Datasets:

leoleoasd

/

learningq_ted_ed

like 0

if you 've watched the news or followed politics chances are you 've heard the term orwellian thrown around in one context or another . but have you ever stopped to think about what it really means , or why it 's used so often ? the term was named after british author eric blair known by his pen name george orwell . because his most famous work , the novel `` 1984 , '' depicts an oppressive society under a totalitarian government , `` orwellian '' is often used simply to mean authoritarian . but using the term in this way not only fails to fully convey orwell 's message , it actually risks doing precisely what he tried to warn against . orwell was indeed opposed to all forms of tyranny , spending much of his life fighting against anti-democratic forces of both the left-wing and the right . but he was also deeply concerned with how such ideologies proliferate . and one of his most profound insights was the importance that language plays in shaping our thoughts and opinions . the government of `` 1984 '' 's oceania controls its people 's actions and speech in some ways that are obvious . their every move and word is watched and heard , and the threat of what happens to those who step out of line is always looming overhead . other forms of control are not so obvious . the population is inundated with a constant barrage of propaganda made up of historical facts and statistics manufactured in the ministry of truth . the ministry of peace is the military . labor camps are called `` joycamps . '' political prisoners are detained and tortured in the ministry of love . this deliberate irony is an example of doublespeak , when words are used not to convey meaning but to undermine it , corrupting the very ideas they refer to . the regime 's control of language goes even further , eliminating words from the english language to create the official dialect of newspeak , a crudely limited collection of acronyms and simple concrete nouns lacking any words complex enough to encourage nuanced or critical thought . this has an effect on the psyche orwell calls , `` doublethink , '' a hypnotic state of cognitive dissonance in which one is compelled to disregard their own perception in place of the officially dictated version of events , leaving the individual completely dependent on the state 's definition of reality itself . the result is a world in which even the privacy of one 's own thought process is violated , where one may be found guilty of thoughtcrime by talking in their sleep , and keeping a diary or having a love affair equals a subversive act of rebellion . this might sound like something that can only happen in totalitarian regimes , but orwell was warning us about the potential for this occurring even in democratic societies . and this is why `` authoritarian '' alone does not `` orwellian '' make . in his essay , `` politics and the english language , '' he described techniques like using pretentious words to project authority , or making atrocities sound acceptable by burying them in euphemisms and convoluted sentence structures . but even more mundane abuses of language can affect the way we think about things . the words you see and hear in everyday advertising have been crafted to appeal to you and affect your behavior , as have the soundbites and talking points of political campaigns which rarely present the most nuanced perspective on the issues . and the way that we use ready-made phrases and responses gleaned from media reports or copied from the internet makes it easy to get away with not thinking too deeply or questioning your assumptions . so the next time you hear someone use the word orwellian , pay close attention . if they 're talking about the deceptive and manipulative use of language , they 're on the right track . if they 're talking about mass surveillance and intrusive government , they 're describing something authoritarian but not necessarily orwellian . and if they use it as an all-purpose word for any ideas they dislike , it 's possible their statements are more orwellian than whatever it is they 're criticizing . words have the power to shape thought . language is the currency of politics , forming the basis of society from the most common , everyday interactions to the highest ideals . orwell urged us to protect our language because ultimately our ability to think and communicate clearly is what stands between us and a world where war is peace and freedom is slavery .

but he was also deeply concerned with how such ideologies proliferate . and one of his most profound insights was the importance that language plays in shaping our thoughts and opinions . the government of `` 1984 '' 's oceania controls its people 's actions and speech in some ways that are obvious .

which of the following is one of the effects of introducing `` newspeak '' ? -- a language with a vocabulary reduced by censorship .

