12 to 15 . the biggest elephant in this photograph here is an elephant who 's about the leave the family . he gets too big , he gets a little fresh , the adult females had enough of him , but he also is independent , he wants to go out and play with the guys .

at what age does a male elephant leave his family and join loosely associated or bonded groups of adult males ?

it can strike without warning , at any moment . you may be walking across a soft carpet and reaching for the door knob when suddenly ... zap ! to understand static electricity , we first need to know a bit about the nature of matter . all matter is made up of atoms that consist of three types of smaller particles : negatively charged electrons , positively charged protons , and neutral neutrons . normally , the electrons and protons in an atom balance out , which is why most matter you come across is electrically neutral . but electrons are tiny and almost insignificant in mass , and rubbing or friction can give loosely bound electrons enough energy to leave their atoms and attach to others , migrating between different surfaces . when this happens , the first object is left with more protons than electrons and becomes positively charged , while the one with more electrons accumulates a negative charge . this situation is called a charge imbalance , or net charge separation . but nature tends towards balance , so when one of these newly charged bodies comes into contact with another material , the mobile electrons will take the first chance they get to go where they 're most needed , either jumping off the negatively charged object , or jumping onto the positively charged one in an attempt to restore the neutral charge equilibrium . and this quick movement of electrons , called static discharge , is what we recognize as that sudden spark . this process does n't happen with just any objects . otherwise you 'd be getting zapped all the time . conductors like metals and salt water tend to have loosely bound outer electrons , which can easily flow between molecules . on the other hand , insulators like plastics , rubber and glass have tightly bound electrons that wo n't readily jump to other atoms . static build-up is most likely to occur when one of the materials involved is an insulator . when you walk across a rug , electrons from your body will rub off onto it , while the rug 's insulating wool will resist losing its own electrons . although your body and the rug together are still electrically neutral , there is now a charge polarization between the two . and when you reach to touch the door knob , zap ! the metal door knob 's loosely bound electrons hop to your hand to replace the electrons your body has lost . when it happens in your bedroom , it 's a minor nuisance . but in the great outdoors , static electricity can be a terrifying , destructive force of nature . in certain conditions , charge separation will occur in clouds . we do n't know exactly how this happens . it may have to do with the circulation of water droplets and ice particles within them . regardless , the charge imbalance is neutralized by being released towards another body , such as a building , the earth , or another cloud in a giant spark that we know as lightning . and just as your fingers can be zapped over and over in the same spot , you better believe that lightning can strike the same place more than once .

on the other hand , insulators like plastics , rubber and glass have tightly bound electrons that wo n't readily jump to other atoms . static build-up is most likely to occur when one of the materials involved is an insulator . when you walk across a rug , electrons from your body will rub off onto it , while the rug 's insulating wool will resist losing its own electrons .

explain why for static electricity to occur between two surfaces that are rubbed against each other , one of the materials has to be an insulator .

[ why do n't we eat bugs ? ] for centuries , people have consumed bugs , everything from beetles to caterpillars , locusts , grasshoppers , termites , and dragonflies . the practice even has a name : entomophagy . early hunter-gatherers probably learned from animals that foraged for protein-rich insects and followed suit . as we evolved and bugs became part of our dietary tradition , they fulfilled the role of both staple food and delicacy . in ancient greece , cicadas were considered luxury snacks . and even the romans found beetle larvae to be scrumptious . why have we lost our taste for bugs ? the reason for our rejection is historical , and the story probably begins around 10,000 bc in the fertile crescent , a place in the middle east that was a major birthplace of agriculture . back then , our once-nomadic ancestors began to settle in the crescent . and as they learned to farm crops and domesticate animals there , attitudes changed , rippling outwards towards europe and the rest of the western world . as farming took off , people might have spurned bugs as mere pests that destroyed their crops . populations grew , and the west became urbanized , weakening connections with our foraging past . people simply forgot their bug-rich history . today , for people not accustomed to entomophagy , bugs are just an irritant . they sting and bite and infest our food . we feel an `` ick factor '' associated with them and are disgusted by the prospect of cooking insects . almost 2,000 insect species are turned into food , forming a big part of everyday diets for two billion people around the world . countries in the tropics are the keenest consumers , because culturally , it 's acceptable . species in those regions are also large , diverse , and tend to congregate in groups or swarms that make them easy to harvest . take cambodia in southeast asia where huge tarantulas are gathered , fried , and sold in the marketplace . in southern africa , the juicy mopane worm is a dietary staple , simmered in a spicy sauce or eaten dried and salted . and in mexico , chopped jumiles are toasted with garlic , lemon , and salt . bugs can be eaten whole to make up a meal or ground into flour , powder , and paste to add to food . but it 's not all about taste . they 're also healthy . in fact , scientists say entomophagy could be a cost-effective solution for developing countries that are food insecure . insects can contain up to 80 % protein , the body 's vital building blocks , and are also high in energy-rich fat , fiber , and micronutrients like vitamins and minerals . did you know that most edible insects contain the same amount or even more mineral iron than beef , making them a huge , untapped resource when you consider that iron deficiency is currently the most common nutritional problem in the world ? the mealworm is another nutritious example . the yellow beetle larvae are native to america and easy to farm . they have a high vitamin content , loads of healthy minerals , and can contain up to 50 % protein , almost as much as in an equivalent amount of beef . to cook , simply sauté in butter and salt or roast and drizzle with chocolate for a crunchy snack . what you have to overcome in `` ick factor , '' you gain in nutrition and taste . indeed , bugs can be delicious . mealworms taste like roasted nuts . locusts are similar to shrimp . crickets , some people say , have an aroma of popcorn . farming insects for food also has less environmental impact than livestock farms do because insects emit far less greenhouse gas and use up less space , water , and food . socioeconomically , bug production could uplift people in developing countries since insect farms can be small scale , highly productive , and yet relatively inexpensive to keep . insects can also be turned into more sustainable food for livestock and can be reared on organic waste , like vegetable peelings , that might otherwise just end up rotting in landfills . feeling hungry yet ? faced with a plate of fried crickets , most people today would still recoil , imagining all those legs and feelers getting stuck between their teeth . but think of a lobster . it 's pretty much just a giant insect with legs and feelers galore that was once regarded as an inferior , repulsive food . now , lobster is a delicacy . can the same paradigm shift happen for bugs ? so , give it a try ! pop that insect into your mouth , and savor the crunch .

and as they learned to farm crops and domesticate animals there , attitudes changed , rippling outwards towards europe and the rest of the western world . as farming took off , people might have spurned bugs as mere pests that destroyed their crops . populations grew , and the west became urbanized , weakening connections with our foraging past .

list some creative ways for changing people ’ s perception of bugs as pests .

is teleportation possible ? could a baseball transform into something like a radio wave , travel through buildings , bounce around corners , and change back into a baseball ? oddly enough , thanks to quantum mechanics , the answer might actually be yes . sort of . here 's the trick . the baseball itself could n't be sent by radio , but all the information about it could . in quantum physics , atoms and electrons are interpreted as a collection of distinct properties , for example , position , momentum , and intrinsic spin . the values of these properties configure the particle , giving it a quantum state identity . if two electrons have the same quantum state , they 're identical . in a literal sense , our baseball is defined by a collective quantum state resulting from its many atoms . if this quantum state information could be read in boston and sent around the world , atoms for the same chemical elements could have this information imprinted on them in bangalore and be carefully directed to assemble , becoming the exact same baseball . there 's a wrinkle though . quantum states are n't so easy to measure . the uncertainty principle in quantum physics implies the position and momentum of a particle ca n't be measured at the same time . the simplest way to measure the exact position of an electron requires scattering a particle of light , a photon , from it , and collecting the light in a microscope . but that scattering changes the momentum of the electron in an unpredictable way . we lose all previous information about momentum . in a sense , quantum information is fragile . measuring the information changes it . so how can we transmit something we 're not permitted to fully read without destroying it ? the answer can be found in the strange phenomena of quantum entanglement . entanglement is an old mystery from the early days of quantum physics and it 's still not entirely understood . entangling the spin of two electrons results in an influence that transcends distance . measuring the spin of the first electron determines what spin will measure for the second , whether the two particles are a mile or a light year apart . somehow , information about the first electron 's quantum state , called a qubit of data , influences its partner without transmission across the intervening space . einstein and his colleagues called this strange communcation spooky action at a distance . while it does seem that entanglement between two particles helps transfer a qubit instantaneously across the space between them , there 's a catch . this interaction must begin locally . the two electrons must be entangled in close proximity before one of them is transported to a new site . by itself , quantum entanglement is n't teleportation . to complete the teleport , we need a digital message to help interpret the qubit at the receiving end . two bits of data created by measuring the first particle . these digital bits must be transmitted by a classical channel that 's limited by the speed of light , radio , microwaves , or perhaps fiberoptics . when we measure a particle for this digital message , we destroy its quantum information , which means the baseball must disappear from boston for it to teleport to bangalore . thanks to the uncertainty principle , teleportation transfers the information about the baseball between the two cities and never duplicates it . so in principle , we could teleport objects , even people , but at present , it seems unlikely we can measure the quantum states of the trillion trillion or more atoms in large objects and then recreate them elsewhere . the complexity of this task and the energy needed is astronomical . for now , we can reliably teleport single electrons and atoms , which may lead to super-secured data encryption for future quantum computers . the philosophical implications of quantum teleportation are subtle . a teleported object does n't exactly transport across space like tangible matter , nor does it exactly transmit across space , like intangible information . it seems to do a little of both . quantum physics gives us a strange new vision for all the matter in our universe as collections of fragile information . and quantum teleportation reveals new ways to influence this fragility . and remember , never say never . in a little over a century , mankind has advanced from an uncertain new understanding of the behavior of electrons at the atomic scale to reliably teleporting them across a room . what new technical mastery of such phenomena might we have in 1,000 , or even 10,000 years ? only time and space will tell .

in quantum physics , atoms and electrons are interpreted as a collection of distinct properties , for example , position , momentum , and intrinsic spin . the values of these properties configure the particle , giving it a quantum state identity . if two electrons have the same quantum state , they 're identical . in a literal sense , our baseball is defined by a collective quantum state resulting from its many atoms . if this quantum state information could be read in boston and sent around the world , atoms for the same chemical elements could have this information imprinted on them in bangalore and be carefully directed to assemble , becoming the exact same baseball .

define a quantum state for a quantum particle :

why do humans drink so much milk ? and given that all mammals lactate , why do we favor certain types of milk over others ? milk is the first thing we drink , and thanks to developments in the production and variety of dairy products , it can take on countless forms for our dietary and sensory well-being . milk 's primary function is as a complete source of nutrition for newborns . in fact , since it has all of the vital nutrients for development and growth , proteins , carbohydrates , fats , vitamins and minerals , and water , milk is the only thing a baby even needs to ingest for the first six months of life . the unique makeup of milk can vary depending on factors like species , diet , and location . reindeer of the arctic circle , for example , make energy-dense milk that 's about 20 % fat , roughly five times more than human or cow 's milk , to help their young survive the harsh , freezing climate . so how is milk made ? in the uniquely mammalian process of lactation , a special class of milk-secreting cells known as mammocytes line up in a single layer around pear-shaped alveoli . those cells absorb all of the building blocks of milk , then synthesize tiny droplets of fat on structures called smooth endoplasmic reticula . the droplets combine with each other and other molecules and are then expelled and stored in spaces between cells . mammary glands eventually secrete the milk through the breasts , udders , or , in the rare case of the platypus , through ducts in the abdomen . although this process is typically reserved for females , in some species , like dayak fruit bats , goats , and even cats , males can also lactate . milk drinkers worldwide consume dairy from buffalo , goats , sheeps , camels , yaks , horses , and cows . almost all of these species are ruminants , a type of mammal with four-chambered stomachs that yield large quantities of milk . of these , cows were the most easily domesticated and produce a milk that is both easily separated into cream and liquid and has a similar fat content to human milk . in their natural environment , mammals secrete milk on call for immediate consumption by their young . but with the demands of thirsty consumers , the dairy industry has enlisted methods to step up production , enhance shelf life , and provide a variety of milk products . in the dairy , centrifugation machines spin milk at high speeds , forcing less dense fats to separate from the liquid and float up . after being skimmed off , this fat , known as butterfat , can be used in dairy products like butter , cream , and cheese . or it can be later added back to the liquid in varying proportions to yield different fat content milks . full fat milk , sometimes referred to as whole milk , has 3.25 % butterfat added compared to 1-2 % for low and reduced fat milk , and less than half a percent for skim milk . to stop reseparation of the fat from the water , or creaming , the mixture undergoes the high-energy pressurized process of homogenization . before milk hits the shelves , it 's also typically heat treated to reduce its level of microbes , a government-sanctioned process that raw milk enthusiasts argue may reduce milk 's nutritional worth . milk spoilage is started by microbes , which consume and break down the nutrients in milk . that process causes butterfat to clump together , leading to a visually unpleasant product . and the byproducts of the microbes ' consumption are compounds that taste and smell nasty . but there 's a bigger problem . raw milk can carry microbes that are the sources of deadly diseases , so in order to kill as many of those microbes as possible , and keep milk fresh longer , we use a technique called pasteurization . one version of this process involves exposing milk to about 30 seconds of high heat . another version , called ultra-high temperature processing , or ultra pasteurization , blasts the milk with considerably higher temperatures over just a few seconds . uht milk boasts a much longer shelf life , up to twelve months unrefrigerated , compared to pasteurized milk 's two weeks in the fridge . that 's because the higher temperatures of uht processing inactivate far more microbes . yet the higher processing temperatures may adversely affect the nutritional and sensory properties of the milk . ultimately , that choice lies in the consumer 's taste and need for convenience . fortunately , there are many choices available in an industry that produces in excess of 840 million tons of products each year .

or it can be later added back to the liquid in varying proportions to yield different fat content milks . full fat milk , sometimes referred to as whole milk , has 3.25 % butterfat added compared to 1-2 % for low and reduced fat milk , and less than half a percent for skim milk . to stop reseparation of the fat from the water , or creaming , the mixture undergoes the high-energy pressurized process of homogenization .

the main component of milk is water , where the other main components in milk are ____ .

cramming for a test ? trying to get more done than you have time to do ? stress is a feeling we all experience when we are challenged or overwhelmed . but more than just an emotion , stress is a hardwired physical response that travels throughout your entire body . in the short term , stress can be advantageous , but when activated too often or too long , your primitive fight or flight stress response not only changes your brain but also damages many of the other organs and cells throughout your body . your adrenal gland releases the stress hormones cortisol , epinephrine , also known as adrenaline , and norepinephrine . as these hormones travel through your blood stream , they easily reach your blood vessels and heart . adrenaline causes your heart to beat faster and raises your blood pressure , over time causing hypertension . cortisol can also cause the endothelium , or inner lining of blood vessels , to not function normally . scientists now know that this is an early step in triggering the process of atherosclerosis or cholesterol plaque build up in your arteries . together , these changes increase your chances of a heart attack or stroke . when your brain senses stress , it activates your autonomic nervous system . through this network of nerve connections , your big brain communicates stress to your enteric , or intestinal nervous system . besides causing butterflies in your stomach , this brain-gut connection can disturb the natural rhythmic contractions that move food through your gut , leading to irritable bowel syndrome , and can increase your gut sensitivity to acid , making you more likely to feel heartburn . via the gut 's nervous system , stress can also change the composition and function of your gut bacteria , which may affect your digestive and overall health . speaking of digestion , does chronic stress affect your waistline ? well , yes . cortisol can increase your appetite . it tells your body to replenish your energy stores with energy dense foods and carbs , causing you to crave comfort foods . high levels of cortisol can also cause you to put on those extra calories as visceral or deep belly fat . this type of fat does n't just make it harder to button your pants . it is an organ that actively releases hormones and immune system chemicals called cytokines that can increase your risk of developing chronic diseases , such as heart disease and insulin resistance . meanwhile , stress hormones affect immune cells in a variety of ways . initially , they help prepare to fight invaders and heal after injury , but chronic stress can dampen function of some immune cells , make you more susceptible to infections , and slow the rate you heal . want to live a long life ? you may have to curb your chronic stress . that 's because it has even been associated with shortened telomeres , the shoelace tip ends of chromosomes that measure a cell 's age . telomeres cap chromosomes to allow dna to get copied every time a cell divides without damaging the cell 's genetic code , and they shorten with each cell division . when telomeres become too short , a cell can no longer divide and it dies . as if all that were n't enough , chronic stress has even more ways it can sabotage your health , including acne , hair loss , sexual dysfunction , headaches , muscle tension , difficulty concentrating , fatigue , and irritability . so , what does all this mean for you ? your life will always be filled with stressful situations . but what matters to your brain and entire body is how you respond to that stress . if you can view those situations as challenges you can control and master , rather than as threats that are insurmountable , you will perform better in the short run and stay healthy in the long run .

it tells your body to replenish your energy stores with energy dense foods and carbs , causing you to crave comfort foods . high levels of cortisol can also cause you to put on those extra calories as visceral or deep belly fat . this type of fat does n't just make it harder to button your pants .

how does cortisol add to belly fat ?

do you ever struggle to find the perfect description when trying to convey an idea ? like a foggy picture , adjectives and modifiers fail to depict what 's in your mind . illustrators often face a similar challenge , especially when attempting to explain complex and difficult concepts . sometimes the imagery is intangible or way too complicated to explain with a picture . although complex information could be relayed using charts and stats , this could get pretty boring . instead , just like when writing an essay to describe , for example , emotions , illustrators can use visual metaphors to bring to life difficult concepts . just as a written metaphor is a description that relates one object to another , a visual metaphor uses imagery to suggest a particular association or point of similarity . our lesson `` big data '' is a great example of a situation where visual metaphors played a huge role in explaining the concept . what is big data in the first place ? good question ! big data is a huge amount of digital information produced worldwide on a daily basis , challenging us to find solutions for storing , analyzing , and also imagining it visually . quite an elusive concept ! how should we depict this ? let 's take a look at our `` big data '' script . we start with smaller computer servers that branch out into bigger networks to produce data , then even bigger networks and production of even more data . you see where we 're going with this -- an object growing and branching out in many directions and producing something as a result ? does that remind you of something ? just like those computer networks , a tree grows and branches out to produce more leaves each year . and every year , just as the data accumulates and faces us with a challenge to find storage solutions , it gets harder to collect those piles of leaves when they fall off the tree . aha ! there 's our visual metaphor ! okay , so we have the script , audio , and a visual metaphor . the next step in visual development is to design the characters and environments of the animation . to do so , we think of an appropriate and appealing style to illustrate the ideas and help the viewer better understand what they 're hearing . let 's go back to the script and see if we can find any clues there . our story starts in the 1960s when the first computer networks were built . this decade will serve as a good point to make the stylistic choice for our animation as it will allow us to refer to artwork from that era . you may want to start by looking at some art books ( design , illustrations , cartoons , etc . ) from that era and find a style that may our own purpose . look closely , study the material , and try to understand the choices artists of that time made and why . for example , the 1960s minimalist animation style was a significant departure from the cinematic realism that was popular in animated films at the time . the choice to use limited animation techniques was originally made for budgetary reasons , but it became a signature style that influenced many future generations of animators . in this stylistic approach , the simplified characters , flat backgrounds , and angular shapes come together to create new interpretations of reality , which also sounds like a good place to begin visualizing our own big data . well , let 's try an experiment . `` in the 1980s islands of similar networks speaking different dialects sprung up all over europe and the states , making remote access possible but tortuous . '' is this better ? `` in the 1980s islands of similar networks speaking different dialects sprung up all over europe and the states , making remote access possible but tortuous . to make it easy for our physicists across the world to access the ever-expanding big data stored at cern without traveling , the networks needed to be talking with the same language . '' as you probably observed , graphic representations are a great way to capture the interest of your audience . by depicting what you want to present and explain with strong , memorable visuals , you can communicate your idea more effectively . so , now , challenge yourself . think of an abstract concept that can not be explained with simple words . go ahead and try your hand at visually developing that idea .

just as a written metaphor is a description that relates one object to another , a visual metaphor uses imagery to suggest a particular association or point of similarity . our lesson `` big data '' is a great example of a situation where visual metaphors played a huge role in explaining the concept . what is big data in the first place ? good question !

at what point in history did the big data lesson start ?

flatulence , or passing gas , is a normal daily phenomenon . most individuals , yes , that includes you , will make anywhere from 500-1500 milliliters of gas and can pass gas ten to twenty times a day . but where does this bodily gas come from ? a small proportion may come from ingesting air during sleep , or at other times , but the majority of gas is produced by bacteria in our intestines as they digest parts of food which we can not . our intestine is home to trillions of bacteria living in a symbiotic relationship with us . we provide them with a safe place to stay and food to eat . in exchange , they help us extract energy from our food , make vitamins for us , like vitamin b and k , boost our immune system , and play an important role in gastrointestinal barrier function , motility and the development of various organ systems . clearly , it 's in our best interest to keep these bacteria happy . gut bacteria get their nutrition primarily from undigested food , such as carbohydrates and proteins , which come to the large intestine . they ferment this undigested food to produce a wide range of compounds , such as short-chain fatty acids and , of course , gases . hydrogen and carbon dioxide are the most common gaseous products of bacterial fermentation , and are odorless . some people also produce methane due to specific microbes present in their gut . but methane is actually odorless , too . well then , what stinks ? the foul smell is usually due to volatile sulfur compounds , such as hydrogen sulfide and methanethiol , or methyl mercaptan . these gases , however , constitute less than 1 % of volume , and are often seen with ingestion of amino acids containing sulfur , which may explain the foul smell of gas from certain high protein diets . increased passage of gas is commonly noticed after eating foods with high amounts of indigestible carbohydrates , like beans , lentils , dairy products , onions , garlic , leeks , radishes , potatoes , oats , wheat , cauliflower , broccoli , cabbage , and brussel sprouts . humans lack the enzymes , so the bacteria able to ferment complex carbohydrates take over , and this naturally leads to more gas than usual . but if you feel uncomfortable , bloated or visibly distended , this may indicate impaired movement of gas along the gastrointestinal track . it 's important not to just blame certain foods for gas and bloating and then avoid them . you do n't want to starve the bacteria that digest these complex carbohydrates , or they 'll have to start eating the sugars in the mucus lining of your intestines . your personal gas will vary based on what you eat , and what bacteria are in your gut . for example , from the same starting sugar , the bacteria clostridium produces carbon dioxide , butyrate and hydrogen , while propionibacterium can produce carbon dioxide , propionate and acetate . at the same time , methanogens can use hydrogen and carbon dioxide produced by other bacteria to generate methane , which can reduce the total volume of gas by using up hydrogen and carbon dioxide . so there 's a complex web among intestinal bacteria allowing them to flourish by either directly consuming undigested food , or using what other bacteria produce . this interaction largely determines the amount and type of gas produced , so gas production is a sign that your gut bacteria are at work . but in some instances , people may develop abnormal increased flatulence . a common example is lactose intolerance . most individuals have the enzyme for breaking down lactose , a sugar present in milk and milk-derived products . but some people either lack it entirely , or have a reduced amount , such as after a gastrointestinal infection , so they 're unable to digest lactose products and may experience cramping , along with increased flatulence due to bacterial fermentation . but remember , most gas is produced as a natural result of bacterial fermentation in the intestine , and indicates healthy functioning of the gut . the amount and type can vary based on your diet and the bacteria in your intestine . exercise social courtesy while passing gas , and do try to forgive your bacteria . they 're only trying to be helpful .

flatulence , or passing gas , is a normal daily phenomenon . most individuals , yes , that includes you , will make anywhere from 500-1500 milliliters of gas and can pass gas ten to twenty times a day .

based on what you learned in the video , which foods could you consume that would give you less flatulence ? create a menu for a four-course flatulence-free family function !

it was much more exciting than i thought . you see the flames . our first video of fluorine was a bit disappointing . there wasn ’ t any , just a few bits of glassware and some funny stories . so at the moment i ’ m in the office of professor eric hope who is one of the country ’ s specialists in fluorine chemistry . he knows how to handle this terrific element safely . i have no idea what to do . i ’ m quite excited to see what happens . one of the things you said in that original video was , on youtube , was that fluorine was one of the few elements that you hadn ’ t seen so i thought there are actually relatively few chemists who have seen fluorine . so what i want to do is produce and show you elemental fluorine . fluorine is slowly released ; you see the pressure slowly going up . the reason that people know about fluorine is that it is one of the really reactive elements . it will react with all the elements of the periodic table , except neon and helium . it will react with gold , it ’ ll react with silver , it ’ ll react with platinum . platinum hexafluoride is bright red as it ’ s a gas . ok so fluorine is going into the apparatus , it ’ s going into this tube . martyn , you can ’ t see anything can you ? i can ’ t see anything at all . you can ’ t see anything at all , and that ’ s because there ’ s only a little under 2 atmospheres of fluorine in there . it ’ s a very pale yellow colour as a gas . a bit disappointed but i suppose it ’ s like oxygen or nitrogen , you can ’ t really see it . but perhaps if we condense it as a liquid then i ’ ll see it properly . ok so now i ’ m going to cool this down with liquid nitrogen to -196oc . i ’ m going to do it slowly . it will take a little while . ok martyn , do you want to help me with this ? yep . so what i want to do is for you to take that flask away and i ’ ll slide this one in . so if you slide it away and back up again . and there we have , oh maybe two inches of liquid fluorine . you can go right up that , there ’ s no problem with that if you want to . just , clear a bit of condensation off there . yeah i ’ m really surprised i thought it would be pale green and its dark yellow . if i ’ d been shown it i ’ d thought it was liquid chlorine . but i ’ ve never seen liquid chlorine either . i ’ m quite pleased with that . so , basically i ’ ve got another fluorine cylinder filled up from the roof with about 5 atmospheres of fluorine in it . so this is now going to release the fluorine . and what i ’ ve got in this demonstration here is just a scouring pad . it ’ s a metal scouring pad , iron wool . it burnt a hole right through the iron wool . it ’ s extraordinary . the iron looks as if it ’ s rusted but the rusty colour is actually iron fluoride or maybe a bit of iron oxide from the hot iron reacting with the oxygen in the air . well the reason that fluorine makes such strong bonds is because it is a small atom and the nucleus is relatively highly charged because it ’ s right on the right-hand side of the periodic table but the electrons don ’ t shield this nucleus . so it is very , so-called , electronegative . it attracts electrons to itself from other elements . i ’ ve changed the prop now for some just normal barbeque briquettes which is pure carbon . so we haven ’ t done anything . this is cold charcoal and cold gas , and the gas just touching it is enough to start the fire . think of that : just the cold gas setting things on fire . most chemists are really too frightened to work with fluorine . you can ’ t use it in glass vessels . it doesn ’ t attack glass but if the glass is a tiny bit wet and most glass has moisture absorbed into it , then the fluorine form hydrogen fluoride and it reacts with the water and the hydrogen fluoride just eats through the glass . so you need to use equipment made out of metal , usually nickel , and the fluorine reacts with the surface of the nickel , the first time you use it and then you get a layer on the surface that protects the rest of the metal . so this is again fluorine with sulphur . so you are going to oxidise the sulphur , probably to sulphur tetrafluoride or sulphur hexafluoride . fluorine has this reputation for being very reactive and very dangerous and something to be careful about . but aren ’ t their fluorine atoms in my toothpaste ? your toothpaste contains fluoride and , just in the same way that you can eat sodium chloride , table salt which contains chlorine , you can use fluorides and once the fluorine has got an extra electron , for example from the tin in tin fluoride , which is often used in toothpaste or sodium fluoride . it ’ s got what it wants and it ’ s not very reactive . and the way it works with teeth is that the enamel of your teeth is a compound of calcium called appetite , which normally the appetite in your teeth can dissolve quite easily in acid . for example , if you eat sweets or drink some fizzy drinks then you have enough acid to start dissolving the surface of your teeth . but if you brush your teeth with fluoride , some of the appetite , which contains oh groups , some of these are replaced with fluoride and you make a material called fluoral appetite which is much less soluble in acid so it can ’ t attacked so easily , so you don ’ t get holes in your teeth .

fluorine has this reputation for being very reactive and very dangerous and something to be careful about . but aren ’ t their fluorine atoms in my toothpaste ? your toothpaste contains fluoride and , just in the same way that you can eat sodium chloride , table salt which contains chlorine , you can use fluorides and once the fluorine has got an extra electron , for example from the tin in tin fluoride , which is often used in toothpaste or sodium fluoride .

how does the professor calm brady down when he becomes concerned about the fluorine in his toothpaste ?

when we talk about english , we often think of it as a single language but what do the dialects spoken in dozens of countries around the world have in common with each other , or with the writings of chaucer ? and how are any of them related to the strange words in beowulf ? the answer is that like most languages , english has evolved through generations of speakers , undergoing major changes over time . by undoing these changes , we can trace the language from the present day back to its ancient roots . while modern english shares many similar words with latin-derived romance languages , like french and spanish , most of those words were not originally part of it . instead , they started coming into the language with the norman invasion of england in 1066 . when the french-speaking normans conquered england and became its ruling class , they brought their speech with them , adding a massive amount of french and latin vocabulary to the english language previously spoken there . today , we call that language old english . this is the language of beowulf . it probably does n't look very familiar , but it might be more recognizable if you know some german . that 's because old english belongs to the germanic language family , first brought to the british isles in the 5th and 6th centuries by the angles , saxons , and jutes . the germanic dialects they spoke would become known as anglo-saxon . viking invaders in the 8th to 11th centuries added more borrowings from old norse into the mix . it may be hard to see the roots of modern english underneath all the words borrowed from french , latin , old norse and other languages . but comparative linguistics can help us by focusing on grammatical structure , patterns of sound changes , and certain core vocabulary . for example , after the 6th century , german words starting with `` p , '' systematically shifted to a `` pf '' sound while their old english counterparts kept the `` p '' unchanged . in another split , words that have `` sk '' sounds in swedish developed an `` sh '' sound in english . there are still some english words with `` sk , '' like `` skirt , '' and `` skull , '' but they 're direct borrowings from old norse that came after the `` sk '' to `` sh '' shift . these examples show us that just as the various romance languages descended from latin , english , swedish , german , and many other languages descended from their own common ancestor known as proto-germanic spoken around 500 b.c.e . because this historical language was never written down , we can only reconstruct it by comparing its descendants , which is possible thanks to the consistency of the changes . we can even use the same process to go back one step further , and trace the origins of proto-germanic to a language called proto-indo-european , spoken about 6000 years ago on the pontic steppe in modern day ukraine and russia . this is the reconstructed ancestor of the indo-european family that includes nearly all languages historically spoken in europe , as well as large parts of southern and western asia . and though it requires a bit more work , we can find the same systematic similarities , or correspondences , between related words in different indo-european branches . comparing english with latin , we see that english has `` t '' where latin has `` d '' , and `` f '' where latin has `` p '' at the start of words . some of english 's more distant relatives include hindi , persian and the celtic languages it displaced in what is now britain . proto-indo-european itself descended from an even more ancient language , but unfortunately , this is as far back as historical and archeological evidence will allow us to go . many mysteries remain just out of reach , such as whether there might be a link between indo-european and other major language families , and the nature of the languages spoken in europe prior to its arrival . but the amazing fact remains that nearly 3 billion people around the world , many of whom can not understand each other , are nevertheless speaking the same words shaped by 6000 years of history .