for most jobs , it 's understood that you can be fired , whether for crime , incompetence , or just poor performance . but what if your job happens to be the most powerful position in the country , or the world ? that 's where impeachment comes in . impeachment is n't the same as actually removing someone from office . like an indictment in criminal court , it 's only the formal accusation that launches a trial , which could end in conviction or acquittal . originating in the united kingdom , impeachment allowed parliament to vote for removing a government official from office even without the king 's consent . although this was an important check on royal power , the king could n't be impeached because the monarch was considered the source of all government power . but for the founders of the american republic , there was no higher authority beyond the people themselves . and so impeachment was adopted in the united states as a power of congress applying to any civil officers , up to and including the president . although demands for impeachment can come from any members of the public , only the house of representatives has the power to actually initiate the process . it begins by referring the matter to a committee , usually the house committee on rules and the house committee on the judiciary . these committees review the accusations , examine the evidence , and issue a recommendation . if they find sufficient grounds to proceed , the house holds a separate vote on each of the specific charges , known as articles of impeachment . if one or more passes by a simple majority , the official is impeached and the stage is set for trial . the actual trial that follows impeachment is held in the senate . selected members of the house , known as managers , act as the prosecution , while the impeached official and their lawyers present their defense . the senate acts as both judge and jury , conducting the trial and deliberating after hearing all the arguments . if it 's the president or vice president being impeached , the chief justice of the supreme court presides . a conviction requires a supermajority of two-thirds and results in automatic removal from power . depending on the original charges , it can also disqualify them from holding office in the future and open them to standard criminal prosecution . so what exactly can get someone impeached ? that 's a bit more complicated . unlike in the united kingdom , impeachment in the u.s. pits an elected legislature against other democratically elected members of government . therefore , to prevent the process from being used as a political weapon , the constitution specifies that an official can only be impeached for treason , bribery , or other high crimes and misdemeanors . that still leaves a lot of room for interpretation , not to mention politics , and many impeachment trials have split along partisan lines . but the process is generally understood to be reserved for serious abuses of power . the first official to be impeached was tennesse senator william blount in 1797 for conspiring with britain to cease the spanish colony of louisiana . since then , the house has launched impeachment investigations about 60 times , but only 19 have led to actual impeachment proceedings . the eight cases that ended in a conviction and removal from office were all federal judges . and impeachment of a sitting president is even more rare . andrew johnson was impeached in 1868 for attempting to replace secretary of war edwin stanton without consulting the senate . over a century later , bill clinton was impeached for making false statements under oath during a sexual harassment trial . both were ultimately acquitted when the senate 's votes to convict fell short of the required two-thirds majority . and contrary to popular belief , richard nixon was never actually impeached for the watergate scandal . he resigned before it could happen knowing he would almost certainly be convicted . theoretically , the u.s. government is already designed to prevent abuses of power , limiting different branches through a system of checks and balances , term limits , and free elections . but impeachment can be seen as an emergency brake for when these safeguards fail .

but for the founders of the american republic , there was no higher authority beyond the people themselves . and so impeachment was adopted in the united states as a power of congress applying to any civil officers , up to and including the president . although demands for impeachment can come from any members of the public , only the house of representatives has the power to actually initiate the process .

where did impeachment originate , and how does it differ in the united states ?

today , more than half of all people in the world live in an urban area . by mid-century , this will increase to 70 % . but as recently as 100 years ago , only two out of ten people lived in a city , and before that , it was even less . how have we reached such a high degree of urbanization , and what does it mean for our future ? in the earliest days of human history , humans were hunter-gatherers , often moving from place to place in search of food . but about 10,000 years ago , our ancestors began to learn the secrets of selective breeding and early agricultural techniques . for the first time , people could raise food rather than search for it , and this led to the development of semi-permanent villages for the first time in history . `` why only semi-permanent ? '' you might ask . well , at first , the villages still had to relocate every few years as the soil became depleted . it was only with the advent of techniques like irrigation and soil tilling about 5,000 years ago that people could rely on a steady and long-term supply of food , making permanent settlements possible . and with the food surpluses that these techniques produced , it was no longer necessary for everyone to farm . this allowed the development of other specialized trades , and , by extension , cities . with cities now producing surplus food , as well as tools , crafts , and other goods , there was now the possibility of commerce and interaction over longer distances . and as trade flourished , so did technologies that facilitated it , like carts , ships , roads , and ports . of course , these things required even more labor to build and maintain , so more people were drawn from the countryside to the cities as more jobs and opportunities became available . if you think modern cities are overcrowded , you may be surprised to learn that some cities in 2000 b.c . had population densities nearly twice as high as that of shanghai or calcutta . one reason for this was that transportation was not widely available , so everything had to be within walking distance , including the few sources of clean water that existed then . and the land area of the city was further restricted by the need for walls to defend against attacks . the roman empire was able to develop infrastructure to overcome these limitations , but other than that , modern cities as we know them , did n't really get their start until the industrial revolution , when new technology deployed on a mass scale allowed cities to expand and integrate further , establishing police , fire , and sanitation departments , as well as road networks , and later electricity distribution . so , what is the future of cities ? global population is currently more than 7 billion and is predicted to top out around 10 billion . most of this growth will occur in the urban areas of the world 's poorest countries . so , how will cities need to change to accommodate this growth ? first , the world will need to seek ways to provide adequate food , sanitation , and education for all people . second , growth will need to happen in a way that does not damage the land that provides us with the goods and services that support the human population . food production might move to vertical farms and skyscrapers , rooftop gardens , or vacant lots in city centers , while power will increasingly come from multiple sources of renewable energy . instead of single-family homes , more residences will be built vertically . we may see buildings that contain everything that people need for their daily life , as well as a smaller , self-sufficient cities focused on local and sustainable production . the future of cities is diverse , malleable , and creative , no longer built around a single industry , but reflecting an increasingly connected and global world .

by mid-century , this will increase to 70 % . but as recently as 100 years ago , only two out of ten people lived in a city , and before that , it was even less . how have we reached such a high degree of urbanization , and what does it mean for our future ?

what percentage of the human population lived in cities 100 years ago ?

translator : andrea mcdonough reviewer : bedirhan cinar every human being starts out the same way : two cells , one from each parent , found each other and became one . and that one cell reproduced itself , dividing , dividing and dividing until there were 10 trillion of them . do you realize there 's more cells in one person 's body than there are stars in the milky way ? but those 10 trillion cells are n't just sitting there in a big pile . that would make for a pretty boring human being ! so what is it that says a nose is a nose , and toes is toes ? what is it that says this is bone and this is brain and this is heart and this is that little thing in the back of your throat you can never remember the name of ? everything you are or ever will be made of starts as a tiny book of instructions found in each and every cell . every time your body wants to make something , it goes back to the instruction book , looks it up and puts it together . so how does one cell hold all that information ? let 's get small . i mean , really small -- smaller than the tip of a sewing needle . then we can take a journey inside a single cell to find out what makes up the book of you , your genome . the first thing we see is that the whole genome , all your dna , is contained inside its own tiny compartment , called the nucleus . if we stretched out all the dna in this one cell into a single thread , it would be over 3 feet long ! we have to make it fit in a tiny compartment that 's a million times smaller . we could just bunch it up like christmas lights , but that could get messy . we need some organization . first , the long thread of dna wraps around proteins clustered into little beads called nucleosomes , which end up looking like a long , beaded necklace . and that necklace is wrapped up in its own spiral , like an old telephone cord . and those spirals get layered on top of one another until we get a neat little shape that fits inside the nucleus . voilà ! three feet of dna squeezed into a tiny compartment . if only we could hire dna to pack our suitcases ! each tiny mass of dna is called a chromosome . the book of you would have 46 chapters , one for each chromosome . twenty-three chapters of your book came from your mom , and 23 chapters came from your dad . two of those chapters , called `` x '' and `` y , '' determine if you 're male , `` xy , '' or female , `` xx . '' put them together , and we get two almost identical but slightly different sets of 23 chapters . the tiny variations are what makes each person different . it 's estimated that all the chapters together hold about 20,000 individual instructions , called genes . written out , all those 20,000 instructions are 30 million letters long ! if someone were writing one letter per second , it would take them almost an entire year to write it once . it turns out that our genome book is much , much longer than just those 30 million letters -- almost 100 times longer ! what are all those extra pages for ? well , each page of instructions has a few pages of nonsense inserted that have to be taken out before we end up with something useful . the parts we throw out , we call introns . the instructions we keep , we call exons . we can also have hundreds of pages in between each gene . some of these excess pages were inserted by nasty little infections in our ancestors , but some of them are actually helpful . they protect the ends of each chapter from being damaged , or some help our cells find a particular thing they 're looking for , or give a cell a signal to stop making something . all in all , for every page of instructions , there 's almost 100 pages of filler . in the end , each of our books ' 46 chapters is between 48 and 250 million letters long . that 's 3.2 billion letters total ! to type all that copy , you 'd be at it for over 100 years , and the book would be over 600,000 pages long . every type of cell carries the same book , but each has a set of bookmarks that tell it exactly which pages it needs to look up . so a bone cell reads only the set of instructions it needs to become bone . your brain cells , they read the set that tells them how to become brain . if some cells suddenly decide to start reading other instructions , they can actually change from one type to another . so every little cell in your body is holding on to an amazing book , full of the instructions for life . your nose reads nose pages , your toes read toes pages . and that little thing in the back of your throat ? it 's got its own pages , too . they 're under `` uvula . ''

i mean , really small -- smaller than the tip of a sewing needle . then we can take a journey inside a single cell to find out what makes up the book of you , your genome . the first thing we see is that the whole genome , all your dna , is contained inside its own tiny compartment , called the nucleus .