when the french-speaking normans conquered england and became its ruling class , they brought their speech with them , adding a massive amount of french and latin vocabulary to the english language previously spoken there . today , we call that language old english . this is the language of beowulf .

english is a member of the _____ language group .

in 1985 , 16-year-old douglas casa , ran the championship 10,000 meter track race at the empire state games . suddenly , with just 200 meters to go , he collapsed , got back up and then collapsed again on the final straightaway , with his body temperature at dangerous levels . he had suffered an exertional heat stroke . fortunately , with immediate and proper treatment , he survived the potentially fatal episode and has since helped save 167 people in similar circumstances . from ancient soldiers on the battlefield to modern day warriors on the gridiron , exertional heat stroke , or sunstroke , has long been a serious concern . and unlike classical heat stroke , which affects vulnerable people such as infants and the elderly during heat waves , exertional heat stroke is caused by intense exercise in the heat , and is one of the top three killers of athletes and soldiers in training . when you exercise , nearly 80 % of the energy you use is transformed into heat . in normal circumstances , this is what 's known as compensable heat stress . and your body can dissipate the heat as quickly as it 's generated through cooling methods like the evaporation of sweat . but with uncompensable heat stress , your body is unable to lose enough heat due to overexertion or high temperatures in humidity , which raises your core temperature beyond normal levels . this causes the proteins and cell membranes to denature , creating cells that no longer function properly and begin to leak their contents . if these leaky cells proliferate through the body , the results can be devastating . including liver damage , blood clot formation in the kidneys , damage to the gastrointestinal tract and even the failure of vital organs . so how do you diagnose an exertional heat stroke ? the main criterion is a core body temperature greater than 40 degrees celsius observed along with physical symptoms such as increased heart rate , low blood pressure and rapid breathing or signs of central nervous system disfunction such as confused behavior , aggression or loss of consciousness . the most feasible and accurate way to assess core body temperature is with a rectal thermometer as other common temperature-taking methods are not accurate in these circumstances . as far as treatment goes , the most important thing to remember is cool first , transport second . because the human body can withstand a core temperature above 40 degrees celsius for about 30 minutes before cell damage sets in , it 's essential to initiate rapid cooling on site in order to lower it as quickly as possible . after any athletic or protective gear has been removed from the victim , place them in an ice water tub while stirring the water and monitoring vitals continuously . if this is not possible , dousing in ice water and applying wet towels over the entire body can help . but before you start anything , emergency services should be called . as you wait , it 's important to keep the victim calm while cooling as much surface area as possible until emergency personnel arrive . if medical staff are available on site , cooling should continue until a core temperature of 38.9 degrees celsius is reached . the sun is known for giving life , but it can also take life away if we 're not careful , even affecting the strongest among us . as dr. jj levick wrote of exertional heat stroke in 1859 , `` it strikes down its victim with his full armor on . youth , health and strength oppose no obstacle to its power . '' but although this condition is one of the top three leading causes of death in sports , it has been 100 % survivable with proper care .

suddenly , with just 200 meters to go , he collapsed , got back up and then collapsed again on the final straightaway , with his body temperature at dangerous levels . he had suffered an exertional heat stroke . fortunately , with immediate and proper treatment , he survived the potentially fatal episode and has since helped save 167 people in similar circumstances .

what is the best method for cooling someone with exertional heat stroke ?

4,000 years ago , the ancient sumerians made a surprising discovery . if they scraped the bark off a particular kind of tree and ate it , their pain disappeared . little did they know that why they 'd found was destined to influence the future course of medicine . what the sumerians had discovered was a precursor to the medicine known today as aspirin . aspirin 's active ingredient is found commonly in willow trees and other wild plants , which is how it came to infuse the medical traditions of sumer , ancient egypt , ancient greece , and other cultures . around 400 bc , hippocrates , thought of as the father of modern medicine , first recommended chewing willow bark for pain relief and making willow leaf tea to ease the pain of childbirth . but it took over 2,000 years for us to comprehensively investigate its potential . in the mid-18th century , an englishman named edward stone ran five years of experiments , showing that willow bark crushed into a powder and eaten could cure a fever . it took nearly another 70 years for a german pharmacist , johann buchner , to finally identify and purify the substance that made all this possible , a compound called salicin . by then , doctors were routinely using willow bark and other salicin-rich plants , like the herb meadowsweet , to ease pain , fever , and inflammation . but identifying the exact compound suddenly opened up the possibility of manipulating its form . in 1853 , a french chemist managed to chemically synthesize the compound , creating a substance called acetylsalicylic acid . then in 1897 , the pharmaceutical company bayer found a new method and began marketing the compound as a pain reliever called aspirin . this was widely recognized as one of the first synthetic pharmaceutical drugs . originally , aspirin was just bayer 's brand name : a for acetyl , and spir for meadowsweet , whose botanical name is spiraea ulmaria . soon , aspirin became synonymous with acetylsalicylic acid . as its influence grew , aspirin was found to ease not just pain , but also many inflammation-related problems , like rheumatoid arthritis , pericarditis , which enflames the fluid-filled sack around the heart , and kawasaki disease , where blood vessels become inflamed . yet , despite aspirin 's medical value , at this point , scientists still did n't actually know how it worked . in the 1960s and 70s , swedish and british scientists changed that . they showed that the drug interrupts the production of certain chemicals called prostaglandins , which control the transmission of pain sensations and inflammation . in 1982 , that discovery won the researchers a nobel prize in medicine . over time , research has also uncovered aspirin 's risks . overconsumption can cause bleeding in the intestines and the brain . it can also trigger reye 's syndrome , a rare but often fatal illness that affects the brain and liver in children with an infection . and in the late 20th century , aspirin 's success had been overshadowed by newer pain killers with fewer side effects , like acetaminophen and ibuprofen . but in the 1980s , further discoveries about aspirin 's benefits revived interest in it . in fact , the 1982 nobel prize winners also demonstrated that aspirin slows production of thromboxanes , chemicals that cause clumping of platelets , which in turn form blood clots . a landmark clinical trial showed that aspirin reduced heart attack risk by 44 % in participants who took the drug . today , we prescribe it to people at risk of heart attack or stroke because it cuts the likelihood of clots forming in the arteries that supply the heart and brain . even more intriguingly , there 's a growing body of research that suggests aspirin reduces the risk of getting and dying from cancer , especially colorectal cancer . this might be due to aspirin 's anti-platelet effects . by reducing platelet activity , aspirin may decrease the levels of a certain protein that helps cancer cells spread . these discoveries have transformed aspirin from a mere pain reliever to a potentially life-saving treatment . today , we consume about 100 billion aspirin tablets each year , and researchers continue searching for new applications . already , aspirin 's versatility has transformed modern medicine , which is astounding considering its humble beginnings in a scraping of willow bark .

originally , aspirin was just bayer 's brand name : a for acetyl , and spir for meadowsweet , whose botanical name is spiraea ulmaria . soon , aspirin became synonymous with acetylsalicylic acid . as its influence grew , aspirin was found to ease not just pain , but also many inflammation-related problems , like rheumatoid arthritis , pericarditis , which enflames the fluid-filled sack around the heart , and kawasaki disease , where blood vessels become inflamed .

which of the following is not likely to be an adverse event resulting from aspirin use ?

baked or fried , boiled or roasted , as chips or fries . at some point in your life , you 've probably eaten a potato . delicious , for sure , but the fact is potatoes have played a much more significant role in our history than just that of the dietary staple we have come to know and love today . without the potato , our modern civilization might not exist at all . 8,000 years ago in south america , high atop the andes , ancient peruvians were the first to cultivate the potato . containing high levels of proteins and carbohydrates , as well as essential fats , vitamins and minerals , potatoes were the perfect food source to fuel a large incan working class as they built and farmed their terraced fields , mined the rocky mountains , and created the sophisticated civilization of the great incan empire . but considering how vital they were to the incan people , when spanish sailors returning from the andes first brought potatoes to europe , the spuds were duds . europeans simply did n't want to eat what they considered dull and tasteless oddities from a strange new land , too closely related to the deadly nightshade plant belladonna for comfort . so instead of consuming them , they used potatoes as decorative garden plants . more than 200 years would pass before the potato caught on as a major food source throughout europe , though even then , it was predominantly eaten by the lower classes . however , beginning around 1750 , and thanks at least in part to the wide availability of inexpensive and nutritious potatoes , european peasants with greater food security no longer found themselves at the mercy of the regularly occurring grain famines of the time , and so their populations steadily grew . as a result , the british , dutch and german empires rose on the backs of the growing groups of farmers , laborers , and soldiers , thus lifting the west to its place of world dominion . however , not all european countries sprouted empires . after the irish adopted the potato , their population dramatically increased , as did their dependence on the tuber as a major food staple . but then disaster struck . from 1845 to 1852 , potato blight disease ravaged the majority of ireland 's potato crop , leading to the irish potato famine , one of the deadliest famines in world history . over a million irish citizens starved to death , and 2 million more left their homes behind . but of course , this was n't the end for the potato . the crop eventually recovered , and europe 's population , especially the working classes , continued to increase . aided by the influx of irish migrants , europe now had a large , sustainable , and well-fed population who were capable of manning the emerging factories that would bring about our modern world via the industrial revolution . so it 's almost impossible to imagine a world without the potato . would the industrial revolution ever have happened ? would world war ii have been lost by the allies without this easy-to-grow crop that fed the allied troops ? would it even have started ? when you think about it like this , many major milestones in world history can all be at least partially attributed to the simple spud from the peruvian hilltops .

containing high levels of proteins and carbohydrates , as well as essential fats , vitamins and minerals , potatoes were the perfect food source to fuel a large incan working class as they built and farmed their terraced fields , mined the rocky mountains , and created the sophisticated civilization of the great incan empire . but considering how vital they were to the incan people , when spanish sailors returning from the andes first brought potatoes to europe , the spuds were duds . europeans simply did n't want to eat what they considered dull and tasteless oddities from a strange new land , too closely related to the deadly nightshade plant belladonna for comfort . so instead of consuming them , they used potatoes as decorative garden plants .

what other reasons could the europeans have had for not wanting to eat potatoes at first ?

in 1985 , three researchers on a dolphin-studying expedition got a little bored . to lighten things up , one pretended to be poseidon by placing a seaweed garland on his head and then throwing it into the ocean . moments later , a dolphin surfaced with the seaweed crowning her head . sure , this could have been a coincidence , but it 's also entirely possible that the dolphin was mimicking the scientist . that 's because dolphins are one of the smartest animals species on earth . so exactly how smart are they ? like whales and porpoises , dolphins belong to the group of aquatic mammals known as cetaceans who comprise 86 different species , and share a common link with ungulates , or hoofed animals . originally land mammals , the first cetaceans entered the water about 55 million years ago as large predators with sharp teeth . then , a shift in ocean temperatures about 35 million years ago reduced the availability of prey . one group of cetaceans who survived this distruption , the odontocetes , wound up smaller with less sharp teeth , but also larger and more complex brains that allowed for complex social relationships , as well as echolocation to navigate and communicate . jump ahead to the present , and modern dolphins ' brains are so large that their encephalization quotient , their brain size compared to the average for their body size , is second only to humans . dolphins have evolved to survive through their ability to form complex social networks that hunt , ward off rivals , and raise offspring together . for example , one group of florida dolphins practices a sophisticated form of cooperation to hunt fish . a dolphin designated as `` the net-maker '' kicks up mud while another gives the signal for the other dolphins to simultaneously line up and catch the escaping fish . achieving a goal like this requires deliberate planning and cooperation , which , in turn , requires some form of intentional communication . dolphins pass down their communication methods and other skills from generation to generation . different dolphin populations exhibit variations in greetings , hunting strategies , and other behaviors . this sort of cultural transmission even extends to tool use . one group of bottlenose dolphins off the australian coast nicknamed the dolphin sponge club , has learned how to cover their rostrums with sponges when rooting in sharp corals , passing the knowledge from mother to daughter . dolphins have even demonstrated language comprehension . when taught a language based on whistles and hand gestures , they not only understood what the signals meant , but that their order had meaning : the difference between bringing the ball to the hoop and bringing the hoop to the ball . so they were able to process two of the main elements of human language : symbols that stand for objects and actions , and syntax that governs how they are structured . dolphins are also one of the few species who pass the mirror test . by recognizing themselves in mirrors , they indicate physical self-awareness , and research shows they can recognize not just their bodies , but also their own thoughts , a property called metacognition . in one study , dolphins comparing two sounds could indicate a same , different , or uncertain response . just like humans , they indicated uncertainty more often with difficult trials , suggesting they 're aware of what they know , and how confident they feel about that knowledge . but some of the most amazing things about dolphins are their senses of empathy , altruism , and attachment . the habit of helping injured individuals extends across the species barrier as evidenced by the many accounts of dolphins carrying humans to the surface to breathe . and like us , dolphins mourn their dead . when we consider all the evidence , we may wonder why humans still hunt dolphins for meat , endanger them through fishing and pollution , or imprison them to perform tricks . the ultimate question may not be whether dolphins are intelligent and complex beings , but whether humans can empathize with them enough to keep them safe and free .

one group of bottlenose dolphins off the australian coast nicknamed the dolphin sponge club , has learned how to cover their rostrums with sponges when rooting in sharp corals , passing the knowledge from mother to daughter . dolphins have even demonstrated language comprehension . when taught a language based on whistles and hand gestures , they not only understood what the signals meant , but that their order had meaning : the difference between bringing the ball to the hoop and bringing the hoop to the ball .

dolphins have metacognition . this means :

this is the microraptor , a carnivorous four-winged dinosaur that was almost two-feet long , ate fish , and lived about 120 million years ago . most of what we know about it comes from fossils that look like this . so , is its coloration here just an artist 's best guess ? the answer is no . we know this shimmering black color is accurate because paleontologists have analyzed clues contained within the fossil . but making sense of the evidence requires careful examination of the fossil and a good understanding of the physics of light and color . first of all , here 's what we actually see on the fossil : imprints of bones and feathers that have left telltale mineral deposits . and from those imprints , we can determine that these microraptor feathers were similar to modern dinosaur , as in bird , feathers . but what gives birds their signature diverse colorations ? most feathers contain just one or two dye-like pigments . the cardinal 's bright red comes from carotenoids , the same pigments that make carrots orange , while the black of its face is from melanin , the pigment that colors our hair and skin . but in bird feathers , melanin is n't simply a dye . it forms hollow nanostructures called melanosomes which can shine in all the colors of the rainbow . to understand how that works , it helps to remember some things about light . light is basically a tiny electromagnetic wave traveling through space . the top of a wave is called its crest and the distance between two crests is called the wavelength . the crests in red light are about 700 billionths of a meter apart and the wavelength of purple light is even shorter , about 400 billionths of a meter , or 400 nanometers . when light hits the thin front surface of a bird 's hollow melanosome , some is reflected and some passes through . a portion of the transmitted light then reflects off the back surface . the two reflected waves interact . usually they cancel each other out , but when the wavelength of the reflected light matches the distance between the two reflections , they reinforce each other . green light has a wavelength of about 500 nanometers , so melanosomes that are about 500 nanometers across give off green light , thinner melanosomes give off purple light , and thicker ones give off red light . of course , it 's more complex than this . the melanosomes are packed together inside cells , and other factors , like how the melanosomes are arranged within the feather , also matter . let 's return to the microraptor fossil . when scientists examined its feather imprints under a powerful microscope , they found nanostructures that look like melanosomes . x-ray analysis of the melanosomes further supported that theory . they contained minerals that would result from the decay of melanin . the scientists then chose 20 feathers from one fossil and found that the melanosomes in all 20 looked alike , so they became pretty sure this dinosaur was one solid color . they compared these microraptor melanosomes to those of modern birds and found a close similarity , though not a perfect match , to the iridescent teal feathers found on duck wings . and by examining the exact size and arrangement of the melanosomes , scientists determined that the feathers were iridescent black . now that we can determine a fossilized feather 's color , paleontologists are looking for more fossils with well-preserved melanosomes . they 've found that a lot of dinosaurs , including velociraptor , probably had feathers , meaning that certain films might not be so biologically accurate . clever girls .

first of all , here 's what we actually see on the fossil : imprints of bones and feathers that have left telltale mineral deposits . and from those imprints , we can determine that these microraptor feathers were similar to modern dinosaur , as in bird , feathers . but what gives birds their signature diverse colorations ?

microraptor 's melanosomes most closely resemble those of which modern-day bird species ?

good morning hank , it 's tuesday . so earlier this morning , i was kayaking on the white river . i came to an island that only exists when the water is low , so i had to choose which stream to follow down . i thought as i always do in these situations of robert frost 's poem , the road not taken . you know , the one that ends in , `` two roads diverged in a yellow wood , and i took the one less travelled by , and that has made all the difference . '' so i followed the road that seemed the less obvious choice . it turns out that it was the less obvious for a reason . so hank , the road not taken is an interesting poem because 1. it 's kind of responsible for the death of the person it was written for and 2. what most people conclude from the poem is the exact opposite of what robert frost intended to conclude . and also , 3. this dissonance points at something terrible about poetry i think hank . but let 's start with 1 - that dead guy . so robert frost was inspired to write this poem by the many walks he took with his friend , the english poet , edward thomas . thomas was very obsessive and indecisive person , and every time they 'd come to a fork in the road , he would n't know which one to take . you know , like how if you 're in the english countryside and if you choose the wrong path , you might get eaten by a lion . but you ca n't know that until after you 've made the choice . i assume that there 'd be lions in england , at least dandy lions . in frost 's mind , the poem was gently mocking people who obsess over the importance of tiny , little decisions , right ? but as often happens with people who are mocked too gently , edward thomas did n't get the joke and took the poem very , very seriously . and so even though edward thomas was too old to be expected to enlist , he went ahead and took the road less travelled , joining the british army to fight in wii , where upon he was promptly shot through the chest and killed . since then hank , pretty much everyone , including me , has adopted edward thomas ' interpretation of the poem despite the fact that it , you know , killed him . i think there 's just something alluring about the idea choosing the less travelled is always a good idea . it would be very helpful if there was some overarching guideline , like `` follow the path that others do n't . '' also , following the road less taken has the added advantage of making everyone feel like a non-conformist , which is nice . but of course , there are a bunch of problems . for one thing , if everyone followed the road less travelled , it quickly becomes the road more travelled . furthermore , there are many times when the road more travelled is more travelled for a reason , because for instance , the road less travelled leads to a kayak unfriendly marsh . or because there 's something kind of nice about having a spouse and two kids and a mini-van . anyways hank , i 've been thinking about this a lot because over at our podcast , dear hank and john , we 've been getting a lot of questions from listeners who are making huge life decisions , you know , should i go into the military ? which college should i attend ? should i attend college at all ? as humans , we constantly have to make all these big , big decisions , with very limited information . like hank , we are both incredibly blessed to have great marriages and great spouses , but i had no idea what i was agreeing to on my wedding day . i thought i was saying , `` i want to be in a romantic relationship with you for the rest of my life . '' i did not realize that i was also saying , `` i want to be co-ceos of a company that raises children and mows lawns and stuff . '' anyways hank , the other thing about dear hank and john is that i insist on beginning each episode with a short poem . and so in the last few weeks , we 've had a bunch of discussions about poetry - whether poetry matters , what poetry does , etc . and i think we have the road not taken as one answer about what poetry can do . because poetry is so often musical and rhythmic , it has a way of sticking in our heads , like i memorized it almost by accident . frost thought that the poem was exploring how people experience choice making rather than offering advice , but precisely because it sounds good hank , it seems like good advice . and even though i know it is n't good advice , at least not consistently , i suspect that the next time i am facing a fork in the road or fork in the river , those iambic feet will wander back into my mind . and i will once again be biased , however minutely , toward the road less travelled . i guess that 's one example of how i think poetry can really matter in the real lives of real people , hank , and why i think that poets and readers alike need to be very careful with language . after all hank , we do n't want to end up like edward thomas , but we also do n't want to end up like the poet , who at least in a roundabout way , killed him . hank , i 'll see you on friday .

and i think we have the road not taken as one answer about what poetry can do . because poetry is so often musical and rhythmic , it has a way of sticking in our heads , like i memorized it almost by accident . frost thought that the poem was exploring how people experience choice making rather than offering advice , but precisely because it sounds good hank , it seems like good advice .

john green says , `` poetry is so often musical and rhythmic it has a way of sticking in our heads . '' what are some sound devices frost uses in `` the road not taken '' that make it musical and rhythmic ?

translator : tom carter reviewer : bedirhan cinar in society , we have to follow laws that maintain order . did you know all chemical matter follows certain laws as well ? in fact , we can describe those laws by looking at relationships . some easy laws to begin with are the ones that govern the gases . back in 1662 , robert boyle realized that gases had an interesting response when he put them into containers and changed their volume . take an empty bottle and put the cap on it , closing that container . now squeeze your bottle , and what happens ? the pressure inside the bottle increases when the size of the container decreases . you can only crush that container so much until the gases inside push back on your hand . this is called an inverse proportion , and it changes at the same rate for every gas . boyle 's law allows chemists to predict the volume of any gas at any given pressure because the relationship is always the same . in 1780 , jacques charles noticed a different relationship between gases and their temperature . if you 've ever seen a hot-air balloon , you 've seen this law in action . when the ballons are laid out , they 're totally flat . instead of blowing the balloon up like a party balloon , they use a giant flame to heat the air inside that envelope . as the air is heated up , the balloon begins to inflate as the gas volume increases . the hotter the gas becomes , the larger the volume , and that 's charles ' law . notice this law is different from boyle 's . charles ' law is a direct relationship . as the temperature increases , the volume increases as well . the third law is also easily demonstrated . when you 're blowing up party balloons , the volume increases . as you are blowing , you 're forcing more and more gas particles into the balloon from your lungs . this causes the balloon volume to increase . this is avogadro 's law in action . as the number of particles of gas added to a container are increased , the volume will increase as well . if you add too many particles , well , you know what happens next . laws are everywhere , even in the tiniest particles of gas . if you squeeze them , the pressure will increase as the particles are pushed together . low volume means a high pressure because those particles push back . as the temperature increases , gases move away from one another , and the volume increases as well . finally , if you add gas to a closed container , that container 's volume will expand . but be careful not to add too much , because otherwise you could end up with a burst balloon .

as the temperature increases , gases move away from one another , and the volume increases as well . finally , if you add gas to a closed container , that container 's volume will expand . but be careful not to add too much , because otherwise you could end up with a burst balloon .

if a gas is cooled , how does the volume change ?

this is a thinker who helps us understand why our lives and relationships are full of so much confusion and pain . he tells us why life is hard , and how to cope . his own life incurred a lot of anxiety . sigmund schlomo freud was born to a middle-class jewish family in 1856 . his professional life was not an immediate success . as a medical student , he dissected hundreds of eels in an unsuccessful attempt to locate their reproductive organs . he promoted cocaine as a medical drug , but it turned out to be a dangerous and addictive idea . a few years later he founded the discipline that would ultimately make his name . a new psychological medicine he called psychoanalysis the landmark study was his 1900 book the interpretation of dreams . many others followed . despite his success , he was often unhappy . during some particularly strenuous research he recorded , “ the chief patient i am preoccupied with is myself… ” he was convinced he would die between 61 and 62 and had great phobias about those numbers . ( although he actually died much later , at age 83 . ) perhaps because of his frustrations , freud achieved a series of deep insights into the sources of human unhappiness . he proposed that we are all driven by the : pleasure principle which inclines us towards easy physical and emotional rewards : and away from unpleasant things like drudgery and discipline . as infants we are guided more or less solely according to the pleasure principle , freud argued . but it will , if adhered to without constraints , lead us to dangerous reckless things : like never doing any work eating too much or , most notoriously , sleeping with members of own family . we need to adjust to what freud called the reality principle though we all have to bow to this reality principle , freud believed that there were better and worse kinds of adaptations . he called the troublesome ones neuroses neuroses are the result of faulty negotiations with –or in freud ’ s language , repression of–the pleasure principle . freud described a conflict between three parts of our minds : the id driven by the pleasure principle , and the the superego driven by a desire to follow the rules and do the right thing according to society . and the ego which has to somehow accomodate the two . to understand more about these dynamics , freud urged us to think back to the origins of our neuroses in childhood . as we grow up , we go through what freud termed : the oral phase where we deal with all the feelings around ingestion and eating . if our parents aren ’ t careful we might pick up all kinds of neuroses here : we might take pleasure in refusing food , or turn to food to calm ourselves down , or hate the idea of depending on anyone else for food . then comes the anal phase which is closely aligned with what we now call “ potty-training ” . during this period , our parents tell us what to do -- and when to go . at this phase we begin to learn about testing the limits of authority . again , if things go wrong , if we don ’ t feel authority is benign enough , we might , for example , choose to withhold out of defiance . then , as adults , we might become “ anally retentive ” ; in other words , not able to give or surrender . next comes : the phallic phase which goes until about age 6 . freud shocked his contemporaries by insisting that little children have sexual feelings . moreover , in the phallic phase children direct their sexual impulses towards their parents , the most immediately available and gratifying people around . freud famously described what he called the oedipus complex where we are unconsciously predisposed towards “ being in love with the one parent and hating the other. ” what is complex is that no matter how much our parents love us , they can not extend this to sexual life and will always have another life with a partner . this makes our young selves feel dangerously jealous and angry – and also ashamed and guilty about this anger . the complex provides a huge amount of internalised worry for a small child . ultimately , most of us experience some form of confusion around our parents that later ties into our ideas of love . mum and dad may both give us love , but they often mix it in with disturbed behaviour . yet because we love them , we remain loyal to them and also to their bizarre , destructive patterns . for example , if our mother is cold , we will be apt nevertheless to long for her . and as a result , however , we may be prone to always associate love with a certain distance . naturally , the result is very difficult adult relationships . often the kind of love we ’ ve learned from mum and dad means we can ’ t fuse sex and love because the people we learnt about love from are also those we were blocked from having sex with . we might find that the more in love with someone we are , the harder it becomes to make love to them . this can reach a pitch of crisis after a few years of marriage and some kids . freud compared the issues we so often have with intimacy to hedgehogs in the winter : they need to cuddle for warmth , but they also can ’ t come too close because they ’ re prickly . there ’ s no easy solution . freud says we can ’ t make ourselves fully rational , and we can ’ t change society , either . in his 1930 book civilisation and its discontents , freud wrote that society provides us with many things , but it does this by imposing heavy dictates on us : insisting that we sleep with only a few ( usually one ) other , imposing the incest taboo , requiring us to put off our immediate desires , demanding that we follow authority and work to make money . societies themselves are neurotic–that is how they function - and it ’ s why there are constant wars and other troubles . freud attempted to invent a treatment for our many neuroses : psychoanalysis . he thought that with a little proper analysis , people could uncover what ails them and better adjust to the difficulties of reality . in his sessions he analysed a number of key things . he looked at people ’ s dreams , which he saw as expressions of wish fulfillments he also looked at parapraxes or slips of the tongue . we now call these revealing mistakes freudian slips like when we write ‘ thigh ’ when we wanted to write ‘ though ’ . he also liked to think about jokes . he believed that jokes often help us make fun of something symbolic like death or marriage , and thus relieve some of our anxiety about these topics . there ’ s a temptation to say freud just made everything up , and life isn ’ t quite so hard as he makes it out to be . but then one morning we find ourselves filled with inexplicable anger towards our partner , or running high with unrelenting anxiety on the train to work , and we ’ re reminded all over again just how elusive , difficult , and freudian our mental workings actually are . we could still reject his work , of course . but as freud said , “ no one who disdains the key will ever be able to unlock the door. ” we could all use a bit more of freud ’ s ideas to help us unpick ourselves .

he proposed that we are all driven by the : pleasure principle which inclines us towards easy physical and emotional rewards : and away from unpleasant things like drudgery and discipline . as infants we are guided more or less solely according to the pleasure principle , freud argued . but it will , if adhered to without constraints , lead us to dangerous reckless things : like never doing any work eating too much or , most notoriously , sleeping with members of own family .

according to freud , we are governed by our struggle to balance the pleasure principle and the reality principle . which of these is an example of this struggle ?

translator : tom carter reviewer : bedirhan cinar it 's march the 17th in a.d. 73 . we 're visiting ancient rome to watch the liberalia , an annual festival that celebrates the liberty of rome 's citizens . we 're looking in at a 17-year-old named lucius popidius secundus . he 's not from a poor family , but he lives in the region known as the subura , a poorer neighborhood in rome , yet close to the center of the city . ( gong ) the tenants of these apartments are crammed in , ( grunting ) which poses considerable risk . fires are frequent and the smell of ash and smoke in the morning is not uncommon . lucius , who awoke at dawn , has family duties to perform today . ( cheering ) his 15-year-old brother is coming of age . half the children in ancient rome die before they reach adulthood , so this is a particularly important milestone . lucius watches his brother stand in his new toga before the household shrine with its protective deities , as he places his bulla , a protective amulet , in the shrine with a prayer of thanks . the bulla had worked . it had protected him . unlike many others , he had survived to become an adult . at 17 , lucius has almost completed his education . he has learned to speak well , make public speeches , and how to read and write both latin and greek . his father has taught him the types of things you ca n't learn in the classroom : how to run , how to swim , and how to fight . lucius could choose , at 17 , to become a military tribune and command soldiers on the edge of the empire . but in other ways , lucius is still a child . he 's not trusted to arrange business deals . his father will take care of that until he is 25 . and dad will arrange lucius ' marriage to a girl 10 years younger . his dad has his eye on a family with a 7-year-old daughter . back to the liberalia . as lucius leaves with his family , the shops are open as the population goes about its business . the streets are full of itinerant traders selling trinkets and people bustling from place to place . large wagons are not allowed in the city until after the ninth hour but the streets are still crowded . fathers and uncles take the kids to the forum augustus to see statues of rome 's famous warriors like aeneas , who led rome 's ancestors , the trojans , to italy . and romulus , rome 's founder . and all the great generals of the republic from more than 100 years earlier . lovingly , we can imagine fathers and guardians with their now adult children remembering stories of rome 's glory and re-telling the good deeds and sayings of the great men of the past : lessons on how to live well , and to overcome the follies of youth . there is a sense of history in this place , relevant to their present . romans made an empire without end in time and space . ( thump ) rome was destined to be eternal through warfare . wars were a fact of life , even in a.d. 73 . there are campaigns in the north of england and into scotland , to the north of the river danube into romania , and on the frontier between syria and iraq to the east . it 's now the eighth hour -- time to head for the baths . lucius and his family head up the via lata , the wide street , to the campus martius , and the enormous baths of agrippa . the family members leave the clients and freedmen outside , and enter the baths with their peer group . baths would change from dark , steamy rooms to light ones . the romans had perfected window glass . everyone moves from the cold room to the tepid room and to the very hot room . ( man ) oops ! more than an hour later , the bathers leave massaged , oiled , ( whistling ) and have been scraped down with a strigil to remove the remaining dirt . at the ninth hour , seven hours after they left home , the men return for a celebratory dinner . dinner is an intimate affair , with nine people reclining around the low table . slaves attend to their every need if the diners , through gestures , demand more food and wine . as the day closes , we can hear the rumble of wagons outside . the clients and freedmen , with a meal of robust -- if inferior -- food inside them , shuffle off to the now tepid baths before returning to their apartment blocks . back at lucius ' house , the drinking continues into the night . lucius and his stepbrother do n't look too well . a slave stands by in case either of them needs to vomit . with hindsight , we know lucius ' future . in 20 years ' time , the emperor vespasian 's youngest son , domitian , as emperor , will enact a reign of terror . will lucius survive ? ( drums )

translator : tom carter reviewer : bedirhan cinar it 's march the 17th in a.d. 73 . we 're visiting ancient rome to watch the liberalia , an annual festival that celebrates the liberty of rome 's citizens . we 're looking in at a 17-year-old named lucius popidius secundus .

what are some major similarities and differences between ancient roman culture and the culture of the average teenager today ? do you think you would have enjoyed life in ancient rome ?