the entire genome ( or , `` the book of you '' ) is contained inside the _________ of the cell .

your rich , eccentric uncle just passed away , and you and your 99 nasty relatives have been invited to the reading of his will . he wanted to leave all of his money to you , but he knew that if he did , your relatives would pester you forever . so he is banking on the fact that he taught you everything you need to know about riddles . your uncle left the following note in his will : `` i have created a puzzle . if all 100 of you answer it together , you will share the money evenly . however , if you are the first to find the pattern and solve the problem without going through all of the leg work , you will get the entire inheritance all to yourself . good luck . '' the lawyer takes you and your 99 relatives to a secret room in the mansion that contains 100 lockers , each hiding a single word . he explains : every relative is assigned a number from 1 to 100 . heir 1 will open every locker . heir 2 will then close every second locker . heir 3 will change the status of every third locker , specifically if it 's open , she 'll close it , but if it 's closed , she 'll open it . this pattern will continue until all 100 of you have gone . the words in the lockers that remain open at the end will help you crack the code for the safe . before cousin thaddeus can even start down the line , you step forward and tell the lawyer you know which lockers will remain open . but how ? pause the video now if you want to figure it out for yourself ! answer in : 3 answer in : 2 answer in : 1 the key is realizing that the number of times a locker is touched is the same as the number of factors in the locker number . for example , in locker # 6 , person 1 will open it , person 2 will close it , person 3 will open it , and person 6 will close it . the numbers 1 , 2 , 3 , and 6 are the factors of 6 . so when a locker has an even number of factors it will remain closed , and when it has an odd number of factors , it will remain open . most of the lockers have an even number of factors , which makes sense because factors naturally pair up . in fact , the only lockers that have an odd number of factors are perfect squares because those have one factor that when multiplied by itself equals the number . for locker 9 , 1 will open it , 3 will close , and 9 will open it . 3 x 3 = 9 , but the 3 can only be counted once . therefore , every locker that is a perfect square will remain open . you know that these ten lockers are the solution , so you open them immediately and read the words inside : `` the code is the first five lockers touched only twice . '' you realize that the only lockers touched twice have to be prime numbers since each only has two factors : 1 and itself . so the code is 2-3-5-7-11 . the lawyer brings you to the safe , and you claim your inheritance . too bad your relatives were always too busy being nasty to each other to pay attention to your eccentric uncle 's riddles .

3 x 3 = 9 , but the 3 can only be counted once . therefore , every locker that is a perfect square will remain open . you know that these ten lockers are the solution , so you open them immediately and read the words inside : `` the code is the first five lockers touched only twice . ''

why are locker numbers that are perfect squares the only ones that remain open ?

in 1815 , the eruption of mount tambora plunged parts of the world into darkness and marked a gloomy period that came to be known as the year without a summer . so when mary and percy shelley arrived at the house of lord byron on lake geneva , their vacation was mostly spent indoors . for amusement , byron proposed a challenge to his literary companions : who could write the most chilling ghost story ? this sparked an idea in 18-year-old mary . over the next few months , she would craft the story of frankenstein . popular depictions may evoke a green and groaning figure , but that 's not mary shelley 's monster . in fact , in the book , frankenstein refers to the nameless monster 's maker , dr. victor frankenstein . so tense is the struggle between creator and creature that the two have merged in our collective imagination . before you read or reread the original text , there are several other things that are helpful to know about frankenstein and how it came to assume its multiple meanings . the book traces dr. frankenstein 's futile quest to impart and sustain life . he constructs his monster part by part from dead matter and electrifies it into conscious being . upon completing the experiment , however , he 's horrified at the result and flees . but time and space are n't enough to banish the abandoned monster , and the plot turns on a chilling chase between the two . shelley subtitled her fireside ghost story , `` the modern prometheus . '' that 's in reference to the greek myth of the titan prometheus who stole fire from the gods and gave it to humanity . this gave humanity knowledge and power , but for tampering with the status quo , prometheus was chained to a rock and eaten by vultures for eternity . prometheus enjoyed a resurgence in the literature of the romantic period during the 18th century . mary was a prominent romantic , and shared the movement 's appreciation for nature , emotion , and the purity of art . two years after mary released `` frankenstein '' , percy reimagined the plight of prometheus in his lyrical drama , `` prometheus unbound . '' the romantics used these mythical references to signal the purity of the ancient world in contrast to modernity . they typically regarded science with suspicion , and `` frankenstein '' is one of the first cautionary tales about artificial intelligence . for shelley , the terror was not supernatural , but born in a lab . in addition , gothic devices infuse the text . the gothic genre is characterized by unease , eerie settings , the grotesque , and the fear of oblivion - all elements that can be seen in `` frankenstein . '' but this horror had roots in personal trauma , as well . the text is filled with references to shelley 's own circumstances . born in 1797 , mary was the child of william godwin and mary wollstonecraft . both were radical intellectual figures , and her mother 's book , `` a vindication of the rights of women , '' is a key feminist text . tragically , she died as a result of complications from mary 's birth . mary was haunted by her mother 's death , and later experienced her own problems with childbirth . she became pregnant following her elopement with percy at 16 , but that baby died shortly after birth . out of four more pregnancies , only one of their children survived . some critics have linked this tragedy to the themes explored in `` frankenstein . '' shelley depicts birth as both creative and destructive , and the monster becomes a disfigured mirror of the natural cycle of life . the monster , therefore , embodies dr. frankenstein 's corruption of nature in the quest for glory . this constitutes his fatal flaw , or hamartia . his god complex is most clear in the line , `` life and death appear to me ideal bounds which i should first break through and pour a torrent of light onto our dark world . '' although he accomplishes something awe-inspiring , he has played with fire at his own ethical expense . and that decision echoes throughout the novel , which is full of references to fire and imagery that contrasts light and dark . these moments suggest not only the spark of prometheus 's fire , but the power of radical ideas to expose darker areas of life .

this gave humanity knowledge and power , but for tampering with the status quo , prometheus was chained to a rock and eaten by vultures for eternity . prometheus enjoyed a resurgence in the literature of the romantic period during the 18th century . mary was a prominent romantic , and shared the movement 's appreciation for nature , emotion , and the purity of art .

an aspect of the shelleys ' writing which places them in the category of romantic writers is the presence of ___ in their writing .

you probably do n't need to be told how important your brain is . after all , every single thing you experience , your thoughts and your actions , your perceptions and your memories are processed here in your body 's control center . but if this already seems like a lot for a single organ to handle , it 's actually only a small part of what the brain does . most of its activities are ones you 'd never be aware of , unless they suddenly stopped . the brain is made up of billions of neurons , and trillions of connections . neurons can be activated by specific stimuli or thoughts , but they are also often spontaneously active . some fire cyclically in a set pattern . others fire rapidly in short bursts before switching off , or remain quiet for long periods until thousands of inputs from other neurons line up in just the right way . on a large scale , this results in elaborate rhythms of internally generated brain activity , humming quietly in the background whether we 're awake , asleep , or trying not to think about anything at all . and these spontaneously occurring brain functions form the foundation upon which all other brain functions rely . the most crucial of these automatically occurring activities are the ones that keep us alive . for example , while you 've been paying attention to this video spontaneous activity in your brain has been maintaining your breathing at 12 to 16 breaths a minute , making sure that you do n't suffocate . without any conscious effort , signals from parts of your brainstem are sent through the spinal cord to the muscles that inflate your lungs , making them expand and contract , whether or not you 're paying attention . the neuronal circuits underlying such rhythmic spontaneous activity are called central pattern generators , and control many simple repetitive behaviors , like breathing , walking , and swallowing . ongoing neural activity also underlies our sensory perception . it may seem that the neurons in your retina that translate light into neural signals would remain quiet in the dark , but in fact , the retinal ganglion cells that communicate with the brain are always active . and the signals they send are increases and decreases in the rate of activity , rather than separate bursts . so at every level , our nervous system is teeming with spontaneous activity that helps it interpret and respond to any signals it might receive . and our brain 's autopilot is n't just limited to our basic biological functions . have you ever been on the way home , started thinking about what 's for dinner , and then realized you do n't remember walking for the past five minutes ? while we do n't understand all the details , we do know that the ongoing activity in multiple parts of your brain is somehow able to coordinate what is actually a complex task involving both cognitive and motor functions , guiding you down the right path and moving your legs while you 're getting dinner figured out . but perhaps the most interesting thing about spontaneous brain function is its involvement in one of the most mysterious and poorly understood phenomena of our bodies : sleep . you may shut down and become inactive at night , but your brain does n't . while you sleep , ongoing spontaneous activity gradually becomes more and more synchronized , eventually developing into large , rhythmic neural oscillations that envelop your brain . this transition to the more organized rhythms of sleep starts with small clusters of neurons tucked in the hypothalamus . despite their small number , these neurons have a huge effect in turning off brainstem regions that normally keep you awake and alert , letting other parts , like the cortex and thalamus , slowly slip into their own default rhythms . the deeper we fall into sleep , the slower and more synchronized this rhythm becomes , with the deepest stages dominated by large amplitude , low frequency delta waves . but surprisingly , in the middle of this slow wave sleep , the brain 's synchronized spontaneous activity repeatedly transitions into the sort of varied bursts that occur when we 're wide awake . this is the sleep stage known as rem sleep , where our eyes move rapidly back and forth as we dream . neuroscientists are still trying to answer many fundamental questions about sleep , such as its role in rejuvenating cognitive capacity , cellular homeostasis , and strengthening memory . and more broadly , they are exploring how it is that brain can accomplish such important and complex tasks , such as driving , or even breathing , without our awareness . but for now , until we are better able to understand the inner workings of their spontaneous functioning , we need to give our brains credit for being much smarter than we ourselves are .