( music ) eight to be great : the eight traits successful people have in common . number two : work . when i was interviewing all these successful people , they kept telling me how hard they worked . and i remember standing there thinking , `` ah , jeez , another comment about work ? why do n't they tell me the real secret to their success ? '' then finally i realized , hard work is a real secret to their success . all successful people work very hard . martha stewart said to me , `` i 'm a real hard worker . i work and work and work all the time . '' media tycoon rupert murdoch said , `` it 's all hard work . nothing comes easily . but i have a lot of fun . '' did he say fun ? yes . successful people have fun working . that 's why i say they 're not really workaholics . they 're workafrolics . jim pattison , chairman of the jim pattison group , is a workafrolic . he says , `` business is my recreation . i 'd rather go to our factories and meet with our people than go to the beach , i can tell you that . '' dave lavery , the nasa whiz who builds those robots for mars , said to me , `` we work our fingers to the bone . but it does n't seem like work . it 's fun . it 's what we want to do . we do n't want to put things down and go home . '' bill gates is a workafrolic . even after he was a multimillionaire , he worked most nights until 10 p.m. , and only took two weeks off in seven years . and he probably spent them on his computer . oprah is a workafrolic . she says , `` i never see daylight . i 'd come into work at 5:30 in the morning when it was dark , and leave at 7 or 8 when it was dark . '' i 'm a workafrolic . and over the years , i 've gone through many days and even weeks without much sleep , just because i was having so much fun . and i got ta admit , at times like that you say to yourself , `` am i the only one working this hard ? '' because there 's a myth it comes easy to some people . you turn on the tv , nobody 's working that hard . a guy like chris rock stands up on stage , tells a few jokes . what 's hard about that ? but even chris says , `` i was n't the funniest guy growing up , but i was the guy who worked on being funny the hardest . '' trust me . i 've interviewed over 500 successful people , not one of them said it came easy , even though they were doing what they loved . we tend to underestimate work and overestimate talent . but in the end , work tops talent . arthur benjamin , america 's best math whiz , said to me , `` i think numbers and i have always gotten along . but i 'm sure my 'talent ' is just due to the time and hours and work that i 've put into it . '' many talented people do n't achieve as much success as they could , unfortunately , because they sit back on their talent and never learn to work hard . that 's what happened to michael jordan when he first started playing basketball . he had the talent , but he was n't putting in the work , and the coach actually cut him from the high school basketball team . boy , that was a wake-up call . he says , `` i was very disappointed . i started working on my game the day after i was cut . '' and he soon became the hardest working player in basketball , who made fun of the other players who were n't working hard . and that hard work is what made him the greatest basketball player of all time . so i 'd say the real gift is n't talent , it 's the ability to work hard . and we tend to underestimate work and overestimate smarts . but in the end , work wins over smarts . in fact , many successful people are n't the smartest , they just work the hardest . francois parenteau , who business week called the top independent analyst on wall street , said to me , `` i 'm certainly not that smart . i ca n't even remember my own zip code . '' but he also says , `` work is a big part of my life . i think about investments pretty much 24 hours a day , seven days a week . '' nez hallett iii is ceo of smart wireless , and i thought , that 's ironic because he told me he 's not that smart . he says , `` i graduated from high school with a c average , and college with a c-minus average . '' but now the smart phd 's are reporting to him . how did he do it ? he said , `` if you 're going to be successful at anything , the key thing is to work hard . '' i 'm not smart . as proof , here 's my actual 12th grade report card . it was the only one my parents ever kept . do n't ask me why they kept it ; it 's nothing to brag about . as you can see , i was a c student , not an a student . i do n't think i 'd even make it into college these days . so how did i achieve some success and wealth ? i just worked hard , many 60- to 80-hour weeks . and now i know i 'm not alone . thomas stanley studied hundreds of millionaires , and he discovered most millionaires were n't a students , did n't score high on tests and teachers did n't think they 'd ever succeed . but they did succeed , because they worked hard . so the good news is if you 're not the smartest , if you 're a c student , not an a student , the really good news is you can still succeed . because the word `` success '' has two c 's and no a 's . ( laughter ) you can still succeed as long as you work hard . and what if you are smart ? well , i 'm sorry , there 's absolutely no hope for you . because many smart people do n't achieve as much success as they could , unfortunately , because they rest on their smarts and never learn to work hard . jeong kim , president of lucent technologies , says , `` people who are the smartest sometimes do n't realize their full potential , because things get too easy , so they do n't push themselves hard . '' after a talk i gave at one of the world 's top 10 business schools , a man came up to me and said , `` you know , when i got my mba here a few years ago , i was one of the smartest people in the class . i thought i had it made . so after i graduated , i sat back and i did n't work hard . and i went downhill . and now , at this point in my life , i 've gone nowhere . i have n't achieved any success at all . '' he said , `` thanks for the wake-up call . now i know what i need to do . i need to work . '' so the bottom line is , whether you 're smart or not , whether you 're talented or not , just keep working . ( applause )

jeong kim , president of lucent technologies , says , `` people who are the smartest sometimes do n't realize their full potential , because things get too easy , so they do n't push themselves hard . '' after a talk i gave at one of the world 's top 10 business schools , a man came up to me and said , `` you know , when i got my mba here a few years ago , i was one of the smartest people in the class . i thought i had it made .

the man who was one of the smartest in his mba class achieved no success . why ?

translator : andrea mcdonough reviewer : bedirhan cinar nearly every one of your science classes starts off with the scientific method . you recognize this ? ask a question , form a hypothesis , perform an experiment , collect data , draw conclusions , and then memorize a bunch of facts . this is really boring ! science is not a simple recipe in a cookbook , and learning is not memorizing facts for tests . yet , that is exactly what we do . we have to change this ! we have to look at how curiosity can ultimately benefit society by looking towards tomorrow , by going through a path from involvement to imagination to invention to innovation . and i 'd like to illustrate this by telling you the real story about how we discovered how geckos stick . first you need to get involved . you need to do curiosity-driven research yourself . we know that learning by being an active researcher is the best way to learn . imagine being in my lab and trying to discover how geckos stick . `` here is one of our subjects . this is a crested gecko . we are going to put the gecko on glass and we 're going to use a high speed camera that can capture up to 1,000 pictures in one second . there he goes . ok , record it . there 's the animal 's toes . '' `` so how do their feet stick and unstick so quickly ? '' how < i > do < /i > they do this ? we wonder , it 's kind of crazy , right ? it 's hard to believe . well it turns out , it was already known that the geckos have hairy toes , and those hairs are really small compared to your hair , and the little tips at the end are even smaller . well , my student tanya , who is not much older than some of you when she did this , a sophomore undergraduate , tried to figure this out , and we told that her that in order to do this , you 'd have to measure the force of a single hair . though we kind of only did this jokingly because these hairs are so small , we did n't think it was possible . but tanya did n't know that , and she went on to build the simplest , most beautiful measurement device ever . here it is : she took one of those tiny little hairs and put it on to a probe , and then she began pushing it into the metal beam . now she was very frustrated for months - it did n't stick . but she had figured out she had to orient it just like the gecko grabs on , and then it worked ! and there 's the little split ends grabbing the beam in that little window . and then she did something magical : for the first time ever , she measured the force of a single gecko hair that allowed her to discover a completely new way to stick to something , something no human has ever known before . they have hairy little toes , huge numbers of hairs , and each hair has the worst case of split ends possible , 100 to 1,000 nano-tips that an animal has on one hair , and 2 billion total , and they do n't stick by glue , or by suction , or by velcro . it was discovered that they stick by inter-molecular forces alone , by van der waals forces , and you 'll learn this in chemistry and physics , if you take it . it 's unbelievable ! it 's a whole new way of thinking about making an adhesive ! well , this is n't the end of the story , there are still mysteries . why are the gecko 's feet looking like this ? they have bizarre toes and we do n't know why . if you go into a museum and look at each gecko species , you see they have all different hairs , different lengths , and thicknesses , and patterns . why ? i do n't know ! but you should come to berkeley and help me figure this out . it 's just about right , so , apply . but it 's a mystery . there is even more stuff that is unknown . this tarantula also has hairs and can stick this way , too , but recently it was found that they also can secrete silk from their feet , not just their behind , like you know they do . and even more recently , my graduate student ann showed that all spiders can secrete glue , and we know nothing about this glue except it was around way before this guy , millions of years before . so do n't stop at the discovery , next imagine the possible uses for society . here is the first human supported by a gecko-inspired adhesive . this is my former graduate student , kellar autumn , who is professor at lewis and clark , offering his second born child for the test . and she 's a very good sport about it ! now imagine all the things you could make from this , not only adhesives , but products in sports , and biomedicine , technology , robotics , toys , automotive , fashion , clothes , and yes , even hair pieces . i swear to you , we got a call from michael jackson 's hairdresser about hair pieces before he passed away . who would have guessed from studying geckos ? ! ? next , invent a game-changing technology , device , or product . like my engineering colleague at berkeley , ron fearing , did when he made one of the first synthetic , self-cleaning dry adhesives after the simplest version that you see in animals . believe it or not , right now , because of this work , you can make your own synthetic gecko nano-tape by nano-molding with just a few parts , and here 's the recipe that we can give you . it 's been incredible since we made this discovery of all the papers and the work and the different ways to make it , it 's emerging into a billion dollar industry . and who would have imagined that it started because we were curious about how geckos can run up walls . next you need to innovate , create a business that ultimately benefits society . did you know that there are 6 million people per year that have chronic wounds , 2 million develop an infection , and infections account for 100,000 hospital deaths ? imagine if you could build a company that could produce a gecko-inspired band-aid that would remove the pain and suffering . just a simple invention . if you look at the last three great earthquakes , over 700,000 people were trapped and lost their lives . imagine the company that made a search-and-rescue robot inspired from a gecko that could move anywhere and quickly find individuals that have been trapped , that sometimes survive as long as two weeks . there is a gecko-inspired robot , stickybot , from the stanford group , that can grab on to any surface . now we ran our own , for ted , mini bio-inspired design challenge to get you to think about these kinds of products . we have a winner . here 's the winner . the winner came up with this design called stickyseat . really clever . it 's a seat that is not only comfortable , but it aids a seat belt , if you were in an accident , in terms of keeping your seat and moving . this is brilliant ! we did n't think about this , although we might think about patenting it now , but there is a winner for this , and the winner , and you ca n't , you ca n't make up something like this , the winner 's name is harry . where 's harry ? harry , come here , we have a prize for you . where 's harry ? harry ! come here ! we have a crested gecko for you that has very cool hairs on it . congratulations for harry ! excellent job ! so do n't worry , if you missed out on this , it 's ok because we are doing another design challenge working with the san diego zoo . they 're developing a best ideas project in san diego , but it 's going to go national . and i 'll leave you with a fact that you should keep being curious because curiosity-based research leads to the biggest benefits , as we showed you in our example , and you < i > can < /i > make a difference < i > now < /i > because like tanya , you do n't know what ca n't be done . thank you .

well , this is n't the end of the story , there are still mysteries . why are the gecko 's feet looking like this ? they have bizarre toes and we do n't know why .

design an original product based on your knowledge of gecko feet . explain it 's purpose and how it works .

here 's what has to happen for pregnancy to occur after sexual intercourse . sperm must swim up the vagina , through the cervical opening , upwards through the uterus , and into one of the two fallopian tubes . if an egg , released during that month 's ovulation , is in the tube , one sperm has a chance to fertilize it . contraceptives are designed to prevent this process , and they work in three basic ways . they block the sperm , disable sperm before they reach the uterus , or suppress ovulation . block is the simplest . male and female condoms prevent sperm from coming into contact with the vaginal space . that barrier is also why they , unlike other contraceptive methods , are able to prevent transmission of certain sexually transmitted diseases . meanwhile , the diaphragm , cervical cap , and sponge work by being placed over the cervix , barricading the entrance to the uterus . these contraceptives are sometimes called barrier methods and can be used with spermicides , an example of the second category , disable . a spermicide is a chemical that immobilizes and destroys sperm . today 's spermicides come as foam , cream , jelly , suppositories , and even a thin piece of translucent film that dissolves in the vagina . these products can be inserted directly into the vagina before intercourse , or can be combined with block methods , like a diaphragm or condom , for added proection . the third category for preventing pregnancy works by suppressing the action of an egg maturing in the ovary . if there is n't an egg available in the fallopian tube , there 's nothing for sperm to fertilize . hormonal contraceptives , including the pill , the patch , the depo shot , and the vaginal ring all release synthetic versions of various combinations of progesterone and estrogen . this hormone cocktail suppresses ovulation , keeping the immature egg safely sequestered in the ovary . synthetic progesterone also has a block trick up its sleeve . it makes cervical mucus too thick and sticky for sperm to swim through easily . there are other contraceptives that use multiple approaches at the same time . for example , many iuds , or intrauterine devices , contain synthetic hormones which suppress ovulation . some also contain copper , which disable sperm while also making egg implantation in the uterus difficult . block , disable , or suppress : is one strategy better than the other ? there are differences , but a lot of it has to do with how convenient and easy it is to use each contraceptive correctly . for example , male condoms would be about 98 % effective if everyone used them perfectly . that 98 % means if 100 couples correctly used condoms for a year , two women would get pregnant . but not everyone uses them correctly , so they 're only 82 % effective in practice . other methods , like the patch and pill , are 99 % effective when they 're used perfectly . but in practice , that 's 91 % . spermicide is only 85 % effective , even with perfect usage , and just 71 % effective with typical usage . another important consideration in the choice of contraceptives are side effects , which almost exclusively affect women rather than men . hormonal methods in particular can cause symptoms like headaches , nausea , and high blood pressure , but they vary from woman to woman . that 's why these methods require a prescription from a doctor . the choice of contraceptive method is a personal one , and what works best for you now may change later . scientists also continue to research new methods , such as a male pill that would prevent sperm production . in the meantime , there are quite a few options to block sperm , disable them , or suppress eggs and keep them out of reach .

but in practice , that 's 91 % . spermicide is only 85 % effective , even with perfect usage , and just 71 % effective with typical usage . another important consideration in the choice of contraceptives are side effects , which almost exclusively affect women rather than men . hormonal methods in particular can cause symptoms like headaches , nausea , and high blood pressure , but they vary from woman to woman .

how does the effectiveness rate differ from the usage rate of contraceptives ?

right now , you 're probably sitting down to watch this video and staying seated for a few minutes to view it is probably okay . but the longer you stay put , the more agitated your body becomes . it sits there counting down the moments until you stand up again and take it for a walk . that may sound ridiculous . our bodies love to sit , right ? not really . sure , sitting for brief periods can help us recover from stress or recuperate from exercise . but nowadays , our lifestyles make us sit much more than we move around , and our bodies simply are n't built for such a sedentary existence . in fact , just the opposite is true . the human body is built to move , and you can see evidence of that in the way it 's structured . inside us are over 360 joints , and about 700 skeletal muscles that enable easy , fluid motion . the body 's unique physical structure gives us the ability to stand up straight against the pull of gravity . our blood depends on us moving around to be able to circulate properly . our nerve cells benefit from movement , and our skin is elastic , meaning it molds to our motions . so if every inch of the body is ready and waiting for you to move , what happens when you just do n't ? let 's start with the backbone of the problem , literally . your spine is a long structure made of bones and the cartilage discs that sit between them . joints , muscles and ligaments that are attached to the bones hold it all together . a common way of sitting is with a curved back and slumped shoulders , a position that puts uneven pressure on your spine . over time , this causes wear and tear in your spinal discs , overworks certain ligaments and joints , and puts strain on muscles that stretch to accommodate your back 's curved position . this hunched shape also shrinks your chest cavity while you sit , meaning your lungs have less space to expand into when you breath . that 's a problem because it temporarily limits the amount of oxygen that fills your lungs and filters into your blood . around the skeleton are the muscles , nerves , arteries and veins that form the body 's soft tissue layers . the very act of sitting squashes , pressurizes and compresses , and these more delicate tissues really feel the brunt . have you ever experienced numbness and swelling in your limbs when you sit ? in areas that are the most compressed , your nerves , arteries and veins can become blocked , which limits nerve signaling , causing the numbness , and reduces blood flow in your limbs , causing them to swell . sitting for long periods also temporarily deactivates lipoprotein lipase , a special enzyme in the walls of blood capillaries that breaks down fats in the blood , so when you sit , you 're not burning fat nearly as well as when you move around . what effect does all of this stasis have on the brain ? most of the time , you probably sit down to use your brain , but ironically , lengthy periods of sitting actually run counter to this goal . being stationary reduces blood flow and the amount of oxygen entering your blood stream through your lungs . your brain requires both of those things to remain alert , so your concentration levels will most likely dip as your brain activity slows . unfortunately , the ill effects of being seated do n't only exist in the short term . recent studies have found that sitting for long periods is linked with some types of cancers and heart disease and can contribute to diabetes , kidney and liver problems . in fact , researchers have worked out that , worldwide , inactivity causes about 9 % of premature deaths a year . that 's over 5 million people . so what seems like such a harmless habit actually has the power to change our health . but luckily , the solutions to this mounting threat are simple and intuitive . when you have no choice but to sit , try switching the slouch for a straighter spine , and when you do n't have to be bound to your seat , aim to move around much more , perhaps by setting a reminder to yourself to get up every half hour . but mostly , just appreciate that bodies are built for motion , not for stillness . in fact , since the video 's almost over , why not stand up and stretch right now ? treat your body to a walk . it 'll thank you later .

our blood depends on us moving around to be able to circulate properly . our nerve cells benefit from movement , and our skin is elastic , meaning it molds to our motions . so if every inch of the body is ready and waiting for you to move , what happens when you just do n't ?

our bodily systems are designed for and in need of movement .

will winning the lottery make you happier ? imagine winning a multi-million dollar lottery tomorrow . if you 're like many of us , you 'd be ecstatic , unable to believe your good luck . but would that joy still be there a few years later ? maybe not . a famous study of 22 lottery winners showed that months after winning , their average reported levels of happiness had increased no more than that of a control group who had n't won the lottery . some were actually unhappier than they had been before winning . and later studies have confirmed that our emotional well-being , how often and how intensely we feel things like joy , sorrow , anxiety , or anger , do n't seem to improve with wealth or status beyond a certain point . this has to do with a phenomenon known as hedonic adaptation , or the hedonic treadmill . it describes our tendency to adapt to new situations to maintain a stable emotional equilibrium . when it comes to feeling happy , most of us seem to have a base level that stays more or less constant throughout our existence . of course , the novelty of better food , superior vacations , and more beautiful homes can at first make you feel like you 're walking on air , but as you get used to those things , you revert to your default emotional state . that might sound pretty gloomy , but hedonic adaptation makes us less emotionally sensitive to any kind of change , including negative ones . the study with the lottery winners also looked at people who had suffered an accident that left them paralyzed . when asked several months after their accidents how happy they were , they reported levels of happiness approaching their original baseline . so while the hedonic treadmill may inhibit our enjoyment of positive changes , it seems to also enable our resilience in recovering from adversity . there are other reasons that winning the lottery may not make us happier in the long run . it can be difficult to manage large sums of money , and some lottery winners wind up spending or losing it all quickly . it can also be socially isolating . some winners experience a deluge of unwelcome requests for money , so they wind up cutting themselves off from others . and wealth may actually make us meaner . in one study , participants played a rigged game of monopoly where the experimenters made some players rich quickly . the wealthy players started patronizing the poorer players and hogging the snacks they were meant to share . but just because a huge influx of cash is n't guaranteed to bring joy into your life does n't mean that money can never make us happier . findings show that we adapt to extrinsic and material things , like a new car or a bigger house , much faster than we do to novel experiences , like visiting a new place or learning a new skill . so by that reasoning , the more you spend money on experiences rather than things , the happier you 'd be . and there 's another way to turn your money into happiness : spend it on other people . in one study , participants were given some money and were either asked to spend it on themselves or on someone else . later that evening , researchers called up these participants and asked them how happy they were . the happiness levels of those who had spent the money on others were significantly greater than that of those who had spent it on themselves . and that seems to be true around the world . another study examined the generosity of over 200,000 people from 136 countries . in over 90 % of these countries , people who donated tended to be happier than those who did n't . but this may all be easier said than done . let 's say a million dollars falls into your lap tomorrow . what do you do with it ?

when asked several months after their accidents how happy they were , they reported levels of happiness approaching their original baseline . so while the hedonic treadmill may inhibit our enjoyment of positive changes , it seems to also enable our resilience in recovering from adversity . there are other reasons that winning the lottery may not make us happier in the long run .

the hedonic adaptation inhibits our enjoyment of positive changes , and it seems to enable our resilience in recovering from adversity . why is this important ?

here are some images of clusters of galaxies . they 're exactly what they sound like . they are these huge collections of galaxies , bound together by their mutual gravity . so most of the points that you see on the screen are not individual stars , but collections of stars , or galaxies . now , by showing you some of these images , i hope that you will quickly see that galaxy clusters are these beautiful objects , but more than that , i think galaxy clusters are mysterious , they are surprising , and they 're useful . useful as the universe 's most massive laboratories . and as laboratories , to describe galaxy clusters is to describe the experiments that you can do with them . and i think there are four major types , and the first type that i want to describe is probing the very big . so , how big ? well , here is an image of a particular galaxy cluster . it is so massive that the light passing through it is being bent , it 's being distorted by the extreme gravity of this cluster . and , in fact , if you look very carefully you 'll be able to see rings around this cluster . now , to give you a number , this particular galaxy cluster has a mass of over one million billion suns . it 's just mind-boggling how massive these systems can get . but more than their mass , they have this additional feature . they are essentially isolated systems , so if we like , we can think of them as a scaled-down version of the entire universe . and many of the questions that we might have about the universe at large scales , such as , how does gravity work ? might be answered by studying these systems . so that was very big . the second things is very hot . okay , if i take an image of a galaxy cluster , and i subtract away all of the starlight , what i 'm left with is this big , blue blob . this is in false color . it 's actually x-ray light that we 're seeing . and the question is , if it 's not galaxies , what is emitting this light ? the answer is hot gas , million-degree gas -- in fact , it 's plasma . and the reason why it 's so hot goes back to the previous slide . the extreme gravity of these systems is accelerating particles of gas to great speeds , and great speeds means great temperatures . so this is the main idea , but science is a rough draft . there are many basic properties about this plasma that still confuse us , still puzzle us , and still push our understanding of the physics of the very hot . third thing : probing the very small . now , to explain this , i need to tell you a very disturbing fact . most of the universe 's matter is not made up of atoms . you were lied to . most of it is made up of something very , very mysterious , which we call dark matter . dark matter is something that does n't like to interact very much , except through gravity , and of course we would like to learn more about it . if you 're a particle physicist , you want to know what happens when we smash things together . and dark matter is no exception . well , how do we do this ? to answer that question , i 'm going to have to ask another one , which is , what happens when galaxy clusters collide ? here is an image . since galaxy clusters are representative slices of the universe , scaled-down versions . they are mostly made up of dark matter , and that 's what you see in this bluish purple . the red represents the hot gas , and , of course , you can see many galaxies . what 's happened is a particle accelerator at a huge , huge scale . and this is very important , because what it means is that very , very small effects that might be difficult to detect in the lab , might be compounded and compounded into something that we could possibly observe in nature . so , it 's very funny . the reason why galaxy clusters can teach us about dark matter , the reason why galaxy clusters can teach us about the physics of the very small , is precisely because they are so very big . fourth thing : the physics of the very strange . certainly what i 've said so far is crazy . okay , if there 's anything stranger i think it has to be dark energy . if i throw a ball into the air , i expect it to go up . what i do n't expect is that it go up at an ever-increasing rate . similarly , cosmologists understand why the universe is expanding . they do n't understand why it 's expanding at an ever-increasing rate . they give the cause of this accelerated expansion a name , and they call it dark energy . and , again , we want to learn more about it . so , one particular question that we have is , how does dark energy affect the universe at the largest scales ? depending on how strong it is , maybe structure forms faster or slower . well , the problem with the large-scale structure of the universe is that it 's horribly complicated . here is a computer simulation . and we need a way to simplify it . well , i like to think about this using an analogy . if i want to understand the sinking of the titanic , the most important thing to do is not to model the little positions of every single little piece of the boat that broke off . the most important thing to do is to track the two biggest parts . similarly , i can learn a lot about the universe at the largest scales by tracking its biggest pieces and those biggest pieces are clusters of galaxies . so , as i come to a close , you might feel slightly cheated . i mean , i began by talking about how galaxy clusters are useful , and i 've given some reasons , but what is their use really ? well , to answer this , i want to give you a quote by henry ford when he was asked about cars . he had this to say : `` if i had asked people what they wanted , they would have said faster horses . '' today , we as a society are faced with many , many difficult problems . and the solutions to these problems are not obvious . they are not faster horses . they will require an enormous amount of scientific ingenuity . so , yes , we need to focus , yes , we need to concentrate , but we also need to remember that innovation , ingenuity , inspiration -- these things come when we broaden our field of vision when we step back when we zoom out . and i ca n't think of a better way to do this than by studying the universe around us . thanks . ( applause )

it is so massive that the light passing through it is being bent , it 's being distorted by the extreme gravity of this cluster . and , in fact , if you look very carefully you 'll be able to see rings around this cluster . now , to give you a number , this particular galaxy cluster has a mass of over one million billion suns .

why do we see rings around some galaxy clusters ?