without any conscious effort , signals from parts of your brainstem are sent through the spinal cord to the muscles that inflate your lungs , making them expand and contract , whether or not you 're paying attention . the neuronal circuits underlying such rhythmic spontaneous activity are called central pattern generators , and control many simple repetitive behaviors , like breathing , walking , and swallowing . ongoing neural activity also underlies our sensory perception .

everything we are aware of , including our thoughts and behaviors , arises from neuronal activity . but the opposite is not true -- we are not aware of all of the neuronal activity in our brain . what is an advantage of not being aware of every little thing our brain is doing all the time ?

hi , i ’ m john green , and this is crash course world history . let ’ s begin today with a question . why am i alive ? also , why don ’ t i have any eyes ? ah , that ’ s better . the way we answer that question ends up organizing all kinds of other thoughts , like what we should value , and how we should behave , and if we should eat meat , and whether we should dump that boy who is very nice , but insanely clingy , in a way that he can not possibly think is attractive . all of which adds up- uh , mr. green , mr. green , uh , are you talking about me ? yes , i ’ m talking about you , me from the past . i ’ m telling you that one of the reasons we study history is so that you can be a less terrible boyfriend , but more on that momentarily . [ theme music ] today we ’ re going to talk about civilizations , but in order to do that , we have to talk about talking about civilizations , because it ’ s a problematic word . so problematic , in fact , that i have to turn to camera 2 to discuss it . certain conglomerations of humans are seen as civilizations , whereas , say , nomadic cultures generally aren ’ t , unless , you are -- say it with me -- the mongols by calling some groups civilizations , you imply that all other social orders are uncivilized , which is basically just another way of saying that they ’ re savages or barbarians . side note : originally greek , the word barbarian denoted anyone who did not speak ancient greek , because to the greeks , all other languages sounded like bar bar bar bar bar bar . so , that is to say that we are all essentially barbarians , except for the classics majors , which is worth remembering when we ’ re discussing civilizations . civilizations are like most of the things we like to study , they ’ re intellectual constructs . no one woke up in the city of thebe ’ s in egypt one morning and said , “ what a beautiful morning , i sure am living at the height of egyptian civilization. ” still , they ’ re useful constructs , particularly when you ’ re comparing one civilization to another . they ’ re less useful when you ’ re comparing a civilization to a non-civilization type social order , which is why we will try to avoid that . and yes , i am getting to the good boyfriend stuff . patience , grasshopper . so what is a civilization ? well , diagnosing a civilization is a little like like diagnosing an illness . if you have four or more of the following symptoms , you might be a civilization . surplus production . once one person can make enough food to feed several people , it becomes possible to build a city , another symptom of civilization . it also leads to the specialization of labor , which in turn leads to trade . like , if everybody picks berries for a living , there ’ s no reason to trade , because i have berries , and you have berries , but if i pick berries for a living and you make hammers , suddenly , we have cause to trade . civilizations are also usually associated with social stratification , centralized government , shared values , generally in the form of religion , and writing . and at least in the early days , they were almost always associated with rivers . these days you can just bisect a segment of land horizontally and vertically , and boom , build a city . but 5000 years ago , civilizations were almost always associated with rivers . whether that ’ s the tigris and euphrates , the yellow river , the nile , the amazon basin , the coatzacoalcos - gaaah ! i was doing so good until i got to coatzacoalcos ! ( computer says : coatzacoalcos ) coatzacoalcos . maybe . why river valleys ? they ’ re flat , they ’ re well watered , and when they flood , they deposit nutrient-rich silt . we ’ ll have more to say about most of these civilizations later , but let ’ s talk about this guy , the indus valley civilization , ‘ cause it ’ s my all time favorite . the indus valley civilization was located in the flood plain of the indus and sarawati rivers , and it was about the best place in the world to have an ancient civilization because the rivers flooded very reliably twice a year , which meant that it had the most available calories per acre of pretty much anywhere on the planet . we know the indus valley civilization flourished a long time ago . probably around 3000 bce . why is that question literally hanging over my head ? but people of the indus valley were trading with mesopotamians as early as 3500 bce . we also know that it was the largest of the ancient civilizations . archaeologists have discovered more than 1500 sites . so what do we know about this civilization ? let ’ s go to the thought bubble . everything we know about the indus valley civilization comes from archaeology , because while they did use written language , we don ’ t know how to read it , and no rosetta stone has thus appeared to help us learn it . i meant the other rosetta stone , thought bubble , yeah . although , come to think of it , either would be acceptable . so here ’ s what we know , they had amazing cities . harappa and mohenjo daro are the best known , with dense , multi-story homes constructed out of uniformly sized bricks along perpendicular