you 're facing a giant bowl of energy packed carbon crunchies . one spoonful . two . three . soon , you 're powered up by the energy surge that comes from your meal . but how did that energy get into your bowl ? energy exists in the form of sugars made by the plant your cereal came from , like wheat or corn . as you can see , carbon is the chemical backbone , and plants get their fix of it in the form of carbon dioxide , co2 , from the air that we all breath . but how does a plant 's energy factory , housed in the stroma of the chloroplast , turn a one carbon gas , like co2 , into a six carbon solid , like glucose ? if you 're thinking photosynthesis , you 're right . but photosynthesis is divided into two steps . the first , which stores energy from the sun in the form of adenosine triphosphate , or atp . and the second , the calvin cycle , that captures carbon and turns it into sugar . this second phase represents one of nature 's most sustainable production lines . and so with that , welcome to world 's most miniscule factory . the starting materials ? a mix of co2 molecules from the air , and preassembled molecules called ribulose biphosphate , or rubp , each containing five carbons . the initiator ? an industrious enzyme named rubisco that welds one carbon atom from a co2 molecule with the rubp chain to build an initial six carbon sequence . that rapidly splits into two shorter chains containing three carbons each and called phosphoglycerates , or pgas , for short . enter atp , and another chemical called nicotinamide adenine dinucleotide phosphate , or just nadph . atp , working like a lubricant , delivers energy , while nadph affixes one hydrogen to each of the pga chains , changing them into molecules called glyceraldehyde 3 phosphates , or g3ps . glucose needs six carbons to form , made from two molecules of g3p , which incidentally have six carbons between them . so , sugar has just been manufactured , right ? not quite . the calvin cycle works like a sustainable production line , meaning that those original rubps that kicked things off at the start , need to be recreated by reusing materials within the cycle now . but each rubp needs five carbons and manufacturing glucose takes a whole six . something does n't add up . the answer lies in one phenomenal fact . while we 've been focusing on this single production line , five others have been happening at the same time . with six conveyor belts moving in unison , there is n't just one carbon that gets soldered to one rubp chain , but six carbons soldered to six rubps . that creates 12 g3p chains instead of just two , meaning that all together , 36 carbons exist : the precise number needed to manufacture sugar , and rebuild those rubps . of the 12 g3ps pooled together , two are siphoned off to form that energy rich six carbon glucose chain . the one fueling you via your breakfast . success ! but back on the manufacturing line , the byproducts of this sugar production are swiftly assembled to recreate those six rubps . that requires 30 carbons , the exact number contained by the remaining 10 g3ps . now a molecular mix and match occurs . two of the g3ps are welded together forming a six carbon sequence . by adding a third g3p , a nine carbon chain is built . the first rubp , made up of five carbons , is cast from this , leaving four carbons behind . but there 's no wastage here . those are soldered to a fourth g3p molecule , making a seven carbon chain . added to a fifth g3p molecule , a ten carbon chain is created , enough now to craft two more rubps . with three full rubps recreated from five of the ten g3ps , simply duplicating this process will renew the six rubp chains needed to restart the cycle again . so the calvin cycle generates the precise number of elements and processes required to keep this biochemical production line turning endlessly . and it 's just one of the 100s of cycles present in nature . why so many ? because if biological production processes were linear , they would n't be nearly as efficient or successful at using energy to manufacture the materials that nature relies upon , like sugar . cycles create vital feedback loops that repeatedly reuse and rebuild ingredients crafting as much as possible out of the planet 's available resources . such as that sugar , built using raw sunlight and carbon converted in plant factories to become the energy that powers you and keeps the cycles revolving in your own life .

the first , which stores energy from the sun in the form of adenosine triphosphate , or atp . and the second , the calvin cycle , that captures carbon and turns it into sugar . this second phase represents one of nature 's most sustainable production lines .

which of the following statements is true about the calvin cycle ?

you and nine other individuals have been captured by super intelligent alien overlords . the aliens think humans look quite tasty , but their civilization forbids eating highly logical and cooperative beings . unfortunately , they 're not sure whether you qualify , so they decide to give you all a test . through its universal translator , the alien guarding you tells you the following : you will be placed in a single-file line facing forward in size order so that each of you can see everyone lined up ahead of you . you will not be able to look behind you or step out of line . each of you will have either a black or a white hat on your head assigned randomly , and i wo n't tell you how many of each color there are . when i say to begin , each of you must guess the color of your hat starting with the person in the back and moving up the line . and do n't even try saying words other than black or white or signaling some other way , like intonation or volume ; you 'll all be eaten immediately . if at least nine of you guess correctly , you 'll all be spared . you have five minutes to discuss and come up with a plan , and then i 'll line you up , assign your hats , and we 'll begin . can you think of a strategy guaranteed to save everyone ? pause the video now to figure it out for yourself . answer in : 3 answer in : 2 answer in : 1 the key is that the person at the back of the line who can see everyone else 's hats can use the words `` black '' or `` white '' to communicate some coded information . so what meaning can be assigned to those words that will allow everyone else to deduce their hat colors ? it ca n't be the total number of black or white hats . there are more than two possible values , but what does have two possible values is that number 's parity , that is whether it 's odd or even . so the solution is to agree that whoever goes first will , for example , say `` black '' if he sees an odd number of black hats and `` white '' if he sees an even number of black hats . let 's see how it would play out if the hats were distributed like this . the tallest captive sees three black hats in front of him , so he says `` black , '' telling everyone else he sees an odd number of black hats . he gets his own hat color wrong , but that 's okay since you 're collectively allowed to have one wrong answer . prisoner two also sees an odd number of black hats , so she knows hers is white , and answers correctly . prisoner three sees an even number of black hats , so he knows that his must be one of the black hats the first two prisoners saw . prisoner four hears that and knows that she should be looking for an even number of black hats since one was behind her . but she only sees one , so she deduces that her hat is also black . prisoners five through nine are each looking for an odd number of black hats , which they see , so they figure out that their hats are white . now it all comes down to you at the front of the line . if the ninth prisoner saw an odd number of black hats , that can only mean one thing . you 'll find that this strategy works for any possible arrangement of the hats . the first prisoner has a 50 % chance of giving a wrong answer about his own hat , but the parity information he conveys allows everyone else to guess theirs with absolute certainty . each begins by expecting to see an odd or even number of hats of the specified color . if what they count does n't match , that means their own hat is that color . and everytime this happens , the next person in line will switch the parity they expect to see . so that 's it , you 're free to go . it looks like these aliens will have to go hungry , or find some less logical organisms to abduct .

so what meaning can be assigned to those words that will allow everyone else to deduce their hat colors ? it ca n't be the total number of black or white hats . there are more than two possible values , but what does have two possible values is that number 's parity , that is whether it 's odd or even . so the solution is to agree that whoever goes first will , for example , say `` black '' if he sees an odd number of black hats and `` white '' if he sees an even number of black hats .

what does a number 's parity refer to ?

in the summer of 1963 , a high school teacher changed the way the world looked at `` the wizard of oz . '' his name was henry littlefield , and he was teaching an american history class . he 'd made it to the late 19th century , a time called the gilded age , but he was struggling to keep his class interested in the complex social and economic issues of the time . then one night , while he was reading `` the wonderful wizard of oz '' to his daughters , he had an idea . in the 1890s , farmers wanted to add silver to the gold standard to put more money in circulation and make it easier for farmers to borrow . in the book , dorothy walked to the emerald city on the yellow brick road in her silver shoes . the movie 's ruby red slippers started out as silver . silver and gold on the road to prosperity . l. frank baum had published the book in 1900 at the height of the gilded age , and the analogy did n't seem out of the question . no one else had seen these connections , but that did n't deter littlefield . he taught his class about the gilded age using the book , and soon he and his students were finding more connections . for instance , in the late 1890s , the u.s. had recently recovered from the civil war and integrated vast new territories , bringing an era of prosperity for some . but while industry and finance in the north and east prospered , farmers across the south and midwest struggled . this led to the populist movement , uniting farmers and workers against urban elites . by 1896 , the movement had grown into the people 's party , and its support of democrat williams jennings bryan put him in reach of the presidency . meanwhile in oz , claimed littlefield , dorothy is a typical american girl whose hard life in kansas is literally turned upside down by powerful forces outside her control . the munchkins are the common people oppressed by the witch of the east , banks and monopolies . the scarecrow is the farmer , considered naive but actually quite resourceful , the tin woodman is the industrial worker dehumanized by factory labor , and the cowardly lion is william jennings bryan who could be an influential figure if only he were brave enough to adopt the populist 's radical program . together , they travel along a golden yellow road towards a grand city whose ruler 's power turns out to be built on illusions . littlefield published some of these observations in an essay . his claim that this fantasy was actually a subversive critique of american capitalism appealed to many people in 1960s . other scholars took up the theme , and the proposed analogies and connections multiplied . they suggested that dorothy 's dog toto represented the teetotalers of the prohibition party . oz was clearly the abbreviation for ounces , an important unit in the silver debate . the list goes on . by the 1980s , this understanding of the book was accepted so widely that several american history textbooks mentioned it in discussions of late 19th century politics . but is the theory right ? l. frank baum 's introduction claims the book is just an innocent children 's story . could he have been deliberately throwing people off the trail ? and is it fair to second guess him so many decades later ? there 's no definitive answer , which is part of why authorial intent is a complex , tangled , fun question to unravel . and some recent scholars have interpreted `` the wonderful wizard of oz '' in the opposite way as littlefield . they claim it 's a celebration of the new urban consumer culture . historian william leach argued that the dazzling emerald city of oz was meant to acclimate people to the shiny , new america . in the end , all we know for sure is that baum , inspired by european folk legends , had set out to create one for american children . and whether or not he intended any hidden meanings , its continuing relevance suggests he succeeded in creating a fairytale america can call its own .

meanwhile in oz , claimed littlefield , dorothy is a typical american girl whose hard life in kansas is literally turned upside down by powerful forces outside her control . the munchkins are the common people oppressed by the witch of the east , banks and monopolies . the scarecrow is the farmer , considered naive but actually quite resourceful , the tin woodman is the industrial worker dehumanized by factory labor , and the cowardly lion is william jennings bryan who could be an influential figure if only he were brave enough to adopt the populist 's radical program .

the wicked witch of the east , according to this interpretation , stood for :

consider the classic white t-shirt . annually , we sell and buy two billion t-shirts globally , making it one of the most common garments in the world . but how and where is the average t-shirt made , and what 's its environmental impact ? clothing items can vary a lot , but a typical t-shirt begins its life on a farm in america , china , or india where cotton seeds are sown , irrigated and grown for the fluffy bolls they produce . self-driving machines carefully harvest these puffs , an industrial cotton gin mechanically separates the fluffy bolls from the seeds , and the cotton lint is pressed into 225-kilogram bales . the cotton plants require a huge quantity of water and pesticides . 2,700 liters of water are needed to produce the average t-shirt , enough to fill more than 30 bathtubs . meanwhile , cotton uses more insecticides and pesticides than any other crop in the world . these pollutants can be carcinogenic , harm the health of field workers , and damage surrounding ecosystems . some t-shirts are made of organic cotton grown without pesticides and insecticides , but organic cotton makes up less than 1 % of the 22.7 million metric tons of cotton produced worldwide . once the cotton bales leave the farm , textile mills ship them to a spinning facility , usually in china or india , where high-tech machines blend , card , comb , pull , stretch , and , finally , twist the cotton into snowy ropes of yarn called slivers . then , yarns are sent to the mill , where huge circular knitting machines weave them into sheets of rough grayish fabric treated with heat and chemicals until they turn soft and white . here , the fabric is dipped into commercial bleaches and azo dyes , which make up the vivid coloring in about 70 % of textiles . unfortunately , some of these contain cancer-causing cadmium , lead , chromium , and mercury . other harmful compounds and chemicals can cause widespread contamination when released as toxic waste water in rivers and oceans . technologies are now so advanced in some countries that the entire process of growing and producing fabric barely touches a human hand . but only up until this point . after the finished cloth travels to factories , often in bangladesh , china , india , or turkey , human labor is still required to stitch them up into t-shirts , intricate work that machines just ca n't do . this process has its own problems . bangladesh , for example , which has surpassed china as the world 's biggest exporter of cotton t-shirts , employs 4.5 million people in the t-shirt industry , but they typically face poor conditions and low wages . after manufacture , all those t-shirts travel by ship , train , and truck to be sold in high-income countries , a process that gives cotton an enormous carbon footprint . some countries produce their own clothing domestically , which cuts out this polluting stage , but generally , apparel production accounts for 10 % of global carbon emissions . and it 's escalating . cheaper garments and the public 's willingness to buy boosted global production from 1994 to 2014 by 400 % to around 80 billion garments each year . finally , in a consumer 's home , the t-shirt goes through one of the most resource-intensive phases of its lifetime . in america , for instance , the average household does nearly 400 loads of laundry per year each using about 40 gallons of water . washing machines and dryers both use energy , with dryers requiring five to six times more than washers . this dramatic shift in clothing consumption over the last 20 years , driven by large corporations and the trend of fast fashion has cost the environment , the health of farmers , and driven questionable human labor practices . it 's also turned fashion into the second largest polluter in the world after oil . but there are things we can do . consider shopping secondhand . try to look for textiles made from recycled or organic fabrics . wash clothes less and line dry to save resources . instead of throwing them away at the end of their life , donate , recycle , or reuse them as cleaning rags . and , finally , you might ask yourself , how many t-shirts and articles of clothing will you consume over your lifetime , and what will be their combined impact on the world ?

the cotton plants require a huge quantity of water and pesticides . 2,700 liters of water are needed to produce the average t-shirt , enough to fill more than 30 bathtubs . meanwhile , cotton uses more insecticides and pesticides than any other crop in the world .

to produce the average t-shirt takes :

just now , somewhere in the universe , a star exploded . there goes another one . in fact , a supernova occurs every second or so in the observable universe , and there is one on average every 25 to 50 years in a galaxy the size and age of the milky way . yet we 've never actually been able to watch one happen from its first violent moments . of course , how would we ? there are hundreds of billions of stars close enough that we could watch the supernova explosion break through the surface of the star . but we 'd have to have our best telescopes focused on the right one at precisely the right time to get meaningful data . suffice it to say , the odds of that happening are astronomically low . but what if we could anticipate a supernova before its light reached us ? that may seem impossible . after all , nothing travels faster than the speed of light , right ? as far as we know , yes . but in a race , fast does n't matter if you take a detour while someone else beelines it for the finish line . for exactly that reason , photons do n't win the supernova race to earth . neutrinos do . here 's why . there are two types of supernova . type 1 is when a star accumulates so much matter from a neighboring star , that a runaway nuclear reaction ignites and causes it to explode . in type 2 , the star runs out of nuclear fuel , so the gravitational forces pulling in overwhelm the quantum mechanical forces pushing out , and the stellar core collapses under its own weight in a hundredth of a second . while the outer reaches of the star are unaffected by the collapsed core , the inner edges accelerate through the void , smash into the core , and rebound to launch the explosion . in both of these scenarios , the star expels an unparalleled amount of energy , as well as a great deal of matter . in fact , all atoms heavier than nickel , including elements like gold and silver , only form in supernova reactions . in type 2 supernovae , about 1 % of the energy consists of photons , which we know of as light , while 99 % radiates out as neutrinos , the elementary particles that are known for rarely interacting with anything . starting from the center of the star , the exploding matter takes tens of minutes , or even hours , or in rare cases , several days , to reach and break through the surface of the star . however , the neutrinos , thanks to their non-interactivity , take a much more direct route . by the time there is any visible change in the star 's suface , the neutrinos typically have a several hour head start over the photons . that 's why astronomers and physicists have been able to set up a project called snews , the supernova early warning system . when detectors around the world pick up bursts of neutrinos , they send messages to a central computer in new york . if multiple detectors receive similar signals within ten seconds , snews will trigger an alert warning that a supernova is imminent . aided by some distance and direction information from the neutrino detectors , the amateur astronomers and scientists alike will scan the skies and share information to quickly identify the new galactic supernova and turn the world 's major telescopes in that direction . the last supernova that sent detectable neutrinos to earth was in 1987 on the edge of the tarantula nebula in the large magellanic cloud , a nearby galaxy . its neutrinos reached earth about three hours ahead of the visible light . we 're due for another one any day now , and when that happens , snews should give you the opportunity to be among the first to witness something that no human has ever seen before .

for exactly that reason , photons do n't win the supernova race to earth . neutrinos do . here 's why .

what percentage of energy from a supernova explosion is expelled as neutrinos ?

massive vines that blanket the southern united states , climbing as high as 100 feet as they uproot trees and swallow buildings . a ravenous snake that is capable of devouring an alligator . rabbit populations that eat themselves into starvation . these are n't horror movie concepts . they 're real stories , but how could such situations exist in nature ? all three are examples of invasive species , organisms harmful not because of what they are , but where they happen to be . the kudzu vine , for example , had grown quality in its native east asia , eaten by various insects and dying off during the cold winters . but its fortunes changed when it was imported into the southeastern united states for porch decoration and cattle feed . its planting was even subsidized by the government to fight soil erosion . with sunny fields , a mild climate , and no natural predators in its new home , the vine grew uncontrollably until it became known as the plant that ate the south . meanwhile in florida 's everglades , burmese pythons , thought to have been released by pet owners , are the cause of decreasing populations of organisms . they 're successfully outcompeting top predators , such as the alligator and panther , causing a significant reduction in their food sources . they 're not a problem in their native asia because diseases , parasites , and predators help to control their population size . and in australia , european rabbits eat so many plants that they wipe out the food supply for themselves and other herbivores . they 're a pretty recent addition , intentionally introduced to the continent because one man enjoyed hunting them . like the burmese pythons , various factors in their native habitat keep their numbers in control . but in australia , the lack of predators and a climate perfect for year-long reproduction allows their populations to skyrocket . so why does this keep happening ? most of the world 's ecosystems are the result of millennia of coevolution by organisms , adapting to their environment and each other until a stable balance is reached . healthy ecosystems maintain this balance via limiting factors , environmental conditions that restrict the size or range of a species . these include things like natural geography and climate , food availability , and the presence or absence of predators . for example , plant growth depends on levels of sunlight and soil nutrients . the amount of edible plants affects the population of herbivores , which in turn impacts the carnivores that feed on them . and a healthy predator population keeps the herbivores from becoming too numerous and devouring all the plants . but even minor changes in one factor can upset this balance , and the sudden introduction of non-native organisms can be a pretty major change . a species that is evolved in a separate habitat will be susceptible to different limiting factors , different predators , different energy sources , and different climates . if the new habitat 's limiting factors fail to restrict the species growth , it will continue to multiply , out-competing native organisms for resources and disrupting the entire ecosystem . species are sometimes introduced into new habitats through natural factors , like storms , ocean currents , or climate shifts . the majority of invasive species , though , are introduced by humans . often this happens unintentionally , as when the zebra mussel was accidentally brought to lake erie by cargo ships . but as people migrate around the world , we have also deliberately brought our plants and animals along , rarely considering the consequences . but now that we 're learning more about the effects of invasive species on ecosystems , many governments closely monitor the transport of plants and animals , and ban the imports of certain organisms . but could the species with the most drastic environmental impact be a group of primates who emerged from africa to cover most of the world ? are we an invasive species ?

a species that is evolved in a separate habitat will be susceptible to different limiting factors , different predators , different energy sources , and different climates . if the new habitat 's limiting factors fail to restrict the species growth , it will continue to multiply , out-competing native organisms for resources and disrupting the entire ecosystem . species are sometimes introduced into new habitats through natural factors , like storms , ocean currents , or climate shifts . the majority of invasive species , though , are introduced by humans .

species evolve to adapt to limiting factors in their native environment . when they are brought to a new environment , the new limiting factors may not restrict their growth .

in the early days of organic chemistry , chemists understood that molecules were made of atoms connected through chemical bonds . however , the three-dimensional shapes of molecules were utterly unclear , since they could n't be observed directly . molecules were represented using simple connectivity graphs like the one you see here . it was clear to savvy chemists of the mid-19th century that these flat representations could n't explain many of their observations . but chemical theory had n't provided a satisfactory explanation for the three-dimensional structures of molecules . in 1874 , the chemist va n't hoff published a remarkable hypothesis : the four bonds of a saturated carbon atom point to the corners of a tetrahedron . it would take over 25 years for the quantum revolution to theoretically validate his hypothesis . but va n't hoff supported his theory using optical rotation . va n't hoff noticed that only compounds containing a central carbon bound to four different atoms or groups rotated plane-polarized light . clearly there 's something unique about this class of compounds . take a look at the two molecules you see here . each one is characterized by a central , tetrahedral carbon atom bound to four different atoms : bromine , chlorine , fluorine , and hydrogen . we might be tempted to conclude that the two molecules are the same , if we just concern ourselves with what they 're made of . however , let 's see if we can overlay the two molecules perfectly to really prove that they 're the same . we have free license to rotate and translate both of the molecules as we wish . remarkably though , no matter how we move the molecules , we find that perfect superposition is impossible to achieve . now take a look at your hands . notice that your two hands have all the same parts : a thumb , fingers , a palm , etc . like our two molecules under study , both of your hands are made of the same stuff . furthermore , the distances between stuff in both of your hands are the same . the index finger is next to the middle finger , which is next to the ring finger , etc . the same is true of our hypothetical molecules . all of their internal distances are the same . despite the similarities between them , your hands , and our molecules , are certainly not the same . try superimposing your hands on one another . just like our molecules from before , you 'll find that it ca n't be done perfectly . now , point your palms toward one another . wiggle both of your index fingers . notice that your left hand looks as if it 's looking in a mirror at your right . in other words , your hands are mirror images . the same can be said of our molecules . we can turn them so that one looks at the other as in a mirror . your hands - and our molecules - possess a spatial property in common called chirality , or handedness . chirality means exactly what we 've just described : a chiral object is not the same as its mirror image . chiral objects are very special in both chemistry and everyday life . screws , for example , are also chiral . that 's why we need the terms right-handed and left-handed screws . and believe it or not , certain types of light can behave like chiral screws . packed into every linear , plane-polarized beam of light are right-handed and left-handed parts that rotate together to produce plane polarization . chiral molecules , placed in a beam of such light , interact differently with the two chiral components . as a result , one component of the light gets temporarily slowed down relative to the other . the effect on the light beam is a rotation of its plane from the original one , otherwise known as optical rotation . va n't hoff and later chemists realized that the chiral nature of tetrahedral carbons can explain this fascinating phenomenon . chirality is responsible for all kinds of other fascinating effects in chemistry , and everyday life . humans tend to love symmetry and so if you look around you , you 'll find that chiral objects made by humans are rare . but chiral molecules are absolutely everywhere . phenomena as separate as optical rotation , screwing together furniture , and clapping your hands all involve this intriguing spatial property .

chiral objects are very special in both chemistry and everyday life . screws , for example , are also chiral . that 's why we need the terms right-handed and left-handed screws .

what is unique about the four groups attached to a chiral carbon ( also called a stereocenter ) ?

there 's a play so powerful that an old superstition says its name should never even be uttered in a theater , a play that begins with witchcraft and ends with a bloody severed head , a play filled with riddles , prophesies , nightmare visions , and lots of brutal murder , a play by william shakespeare sometimes referred to as the `` scottish play '' or the `` tragedy of macbeth . '' first performed at the globe theater in london in 1606 , `` macbeth '' is shakespeare 's shortest tragedy . it is also one of his most action-packed . in five acts , he recounts a story of a scottish nobleman who steals the throne , presides over a reign of terror , and then meets a bloody end . along the way , it asks important questions about ambition , power , and violence that spoke directly to the politics of shakespeare 's time and continue to echo in our own . england in the early 17th century was politically precarious . queen elizabeth i died in 1603 without producing an heir , and in a surprise move , her advisors passed the crown to james stewart , king of scotland . two years later , james was subject to an assassination attempt called the gunpowder plot . questions of what made for a legitimate king were on everyone 's lips . so shakespeare must have known he had potent material when he conflated and adapted the stories of a murderous 11th century scottish king named macbeth and those of several other scottish nobles . he found their annals in hollinshed 's `` chronicles , '' a popular 16th century history of britain and ireland . shakespeare would also have known he needed to tell his story in a way that would immediately grab the attention of his diverse and rowdy audience . the globe welcomed all sections of society . wealthier patrons watched the stage from covered balconies while poorer people paid a penny to take in the show from an open-air section called the pit . talking , jeering , and cheering was common during performances . there are even accounts of audiences throwing furniture when plays were flops . so `` macbeth '' opens with a literal bang . thunder cracks and three witches appear . they announce they 're searching for a scottish nobleman and war hero named macbeth , then fly off while chanting a curse that predicts a world gone mad . `` fair is foul and foul is fair . hover through the fog and filthy air . '' as seen later , they find macbeth and his fellow nobleman banquo . `` all hail macbeth , '' they prophesize , `` that shalt be king hereafter ! '' `` king ? '' macbeth wonders . just what would he have to do to gain the crown ? macbeth and his wife lady macbeth soon chart a course of murder , lies , and betrayal . in the ensuing bloodbath , shakespeare provides viewers with some of the most memorable passages in english literature . `` out , damned spot ! out , i say ! '' lady macbeth cries when she believes she ca n't wipe her victim 's blood off her hands . her obsession with guilt is one of many themes that runs through the play , along with the universal tendency to abuse power , the endless cycles of violence and betrayal , the defying political conflict . as is typical with shakespeare 's language , a number of phrases that got their start in the play have been repeated so many times that they now feel commonplace . they include `` the milk of human kindness , '' `` what 's done is done , '' and the famous witches ' spell , `` double , double toil and trouble ; fire burn , and caldron bubble . '' but shakespeare saves the juiciest bit of all for macbeth himself . towards the end of the play , macbeth reflects on the universality of death and the futility of life . `` out , out , brief candle ! '' he laments . `` life 's but a walking shadow , a poor player that struts and frets his hour upon the stage and then is heard no more . it is a tale told by an idiot , full of sound and fury signifying nothing . '' life may be a tale told my an idiot , but `` macbeth '' is not . shakespeare 's language and characters have entered our cultural consciousness to a rare extent . directors often use the story to shed light on abuses of power , ranging from the american mafia to dictators across the globe . the play has been adapted to film many times , including akira kurosawa 's `` throne of blood , '' which takes place in feudal japan , and a modernized version called `` scotland , pa , '' in which macbeth and his rivals are managers of competing fast food restaurants . no matter the presentation , questions of morality , politics , and power are still relevant today , and so , it seems , is shakespeare 's `` macbeth . ''

`` king ? '' macbeth wonders . just what would he have to do to gain the crown ?

lady macbeth sees a bloodstain on her hands because she :

translator : andrea mcdonough reviewer : bedirhan cinar being human , we each view ourselves as a unique and independent individual , but we 're never alone ! millions of microscopic beings inhabit our bodies , and no two bodies are the same . each is a different habitat for microbial communities : from the arid deserts of our skin , to the villages on our lips , and the cities in our mouths . even every tooth is its own distinctive neighborhood , and our guts are teaming metropolises of interacting microbes . and in these bustling streets of our guts , we see a constant influx of food , and every microbe has a job to do . here 's a cellulolytic bacteria , for example . their one job is to break down cellulose , a common compound in vegetables , into sugars . those simple sugars then move along to the respirators , another set of microbes that snatch up these simple sugars and burn them as fuel . as food travels through our digestive tract , it reaches the fermentors who extract energy from these sugars by converting them into chemicals , like alcohol and hydrogen gas , which they spew out as waste products . deeper in the depths of our gut city , the syntrophs eke out a living off the fermenters ' trash . at each step of this process , energy is released , and that energy is absorbed by the cells of the digestive tract . this city we just saw is different in everyone . every person has a unique and diverse community of gut microbes that can process food in different ways . one person 's gut microbes may be capable of releasing only a fraction of the calories that another person 's gut microbes can extract . so , what determines the membership of our gut microbial community ? well , things like our genetic makeup and the microbes we encounter throughout our lives can contribute to our microbial ecosystems . the food we eat also influences which microbes live in our gut . for example , food made of complex molecules , like an apple , requires a lot of different microbial workers to break it down . but , if a food is made of simple molecules , like a lollipop , some of these workers are put out of a job . those workers leave the city , never to return . what does n't function well are gut microbial communities with only a few different types of workers . for example , humans who suffer from diseases like diabetes or chronic gut inflamation typically have less microbial variety in their guts . we do n't fully understand the best way to manage our individual microbial societies , but it is likely that lifestyle changes , such as eating a varied diet of complex , plant-based foods , can help revitalize our microbial ecosystems in our gut and across the entire landscape of our body . so , we are really not alone in our body . our bodies are homes to millions of different microbes , and we need them just as much as they need us . as we learn more about how our microbes interact with each other and with our bodies , we will reveal how we can nurture this complex , invisible world that shapes our personal identity , our health , and our well-being .

and in these bustling streets of our guts , we see a constant influx of food , and every microbe has a job to do . here 's a cellulolytic bacteria , for example . their one job is to break down cellulose , a common compound in vegetables , into sugars . those simple sugars then move along to the respirators , another set of microbes that snatch up these simple sugars and burn them as fuel .

what is a cellulolytic bateria 's one job ?

humans know the surprising prick of a needle , the searing pain of a stubbed toe , and the throbbing of a toothache . we can identify many types of pain and have multiple ways of treating it . but what about other species ? how do the animals all around us experience pain ? it 's important that we find out . we keep animals as pets , they enrich our environment , we farm many species for food , and we use them in experiments to advance science and human health . animals are clearly important to us , so it 's equally important that we avoid causing them unnecessary pain . for animals that are similar to us , like mammals , it 's often obvious when they 're hurting . but there 's a lot that is n't obvious , like whether pain relievers that work on us also help them . and the more different an animal is from us , the harder it is to understand their experience . how do you tell whether a shrimp is in pain ? a snake ? a snail ? in vertebrates , including humans , pain can be split into two distinct processes . in first , nerves and the skin sense something harmful and communicate that information to the spinal cord . there , motor neurons activate movements that make us rapidly jerk away from the threat . this is the physical recognition of harm called nociception , and nearly all animals , even those with very simple nervous systems , experience it . without this ability , animals would be unable to avoid harm and their survival would be threatened . the second part is the conscious recognition of harm . in humans , this occurs when the sensory neurons in our skin make a second round of connections via the spinal cord to the brain . there , millions of neurons in multiple regions create the sensations of pain . for us , this is a very complex experience associated with emotions like fear , panic , and stress , which we can communicate to others . but it 's harder to know exactly how animals experience this part of the process because most them ca n't show us what they feel . however , we get clues from observing how animals behave . wild , hurt animals are known to nurse their wounds , make noises to show their distress , and become reclusive . in the lab , scientists have discovered that animals like chickens and rats will self-administer pain-reducing drugs if they 're hurting . animals also avoid situations where they 've been hurt before , which suggests awareness of threats . we 've reached the point that research has made us so sure that vertebrates recognize pain that it 's illegal in many countries to needlessly harm these animals . but what about other types of animals like invertebrates ? these animals are n't legally protected , partly because their behaviors are harder to read . we can make good guesses about some of them , like oysters , worms , and jellyfish . these are examples of animals that either lack a brain or have a very simple one . so an oyster may recoil when squirted with lemon juice , for instance , because of nociception . but with such a simple nervous system , it 's unlikely to experience the conscious part of pain . other invertebrate animals are more complicated , though , like the octopus , which has a sophisticated brain and is thought to be one of the most intelligent invertebrate animals . yet , in many countries , people continue the practice of eating live octopus . we also boil live crawfish , shrimp , and crabs even though we do n't really know how they 're affected either . this poses an ethical problem because we may be causing these animals unnecessary suffering . scientific experimentation , though controversial , gives us some clues . tests on hermit crabs show that they 'll leave an undesirable shell if they 're zapped with electricity but stay if it 's a good shell . and octopi that may originally curl up an injured arm to protect it will risk using it to catch prey . that suggests that these animals make value judgements around sensory input instead of just reacting reflexively to harm . meanwhile , crabs have been known to repeatedly rub a spot on their bodies where they 've received an electric shock . and even sea slugs flinch when they know they 're about to receive a noxious stimulus . that means they have some memory of physical sensations . we still have a lot to learn about animal pain . as our knowledge grows , it may one day allow us to live in a world where we do n't cause pain needlessly .

but what about other species ? how do the animals all around us experience pain ? it 's important that we find out .

how many kinds of animals experience nociception ?

how do nerves work ? are nerves simply the wires in the body that conduct electricity , like the wires in the walls of your home or in your computer ? this is an analogy often made , but the reality is that nerves have a much more complex job in the body . they are not just the wires , but the cells that are the sensors , detectors of the external and internal world , the transducers that convert information to electrical impulses , the wires that transmit these impulses , the transistors that gate the information and turn up or down the volume- and finally , the activators that take that information and cause it to have an effect on other organs . consider this . your mother gently strokes your forearm and you react with pleasure . or a spider crawls on your forearm and you startle and slap it off . or you brush your forearm against a hot rack while removing a cake from the oven and you immediately recoil . light touch produced pleasure , fear , or pain . how can one kind of cell have so many functions ? nerves are in fact bundles of cells called neurons and each of these neurons is highly specialized to carry nerve impulses , their form of electricity , in response to only one kind of stimulus , and in only one direction . the nerve impulse starts with a receptor , a specialized part of each nerve , where the electrical impulse begins . one nerve 's receptor might be a thermal receptor , designed only to respond to a rapid increase in temperature . another receptor type is attached to the hairs of the forearm , detecting movement of those hairs , such as when a spider crawls on your skin . yet another kind of neuron is low-threshold mechanoreceptor , activated by light touch . each of these neurons then carry their specific information : pain , warning , pleasure . and that information is projected to specific areas of the brain and that is the electrical impulse . the inside of a nerve is a fluid that is very rich in the ion potassium . it is 20 times higher than in the fluid outside the nerve while that outside fluid has 10 times more sodium than the inside of a nerve . this imbalance between sodium outside and potassium inside the cell results in the inside of the nerve having a negative electrical charge relative to the outside of the nerve , about equal to -70 or -80 millivolts . this is called the nerve 's resting potential . but in response to that stimulus the nerve is designed to detect , pores in the cell wall near the receptor of the cell open . these pores are specialized protein channels that are designed to let sodium rush into the nerve . the sodium ions rush down their concentration gradient , and when they do , the inside of the nerve becomes more positively charged- about +40 millivolts . while this happens , initially in the nerve right around the receptor , if the change in the nerve 's electrical charge is great enough , if it reaches what is called threshold , the nearby sodium ion channels open , and then the ones nearby those , and so on , and so forth , so that the positivity spreads along the nerve 's membrane to the nerve 's cell body and then along the nerve 's long , thread-like extension , the axon . meanwhile , potassium ion channels open , potassium rushes out of the nerve , and the membrane voltage returns to normal . actually , overshooting it a bit . and during this overshoot , the nerve is resistant to further depolarization-it is refractory , which prevents the nerve electrical impulse from traveling backwards . then , ion pumps pump the sodium back back out of the nerve , and the potassium back into the nerve , restoring the nerve to its normal resting state . the end of the nerve , the end of the axon , communicates with the nerve 's target . this target will be other nerves in a specialized area of the spinal cord , to be processed and then transmitted up to the brain . or the nerve 's target may be another organ , such as a muscle . when the electrical impulse reaches the end of the nerve , small vesicles , or packets , containing chemical neurotransmitters , are released by the nerve and rapidly interact with the nerve 's target . this process is called synaptic transmission , because the connection between the nerve and the next object in the chain is called a synapse . and it is here , in this synapse , that the neuron 's electrical information can be modulated , amplified , blocked altogether or translated to another informational process .

another receptor type is attached to the hairs of the forearm , detecting movement of those hairs , such as when a spider crawls on your skin . yet another kind of neuron is low-threshold mechanoreceptor , activated by light touch . each of these neurons then carry their specific information : pain , warning , pleasure .

low threshold mechano-receptors are activated by light touch and carry specific information regarding :

using the word shakespeare within any classroom in the 21st century has become almost as dangerous for teachers as putting balloons in a toaster . after uttering this simple word , the common teacher is met with a mass of groans , moans , devastated looks , and the occasional chair tossed in his or her direction . but shakespearean works are not boring , confusing , long and painful plays written more than 400 years ago . they 're adventures relating to the extremities of human nature : love , hate , jealousy , zealous ambition , fear , mistrust , deception , and murder . we owe much of our own language to his invention . he invented over 2,000 words for use in his plays , which still remain in the oxford english dictionary . words like `` countless '' and `` assassination '' as well as phrases like `` one fell swoop , '' `` foul play , '' and even `` to be in a pickle '' all originated from william 's brilliant brain . and there are many echoes of shakespeare 's romantic language too . if you read < em > romeo and juliet < /em > , you 'll come across sentences like , `` she doth teach the torches to burn bright , '' and , `` so shows a snowy dove trooping with crows . '' both are quite clever metaphors , suggesting that juliet is both exceptionally beautiful and far moreso than anyone else . `` for thou art as glorious to this night , being o'er my head , as is a winged messenger of heaven , '' is a simile suggesting angelic qualities of the lady in question . this is not too different from today 's comments like , `` hey , beautiful ! '' and , `` you 're the hottest girl in the room . '' shakespeare also uses slightly more complex metaphors to describe the intentions of a mischievous man . for instance , `` this holy shrine , the gentle sin is this : my lips , two blushing pilgrims , ready stand to smooth that rough touch with a tender kiss , '' essentially means , `` i wish to kiss you . '' such male intentions were not limited to simple pecks on the cheek either . an intentional ambiguity was often used as a cheeky means to proposition marriage or a more intimate relationship . therefore , instead of viewing shakespearean works as out-dated , boring , and unhelpful , start reading today and discover the best ways to get the one you love to love you back .

words like `` countless '' and `` assassination '' as well as phrases like `` one fell swoop , '' `` foul play , '' and even `` to be in a pickle '' all originated from william 's brilliant brain . and there are many echoes of shakespeare 's romantic language too . if you read < em > romeo and juliet < /em > , you 'll come across sentences like , `` she doth teach the torches to burn bright , '' and , `` so shows a snowy dove trooping with crows . ''

using shakespearean phrases to get a date was considered very polite and romantic in the 16th and 17th centuries . what polite language phrases are used to get a date in modern society ?

a lone priestess walks towards an underground chamber . people line the streets to watch as she proclaims her innocence . it does n't matter . she 's already been judged and found guilty . the sentence ? live burial . the underground chamber contains a portion of bread , water , milk , and oil . she will have a lamp , a bed , and a blanket , but she wo n't emerge alive . at the threshold , the priestess pauses , claims her innocence one last time , then enters the chamber never to be seen again by the roman people . the priestess is one of rome 's six vestal virgins , each carefully selected as children from rome 's most aristocratic families . but now with her death , there are only five , and a new priestess must be chosen . the six-year-old licinia witnessed the spectacle , never suspecting that a few days later , she 'd be chosen as the next vestal virgin . her age , her patrician family lineage , and her apparent good health makes her the best candidate to serve the goddess vesta in the eyes of the romans . her parents are proud that their daughter 's been chosen . licinia is afraid , but she has no choice in the matter . she must serve the goddess for at least the next 30 years . for the first ten years of licinia 's service , she 's considered in training , learning how to be a vestal virgin . her most important duty is keeping vigil over the flame of vesta , the virgin goddess of the hearth . vesta does n't have a statue like other roman gods and goddesses . instead , she 's represented by the flame which burns day and night in her temple located next to the forum in the center of the city . like all vestal priestesses , licinia spends part of each day on shift , watching and tending to the flame . the flame represents two things . the first is the continuation of rome as a power in the world . the romans believed that if the flame goes out , the city 's in danger . the flame also symbolizes the continuing virginity of vesta 's priestesses . for the romans , a vestal 's virginity signaled not only her castitas , or modest spirit and body , but also her ritual purity . so licinia knows she must never let the flame go out . her life , the lives of her fellow vestals , and the safety of rome itself depends upon it . licinia learns to collect water each day from a nearby fountain to cleanse the temple . she learns the fasti , the calendar of sacred rituals and she watches while the senior priestesses conduct sacrifices . by the time licinia completes her training , she 's 16 years old . licinia understands that the way she must act is a reflection of the goddess she serves . when it 's her turn to collect the water , she keeps her eyes lowered to the ground . when she performs sacrifices , she focuses intently on the task . licinia directs her energy towards being the best priestess she can be . she 's worried that someday the state will claim her life for its own purposes to protect itself from danger . licinia could be accused of incestum , meaning unchastity , at any time and be sacrificed whether she 's innocent or guilty . licinia fully understands now why her predecessor was buried alive . ten years ago , the flame of vesta went out . the priestesses knew that they could n't keep it a secret . the future of rome depended upon it . they went to the chief priest and he opened an investigation to discover why the flame had failed . someone came forward and claimed that one of the vestals was no longer a virgin . that was the beginning of the end . the accused protested her innocence , but it was n't enough . she was tried and found guilty . that vestal 's death was meant to protect the city , but licinia weeps for what has been lost and for what she knows now . her own path was paved by the death of another , and her life could be taken just as easily for something as simple as a flame going out .

the sentence ? live burial . the underground chamber contains a portion of bread , water , milk , and oil .

live burial was a very extreme punishment that a vestal virgin faced if she was found guilty of incestum ( unchastity ) . why do you think the ancient romans were so severe in cases like this ? what might it suggest about what the ancient romans valued ?

translator : andrea mcdonough reviewer : bedirhan cinar why do we see illusions ? i 'm going to tell you about some of my research , where i provided evidence for a different kind of hypothesis than the one that might be in the book on your coffee stand . alright , so let 's look at one of the illusions here . and this is a stand-in for many , many kinds of illusions that are explained by this hypothesis . i 'm just going to walk through it for this particular one . as usual in these things , these two lines are , in fact , parallel , but you perceive them to bow outwards at their centers . at the center where those radial lines are , it 's wider in your visual field than the parts above and below . and this is remarkable , because it 's a remarkably simple stimulus . it 's just a bunch of straight lines . why should one of the most complicated objects in the universe be unable to render this incredibly simple image ? when you want to answer questions like this , you need to ask , well , what might this mean to your brain ? and what your brain is going to think this is , is not some lines on a page . your brain has evolved to handle the kinds of natural stimuli that it encounters in real life . so when does the brain encounter stimuli like this ? well , it seems a bit odd , but in fact , you 've been encountering this stimulus all day long . whenever you move , whenever you move forward , in particular . when you move forward , you get optic flow , flowing outwards in your visual field , like when the enterprise goes into warp . all of these objects flow outwards and they leave trails , or blur lines , on your retina . they 're activating mini-neurons all in a row . so , this is a version of what happens in real life and this another version of what happens in real life all the time . in fact , cartoonists know about this . they put these blur lines in their cartoons and it means to your brain : motion . now , it 's not that in real life you see blur lines . the point is that it 's the stimulus at the back of your eye that has these optic blurs in them , and that 's what tells your brain that you 're moving . when you move forward , your eyes fixate like cameras , like snapshot cameras , it fixates , it fixates , little ( snapshot sound ) camera shots , and each time it fixates when you 're moving forward , you get all this flowing outwards . so when you take a fixation , you end up with this weird optic blur stuff , and it tells you the direction you 're moving . alright , that 's half the story . that 's what this stimulus means . it means that your brain thinks , when it 's looking at the first image , that you 're actually on your way , moving towards the center . it still does n't explain why you should perceive these straight lines as bowed outwards . to understand the rest of the story , you have to understand that our brains are slow . what you would like is that when light hits your eye , then -- ping ! -- immediately you have a perception of what the world is like . but it does n't work that way . it takes about a tenth of a second for your perception to be created . and a tenth of a second does n't sound very long , but it 's a long time in normal behaviors . if you 're moving just at one meter per second , which is fairly slow , then in a tenth of second , you 've moved 10 centimeters . so if you did n't correct for this delay , then anything that you perceived to be within 10 centimeters of you , by the time you perceived it , you would have bumped into it or just passed it . and of course , this is going to be much worse -- ( laughter ) it 's going to be much worse in a situation like this . your perception is behind . what you want is that your perception should look like this . you want your perceptions at any time t to be of the world at time t. but the only way your brain can do that , is that it has to , instead of generating a perception of the way the world was when light hit your retina , it has to do something fancier . it ca n't passively respond and create a best guess , it has to create a best guess about the next moment . what will the world look like in a tenth of a second ? build a perception of that , because by the time your perception of the near future occurs in your brain , the near future will have arrived and you 'll have a perception of the present , which is what you want . in my research , i provided a lot of evidence -- and there 's other research areas that have provided evidence -- that the brain is filled with mechanisms that try to compensate for its slowness . and i 've shown that huge swaths of illusions are explained by this , this just being one example . but let me finish by saying , how exactly does this explain this particular example ? so , the question , really , we have to ask is : how do those two vertical lines in that first stimulus , how do they change in the next moment were i moving towards the center , that all those optical lines are suggesting that i 'm moving . what happens to them ? well , let 's imagine . imagine you 've got a doorway . you 've got a doorway . imagine it 's a cathedral doorway , to make it more concrete -- it 'll be helpful in a second . when you 're very far away from it , the sides are perfectly parallel . but now imagine what happens when you get closer . it all flows outwards in your visual field , flowing outwards . but when you 're really close -- imagine the sides of the doorway are here and here , but if you look up at this cathedral doorway and do your fingers like this , the sides of the doorway are going up , like railroad tracks in the sky . what started off as two parallel lines , in fact , bows outwards at eye level , and does n't go outwards nearly as much above . so in the next moment , you have a shape that 's more like this next picture . the projective geometry -- that is , the way the things project , in fact , change in this way in the next moment . so when you have a stimulus like this , well , your brain has no problem , there 's just two vertical lines and no cues that there 'll be a change in the next moment , so just render it as it is . but if you add cues -- and this is just one of many kinds of cues that can lead to these kinds of illusions , this very strong optic blur cue -- then you 're going to perceive instead exactly how it will appear in the next moment . all of our perceptions are always trying to be about the present , but you have to perceive the future to , in fact , perceive the present . and these illusions are failed perceptions of the future , because they 're just static images on the page , they 're not changing like in real life . and let me just end by showing one illusion here . if i can , i 'll quickly show two . this one 's fun . if you just fixate at the middle there , and make stabbing motions with your head , looming towards it like this . everybody do that . make short , stabbing motions . because i 've added blur to these optic flow lines , your brain says , `` they 're probably already moving , that 's why they 're blurry . '' when you do it , they should be bursting out in your visual field faster than they should . they should n't be moving that much . and a final one i 'll just leave in the background is this . here are the cues of motion , the kinds of cues that you get on your retina when things are moving . you do n't have to do anything -- just look at it . raise your hand if things are moving when they should n't be . it 's weird , right ? but what you have now are the cues that , from your brain 's point of view , you have the stimulus on your eyes , like , `` oh , these things are moving . '' render a perception of what they 'll do in the next moment -- they should be moving and they should have shifted . alright , thank you very much . ( applause )

so , this is a version of what happens in real life and this another version of what happens in real life all the time . in fact , cartoonists know about this . they put these blur lines in their cartoons and it means to your brain : motion . now , it 's not that in real life you see blur lines . the point is that it 's the stimulus at the back of your eye that has these optic blurs in them , and that 's what tells your brain that you 're moving .

why do cartoonists add blur lines behind a flying superhero ?

vatican city : capitol of the catholic church , home to the pope , owner of impressive collections of art and history all contained within the borders of the world 's smallest country : conveniently circumnavigateable on foot in only 40 minutes . just how did the world end up with this tiny nation ? the short answer is : because mussolini and the long answer is fiendishly complicated so here 's a simplified medium version : the popes used to rule a country called the papal states that covered much of modern day italy . it was during this 1,000+ year reign that the popes constructed st. peter 's basilica the largest church in the world -- and also built a wall around the base of a hill known as vatican upon which st. peter 's stood . but the kingdom of italy next door thought rome would be an awesome capital for their country and so conquered the papal states . his nation destroyed the pope hid behind the walls of vatican and conflictingly refused to acknowledge that the kingdom of italy existed , while simultaneously complaining about being a prisoner of the kingdom of italy -- which according to him did n't exist . rather than risk religious civil war by getting rid of the pope the kingdom of italy decided to wait him out assuming he 'd eventually give up -- but religion is nothing if not obstinate -- and 1 , 2 , 3 , 4 , 5 popes and sixty years later nothing had changed . which brings us to benito mussolini the then prime minister of italy who was tired of listing to the pope complain to italian catholics about his self-imposed imprisonment so mussolini thought he could score some political points by striking a deal which looked like this : 1 ) italy gave the land of vatican to the pope . and… 2 ) italy gave the pope a bunch of apology money in return 1 ) the pope acknowledged that italy existed and and… 2 ) the pope promised to remain neutral in politics and wars . on the off chance that , you know , mussolini thought this might be a thing . the deal was signed and a new country , vatican city was born . and today the tiny nation on a hill has all the things you 'd expect of a country : its own government that makes its own laws that are enforced by its own police , who put people who break them in its own jail . it also has its own bank and prints its own stamps and issues its own license plates , though only its citizens can drive within its borders presumably because of terrible , terrible parking -- and as the true mark of any self-respecting nation : it has its own top-level domain : .va but , despite all these national trappings vatican city is not really like any other country . hold on to your fancy hat , because it 's about to get weird : to understand the vatican : there are two people and two things that you need to know about : the famous pope , the incredibly confusing holy see , the country of vatican city and along with that the almost completely unknown king of vatican city . but first the pope : who gets a throne to sit upon and from which he acts as the bishop for all the catholics in rome . actually all bishops in the catholic church get their own thrones but because the bishop of rome is also the pope his thrown is special and has it 's own special name : the holy see . every time a pope dies or retires there is a sort of game of thrones to see which of the bishops will next get to occupy the holy see . so while popes come and go the throne is eternal . as such the name the holy see not only refers to the throne but also all the rules that make the catholic church the catholic church . when mussolini crafted that aforementioned deal , technically he gave the land of vatican city to the holy see -- which , believe it or not , is a legal corporate person in international law . basically every time you hear the words the holy see think catholic church , inc of which the pope is the ceo . now back to the king . the king of vatican city has absolute , unchecked power within the country 's borders and his presence makes vatican city one of only six remanning absolute monarchies in the world , including brunei , oman , qatar , saudi arabia , and swaziland . the king 's absolute power is why vatican city ca n't join the european union because only democracies are allowed . through vatican city does , strictly speaking , have a legislative brach of government -- staffed by cardinals , appointed by the pope -- the king of vatican city can overrule their decisions and at any time for any reason . so why do you never hear about the king of vatican city ? because though king and pope are two different roles , they just happen to be occupied by the same person at the same time -- which has the funny consequence that , because the pope is elected and the king is all-powerful but they 're the same guy it makes vatican city the world 's only elected , non-hereditary absolute monarchy . it 's this dual-role that makes untangling vatican city so difficult because the pope , depending on the situation either acts as the king of the country of vatican city or the pope of the holy see . got it ? no ? ok , here 's an analogy : imagine if a powerful international company , say grey industries , had a ceo who convinced the united states to give one of its islands to the company which then made the island into a new country -- greytropolis -- with an absolute monarchy as its government and the law that the king of greytropolis is , by definition , the ceo of grey industries . it 's pretty obvious at that point that the ceo should move his corporate headquarters to the new nation -- so that the laws of the country can benefit the company and the company 's global reach can benefit the country . as for the man in the middle sometimes it 's good to the the ceo and sometimes it 's good to be the king . that is essentially vatican city . but if you 're still confused , do n't worry even other countries ca n't keep it straight . for example the united nations has the holy see the corporation as a member but not vatican city the actual country . and the holy see gives passports to vatican city citizens that other countries accept even though those passports come from a company , not a country . and speaking of vatican city citizens , they are perhaps the strangest consequence of the pope 's dual role as religious leader and monarch . while other countries mint new citizens with the ever popular process of human reproduction vatican city does not . no one in vatican city is born a citizen -- and that 's not just because , within a rounding error , there are no female vaticans . the only way to become a citizen is for the king of vatican city to appoint you as one . and the king only appoints you a citizen if you work for the pope -- who is also the king . and because the king is all-powerful your citizenship is at his whim . if you quit your job for the pope , the king -- who is also the pope -- will revoke your citizenship . these rules mean that vatican city does n't have a real permanent population to speak of : there are only about 500 full citizens -- which is fewer people that live in single skyscrapers in many countries -- and all these citizens work for the holy see as either cardinals or diplomats or the pope 's bodyguards or other catholic-related jobs . so it 's best to think of vatican city as a kind of sovereign corporate headquarters that grants temporary citizenship to its managers rather than a real city-state like singapore : which has a self-reproducing population of citizens engaged in a variety of economic activities both of which vatican city lacks . but in the end , the reason the world cares about vatican city is not because of the citizens within its walls but because of the billion members of its church outside those walls .

as for the man in the middle sometimes it 's good to the the ceo and sometimes it 's good to be the king . that is essentially vatican city . but if you 're still confused , do n't worry even other countries ca n't keep it straight .

why is the fact that there is a king of vatican city so unique in shaping the country ?

translator : andrea mcdonough reviewer : bedirhan cinar have you heard the one about thomas jefferson and the louisiana territory ? thomas jefferson , author of the declaration of independence , was not a fan of the new constitution presented in 1787 . he was very worried that the constitution gave too much power to the new , national government , and not enough power to the states , an issue known as `` big government '' . jefferson only reluctantly agreed to support it when his friend , james madison , promised to propose a bill of rights after it was ratified . but jefferson 's fears about big government did not go away . for example , secretary of the treasury , alexander hamilton , proposed a national bank in 1790 , and jefferson knew there was no provision in the constitution to permit such a thing . hamilton claimed some sort of implied powers mumbo-jumbo . sure , it was n't written in the constitution , but the constitution implied that it could be done . but , jefferson was n't buying it . nonetheless , the bank was established by hamilton and president washington . when jefferson was sworn in as president in 1801 , he pledged to reduce the size and scope of the national government . but , of course , things did n't go exactly as he had planned . spain secretly transferred the louisiana territory to france right beneath jefferson 's nose . when congress found out , they quickly began discussions with france to buy a piece of the territory along the mississippi river for about $ 2 million . but , there was one little problem : jefferson knew there was no provision in the constitution to buy foreign territory . so what was a strict constructionist to do ? first , he tried to get an amendment to the constitution passed that would expressly permit the purchase , but congress was n't willing to do it . then , without permission , the u.s. negotiators in france cut a deal for all of the territory for a cool $ 15 million dollars . that new land doubled the size of the nation ! now jefferson was really stuck . he knew that the territory would be a great acquisition for the country , providing lots of new land for farmers and other settlers , but how could he constitutionally justify it ? in the end , jefferson turned to the argument used by his old foe alexander hamilton . he claimed that the power to purchase the territory is implied in the constitution 's treaty-making power . this was the exact argument that he had mocked openly a decade before , so it must have crushed his pride to have to use it . but more importantly , he may have committed the biggest big government play ever ! how ironic is it that one of the biggest opponents of big government doubled the size of the young country and did so while openly questioning its constitutionality ? at $ 15 million , which is about three cents an acre , it has been called by many the greatest real estate deal in the history of the united states .

nonetheless , the bank was established by hamilton and president washington . when jefferson was sworn in as president in 1801 , he pledged to reduce the size and scope of the national government . but , of course , things did n't go exactly as he had planned .

when thomas jefferson was elected president in 1800 , he pledged to

in 1861 , two scientists got into a very brainy argument . specifically , they had opposing ideas of how speech and memory operated within the human brain . ernest aubertin , with his localistic model , argued that a particular region or the brain was devoted to each separate process . pierre gratiolet , on the other hand , argued for the distributed model , where different regions work together to accomplish all of these various functions . the debate they began reverberated throughout the rest of the century , involving some of the greatest scientific minds of the time . aubertin and his localistic model had some big names on his side . in the 17th century , rené descartes had assigned the quality of free will and the human soul to the pineal gland . and in the late 18th century , a young student named franz joseph gall had observed that the best memorizers in his class had the most prominent eyes and decided that this was due to higher development in the adjacent part of the brain . as a physician , gall went on to establish the study of phrenology , which held that strong mental faculties corresponded to highly developed brain regions , observable as bumps in the skull . the widespread popularity of phrenology throughout the early 19th century tipped the scales towards aubertin 's localism . but the problem was that gall had never bothered to scientifically test whether the individual brain maps he had constructed applied to all people . and in the 1840 's , pierre flourens challenged phrenology by selectively destroying parts of animal brains and observing which functions were lost . flourens found that damaging the cortex interfered with judgement or movement in general , but failed to identify any region associated with one specific function , concluding that the cortex carried out brain functions as an entire unit . flourens had scored a victory for gratiolet , but it was not to last . gall 's former student , jean-baptiste bouillaud , challenged flourens ' conclusion , observing that patients with speech disorders all had damage to the frontal lobe . and after paul broca 's 1861 autopsy of a patient who had lost the power to produce speech , but not the power to understand it , revealed highly localized frontal lobe damage , the distributed model seemed doomed . localism took off . in the 1870 's , karl wernicke associated part of the left temporal lobe with speech comprehension . soon after , eduard hitzig and gustav fritsch stimulated a dog 's cortex and discovered a frontal lobe region responsible for muscular movements . building on their work , david ferrier mapped each piece of cortex associated with moving a part of the body . and in 1909 , korbinian brodmann built his own cortex map with 52 separate areas . it appeared that the victory of aubertin 's localistic model was sealed . but neurologist karl wernicke had come up with an interesting idea . he reasoned that since the regions for speech production and comprehension were not adjacent , then injuring the area connecting them might result in a special type of language loss , now known as receptive aphasia . wernicke 's connectionist model helped explain disorders that did n't result from the dysfunction of just one area . modern neuroscience tools reveal a brain more complex than gratiolet , aubertin , or even wernicke imagined . today , the hippocampus is associated with two distinct brain functions : creating memories and processing location in space . we also now measure two kinds of connectivity : anatomical connectivity between two adjoining regions of cortex working together , and functional connectivity between separated regions working together to accomplish one process . a seemingly basic function like vision is actually composed of many smaller functions , with different parts of the cortex representing shape , color and location in space . when certain areas stop functioning , we may recognize an object , but not see it , or vice versa . there are even different kinds of memory for facts and for routines . and remembering something like your first bicycle involves a network of different regions each representing the concept of vehicles , the bicycle 's shape , the sound of the bell , and the emotions associated with that memory . in the end , both gratiolet and aubertin turned out to be right . and we still use both of their models to understand how cognition happens . for example , we can now measure brain activity on such a fine time scale that we can see the individual localized processes that comprise a single act of remembering . but it is the integration of these different processes and regions that creates the coherent memory we experience . the supposedly competing theories prove to be two aspects of a more comprehensive model , which will in turn be revised and refined as our scientific techologies and methods for understanding the brain improve .

wernicke 's connectionist model helped explain disorders that did n't result from the dysfunction of just one area . modern neuroscience tools reveal a brain more complex than gratiolet , aubertin , or even wernicke imagined . today , the hippocampus is associated with two distinct brain functions : creating memories and processing location in space . we also now measure two kinds of connectivity : anatomical connectivity between two adjoining regions of cortex working together , and functional connectivity between separated regions working together to accomplish one process . a seemingly basic function like vision is actually composed of many smaller functions , with different parts of the cortex representing shape , color and location in space .

two types of connectivity -- when areas of the brain work together -- have been measured by modern neuroscientific methods . they are called _____ and _____ .

way before the first selfie , the ancient greeks and romans had a myth about someone a little too obsessed with his own image . in one telling , narcissus was a handsome guy wandering the world in search of someone to love . after rejecting a nymph named echo , he caught a glimpse of his own reflection in a river , and fell in love with it . unable to tear himself away , narcissus drowned . a flower marked the spot of where he died , and we call that flower the narcissus . the myth captures the basic idea of narcissism , elevated and sometimes detrimental self-involvement . but it 's not just a personality type that shows up in advice columns . it 's actually a set of traits classified and studied by psychologists . the psychological definition of narcissism is an inflated , grandiose self-image . to varying degrees , narcissists think they 're better looking , smarter , and more important than other people , and that they deserve special treatment . psychologists recognize two forms of narcissism as a personality trait : grandiose and vulnerable narcissism . there 's also narcissistic personality disorder , a more extreme form , which we 'll return to shortly . grandiose narcissism is the most familiar kind , characterized by extroversion , dominance , and attention seeking . grandiose narcissists pursue attention and power , sometimes as politicians , celebrities , or cultural leaders . of course , not everyone who pursues these positions of power is narcissistic . many do it for very positive reasons , like reaching their full potential , or helping make people 's lives better . but narcissistic individuals seek power for the status and attention that goes with it . meanwhile , vulnerable narcissists can be quiet and reserved . they have a strong sense of entitlement , but are easily threatened or slighted . in either case , the dark side of narcissism shows up over the long term . narcissists tend to act selfishly , so narcissistic leaders may make risky or unethical decisions , and narcissistic partners may be dishonest or unfaithful . when their rosy view of themselves is challenged , they can become resentful and aggressive . it 's like a disease where the sufferers feel pretty good , but the people around them suffer . taken to the extreme , this behavior is classified as a psychological disorder called narcissistic personality disorder . it affects one to two percent of the population , more commonly men . it is also a diagnosis reserved for adults . young people , especially children , can be very self-centered , but this might just be a normal part of development . the fifth edition of the american psychiatric association 's diagnostic and statistical manual describes several traits associated with narcissistic personality disorder . they include a grandiose view of oneself , problems with empathy , a sense of entitlement , and a need for admiration or attention . what makes these trait a true personality disorder is that they take over people 's lives and cause significant problems . imagine that instead of caring for your spouse or children , you used them as a source of attention or admiration . or imagine that instead of seeking constructive feedback about your performance , you instead told everyone who tried to help you that they were wrong . so what causes narcissism ? twin studies show a strong genetic component , although we do n't know which genes are involved . but environment matters , too . parents who put their child on a pedestal can foster grandiose narcissism . and cold , controlling parents can contribute to vulnerable narcissism . narcissism also seems to be higher in cultures that value individuality and self-promotion . in the united states , for example , narcissism as a personality trait has been rising since the 1970s , when the communal focus of the 60s gave way to the self-esteem movement and a rise in materialism . more recently , social media has multiplied the possibilities for self-promotion , though it 's worth noting that there 's no clear evidence that social media causes narcissism . rather , it provides narcissists a means to seek social status and attention . so can narcissists improve on those negative traits ? yes ! anything that promotes honest reflection on their own behavior and caring for others , like psychotherapy or practicing compassion towards others , can be helpful . the difficulty is it can be challenging for people with narcissistic personality disorder to keep working at self-betterment . for a narcissist , self-reflection is hard from an unflattering angle .