streets . i mean this wasn ’ t some ancient world version of houston , more like chicago . this means they must have had some form of government and zoning , but we don ’ t know what gave this government its authority . cities were oriented to catch the wind and provide a natural form of air conditioning . and they were clean . most homes were connected to a centralized drainage system that used gravity to carry waste and water out of the city in big sewer ditches that ran under the main avenues , a plumbing system that would have been the envy of many 18th century european cities . also , in mohenjo daro , the largest public building was not a temple or a palace , but a public bath , which historians call the great bath . we don ’ t know what the great bath was used for , but since later indian culture placed a huge emphasis on ritual purity , which is the basis for the caste system , some historians have speculated that the bath might have been like a giant baptismal pool . also , they traded . one of the coolest things that the indus valley civilization produced were seals used as identification markers on goods and clay tablets . these seals contained the writing that we still can ’ t decipher , and a number of fantastic designs , many featuring animals and monsters . one of the most famous and frightening is of a man with what looks like water buffalo horns on his head , sitting cross-legged between a tiger and a bull . we don ’ t know what ’ s really going on here , but it ’ s safe to say that this was a powerful dude , because he seems to be able to control the tiger . how do these seals let us know that they traded ? well , because we found them in mesopotamia , not the indus valley . plus , archaeologists have found stuff like bronze in the indus valley that is not native to the region . so what did they trade ? cotton cloth . still such a fascinating export , incidentally that it will be the subject of the 40th and final video in this very series . but here ’ s the most amazing thing about the indus valley people . they were peaceful . despite archaeologists finding 1500 sites , they have found very little evidence of warfare , almost no weapons . thanks thought bubble . ok , before we talk about the fascinating demise of the indus valley civilization . it ’ s time for the open letter . magic ! i wonder what the secret compartment has for me today ? oh ! fancy clothes . i guess the secret compartment didn ’ t think i was dressed up enough for the occasion . an open letter to historians . dear historians , the great bath ? really ? the great bath ? i ’ m trying to make history fascinating , and you give me a term that evokes scented candles , bath salts and frederic fekkai hair products ? i know sometimes the crushingly boring names of history aren ’ t your fault . you didn ’ t name the federalist papers or the austro-hungarian empire or adam smith . but when you do get a chance to name something , you go with the great bath ? not the epic bath of mohenjo daro , or the bath to end all baths , or the pool that ruled , or the moist mystery of mohenjo daro or the wet wonder ? the great bath ? really ? you can do better . best wishes , john green . so what happened to these people ? well , here ’ s what didn ’ t happen to them . they didn ’ t morph into the current residents of that area of the world , hindu indians or muslim pakistanis . those people probably came from the caucasus . instead , sometime around 1750 bce , the indus valley civilization declined until it faded into obscurity . why ? historians have three theories . one : conquest ! turns out to be a terrible military strategy not to have any weapons , and it ’ s possible people from the indus valley were completely overrun by people from the caucasus . two : environmental disaster ! it ’ s possible they brought about their own end by destroying their environment . three : earthquake ! the most interesting theory is that a massive earthquake changed the course of the rivers so much that a lot of the tributaries dried up . without adequate water supplies for irrigation , the cities couldn ’ t sustain themselves , so people literally picked up and headed for greener pastures . well , probably not pastures , it ’ s unlikely they became nomads . they probably just moved to a different plain an continued their agricultural ways . i am already boring you and i haven ’ t even told you yet how to be a better boyfriend and/or girlfriend . i ’ m going to do that now . so we don ’ t know why the indus valley civilization ended , but we also don ’ t really know why it started . why did these people build cities , and dig swimming pools , and make unnecessarily ornate seals ? were they motivated by hunger , fear , a desire for companionship , the need to be near their sacred spaces , or a general feeling that city life was just more awesome than foraging ? thinking about what motivated them to structure their life as they did helps us to think about how we structure our own lives . in short , you ’ re clingy because you ’ re motivated by fear and a need for companionship , and she finds it annoying because it ’ s enough work having to be responsible for herself without having to also be responsible for you . also , you ’ re not really helping her by clinging , and from the indus valley in the bronze age , to school life today , human life is all about collaboration . trading cloth for bronze , building cities together , and collaborating to make sure that human lives are tilted to catch the wind . next week we will travel here to discuss the hot mess o ’ potamia , but in the meantime , if you have any questions , leave them in comments , and our team of semi-trained semi-professionals will do their best to answer them . also , you ’ ll find some suggested resources in the video info below , he said , pointing at his pants . thanks for watching , and we ’ ll see you next week !