in either case , the dark side of narcissism shows up over the long term . narcissists tend to act selfishly , so narcissistic leaders may make risky or unethical decisions , and narcissistic partners may be dishonest or unfaithful . when their rosy view of themselves is challenged , they can become resentful and aggressive .

problems that can occur with narcissistic leaders include :

in the summer of 1976 , a mysterious epidemic suddenly struck two central african towns , killing the majority of its victims . medical researchers suspected the deadly marburg virus to be the culprit . but what they saw in microscope images was an entirely new pathogen , which would be named after the nearby ebola river . like yellow fever or dengue , the disease caused by the ebola virus is a severe type of hemorrhagic fever . it begins by attacking the immune system 's cells and neutralizing its responses , allowing the virus to proliferate . starting anywhere from two to twenty days after contraction , initial symptoms like high temperature , aching , and sore throat resemble those of a typical flu , but quickly escalate to vomiting , rashes , and diarrhea . and as the virus spreads , it invades the lymph nodes and vital organs , such as kidneys and liver , causing them to lose function . but the virus itself is not what kills ebola victims . instead , the mounting cell deaths trigger an immune system overload , known as a cytokine storm , an explosion of immune responses that damages blood vessels , causing both internal and external bleeding . the excessive fluid loss and resulting complications can be fatal within six to sixteen days of the first symptoms , though proper care and rehydration therapy can significantly reduce mortality rates in patients . fortunately , while ebola is highly virulent , several factors limit its contagiousness . unlike viruses that proliferate through small , airborne particles , ebola only exists in bodily fluids , such as saliva , blood , mucus , vomit , or feces . in order to spread , these must be transmitted from an infected person into another 's body through passageways such as the eyes , mouth , or nose . and because the disease 's severity increases directly along with the viral load , even an infected person is unlikely to be contagious until they have begun to show symptoms . while ebola has been shown to survive on surfaces for several hours , and transmission through sneezing or coughing is theoretically possible , virtually all known cases of contraction have been through direct contact with the severely ill , with the greatest risk posed to medical workers and friends or relatives of the victims . this is why , despite its horrifying effects , ebola has been far less deadly overall than more common infections , such as measles , malaria , or even influenza . once an outbreak has been contained , the virus does not exist in the human population until the next outbreak begins . but while this is undoubtedly a good thing , it also makes ebola difficult to study . scientists believe fruit bats to be its natural carriers , but just how it is transmitted to humans remains unknown . furthermore , many of the countries where ebola outbreaks occur suffer from poor infrastructure and sanitation , which enables the disease to spread . and the poverty of these regions , combined with the relatively low amount of overall cases means there is little economic incentive for drug companies to invest in research . though some experimental medicines have shown promise , and governments are funding development of a vaccine , as of 2014 , the only widespread and effective solutions to an ebola outbreak remain isolation , sanitation , and information .

once an outbreak has been contained , the virus does not exist in the human population until the next outbreak begins . but while this is undoubtedly a good thing , it also makes ebola difficult to study . scientists believe fruit bats to be its natural carriers , but just how it is transmitted to humans remains unknown .

what makes ebola so difficult to study ?

what makes a good horror story ? sure , you could throw in some hideous monsters , fountains of blood , and things jumping out from every corner , but as classic horror author h.p . lovecraft wrote , `` the oldest and strongest kind of fear is fear of the unknown . '' and writers harness that fear not by revealing horrors , but by leaving the audience hanging in anticipation of them . that is , in a state of suspense . the most familiar examples of suspense come from horror films and mystery novels . what 's inside the haunted mansion ? which of the dinner guests is the murderer ? but suspense exists beyond these genres . will the hero save the day ? will the couple get together in the end ? and what is the dark secret that causes the main character so much pain ? the key to suspense is that it sets up a question , or several , that the audience hopes to get an answer to and delays that answer while maintaining their interest and keeping them guessing . so what are some techniques you can use to achieve this in your own writing ? limit the point of view . instead of an omniscient narrator who can see and relay everything that happens , tell the story from the perspective of the characters . they may start off knowing just as little as the audience does , and as they learn more , so do we . classic novels , like `` dracula , '' for example , are told through letters and diary entries where characters relate what they 've experienced and fear what 's to come . next , choose the right setting and imagery . old mansions or castles with winding halls and secret passageways suggest that disturbing things are being concealed . nighttime , fog , and storms all play similar roles in limiting visibility and restricting characters ' movements . that 's why victorian london is such a popular setting . and even ordinary places and objects can be made sinister as in the gothic novel `` rebecca '' where the flowers at the protagonist 's new home are described as blood red . three : play with style and form . you can build suspense by carefully paying attention not just to what happens but how it 's conveyed and paced . edgar allan poe conveys the mental state of the narrator in `` the tell-tale heart '' with fragmented sentences that break off suddenly . and other short declarative sentences in the story create a mix of breathless speed and weighty pauses . on the screen , alfred hitchcock 's cinematography is known for its use of extended silences and shots of staircases to create a feeling of discomfort . four : use dramatic irony . you ca n't just keep the audience in the dark forever . sometimes , suspense is best served by revealing key parts of the big secret to the audience but not to the characters . this is a technique known as dramatic irony , where the mystery becomes not what will happen but when and how the characters will learn . in the classic play `` oedipus rex , '' the title character is unaware that he has killed his own father and married his mother . but the audience knows , and watching oedipus gradually learn the truth provides the story with its agonizing climax . and finally , the cliffhanger . beware of overusing this one . some consider it a cheap and easy trick , but it 's hard to deny its effectiveness . this is where a chapter , episode , volume , or season cuts off right before something crucial is revealed , or in the midst of a dangerous situation with a slim chance of hope . the wait , whether moments or years , makes us imagine possibilities about what could happen next , building extra suspense . the awful thing is almost always averted , creating a sense of closure and emotional release . but that does n't stop us from worrying and wondering the next time the protagonists face near-certain disaster .

on the screen , alfred hitchcock 's cinematography is known for its use of extended silences and shots of staircases to create a feeling of discomfort . four : use dramatic irony . you ca n't just keep the audience in the dark forever .

‘ dramatic irony ’ means…

let 's say you 're on a game show . you 've already earned $ 1000 in the first round when you land on the bonus space . now , you have a choice . you can either take a $ 500 bonus guaranteed or you can flip a coin . if it 's heads , you win $ 1000 bonus . if it 's tails , you get no bonus at all . in the second round , you 've earned $ 2000 when you land on the penalty space . now you have another choice . you can either take a $ 500 loss , or try your luck at the coin flip . if it 's heads , you lose nothing , but if it 's tails , you lose $ 1000 instead . if you 're like most people , you probably chose to take the guaranteed bonus in the first round and flip the coin in the second round . but if you think about it , this makes no sense . the odds and outcomes in both rounds are exactly the same . so why does the second round seem much scarier ? the answer lies in a phenomenon known as loss aversion . under rational economic theory , our decisions should follow a simple mathematical equation that weighs the level of risk against the amount at stake . but studies have found that for many people , the negative psychological impact we feel from losing something is about twice as strong as the positive impact of gaining the same thing . loss aversion is one cognitive bias that arises from heuristics , problem-solving approaches based on previous experience and intuition rather than careful analysis . and these mental shortcuts can lead to irrational decisions , not like falling in love or bungee jumping off a cliff , but logical fallacies that can easily be proven wrong . situations involving probability are notoriously bad for applying heuristics . for instance , say you were to roll a die with four green faces and two red faces twenty times . you can choose one of the following sequences of rolls , and if it shows up , you 'll win $ 25 . which would you pick ? in one study , 65 % of the participants who were all college students chose sequence b even though a is shorter and contained within b , in other words , more likely . this is what 's called a conjunction fallacy . here , we expect to see more green rolls , so our brains can trick us into picking the less likely option . heuristics are also terrible at dealing with numbers in general . in one example , students were split into two groups . the first group was asked whether mahatma gandhi died before or after age 9 , while the second was asked whether he died before or after age 140 . both numbers were obviously way off , but when the students were then asked to guess the actual age at which he died , the first group 's answers averaged to 50 while the second group 's averaged to 67 . even though the clearly wrong information in the initial questions should have been irrelevant , it still affected the students ' estimates . this is an example of the anchoring effect , and it 's often used in marketing and negotiations to raise the prices that people are willing to pay . so , if heuristics lead to all these wrong decisions , why do we even have them ? well , because they can be quite effective . for most of human history , survival depended on making quick decisions with limited information . when there 's no time to logically analyze all the possibilities , heuristics can sometimes save our lives . but today 's environment requires far more complex decision-making , and these decisions are more biased by unconscious factors than we think , affecting everything from health and education to finance and criminal justice . we ca n't just shut off our brain 's heuristics , but we can learn to be aware of them . when you come to a situation involving numbers , probability , or multiple details , pause for a second and consider that the intuitive answer might not be the right one after all .

so why does the second round seem much scarier ? the answer lies in a phenomenon known as loss aversion . under rational economic theory , our decisions should follow a simple mathematical equation that weighs the level of risk against the amount at stake .

according to loss aversion , people ’ s choices are biased on the fact that :

every chicken was once an egg , every oak tree an acorn , every frog a tadpole . the patch of mold on that old piece of bread in the back of your fridge , not so long ago that was one , solitary cell . even you were once but a gleam in your parents ' eyes . all these organisms share the same basic goal : to perpetuate their own existence . all lifeforms that we 've discovered so far stay alive by using basically the same rules , materials , and machinery . imagine a factory full of robots . these robots have two missions : one , keep the factory running , and two , when the time is right , set up an entirely new factory . to do those things , they need assembly instructions , raw materials , plenty of energy , a few rules about when to work normally , when to work quickly , or when to stop , and some exchange currencies because even robots need to get paid . each factory has a high security office with blueprints for all the possible factory configurations and complete sets of instructions to make all the different types of robots a factory could ever need . special robots photocopy these instructions and send them off to help make the building blocks of more robots . their colleagues assemble those parts into still more robots , which are transported to the right location in the factory and given the tools they need to start working . every robot draws energy from the central power plant , a giant furnace that can burn regular fuel but also scrap materials if not enough regular fuel is available . certain zones in the factory have harsher working conditions , so these areas are walled off . but the robots inside can at least communicate with the rest of the factory through specialized portals embedded directly into the walls . and as you 've probably figured out , what we 're describing here is a cell . the high security office is the nucleus . it stores the blueprints and instructions as deoxyribonucleic acid , or dna . the photocopied instructions are rna . the robots themselves are mostly proteins built from amino acids , but they 'll often use special tools that are , or are derived from , vitamins and minerals . the walls between factory zones and around the factory itself are mostly made up of lipids , a.k.a . fats . in most organisms , the primary fuel source are sugars , but in a pinch , fats and proteins can be broken down and burned in the furnace as well . the portals are membrane proteins which allow very specific materials and information to pass through the walls at the right times . many interactions between robot proteins require some kind of push , think robot minimum wage . a few small but crucial forms of money are transferred between proteins to provide this push . electrons , protons , oxygen , and phosphate groups are the main chemical currencies , and they 're kept in small molecular wallets or larger tote bags to keep them safe . this is biochemistry , the study of how every part of the factory interacts to keep your life running smoothly in the face of extreme challenges . maybe there 's too much fuel ; your body will store the excess as glycogen or fat . maybe there 's not enough ; your body will use up those energy reserves . maybe a virus or bacteria tries to invade ; your body will mobilize the immune system . maybe you touched something hot or sharp ; your nerves will let you know so you can stop . maybe it 's time to create a new cell or a new person . amazingly , oak trees , chickens , frogs , and , yes , even you share so many of the same basic robot and factory designs that biochemists can learn a lot about all of them all at the same time .

this is biochemistry , the study of how every part of the factory interacts to keep your life running smoothly in the face of extreme challenges . maybe there 's too much fuel ; your body will store the excess as glycogen or fat . maybe there 's not enough ; your body will use up those energy reserves .

when would your body convert sugar to fat ?

translator : jessica ruby reviewer : brian greene could human civilization eventually spread across the whole milky way galaxy ? could we move beyond our small blue planet to establish colonies in the multitude of star systems out there ? this question 's a pretty daunting one . there are around 300 billion stars in the galaxy , which is about 160,000 light-years across . so far we 've sent a single spacecraft outside our solar system , trudging along at 0.006 % of the speed of light . at that rate , it would take over 2.5 billion years just to get from one end of the galaxy to the other . and then there 's the question of human survival . the gulf between stars is simply enormous . we could n't live sustainably on most planets , and we require a lot of resources to stay alive . and yet , decades ago , scholars found that it 's theoretically possible to not just spread human civilization across the galaxy , but to do so quite quickly , without breaking any known laws of physics . their idea is based on the work of a mathematician named john von neumann , who designed on paper machines that could self-replicate and create new generations of themselves . these would later come to be known as von neumann machines . in the context of space exploration , von neumann machines could be built on earth and launched into space . there , the self-sufficient machines would land on distant planets . they would then mine the available resources and harvest energy , build replicas of themselves , launch those to the nearest planets , and continue the cycle . the result is the creation of millions of probes spreading outwards into the universe like a drop of ink in a fishbowl . scholars crunched the numbers and found that a single von neumann machine traveling at 5 % of the speed of light should be able to replicate throughout our galaxy in 4 million years or less . that may sound like a long time , but when you consider that our universe is 14 billion years old , on a cosmic scale , it 's incredibly fast - the equivalent of about 2.5 hours in an entire year . creating von neumann machines would require a few technologies we do n't have yet , including advanced artificial intelligence , miniaturization , and better propulsion systems . if we wanted to use them to spread actual humans throughout the galaxy , we would need yet another technological leap - the ability to artificially grow biological organisms and bodies using raw elements and genetic information . regardless , if in the last billion years an alien civilization created such a machine and set it multiplying its way toward us , our galaxy would be swarming with them by now . so then where are all these machines ? some astronomers , like carl sagan , say that intelligent aliens would n't build self-replicating machines at all . they might hurtle out of control , scavenging planets to their cores in order to keep replicating . others take the machines absence as proof that intelligent alien civilizations do n't exist , or that they go extinct before they can develop the necessary technologies . but all this has n't stopped people from imagining what it would be like if they were out there . science fiction author david brin writes about a universe in which many different von neumann machines exist and proliferate simultaneously . some are designed to greet young civilizations , others to locate and destroy them before they become a threat . in fact , in brin 's story `` lungfish , '' some von neumann machines are keeping a close watch over the earth right now , waiting for us to reach a certain level of sophistication before they make their move . for now , all we have is curiosity and theory . but the next time you look at the night sky , consider that billions of self-replicating machines could be advancing between stars in our galaxy right now . if they exist , one of them will eventually land on earth , or maybe , just maybe , they 're already here .

their idea is based on the work of a mathematician named john von neumann , who designed on paper machines that could self-replicate and create new generations of themselves . these would later come to be known as von neumann machines . in the context of space exploration , von neumann machines could be built on earth and launched into space . there , the self-sufficient machines would land on distant planets .

why are some people concerned about von neumann machines ?

myths and misconceptions about evolution . let 's talk about evolution . you 've probably heard that some people consider it controversial , even though most scientists do n't . but even if you are n't one of those people and you think you have a pretty good understanding of evolution , chances are you still believe some things about it that are n't entirely right , things like , `` evolution is organisms adapting to their environment . '' this was an earlier , now discredited , theory of evolution . almost 60 years before darwin published his book , jean-baptiste lamarck proposed that creatures evolve by developing certain traits over their lifetimes and then passing those on to their offspring . for example , he thought that because giraffes spent their lives stretching to reach leaves on higher branches , their children would be born with longer necks . but we know now that 's not how genetic inheritance works . in fact , individual organisms do n't evolve at all . instead , random genetic mutations cause some giraffes to be born with longer necks , and that gives them a better chance to survive than the ones who were n't so lucky , which brings us to `` survival of the fittest '' . this makes it sound like evolution always favors the biggest , strongest , or fastest creatures , which is not really the case . for one thing , evolutionary fitness is just a matter of how well-suited they are to their current environment . if all the tall trees suddenly died out and only short grass was left , all those long-necked giraffes would be at a disadvantage . secondly , survival is not how evolution occurs , reproduction is . and the world if full of creatures like the male anglerfish , which is so small and ill-suited for survival at birth that it has to quickly find a mate before it dies . but at least we can say that if an organism dies without reproducing , it 's evolutionarily useless , right ? wrong ! remember , natural selection happens not at the organism level , but at the genetic level , and the same gene that exists in one organism will also exist in its relatives . so , a gene that makes an animal altruistically sacrifice itself to help the survival and future reproduction of its siblings or cousins , can become more widespread than one that is solely concerned with self-preservation . anything that lets more copies of the gene pass on to the next generation will serve its purpose , except evolutionary purpose . one of the most difficult things to keep in mind about evolution is that when we say things like , `` genes want to make more copies of themselves , '' or even , `` natural selection , '' we 're actually using metaphors . a gene does n't want anything , and there 's no outside mechanism that selects which genes are best to preserve . all that happens is that random genetic mutations cause the organisms carrying them to behave or develop in different ways . some of those ways result in more copies of the mutated gene being passed on , and so forth . nor is there any predetermined plan progressing towards an ideal form . it 's not ideal for the human eye to have a blind spot where the optic nerve exits the retina , but that 's how it developed , starting from a simple photoreceptor cell . in retrospect , it would have been much more advantageous for humans to crave nutrients and vitamins rather than just calories . but over the millenia , during which our ancestors evolved , calories were scarce , and there was nothing to anticipate that this would later change so quickly . so , evolution proceeds blindly , step by step by step , creating all of the diversity we see in the natural world .

anything that lets more copies of the gene pass on to the next generation will serve its purpose , except evolutionary purpose . one of the most difficult things to keep in mind about evolution is that when we say things like , `` genes want to make more copies of themselves , '' or even , `` natural selection , '' we 're actually using metaphors . a gene does n't want anything , and there 's no outside mechanism that selects which genes are best to preserve .

explain the concept of ‘ natural selection ’ and what it really means . specify what mechanism actually causes the natural selection and why it occurs .

in 1985 , 16-year-old douglas casa , ran the championship 10,000 meter track race at the empire state games . suddenly , with just 200 meters to go , he collapsed , got back up and then collapsed again on the final straightaway , with his body temperature at dangerous levels . he had suffered an exertional heat stroke . fortunately , with immediate and proper treatment , he survived the potentially fatal episode and has since helped save 167 people in similar circumstances . from ancient soldiers on the battlefield to modern day warriors on the gridiron , exertional heat stroke , or sunstroke , has long been a serious concern . and unlike classical heat stroke , which affects vulnerable people such as infants and the elderly during heat waves , exertional heat stroke is caused by intense exercise in the heat , and is one of the top three killers of athletes and soldiers in training . when you exercise , nearly 80 % of the energy you use is transformed into heat . in normal circumstances , this is what 's known as compensable heat stress . and your body can dissipate the heat as quickly as it 's generated through cooling methods like the evaporation of sweat . but with uncompensable heat stress , your body is unable to lose enough heat due to overexertion or high temperatures in humidity , which raises your core temperature beyond normal levels . this causes the proteins and cell membranes to denature , creating cells that no longer function properly and begin to leak their contents . if these leaky cells proliferate through the body , the results can be devastating . including liver damage , blood clot formation in the kidneys , damage to the gastrointestinal tract and even the failure of vital organs . so how do you diagnose an exertional heat stroke ? the main criterion is a core body temperature greater than 40 degrees celsius observed along with physical symptoms such as increased heart rate , low blood pressure and rapid breathing or signs of central nervous system disfunction such as confused behavior , aggression or loss of consciousness . the most feasible and accurate way to assess core body temperature is with a rectal thermometer as other common temperature-taking methods are not accurate in these circumstances . as far as treatment goes , the most important thing to remember is cool first , transport second . because the human body can withstand a core temperature above 40 degrees celsius for about 30 minutes before cell damage sets in , it 's essential to initiate rapid cooling on site in order to lower it as quickly as possible . after any athletic or protective gear has been removed from the victim , place them in an ice water tub while stirring the water and monitoring vitals continuously . if this is not possible , dousing in ice water and applying wet towels over the entire body can help . but before you start anything , emergency services should be called . as you wait , it 's important to keep the victim calm while cooling as much surface area as possible until emergency personnel arrive . if medical staff are available on site , cooling should continue until a core temperature of 38.9 degrees celsius is reached . the sun is known for giving life , but it can also take life away if we 're not careful , even affecting the strongest among us . as dr. jj levick wrote of exertional heat stroke in 1859 , `` it strikes down its victim with his full armor on . youth , health and strength oppose no obstacle to its power . '' but although this condition is one of the top three leading causes of death in sports , it has been 100 % survivable with proper care .

and your body can dissipate the heat as quickly as it 's generated through cooling methods like the evaporation of sweat . but with uncompensable heat stress , your body is unable to lose enough heat due to overexertion or high temperatures in humidity , which raises your core temperature beyond normal levels . this causes the proteins and cell membranes to denature , creating cells that no longer function properly and begin to leak their contents .

how long can your body sustain exercise during uncompensable heat stress before cell damage begins ?

can i hold it ? only if you promise to be really , really careful . i promise i will be so incredibly careful . i will be incredibly careful with it . i promise . so , it 's slippery , be careful . alright , are we ready ? i 'm about to touch a 1kg sphere of silicon-28 atoms . there are about 2.15x10^25 of them . it feels absolutely incredible . wow , that is amazing . besides its creators , i am one of only a handful of people ever to hold this sphere . the raw material used to make it was worth 1 million euros but now that it has been so precisely sculpted -- how much is that worth ? it 's priceless . ... this you are looking at now is the roundest object in the world . how can you say for sure it 's the roundest object ? i mean the earth is pretty round , is n't it ? if this was the earth ... if this were the earth then the highest mountain to the lowest valley would be ... about 14m apart . that is shocking . that is shockingly round . but why would you invest one million euros and thousands of man-hours perfecting a pure , polished silicon sphere ? well the answer is grave . or rather 'grave ' as it would have been pronounced in the original french . you see the grave was the original name for the base unit of mass in the metric system , which became the systeme international d'unites or si units . in 1793 , a commision which included notable scientist and aristocrat antoine lavoisier , defined the base unit of mass as the weight of a cubic decimeter of water at the melting temperature of ice -- essentially just a litre of ice water . the name grave came from the latin gravitas , meaning weight . but it was n't to last . it sounded too similar to the aristocratic title 'graf ' -- which is the equivalent of an earl or a count . and with the french revolution in full swing with the rallying cry of equality for all , you could n't exactly have one unit nobler than the others . at this lavoisier lost his head , literally , not because he helped devise one of the greatest systems of measurement of all time , but because he was collecting taxes as a nobleman . so things really were grave . the new republican government believed a grave would be too big for the things they wanted to measure anyway and and so they settled on the gramme , which was just a thousandth of the grave . but soon they realized that a gram was too small and so they returned to the grave , but since they could n't call it that , they invented the kilogram -- a thousand grams . and that is why out of the seven base si units , the kilogram is the only one to have a prefix in its name . in 1799 the kilogram definition was refined to be the mass of a litre of water at 4 degrees celcius -- the temperature at which it is densest . but water itself is obviously not the most sensible thing to use as a mass standard . so a pure platinum cylinder was created to have the same mass as the water definition and it was declared kilogram of the archives . now it 's important to note at this point the kilogram is no longer tied to the mass of a volume of water -- the kilogram of the archives is by definition the kilogram . 90 years later , in 1889 the kilogram was upgraded to a platinum-iridium alloy cylinder . now it was much harder than the original but was otherwise basically identical . and to this day , it remains the definition of the kilogram . it is officially called the international prototype kilogram , though it 's affectionately known as le grand k -- or big k. oh , and it 's about this big ... it is the only thing in the entire universe with a mass of exactly one kilogram because it is the kilogram . it is also the only si unit that is still defined by a physical object . it sits under three bell jars , next to six sister kilograms , in a climate-controlled vault locked by three independently controlled keys , in the basement of the international bureau of weights and measures on the outskirts of paris . now if you were able to break into the vault and tamper with big k , you would be changing the definition of the kilogram , a definition on which many of our measurements rely , and so you would throw the world into chaos ! well no , not actually -- but how would anyone ever know if the mass of big k changed ? well when it was first created , 40 identical replicas were also made . well they were n't quite identical - they had a mass which was slightly different to big k but those offsets were recorded . now these replicas were sent out to countries around the world to serve as their national standards . in 1948 the kilograms were reunited for a weigh-in . and this is when the problems started . because even though all the cylinders were made of the same alloy and stored under virtually the same conditions , their masses had diverged over time . the mass of big k was n't even the same as the six sister cylinders stored with it . and to make matters worse when they were brought together again forty years later , their masses had further diverged , up to about 50 micrograms - that 's about the weight of a fingerprint . but fingerprints were not the culprits since the kilograms were carefully washed before their weigh-ins . so some physical process must have actually changed the mass of the cylinders , but how that exactly works remains a matter of speculation . one this is for certain , the mass of a platinum-iridium cylinder is not stable over time . and this is a big problem . you ca n't have a unit which changes its value . and the fallout is n't limited to measurements of mass since of the seven base si units , four of them depend on the mass of the kilogram , not to mention all the derived units like newtons , joules , volts and watts . at this point those of you in countries that have not adopted the metric system -- yes i 'm speaking to you liberia , burma , and the us -- you may be feeling rather smug that your unit of mass , the avoirdupois pound , is no longer defined by a physical object . no , instead it is defined as precisely 0.45359237 kilograms . sucked in . so clearly something needs to be done to eliminate the kilogram 's dependence on a physical object and this is where the silicon sphere comes in , but how exactly does that help ? here you have a physical object and it 's beautiful but you know it 's still a physical object . you 're trying to get away from that . we 're trying to get away from the physical object but what we 're doing with this particular object is counting how many atoms are in there . you ca n't actually count how many are in there can you ? you ca n't count how many are in there but you can calculate how many are in there because this material is silicon , there 's no voids or dislocations . so this is like a perfect crystal of silicon . that 's right . not only is it pure silicon , it contains only one isotope of silicon , silicon-28 , and that explains why the original material was so expensive . and why a sphere ? well , a sphere is a pretty simple object . if you know the diameter of the sphere you can characterise the entire dimension of the object . well that explains why the sphere has to be the roundest object ever created , but how do you actually make something that round ? we actually start with an oversized sphere . so it was about two millimetres larger in diameter and then we just grind it progressively finer and finer using abrasive . it 's actually massaging atoms . you 're down at that level of trying to control the shape of an object down at the atomic level . but making the sphere is only half the battle , then you need to accurately measure its diameter . the diameter is actually measured via a laser . so you 're actually measuring having the sphere in the centre of a cavity and a laser is hitting both sides and you 're actually measuring the gap . by knowing the diameter you can determine its volume . and since the atom spacing in silicon is known to high precision , you can the calculate how many atoms make up the sphere . this allows you to redefine avogadro 's constant . at the moment , avogadro 's constant is defined based on the kilogram . it is equal to the number of atoms in twelve grams of carbon 12 . but using this approach , the number of silicon atoms in the sphere would be used to fix avogadro 's constant , which would then define the kilogram . so even if the silicon spheres were lost or damaged , it would have no effect on the definition of the kilogram because it would be defined not by a physical object but by a concept . you would like to see the official definition of the kilogram say `` a kilogram is the mass of 2.15x10^25 silicon-28 atoms '' yes . is it - is it going to happen ? there 's a likelihood , a high likelihood that it 's going to happen . but there is another approach to redefining the kilogram which involves fixing planck 's constant and it 's done using something called a watt balance . these two approaches are complimentary . each one provides a check on the other , and if they show good agreement and are able to bring their uncertainties down to about twenty micrograms they may redefine the kilogram as early as 2014 . and then the kilogram finally will be an unchanging unit , no longer defined by a physical object in the basement vault of some place in paris . now if the kilogram was originally intended to be the mass of a litre of water at its densest temperature then how well did we do ? well if you look at a litre of water at nearly four degrees celcius it has a mass of 999.975 grams . so i guess you could look at this two ways . on the one hand you could say the kilogram is slightly heavier than it should be , but on the other hand 214 years ago , scientists were able to create an artifact that was correct within the margin of error of a grain of rice . now that is truly remarkable . now if you want to hear more about the watt balance , let me know in the comments and i will see what i can do . it does seem to be the frontrunner in terms of redefining the kilogram , so we will have to wait and see what happens . one last thing , i should point out that it took an international collaboration of scientists to create the silicon sphere but do n't you think that the scientist who originally conceived of silicon as an element should receive some of the credit . well in 1787 , that was none other than antoine lavoisier . so he 's been involved in the definition of a kilogram from start to finish or from cradle to grave .

so a pure platinum cylinder was created to have the same mass as the water definition and it was declared kilogram of the archives . now it 's important to note at this point the kilogram is no longer tied to the mass of a volume of water -- the kilogram of the archives is by definition the kilogram . 90 years later , in 1889 the kilogram was upgraded to a platinum-iridium alloy cylinder .

which of the following did not define the kilogram ?

in the biblical story of the tower of babel , all of humanity once spoke a single language until they suddenly split into many groups unable to understand each other . we do n't really know if such an original language ever existed , but we do know that the thousands of languages existing today can be traced back to a much smaller number . so how did we end up with so many ? in the early days of human migration , the world was much less populated . groups of people that shared a single language and culture often split into smaller tribes , going separate ways in search of fresh game and fertile land . as they migrated and settled in new places , they became isolated from one another and developed in different ways . centuries of living in different conditions , eating different food and encountering different neighbors turned similar dialects with varied pronunciation and vocabulary into radically different languages , continuing to divide as populations grew and spread out further . like genealogists , modern linguists try to map this process by tracing multiple languages back as far as they can to their common ancestor , or protolanguage . a group of all languages related in this way is called a language family , which can contain many branches and sub-families . so how do we determine whether languages are related in the first place ? similar sounding words do n't tell us much . they could be false cognates or just directly borrowed terms rather than derived from a common root . grammar and syntax are a more reliable guide , as well as basic vocabulary , such as pronouns , numbers or kinship terms , that 's less likely to be borrowed . by systematically comparing these features and looking for regular patterns of sound changes and correspondences between languages , linguists can determine relationships , trace specific steps in their evolution and even reconstruct earlier languages with no written records . linguistics can even reveal other important historical clues , such as determining the geographic origins and lifestyles of ancient peoples based on which of their words were native , and which were borrowed . there are two main problems linguists face when constructing these language family trees . one is that there is no clear way of deciding where the branches at the bottom should end , that is , which dialects should be considered separate languages or vice versa . chinese is classified as a single language , but its dialects vary to the point of being mutually unintelligible , while speakers of spanish and portuguese can often understand each other . languages actually spoken by living people do not exist in neatly divided categories , but tend to transition gradually , crossing borders and classifications . often the difference between languages and dialects is a matter of changing political and national considerations , rather than any linguistic features . this is why the answer to , `` how many languages are there ? '' can be anywhere between 3,000 and 8,000 , depending on who 's counting . the other problem is that the farther we move back in time towards the top of the tree , the less evidence we have about the languages there . the current division of major language families represents the limit at which relationships can be established with reasonable certainty , meaning that languages of different families are presumed not to be related on any level . but this may change . while many proposals for higher level relationships -- or super families -- are speculative , some have been widely accepted and others are being considered , especially for native languages with small speaker populations that have not been extensively studied . we may never be able to determine how language came about , or whether all human languages did in fact have a common ancestor scattered through the babel of migration . but the next time you hear a foreign language , pay attention . it may not be as foreign as you think .

like genealogists , modern linguists try to map this process by tracing multiple languages back as far as they can to their common ancestor , or protolanguage . a group of all languages related in this way is called a language family , which can contain many branches and sub-families . so how do we determine whether languages are related in the first place ? similar sounding words do n't tell us much .

what does it mean for two languages to be related ?

you 're telling a friend an amazing story , and you just get to the best part when suddenly he interrupts , `` the alien and i , '' not `` me and the alien . '' most of us would probably be annoyed , but aside from the rude interruption , does your friend have a point ? was your sentence actually grammatically incorrect ? and if he still understood it , why does it even matter ? from the point of view of linguistics , grammar is a set of patterns for how words are put together to form phrases or clauses , whether spoken or in writing . different languages have different patterns . in english , the subject normally comes first , followed by the verb , and then the object , while in japanese and many other languages , the order is subject , object , verb . some scholars have tried to identify patterns common to all languages , but apart from some basic features , like having nouns or verbs , few of these so-called linguistic universals have been found . and while any language needs consistent patterns to function , the study of these patterns opens up an ongoing debate between two positions known as prescriptivism and descriptivism . grossly simplified , prescriptivists think a given language should follow consistent rules , while descriptivists see variation and adaptation as a natural and necessary part of language . for much of history , the vast majority of language was spoken . but as people became more interconnected and writing gained importance , written language was standardized to allow broader communication and ensure that people in different parts of a realm could understand each other . in many languages , this standard form came to be considered the only proper one , despite being derived from just one of many spoken varieties , usually that of the people in power . language purists worked to establish and propagate this standard by detailing a set of rules that reflected the established grammar of their times . and rules for written grammar were applied to spoken language , as well . speech patterns that deviated from the written rules were considered corruptions , or signs of low social status , and many people who had grown up speaking in these ways were forced to adopt the standardized form . more recently , however , linguists have understood that speech is a separate phenomenon from writing with its own regularities and patterns . most of us learn to speak at such an early age that we do n't even remember it . we form our spoken repertoire through unconscious habits , not memorized rules . and because speech also uses mood and intonation for meaning , its structure is often more flexible , adapting to the needs of speakers and listeners . this could mean avoiding complex clauses that are hard to parse in real time , making changes to avoid awkward pronounciation , or removing sounds to make speech faster . the linguistic approach that tries to understand and map such differences without dictating correct ones is known as descriptivism . rather than deciding how language should be used , it describes how people actually use it , and tracks the innovations they come up with in the process . but while the debate between prescriptivism and descriptivism continues , the two are not mutually exclusive . at its best , prescriptivism is useful for informing people about the most common established patterns at a given point in time . this is important , not only for formal contexts , but it also makes communication easier between non-native speakers from different backgrounds . descriptivism , on the other hand , gives us insight into how our minds work and the instinctive ways in which we structure our view of the world . ultimately , grammar is best thought of as a set of linguistic habits that are constantly being negotiated and reinvented by the entire group of language users . like language itself , it 's a wonderful and complex fabric woven through the contributions of speakers and listeners , writers and readers , prescriptivists and descriptivists , from both near and far .

this could mean avoiding complex clauses that are hard to parse in real time , making changes to avoid awkward pronounciation , or removing sounds to make speech faster . the linguistic approach that tries to understand and map such differences without dictating correct ones is known as descriptivism . rather than deciding how language should be used , it describes how people actually use it , and tracks the innovations they come up with in the process .

descriptivism is an approach to examining language which :

as you can see , i was born without fingers on my right hand . and also my right leg was several inches shorter than my left one . they broke the bones in the leg , then they screwed metal spikes into the bone . it has not only spikes , but wires that go all the way through the leg to stabilize it . i have to walk on it . i have to stretch it out so that my muscles do n't just get all atrophied . people always ask me , `` does it hurt ? '' yes , it does , but i focus on what i can do , not on what i can not do . i want to talk with you guys about overcoming obstacles . everybody has obstacles , a disability , a hurdle . we face a choice : let the obstacle overcome you or overcome the obstacle . maybe some of you have heard of jim abbott . he was a major league baseball player . he won a gold metal in the olympics . he played for the yankees , the angels . but he threw a no-hitter , and he only had one arm . when he was a kid , he came home mad one time and told his dad , `` the kids wo n't let me play baseball because i only have one hand . '' his dad replied , `` no , the kids wo n't let you play baseball because you stink at baseball . you ca n't change the fact that you only have one hand , but you can change the fact that you stink . '' so , his dad began to practice with him , and he got good . he overcame obstacles . teams would try to exploit his weak side . they would try to bunt to the side that he had a missing arm . but they never succeeded because he practiced and practiced fielding bunts to that side . there 's no dishonor in having a disability , and i wo n't let anyone diss my ability , but i do n't want anyone 's pity either . i will not use the obstacles i face as an excuse for having a pity party . i will practice harder , play harder , and push myself harder to keep getting better . last season i started on my varsity high school basketball team as a freshman , and i won rookie of the year . i was one of the top scorers on the team . one of the things that i find funny is that people judge me by appearance . they say , `` oh , look at this one-handed whitey with the limp . i do n't want him on my team ! '' but what they do n't know is that i do n't just have a disability , i have an ability . one of my favorite moments from this last season was we played a team that we had never played before . and when the game started , you could tell that they were dissing my disability . i mean , they double-teamed our tallest player . they just were playing really soft on me , and they just , you could tell they thought , `` what can this guy with one hand do ? '' so , they left me open for a three . i made that one . they left me open for another one . i made that one . then , they started to get frustrated , so they actually fouled me . i made both free throws . and they called time out . and as we were in the huddle , i could hear the other coach yelling at his players about me . they went from not covering me at all to double-teaming me . it 's all about overcoming obstacles . it 's true , i have a disability , but so do you . i also have an ability , so do you . everyone has obstacles to overcome . some are visible like mine . some are less visible . maybe your obstacle is that you come from a poor neighborhood . maybe people say you 'll never amount to anything . prove them wrong . maybe your obstacle is that you have a learning disability , and people think that you 're dumb . prove them wrong . maybe people judge you because of the color of your skin or your family background . prove them wrong . i know a lot of people who take one look at me and judge me . they say , `` oh , that kid ca n't be any good at basketball . one leg , one hand . '' if someone things you ca n't overcome the obstacles , prove them wrong .

it 's all about overcoming obstacles . it 's true , i have a disability , but so do you . i also have an ability , so do you .

which of the following are true of steven ?

there 's a quote usually attributed to the writer mark twain that goes , `` a lie can travel halfway around the world while the truth is putting on its shoes . '' funny thing about that . there 's reason to doubt that mark twain ever said this at all , thus , ironically , proving the point . and today , the quote , whoever said it , is truer than ever before . in previous decades , most media with global reach consisted of several major newspapers and networks which had the resources to gather information directly . outlets like reuters and the associated press that aggregate or rereport stories were relatively rare compared to today . the speed with which information spreads now has created the ideal conditions for a phenomenon known as circular reporting . this is when publication a publishes misinformation , publication b reprints it , and publication a then cites b as the source for the information . it 's also considered a form of circular reporting when multiple publications report on the same initial piece of false information , which then appears to another author as having been verified by multiple sources . for instance , the 1998 publication of a single pseudoscientific paper arguing that routine vaccination of children causes autism inspired an entire antivaccination movement , despite the fact that the original paper has repeatedly been discredited by the scientific community . deliberately unvaccinated children are now contracting contagious diseases that had been virtually eradicated in the united states , with some infections proving fatal . in a slightly less dire example , satirical articles that are formatted to resemble real ones can also be picked up by outlets not in on the joke . for example , a joke article in the reputable british medical journal entitled `` energy expenditure in adolescents playing new generation computer games , '' has been referenced in serious science publications over 400 times . user-generated content , such as wikis , are also a common contributer to circular reporting . as more writers come to rely on such pages for quick information , an unverified fact in a wiki page can make its way into a published article that may later be added as a citation for the very same wiki information , making it much harder to debunk . recent advances in communication technology have had immeasurable benefits in breaking down the barriers between information and people . but our desire for quick answers may overpower the desire to be certain of their validity . and when this bias can be multiplied by billions of people around the world , nearly instantaneously , more caution is in order . avoiding sensationalist media , searching for criticisms of suspicious information , and tracing the original source of a report can help slow down a lie , giving the truth more time to put on its shoes .

for example , a joke article in the reputable british medical journal entitled `` energy expenditure in adolescents playing new generation computer games , '' has been referenced in serious science publications over 400 times . user-generated content , such as wikis , are also a common contributer to circular reporting . as more writers come to rely on such pages for quick information , an unverified fact in a wiki page can make its way into a published article that may later be added as a citation for the very same wiki information , making it much harder to debunk .

why might the anti-vaccer movement be considered a product of circular reporting ?

on a december afternoon in chicago during the middle of world war ii , scientists cracked open the nucleus at the center of the uranium atom and turned nuclear mass into energy over and over again . they did this by creating for the first time a chain reaction inside a new engineering marvel : the nuclear reactor . since then , the ability to mine great amounts of energy from uranium nuclei has led some to bill nuclear power as a plentiful utopian source of electricity . a modern nuclear reactor generates enough electricity from one kilogram of fuel to power an average american household for nearly 34 years . but rather than dominate the global electricity market , nuclear power has declined from an all-time high of 18 % in 1996 to 11 % today . and it 's expected to drop further in the coming decades . what happened to the great promise of this technology ? it turns out nuclear power faces many hurdles , including high construction costs and public opposition . and behind these problems lie a series of unique engineering challenges . nuclear power relies on the fission of uranium nuclei and a controlled chain reaction that reproduces this splitting in many more nuclei . the atomic nucleus is densely packed with protons and neutrons bound by a powerful nuclear force . most uranium atoms have a total of 238 protons and neutrons , but roughly one in every 140 lacks three neutrons , and this lighter isotope is less tightly bound . compared to its more abundant cousin , a strike by a neutron easily splits the u-235 nuclei into lighter , radioactive elements called fission products , in addition to two to three neutrons , gamma rays , and a few neutrinos . during fission , some nuclear mass transforms into energy . a fraction of the newfound energy powers the fast-moving neutrons , and if some of them strike uranium nuclei , fission results in a second larger generation of neutrons . if this second generation of neutrons strike more uranium nuclei , more fission results in an even larger third generation , and so on . but inside a nuclear reactor , this spiraling chain reaction is tamed using control rods made of elements that capture excess neutrons and keep their number in check . with a controlled chain reaction , a reactor draws power steadily and stably for years . the neutron-led chain reaction is a potent process driving nuclear power , but there 's a catch that can result in unique demands on the production of its fuel . it turns out , most of the neutrons emitted from fission have too much kinetic energy to be captured by uranium nuclei . the fission rate is too low and the chain reaction fizzles out . the first nuclear reactor built in chicago used graphite as a moderator to scatter and slow down neutrons just enough to increase their capture by uranium and raise the rate of fission . modern reactors commonly use purified water as a moderator , but the scattered neutrons are still a little too fast . to compensate and keep up the chain reaction , the concentration of u-235 is enriched to four to seven times its natural abundance . today , enrichment is often done by passing a gaseous uranium compound through centrifuges to separate lighter u-235 from heavier u-238 . but the same process can be continued to highly enrich u-235 up to 130 times its natural abundance and create an explosive chain reaction in a bomb . methods like centrifuge processing must be carefully regulated to limit the spread of bomb-grade fuel . remember , only a fraction of the released fission energy goes into speeding up neutrons . most of the nuclear power goes into the kinetic energy of the fission products . those are captured inside the reactor as heat by a coolant , usually purified water . this heat is eventually used to drive an electric turbine generator by steam just outside the reactor . water flow is critical not only to create electricity , but also to guard against the most dreaded type of reactor accident , the meltdown . if water flow stops because a pipe carrying it breaks , or the pumps that push it fail , the uranium heats up very quickly and melts . during a nuclear meltdown , radioactive vapors escape into the reactor , and if the reactor fails to hold them , a steel and concrete containment building is the last line of defense . but if the radioactive gas pressure is too high , containment fails and the gasses escape into the air , spreading as far and wide as the wind blows . the radioactive fission products in these vapors eventually decay into stable elements . while some decay in a few seconds , others take hundreds of thousands of years . the greatest challenge for a nuclear reactor is to safely contain these products and keep them from harming humans or the environment . containment does n't stop mattering once the fuel is used up . in fact , it becomes an even greater storage problem . every one to two years , some spent fuel is removed from reactors and stored in pools of water that cool the waste and block its radioactive emissions . the irradiated fuel is a mix of uranium that failed to fission , fission products , and plutonium , a radioactive material not found in nature . this mix must be isolated from the environment until it has all safely decayed . many countries propose deep time storage in tunnels drilled far underground , but none have been built , and there 's great uncertainty about their long-term security . how can a nation that has existed for only a few hundred years plan to guard plutonium through its radioactive half-life of 24,000 years ? today , many nuclear power plants sit on their waste , instead , storing them indefinitely on site . apart from radioactivity , there 's an even greater danger with spent fuel . plutonium can sustain a chain reaction and can be mined from the waste to make bombs . storing spent fuel is thus not only a safety risk for the environment , but also a security risk for nations . who should be the watchmen to guard it ? visionary scientists from the early years of the nuclear age pioneered how to reliably tap the tremendous amount of energy inside an atom - as an explosive bomb and as a controlled power source with incredible potential . but their successors have learned humbling insights about the technology 's not-so-utopian industrial limits . mining the subatomic realm makes for complex , expensive , and risky engineering .

if water flow stops because a pipe carrying it breaks , or the pumps that push it fail , the uranium heats up very quickly and melts . during a nuclear meltdown , radioactive vapors escape into the reactor , and if the reactor fails to hold them , a steel and concrete containment building is the last line of defense . but if the radioactive gas pressure is too high , containment fails and the gasses escape into the air , spreading as far and wide as the wind blows .

if a nuclear reactor were to have a meltdown , radioactive materials could escape in the form of gases from the reactor into the atmosphere and harm humans and the environment . one safety system that might be able to prevent such an escape is a :

the heisenberg uncertainty principle is one of a handful of ideas from quantum physics to expand into general pop culture . it says that you can never simultaneously know the exact position and the exact speed of an object and shows up as a metaphor in everything from literary criticism to sports commentary . uncertainty is often explained as a result of measurement , that the act of measuring an object 's position changes its speed , or vice versa . the real origin is much deeper and more amazing . the uncertainty principle exists because everything in the universe behaves like both a particle and a wave at the same time . in quantum mechanics , the exact position and exact speed of an object have no meaning . to understand this , we need to think about what it means to behave like a particle or a wave . particles , by definition , exist in a single place at any instant in time . we can represent this by a graph showing the probability of finding the object at a particular place , which looks like a spike , 100 % at one specific position , and zero everywhere else . waves , on the other hand , are disturbances spread out in space , like ripples covering the surface of a pond . we can clearly identify features of the wave pattern as a whole , most importantly , its wavelength , which is the distance between two neighboring peaks , or two neighboring valleys . but we ca n't assign it a single position . it has a good probability of being in lots of different places . wavelength is essential for quantum physics because an object 's wavelength is related to its momentum , mass times velocity . a fast-moving object has lots of momentum , which corresponds to a very short wavelength . a heavy object has lots of momentum even if it 's not moving very fast , which again means a very short wavelength . this is why we do n't notice the wave nature of everyday objects . if you toss a baseball up in the air , its wavelength is a billionth of a trillionth of a trillionth of a meter , far too tiny to ever detect . small things , like atoms or electrons though , can have wavelengths big enough to measure in physics experiments . so , if we have a pure wave , we can measure its wavelength , and thus its momentum , but it has no position . we can know a particles position very well , but it does n't have a wavelength , so we do n't know its momentum . to get a particle with both position and momentum , we need to mix the two pictures to make a graph that has waves , but only in a small area . how can we do this ? by combining waves with different wavelengths , which means giving our quantum object some possibility of having different momenta . when we add two waves , we find that there are places where the peaks line up , making a bigger wave , and other places where the peaks of one fill in the valleys of the other . the result has regions where we see waves separated by regions of nothing at all . if we add a third wave , the regions where the waves cancel out get bigger , a fourth and they get bigger still , with the wavier regions becoming narrower . if we keep adding waves , we can make a wave packet with a clear wavelength in one small region . that 's a quantum object with both wave and particle nature , but to accomplish this , we had to lose certainty about both position and momentum . the positions is n't restricted to a single point . there 's a good probability of finding it within some range of the center of the wave packet , and we made the wave packet by adding lots of waves , which means there 's some probability of finding it with the momentum corresponding to any one of those . both position and momentum are now uncertain , and the uncertainties are connected . if you want to reduce the position uncertainty by making a smaller wave packet , you need to add more waves , which means a bigger momentum uncertainty . if you want to know the momentum better , you need a bigger wave packet , which means a bigger position uncertainty . that 's the heisenberg uncertainty principle , first stated by german physicist werner heisenberg back in 1927 . this uncertainty is n't a matter of measuring well or badly , but an inevitable result of combining particle and wave nature . the uncertainty principle is n't just a practical limit on measurment . it 's a limit on what properties an object can have , built into the fundamental structure of the universe itself .

a heavy object has lots of momentum even if it 's not moving very fast , which again means a very short wavelength . this is why we do n't notice the wave nature of everyday objects . if you toss a baseball up in the air , its wavelength is a billionth of a trillionth of a trillionth of a meter , far too tiny to ever detect .

we can see wave behavior in electrons more easily than in baseballs because :

a toothpaste brand claims their product will destroy more plaque than any product ever made . a politician tells you their plan will create the most jobs . we 're so used to hearing these kinds of exaggerations in advertising and politics that we might not even bat an eye . but what about when the claim is accompanied by a graph ? afterall , a graph is n't an opinion . it represents cold , hard numbers , and who can argue with those ? yet , as it turns out , there are plenty of ways graphs can mislead and outright manipulate . here are some things to look out for . in this 1992 ad , chevy claimed to make the most reliable trucks in america using this graph . not only does it show that 98 % of all chevy trucks sold in the last ten years are still on the road , but it looks like they 're twice as dependable as toyota trucks . that is , until you take a closer look at the numbers on the left and see that the figure for toyota is about 96.5 % . the scale only goes between 95 and 100 % . if it went from 0 to 100 , it would look like this . this is one of the most common ways graphs misrepresent data , by distorting the scale . zooming in on a small portion of the y-axis exaggerates a barely detectable difference between the things being compared . and it 's especially misleading with bar graphs since we assume the difference in the size of the bars is proportional to the values . but the scale can also be distorted along the x-axis , usually in line graphs showing something changing over time . this chart showing the rise in american unemployment from 2008 to 2010 manipulates the x-axis in two ways . first of all , the scale is inconsistent , compressing the 15-month span after march 2009 to look shorter than the preceding six months . using more consistent data points gives a different picture with job losses tapering off by the end of 2009 . and if you wonder why they were increasing in the first place , the timeline starts immediately after the u.s. 's biggest financial collapse since the great depression . these techniques are known as cherry picking . a time range can be carefully chosen to exclude the impact of a major event right outside it . and picking specific data points can hide important changes in between . even when there 's nothing wrong with the graph itself , leaving out relevant data can give a misleading impression . this chart of how many people watch the super bowl each year makes it look like the event 's popularity is exploding . but it 's not accounting for population growth . the ratings have actually held steady because while the number of football fans has increased , their share of overall viewership has not . finally , a graph ca n't tell you much if you do n't know the full significance of what 's being presented . both of the following graphs use the same ocean temperature data from the national centers for environmental information . so why do they seem to give opposite impressions ? the first graph plots the average annual ocean temperature from 1880 to 2016 , making the change look insignificant . but in fact , a rise of even half a degree celsius can cause massive ecological disruption . this is why the second graph , which show the average temperature variation each year , is far more significant . when they 're used well , graphs can help us intuitively grasp complex data . but as visual software has enabled more usage of graphs throughout all media , it 's also made them easier to use in a careless or dishonest way . so the next time you see a graph , do n't be swayed by the lines and curves . look at the labels , the numbers , the scale , and the context , and ask what story the picture is trying to tell .

a time range can be carefully chosen to exclude the impact of a major event right outside it . and picking specific data points can hide important changes in between . even when there 's nothing wrong with the graph itself , leaving out relevant data can give a misleading impression . this chart of how many people watch the super bowl each year makes it look like the event 's popularity is exploding .

when looking at the graph that presents data on truck reliability , which statement is true ?

there 's a common misconception that if you like to meticulously organize your things , keep your hands clean , or plan out your weekend to the last detail , you might have ocd . in fact , ocd , which stands for obsessive compulsive disorder , is a serious psychiatric condition that is frequently misunderstood by society and mental health professionals alike . so let 's start by debunking some myths . myth one : repetitive or ritualistic behaviors are synonymous with ocd . as its name suggests , obsessive compulsive disorder has two aspects : the intrusive thoughts , images , or impulses , known as obsessions , and the behavioral compulsions people engage in to relieve the anxiety the obsessions cause . the kinds of actions that people often associate with ocd , like excessive hand washing , or checking things repeatedly , may be examples of obsessive or compulsive tendencies that many of us exhibit from time to time . but the actual disorder is far more rare and can be quite debilitating . people affected have little or no control over their obsessive thoughts and compulsive behaviors , which tend to be time consuming and interfere with work , school or social life to the point of causing significant distress . this set of diagnostic criteria is what separates people suffering from ocd from those who may just be a bit more meticulous or hygiene obsessed than usual . myth two : the main symptom of ocd is excessive hand washing . although hand washing is the most common image of ocd in popular culture , obsessions and compulsions can take many different forms . obsessions can manifest as fears of contamination and illness , worries about harming others , or preoccupations with numbers , patterns , morality , or sexual identity . and compulsions can range from excessive cleaning or double checking , to the fastidious arrangement of objects , or walking in predetermined patterns . myth three : individuals with ocd do n't understand that they are acting irrationally . many individuals with ocd actually understand the relationship between their obsessions and compulsions quite well . being unable to avoid these thoughts and actions despite being aware of their irrationality is part of the reason why ocd is so distressing . ocd sufferers report feeling crazy for experiencing anxiety based on irrational thoughts and finding it difficult to control their responses . so what exactly causes ocd ? the frustrating answer is we do n't really know . however , we have some important clues . ocd is considered a neurobiological disorder . in other words , research suggests that ocd sufferers brains are actually hardwired to behave in a certain fashion . research has implicated three regions of the brain variously involved in social behavior and complex cognitive planning , voluntary movement , and emotional and motivational responses . the other piece of the puzzle is that ocd is associated with low levels of serotonin , a neurotransmitter that communicates between brain structures and helps regulate vital processes , such as mood , aggression , impulse control , sleep , appetite , body temperature and pain . but are serotonin and activity in these brain regions the sources of ocd or symptoms of an unknown underlying cause of the disorder . we probably wo n't know until we have a much more intimate understanding of the brain . the good news is there are effective treatments for ocd , including medications , which increase serotonin in the brain by limiting its reabsorption by brain cells , behavioral therapy that gradually desensitizes patients to their anxieties , and in some cases , electroconvulsive therapy , or surgery , when ocd does n't respond to other forms of treatment . knowing that your own brain is lying to you while not being able to resist its commands can be agonizing . but with knowledge and understanding comes the power to seek help , and future research into the brain may finally provide the answers we 're looking for .

ocd sufferers report feeling crazy for experiencing anxiety based on irrational thoughts and finding it difficult to control their responses . so what exactly causes ocd ? the frustrating answer is we do n't really know .

in what ways does ocd affect school-aged youth ? how can you incorporate treatment into the school setting ?

if you spent any time on earth you might have noticed that humans are not the most rational creatures we make decisions based mostly on emotions instead of facts and a lot of times we 're guided by tribal instinct part of the problem is that the human brain evolved to help us survive and not necessarily to help us be factually accurate so we often respond better to social and tribal dynamics than to intellectual analysis for example if someone 's tribe believes that obama is a secret muslim born in kenya that person probably thinks the hard proof of his us birth certificate is fake that conclusion is neither rational nor accurate but from a tribal perspective it makes sense it 's safer to agree with your tribe and stay united ideologically even if you 're wrong about the facts than to disagree and isolate yourself another part of the problem is that our brain is constantly protecting our worldview and sense of identity so when our worldview is challenged that same part of the brain that processes physical danger gets activated this is why people sometimes react so aggressively to information that proves them wrong and this is why it 's often so hard to have an intelligent political debate several studies have also shown that there is a backfire effect that happens when people encounter facts that contradict their current beliefs they actually become more convinced of their original ideas so fighting ignorant with facts is like fighting a grease fire with water it seems like it should work but it actually just makes the whole thing work lastly there 's the problem of lack of empathy several studies have found that when humans are divided into groups of any kind we instinctively become less and pathetic to members of other groups that means that for survivals sake we men instinctively empathize less with other races other nationalities and even though their sports teams this instinctive the humanization of other groups is what makes things like slavery and genocide possible in our society so what can you do if you want someone to consider factual information that clashes with their beliefs first you have to prevent their brain from seeing you as a personal threat so look for ways to identify the person as part of your tribe and you as part of theirs hey we 're part of the same family hey we 're both parents hey we both still play pokemon go whatever anything that communicates that you 're part of the same that 's the first step second consider the possibility that you may be wrong maybe the facts are not on your side in which case admitting it will help you model to the other person that it 's okay to be wrong i understand that none of this is easy or smooth but if we want to continue to function as a stable society we have to learn to get past our own natural biases only when that happens we will be able to move forward towards a better future

if you spent any time on earth you might have noticed that humans are not the most rational creatures we make decisions based mostly on emotions instead of facts and a lot of times we 're guided by tribal instinct part of the problem is that the human brain evolved to help us survive and not necessarily to help us be factually accurate so we often respond better to social and tribal dynamics than to intellectual analysis for example if someone 's tribe believes that obama is a secret muslim born in kenya that person probably thinks the hard proof of his us birth certificate is fake that conclusion is neither rational nor accurate but from a tribal perspective it makes sense it 's safer to agree with your tribe and stay united ideologically even if you 're wrong about the facts than to disagree and isolate yourself another part of the problem is that our brain is constantly protecting our worldview and sense of identity so when our worldview is challenged that same part of the brain that processes physical danger gets activated this is why people sometimes react so aggressively to information that proves them wrong and this is why it 's often so hard to have an intelligent political debate several studies have also shown that there is a backfire effect that happens when people encounter facts that contradict their current beliefs they actually become more convinced of their original ideas so fighting ignorant with facts is like fighting a grease fire with water it seems like it should work but it actually just makes the whole thing work lastly there 's the problem of lack of empathy several studies have found that when humans are divided into groups of any kind we instinctively become less and pathetic to members of other groups that means that for survivals sake we men instinctively empathize less with other races other nationalities and even though their sports teams this instinctive the humanization of other groups is what makes things like slavery and genocide possible in our society so what can you do if you want someone to consider factual information that clashes with their beliefs first you have to prevent their brain from seeing you as a personal threat so look for ways to identify the person as part of your tribe and you as part of theirs hey we 're part of the same family hey we 're both parents hey we both still play pokemon go whatever anything that communicates that you 're part of the same that 's the first step second consider the possibility that you may be wrong maybe the facts are not on your side in which case admitting it will help you model to the other person that it 's okay to be wrong i understand that none of this is easy or smooth but if we want to continue to function as a stable society we have to learn to get past our own natural biases only when that happens we will be able to move forward towards a better future

briefly describe a few reasons cited in the video for why humans do n't tend to be convinced by facts .

in 1997 , in a game between france and brazil , a young brazilian player named roberto carlos set up for a 35 meter free kick . with no direct line to the goal , carlos decided to attempt the seemingly impossible . his kick sent the ball flying wide of the players , but just before going out of bounds , it hooked to the left and soared into the goal . according to newton 's first law of motion , an object will move in the same direction and velocity until a force is applied on it . when carlos kicked the ball , he gave it direction and velocity , but what force made the ball swerve and score one of the most magnificent goals in the history of the sport ? the trick was in the spin . carlos placed his kick at the lower right corner of the ball , sending it high and to the right , but also rotating around its axis . the ball started its flight in an apparently direct route , with air flowing on both sides and slowing it down . on one side , the air moved in the opposite direction to the ball 's spin , causing increased pressure , while on the other side , the air moved in the same direction as the spin , creating an area of lower pressure . that difference made the ball curve towards the lower pressure zone . this phenomenon is called the magnus effect . this type of kick , often referred to as a banana kick , is attempted regularly , and it is one of the elements that makes the beautiful game beautiful . but curving the ball with the precision needed to both bend around the wall and back into the goal is difficult . too high and it soars over the goal . too low and it hits the ground before curving . too wide and it never reaches the goal . not wide enough and the defenders intercept it . too slow and it hooks too early , or not at all . too fast and it hooks too late . the same physics make it possible to score another apparently impossible goal , an unassisted corner kick . the magnus effect was first documented by sir isaac newton after he noticed it while playing a game of tennis back in 1670 . it also applies to golf balls , frisbees and baseballs . in every case , the same thing happens . the ball 's spin creates a pressure differential in the surrounding air flow that curves it in the direction of the spin . and here 's a question . could you theoretically kick a ball hard enough to make it boomerang all the way around back to you ? sadly , no . even if the ball did n't disintegrate on impact , or hit any obstacles , as the air slowed it , the angle of its deflection would increase , causing it to spiral into smaller and smaller circles until finally stopping . and just to get that spiral , you 'd have to make the ball spin over 15 times faster than carlos 's immortal kick . so good luck with that .

and here 's a question . could you theoretically kick a ball hard enough to make it boomerang all the way around back to you ? sadly , no .

can a soccer ball be boomeranged back to the player ?

studies have shown that taking vitamins is good for your health and bad for your health . that newly discovered herb can improve your memory or destroy your liver . headlines proclaim a promising new cancer treatment and never mention it again . on a daily basis , we are bombarded with attention-grabbing news , backed up by scientific studies , but what are these studies ? how are they performed ? and how do we know whether they 're reliable ? when it comes to dietary or medical information , the first thing to remember is that while studies on animals or individual cells can point the way towards further research , the only way to know how something will affect humans is through a study involving human subjects . and when it comes to human studies , the scientific gold standard is the randomized clinical trial , or rct . the key to rcts is that the subjects are randomly assigned to their study groups . they are often blinded to make them more rigorous . this process attempts to ensure that the only difference between the groups is the one the researchers are attempting to study . for example , when testing a new headache medication , a large pool of people with headaches would be randomly divided into two groups , one receiving the medication and another receiving a placebo . with proper randomization , the only significant overall difference between the two groups will be whether or not they received the medication , rather than other differences that could affect results . randomized clinical trials are incredible tools , and , in fact , the us food and drug administration often requires at least two to be conducted before a new drug can be marketed . but the problem is that an rct is not possible in many cases , either because it 's not practical or would require too many volunteers . in such cases , scientists use an epidemiological study , which simply observes people going about their usual behavior , rather than randomly assigning active participants to control invariable groups . let 's say we wanted to study whether an herbal ingredient on the market causes nausea . rather than deliberately giving people something that might make them nauseated , we would find those who already take the ingredient in their everyday lives . this group is called the cohort . we would also need a comparison group of people who do not have exposure to the ingredient . and we would then compare statistics . if the rate of nausea is higher in the herbal cohort , it suggests an association between the herbal supplement and nausea . epidemiological studies are great tools to study the health effects of almost anything , without directly interfering in people 's lives or assigning them to potentially dangerous exposures . so , why ca n't we rely on these studies to establish causal relationships between substances and their effects on health ? the problem is that even the best conducted epidemiological studies have inherent flaws . precisely because the test subjects are not randomly assigned to their groups . for example , if the cohort in our herbal study consisted of people who took the supplement for health reasons , they may have already had higher rates of nausea than the other people in the sample . or the cohort group could 've been composed of people who shop at health food stores and have different diets or better access to healthcare . these factors that can affect results , in addition to the factor being studied , are known as confounding variables . these two major pitfalls , combined with more general dangers , such as conflicts of interest or selective use of data , can make the findings of any particular epidemiological study suspect , and a good study must go out of its way to prove that its authors have taken steps to eliminate these types of errors . but even when this has been done , the very nature of epidemiological studies , which examine differences between preexisting groups , rather than deliberately inducing changes within the same individuals , means that a single study can only demonstrate a correlation between a substance and a health outcome , rather than a true cause and effect relationship . at the end of the day , epidemiological studies have served as excellent guides to public health , alerting us to critical health hazards , such as smoking , asbestos , lead , and many more . but these were demonstrated through multiple , well-conducted epidemiological studies , all pointing in the same direction . so , the next time you see a headline about a new miracle cure or the terrible danger posed by an everyday substance , try to learn more about the original study and the limitations inherent in any epidemiological study or clinical trial before jumping to conclusions .

at the end of the day , epidemiological studies have served as excellent guides to public health , alerting us to critical health hazards , such as smoking , asbestos , lead , and many more . but these were demonstrated through multiple , well-conducted epidemiological studies , all pointing in the same direction . so , the next time you see a headline about a new miracle cure or the terrible danger posed by an everyday substance , try to learn more about the original study and the limitations inherent in any epidemiological study or clinical trial before jumping to conclusions .

data from multiple , well-conducted epidemiological studies pointing in the same direction can be quite informative about causes of human health risks .

an estimated 20 million cases of blindness worldwide are caused by cataracts , a curable condition affecting the lens that focuses images onto the eye 's retina . a cataract occurs when proteins in the lens lose their normal arrangement , clumping together in a way that causes discoloration or clouding , and eventually blocks most vision . cataracts can be caused by eye injury , certain medications , ultraviolet radiation , diabetes , smoking , or some genetic disorders . but the most common cause is aging . in the united states , more than 50 % of people over the age of 80 develop them . cataracts were treated over 2,500 years ago in india , though similar procedures may have existed even earlier in ancient egypt and babylon . the most common procedure , called couching , involved pressing a sharp instrument into the eye to loosen and push the clouded lens out of the way . although this could increase the amount of light entering the eye , the lack of a lens would leave the patient 's vision out of focus . despite its low success rate , and high risk of infection or injury , couching is still performed in some parts of the world . later procedures would also focus on removing the cloudy lens , for example , by making an opening in the cornea to pull out the lens along with the membrane capsule surrounding it . while the invention of eyeglasses allowed for some restoration of focus , they had to be extremely thick to help . furthermore , such techniques still caused complications , like damaging the retina , or leaving the eye with uncomfortable stitches . but in the 20th century , something unexpected happened . eye surgeon sir harold ridley was treating world war ii casualties when he noticed that acrylic plastic from a shattered aircraft cockpit had become lodged in a pilot 's eyes without triggering an adverse reaction . this led him to propose surgically implanting artificial lenses into the eye to replace cataracts . and despite initial resistance , the method became standard practice by the 1980s . since ridley 's discovery , the intraocular lens has undergone several improvements . modern lenses can fit into the membrane capsule that the cataract is extracted from , leaving more of the eye 's natural anatomy intact . and the ability to fine-tune the lens curvature allows the surgery to restore a patient 's normal vision without the need for glasses . of course , surgical techniques have also progressed . microscopic procedures use small instruments or lasers to make precise incisions of one or two millimeters in the cornea , while an ultrasound probe breaks up and removes the cataracted lens with minimal trauma to the eye . low-tech versions of this operation have made the surgery quick and inexpensive , helping it spread across the developing world . places like aravind eye hospital in india have pioneered high-volume , low-cost cataract surgery for as little as six dollars . why then , with all these advances , are there still so many blind people in the world ? the main issue is access to health care , with poor infrastructure and a shortage of doctors being a major barrier in many regions . but this is not the only problem . in many rural areas with poor education , blindness is often accepted as an inevitable part of aging , for which someone might not think to seek treatment . this is why information is crucial . increased community awareness programs and the spread of mobile phones mean that many of those who might have remained blind for the rest of their lives due to cataracts are now reachable . and for them , a brighter future is in sight .

a cataract occurs when proteins in the lens lose their normal arrangement , clumping together in a way that causes discoloration or clouding , and eventually blocks most vision . cataracts can be caused by eye injury , certain medications , ultraviolet radiation , diabetes , smoking , or some genetic disorders . but the most common cause is aging .

modern day treatment of cataracts involves :

when reverend jim jones founded the peoples temple in 1955 , few could have imagined its horrifying end . this progressive religious movement rose in popularity and gained support from some of san francisco 's most prominent politicians . but in 1977 , amidst revelations of brainwashing and abuse , jones moved with several hundred followers to establish the commune of jonestown in guyana . billed as a utopian paradise , the colony was more like a prison camp , and when a congressional delegation arrived to investigate its conditions , jones executed his final plan . on november 18 , 1978 , 909 men , women , and children died after being forced to drink poisoned flavor aid . that grizzly image has since been immortalized as shorthand slang for single-minded cult-like thinking , `` they drank the kool-aid . '' today , there are thousands of cults around the world . it 's important to note two things about them . first , not all cults are religious . some are political , therapy-based , focused on self-improvement , or otherwise . and on the flip side , not all new religions are what we 're referring to as cults . so what exactly defines our modern understanding of cults , and why do people join them ? broadly speaking , a cult is a group or movement with a shared commitment to a usually extreme ideology that 's typically embodied in a charismatic leader . and while few turn out as deadly as jonestown or heaven 's gate , which ended in a mass suicide of 39 people in 1997 , most cults share some basic characteristics . a typical cult requires a high level of commitment from its members and maintains a strict hierarchy , separating unsuspecting supporters and recruits from the inner workings . it claims to provide answers to life 's biggest questions through its doctrine , along with the required recipe for change that shapes a new member into a true believer . and most importantly , it uses both formal and informal systems of influence and control to keep members obedient , with little tolerance for internal disagreement or external scrutiny . you might wonder whether some of these descriptions might also apply to established religions . in fact , the world `` cultus '' originally described people who cultivated the worship of certain gods by performing rituals and maintaining temples . but in time , it came to mean excessive devotion . many religions began as cults , but integrated into the fabric of the larger society as they grew . a modern cult , by contrast , separates its members from others . rather than providing guidelines for members to live better lives , a cult seeks to directly control them , from personal and family relationships , to financial assets and living arrangements . cults also demand obedience to human leaders who tend to be highly persuasive people with authoritarian and narcissistic streaks motivated by money , sex , power , or all three . while a cult leader uses personal charisma to attract initial followers , further expansion works like a pyramid scheme , with early members recruiting new ones . cults are skilled at knowing whom to target , often focusing on those new to an area , or who have recently undergone some personal or professional loss . loneliness and a desire for meaning make one susceptible to friendly people offering community . the recruitment process can be subtle , sometimes taking months to establish a relationship . in fact , more than two-thirds of cult members are recruited by a friend , family member , or co-worker whose invitations are harder to refuse . once in the cult , members are subjected to multiple forms of indoctrination . some play on our natural inclination to mimic social behaviors or follow orders . other methods may be more intense using techniques of coercive persuasion involving guilt , shame , and fear . and in many cases , members may willingly submit out of desire to belong and to attain the promised rewards . the cult environment discourages critical thinking , making it hard to voice doubts when everyone around you is modeling absolute faith . the resulting internal conflict , known as cognitive dissonance , keeps you trapped , as each compromise makes it more painful to admit you 've been deceived . and though most cults do n't lead members to their death , they can still be harmful . by denying basic freedoms of thought , speech , and association , cults stunt their members ' psychological and emotional growth , a particular problem for children , who are deprived of normal developmental activities and milestones . nevertheless , many cult members eventually find a way out , whether through their own realizations , the help of family and friends , or when the cult falls apart due to external pressure or scandals . many cults may be hard to identify , and for some , their beliefs , no matter how strange , are protected under religious freedom . but when their practices involve harassment , threats , illegal activities , or abuse , the law can intervene . believing in something should not come at the cost of your family and friends , and if someone tells you to sacrifice your relationships or morality for the greater good , they 're most likely exploiting you for their own .

many religions began as cults , but integrated into the fabric of the larger society as they grew . a modern cult , by contrast , separates its members from others . rather than providing guidelines for members to live better lives , a cult seeks to directly control them , from personal and family relationships , to financial assets and living arrangements .

what are some of the ways by which cult leaders influence their members ?

energy is not easy to define . things have energy , but you ca n't hold a bushel of energy in your hands . you can see what it does , but you ca n't see it directly . there are different types of energy , but the differences between them are manifested only in how they make stuff behave . we do know that the total amount of all the different types of energy in the universe is always the same . and , for chemists , two important types of energy are chemical potential energy and kinetic energy . potential energy is energy waiting to happen . think of a stretched rubber band . if you cut it , all that potential energy gets converted to kinetic energy , which is registered by you as pain . like a stretched rubber band , chemical bonds also store energy , and when those bonds are broken , that potential energy gets converted to other types of energy , like heat or light , or gets used to make different bonds . kinetic energy is the energy of motion , and molecules are always moving . they 're not necessarily going somewhere , though they could be , but they are vibrating , stretching , bending , and/or spinning . take methane , which is four hydrogens attached to a central carbon , as an example . drawn on paper , it 's just a still tetrahedron . but in real life , it 's a jiggling mess . the kinetic energy of molecules is exactly the same type of energy as the energy you have when you 're moving around , except that you can be still and molecules ca n't . if you suck the kinetic energy out of a group of molecules , they 'll move less , but they 'll never fully stop . now , in any group of molecules , some will have more kinetic energy than others . and if we calculate the average kinetic energy of the group , we 'd have a number mathematically related to temperature . so , the more kinetic energy a group of molecules has , the higher its temperature . and that means that on a hot day , the molecules in the air around you are spinning , stretching , bending , and generally shooting around much faster than on a cold day . now , hot and cold , by the way , are relative terms . they 're always used to compare one thing to something else . so , on that hot summer day , the air molecules have more kinetic energy than the molecules in your skin . so , when those air molecules crash into you , they transfer some of their energy to the molecules in your skin , and you feel that as heat . on a cold day , the air molecules have less kinetic energy than the molecules in your skin , so when you crash into those air molecules , you actually transfer some of your kinetic energy to them , and you feel that as cold . you can trace the path of energy around you . try it at your next cookout . you burn charcoal and the release of that chemical potential energy shows up as extreme heat and light . the heat then makes the molecules of your burgers , your hot dogs , or your vegetables vibrate until their own bonds break and new chemical structures are formed . too much heat and you have a charred mess ; just enough and you have dinner . once in your body , the food molecules in your delicious , or charred , dinner get broken down , and the energy released is used to either keep you alive right now or it 's stored for later in different molecules . as night falls , the hot summer air cools and the flow of energy into you slows . then , as the air reaches your skin temperature , for the briefest of moments , the flow stops . and then it starts up again in the opposite direction as energy leaves the warmer surface of your skin to return to the universe around you , that energy , neither created nor destroyed , but ever shape-shifting , the chameleon phoenix of our physical world .

and if we calculate the average kinetic energy of the group , we 'd have a number mathematically related to temperature . so , the more kinetic energy a group of molecules has , the higher its temperature . and that means that on a hot day , the molecules in the air around you are spinning , stretching , bending , and generally shooting around much faster than on a cold day .

temperature is a measure of a group of molecules ’ ________ .

translator : tom carter reviewer : bedirhan cinar ( zombie noises ) doctor 1 : so , here we are again . you know , i 've been thinking . why is this thing so angry ? doctor 2 : maybe he 's just hungry . d1 : ( laughs ) i 'm not going in there to feed it . no , this seems like something very primal . d2 : this is kind of a hard one , because we do n't really have any biological definitions for emotions like anger . sure , brain imaging studies have shown that some brain regions are more active when people are angry , but these are almost always correlational . when it 's warmer outside , people wear less clothing , but if i strip down to my birthday suit , it does n't make it sunny . d1 : ( laughs ) it 's like having someone run on a treadmill and saying `` look at how much more his arms move when he runs faster ! the arms must be where running happens . '' d2 : that 's why working with people with brain lesions is so important to neuroscience . it adds some causal evidence that a brain area might be required for a behavior . same with brain simulation studies . if stimulating a brain area causes a behavior , then that 's good evidence that the brain region is involved in that behavior . so like studies with cats in the 1950s showed that stimulating a small almond-shaped area deep in the brain called the amygdala leads to aggressive or predatory behaviors . these things look pretty aggressive to me . d1 : right . but other studies have shown that stimulating different parts of the amygdala can actually suppress predatory behaviors . so it 's kind of a complicated little brain structure . d2 : yeah . and fmri studies have found that the amygdala is active in violent criminals . d1 : whoa , whoa , whoa . careful there . just because criminals have the same active brain regions as people who are angry , does n't mean that they 're inherently aggressive . that 's like saying because i kiss with the same face hole that i use to burp , then these two things are related . it 's a false equivalence . d2 : huh ! never thought of it like that . that 's a good point . d1 : you know , the amygdala is part of the papez circuit . this system was discovered by james papez , who used the rabies virus to lesion different areas in the cat 's brain . he found that the amygdala was physically connected to another region called the hippocampus -- a little seahorse-shaped area that is needed to turn short-term memories into long-term memories . it 's thought that this connection between the amygdala and hippocampus links emotion and memory together , so that you remember really emotional stuff better than boring everyday things . d2 : yeah , like patient h.m . in the 1950s , surgeons removed both his left and right hippocampuses to treat his epilepsy . but after the surgery , he could n't remember any new information for longer than a few minutes . zombies appear to be pretty forgetful , would n't you agree ? d1 : ( laughs ) absolutely . between the amygdala-related aggression , and memory deficits from the hippocampus , papez may have actually accidentally created the first zombie cat . d2 : aw , come on now , let 's not get carried away . but now we do have some testable hypotheses . i 'd put money on its aggression and memory problems being linked to abnormalities in its amygdala and hippocampus , respectively . d1 : great ! so all we need to do now is figure out how to experimentally test this . do you think it 'll let us examine its brain to verify our hypothesis ? d2 : uh , you know , i think i might be more comfortable not knowing the answer to this one . d1 : hmm . maybe we could get a graduate student to do it for us ?

d2 : this is kind of a hard one , because we do n't really have any biological definitions for emotions like anger . sure , brain imaging studies have shown that some brain regions are more active when people are angry , but these are almost always correlational . when it 's warmer outside , people wear less clothing , but if i strip down to my birthday suit , it does n't make it sunny .

studies showing that convicted criminals have more activity in brain areas that are typically engaged when people are angry suggests that :

imagine you 're asked to invent something new . it could be whatever you want made from anything you choose in any shape or size . that kind of creative freedom sounds so liberating , does n't it ? or does it ? if you 're like most people , you 'd probably be paralyzed by this task . without more guidance , where would you even begin ? as it turns out , boundless freedom is n't always helpful . in reality , any project is restricted by many factors , such as the cost , what materials you have at your disposal , and unbreakable laws of physics . these factors are called creative constraints , and they 're the requirements and limitations we have to address in order to accomplish a goal . creative constraints apply across professions , to architects and artists , writers , engineers , and scientists . in many fields , constraints play a special role as drivers of discovery and invention . during the scientific process in particular , constraints are an essential part of experimental design . for instance , a scientist studying a new virus would consider , `` how can i use the tools and techniques at hand to create an experiment that tells me how this virus infects the body 's cells ? and what are the limits of my knowledge that prevent me from understanding this new viral pathway ? '' in engineering , constraints have us apply our scientific discoveries to invent something new and useful . take , for example , the landers viking 1 and 2 , which relied on thrusters to arrive safely on the surface of mars . the problem ? those thrusters left foreign chemicals on the ground , contaminating soil samples . so a new constraint was introduced . how can we land a probe on mars without introducing chemicals from earth ? the next pathfinder mission used an airbag system to allow the rover to bounce and roll to a halt without burning contaminating fuel . years later , we wanted to send a much larger rover : curiosity . however , it was too large for the airbag design , so another constraint was defined . how can we land a large rover while still keeping rocket fuel away from the martian soil ? in response , engineers had a wild idea . they designed a skycrane . similar to the claw machine at toy stores , it would lower the rover from high above the surface . with each invention , the engineers demonstrated an essential habit of scientific thinking - that solutions must recognize the limitations of current technology in order to advance it . sometimes this progress is iterative , as in , `` how can i make a better parachute to land my rover ? '' and sometimes , it 's innovative , like how to reach our goal when the best possible parachute is n't going to work . in both cases , the constraints guide decision-making to ensure we reach each objective . here 's another mars problem yet to be solved . say we want to send astronauts who will need water . they 'd rely on a filtration system that keeps the water very clean and enables 100 % recovery . those are some pretty tough constraints , and we may not have the technology for it now . but in the process of trying to meet these objectives , we might discover other applications of any inventions that result . building an innovative water filtration system could provide a solution for farmers working in drought-stricken regions , or a way to clean municipal water in polluted cities . in fact , many scientific advances have occurred when serendipitous failures in one field address the constraints of another . when scientist alexander fleming mistakenly contaminated a petri dish in the lab , it led to the discovery of the first antibiotic , penicillin . the same is true of synthetic dye , plastic , and gunpowder . all were created mistakenly , but went on to address the constraints of other problems . understanding constraints guides scientific progress , and what 's true in science is also true in many other fields . constraints are n't the boundaries of creativity , but the foundation of it .

in both cases , the constraints guide decision-making to ensure we reach each objective . here 's another mars problem yet to be solved . say we want to send astronauts who will need water .

what was the name of the first lander on mars ?

translator : denise rq reviewer : callum downs i just want to start with a little bit of a word of warning and that is my job here tonight it 's to be a little bit of a doctor bring me down . so bear with me for a few minutes , and know that after this , things will get lighter and brighter . let 's start . i know that many of you have heard the traveler 's adage , `` take nothing but pictures , leave nothing but footprints . '' well , i 'm going to say i do n't think that 's either as benign or as simple as it sounds , particularly for those of us in industries who are portraying people in poor countries , in developing countries and portraying the poor . and those of us in those industries are reporters , researchers , and people working for ngos ; i suspect there are a lot of us in those industries in the audience . we are going overseas and bringing back pictures like these : of the utterly distressed , or the displaced , or the hungry , or the child labor , or the exotic . now susan sontag reminds us that photographs in part help define what we have the right to observe , but more importantly , they are an ethics of seeing , and i think right now , is a good time to review our ethics of seeing as our industries of reporting , and research and ngo work are collapsing and changing in part by what it 's been happening in the economy , but it 's making us forge new relationships . and those new relationships have some fuzzy boundaries . i worked at the edge of some of these fuzzy boundaries and i want to share with you some of my observations . my ethics of seeing is informed by 25 years as a reporter covering emerging economies and international relations . i believe in a free and independent press . i believe that journalism is a public good . but it 's getting harder to do that job , in part because of the massive layoffs , because the budgets for international reporting are n't there anymore , new technologies and new platforms begging new content , and there are a lot of new journalisms . there is activist journalism , humanitarian journalism , peace journalism , and we are all looking to cover the important stories of our time . so we are going to ngos and asking them if we can embed in their projects . this is in part because they are doing important work in interesting places . that 's one example here : this is a project i worked on in the blue nile in ethiopia . ngos understand the benefits of having reporters tag along on their team . they need the publicity , they are under tremendous pressure , they are competing in a very crowded market for compassion . so they are also looking to reporters and to hire freelance reporters to help them develop their public relations material and their media material . now , researchers are also under pressure . they 're under pressure to communicate their science outside of the academy . so they 're collaborating with reporters because for many researchers is difficult to write a simple story or a clear story . and the benefit for reporters is that covering field research is some of the best work out there . you not only get to cover science , but you get to meet interesting scientists , like my phd adviser revi sterling ; she 's one of the magic research high tops there . and it was in a discussion with revi that brought us to the edge of the researcher and reporter , that fuzzy boundary . and i said to her , `` i was looking forward to going to developing countries and doing research and covering stories at the same time . '' she said , `` i do n't think so , girlfriend . '' that confusion , mutual confusion , drove us to publish a paper on the conflicting ethics and the contradictory practices of research and reporting . we started with the understanding that researchers and reporters are distant cousins equally story tellers and social analysts . but we do n't see nor portray developing communities the same way . here 's a very classic example : this is somalia 1992 . it could be somalia today . and this is a standard operating procedure for much of the news video and the news pictures that you see , where a group of reporters will be trucked in , escorted to the site of a disaster , they 'll produce their material , take their pictures , get their interviews , and then they will be escorted out . this is decidedly not a research setting . sometimes , we are working on feature stories . this is an image i took of a woman in bhongir village in andhra pradesh in india . she is at a micro-finance meeting . it 's a terrific story . what is important here is that she is identifiable . you can see her face . this also is not a research picture . this is much more representative of a research picture . it 's a research site : you see young women accessing new technologies . it 's more of a time stamp , it 's a documentation of research . i could n't use this for news . it does n't tell enough , and it would n't sell . but then , the differences are even deeper than that . revi and i analyzed some of the mandates that researchers are under , they are under some very strict rules governed by their university research review boards when it comes to content and confidentiality . researchers are mandated to acquire a document of informed consent , while as a reporter , if i hang a microphone on someone , that is consent . and when it comes to creating the story , i 'll fact check as a reporter , but i do n't invite company to create that story . whereas social scientists , researchers , and particularly participatory researchers will often work on constructing the narrative with the community . and when it comes to paying for information , checkbook journalism is roundly discouraged . in part because of the bias it introduces in the kind of information you get . but social scientists understand that people 's time is valuable so they pay them for that time . while journalists are well-placed to convey the beauty of the scientific process - and i would add the ngo process - what about the words ? what happens if a research project is not particularly well designed or an ngo project does n't fulfill its goals ? or the other kind of words ; that happens after dark when the drinks happen . research environments , and reporting , trips and ngos projects are very intimate environments ; you make good friends while you are doing good work , but there is a little bit of johnnie walker journalism after dark and what happens to that line between embedded and inbedded ? what do you do with the odd and odious behavior ? the point is that you 'll want to negotiate in advance what is on the record or off the record . i will turn now to some ngo imagery which will be familiar to some of you in this audience . ( video ) for about 70 cents , you can buy a can of soda . regular or diet . in ethiopia , for just 70 cents a day , you can feed a child like jaamal nourishing meals . for about 70 cents , you can also buy a cup of coffee . in guatemala , for 70 cents a day , you can help a child like vilma get the clothes she needs to attend school . leslie dodson : there is some very common imagery that 's been around for 40 years . that 's part of sally struthers ' famine campaign . some of it is very familiar ; it 's the madonna and child . women and children are very effective in terms of ngo campaigns . we 've been looking at this imagery for a long time , for hundreds and hundreds of years ; the madonna and child . here is [ duccio ] , and here is michelangelo . my concern is : are we one noting the genders in our narratives of poverty in developing communities ? do we have women as victims and are men only the perpetrators ? the guys with the ak 47s or the boys soldiers ? because that does n't leave room for stories like : the man who is selling ice-cream at the refuge camp in southern sudan , where we did a project . or the stories of the men who are working on the bridge over the blue nile . i wonder , are these stories inconvenient to our narratives ? and what about this narrative ? this is a for profit game , and its aim is to make development fun . one question is did they inadvertently make fun of ? another set of questions is what are the rights of these children ? what rights of publicity or privacy do they have ? did they get paid ? should they get paid ? should they share their profit ? this is a for profit game . did they sign talent wavers ? i have to use these when i 'm working with ngos and documentary film makers here in the states . in the states , we take our right to privacy and publicity very seriously . so what is it about getting on a long , whole flight that makes these rights vaporize ? i do n't want to just pick on our friends in the gaming arts , i 'll turn to the graphic arts where we often see these monolithic , homogeneous stories about the great country of africa . but africa is not a country , it 's a continent . it 's 54 countries and thousands and thousands of languages . so my question is is this imagery productive ? or is it reductive ? i know that is popular . we have usaid just launched their campaign `` forward '' -- fwd : famine war and drought . and by looking at it , you 'd think that was happening all the time , all over africa , but this is about what 's happening in the horn of africa . and i 'm still trying to make sense of africa in a piece of wonder bread . i 'm wondering about that . germaine greer has wondered about the same things and she says , `` at breakfast and at dinner , we can sharpen our own appetites with a plentiful dose of the pornography of war , genocide , destitution , and disease . '' she is right . we have sharpened our appetites , but we can also sharpen our insights . it is not always war , insurrection , and disease . this is a picture out of south sudan just a couple of months before the new country was born . i will continue to work as a researcher and a reporter in developing countries , but i do it with an altered ethic of seeing : i ask myself whether my pictures are pandering , whether they contribute to stereotypes , whether the images match the message , and am i complacent , or am i complicit ? thank you ( applause )

this is in part because they are doing important work in interesting places . that 's one example here : this is a project i worked on in the blue nile in ethiopia . ngos understand the benefits of having reporters tag along on their team .

what ’ s dodson ’ s example of how we “ one-note ” africa ?