still such a fascinating export , incidentally that it will be the subject of the 40th and final video in this very series . but here ’ s the most amazing thing about the indus valley people . they were peaceful .

the people of the ancient indus valley were ________ .

we all know that there are certain virtues that are good for us . intelligence , wisdom , bravery , justice , respect , responsibility , honesty , unselfishness , compassion , patience , and perseverance always have been and always will be positive virtues . think of some people who have those traits . maybe it 's martin luther king or abraham lincoln or george washington . i bet you know a lot of facts about these historical figures , but maybe you 've never taken the time to think about their character . let 's talk about sybil ludington . she 's a little-known revolutionary figure , but boy , was she something ! she rode 40 miles through the damp , cold night of april 26 , 1777 to alert the colonial militia of a british attack . her action was similar to that of paul revere , only she rode twice as far and was only 16 years old . that takes some real guts ! beriah green ? anyone ever heard of beriah green ? he was president of the first integrated school in the united states . he also spent the majority of his life fighting for the immediate abolition of slavery . he used his voice , pen , and good deed to fight slavery . beriah green was fiercely devoted to abolition before it was popular because he believed it was the right thing to do . and then there 's abraham lincoln . you know he was president during the civil war . he wrote the emancipation proclaimation and is credited with freeing the slaves . he went to war with the south to save the union . he helped the country get through one of its most difficult times . he kept the united states united . but , above all that , abraham lincoln showed great leadership . could any of these people have done the deeds they 're famous for without bravery , compassion , dedication , or wisdom ? no ! history can teach us much more than just the facts . it 's full of examples of how to live better . and for you , even if you 're not freeing the slaves or riding 40 miles on horseback , bravery and wisdom will help you get an a on that test , ask out that cute boy , and get that great job .

we all know that there are certain virtues that are good for us . intelligence , wisdom , bravery , justice , respect , responsibility , honesty , unselfishness , compassion , patience , and perseverance always have been and always will be positive virtues .

what is a virtue ?

on january 1 , 1863 , abraham lincoln legally changed the status of over 3 million enslaved blacks across ten states from slave to free . his emancipation proclamation was n't a law , or a presidential decree . it was an executive order . the framers of the american constitution made the power of executive order available to the executive branch . but what exactly is this tool ? how does it work ? and what is the extent of its power ? well , an executive order is n't a law , but it can carry the weight of one . passing laws involves a fairly lengthy process . first , a member of congress proposes a piece of legislation in the form of a bill . after many committees and revisions , if the bill is approved by a majority votes in congress , that is both the house and senate , the bill is then sent to the president for signature . if the president signs the bill , it then becomes a law . an executive order , on the other hand , is something the president issues without consultation or permission from congress . they are , however , enforced like laws , and are subject to judicial review by the court system to make sure they 're within the limits of the constitution . that means the courts have the power to invalidate any executive decisions that they determine are an overreach of the president in trying to assert power . and once the president leaves office , if his or her successor wants to eliminate the executive order , they can do so . so when does a president use an executive order ? sometimes a president feels the need to exert power without working with congress , and in times of crisis , quick decisions can be justified . but most executive orders are not responses to emergencies . they 're often directed towards agencies in the federal government in order to expand or contract their power . others determine the extent to which legislation should be enforced . and sometimes , a president may use an executive order to clarify and help implement a policy that needs to be easily defined . some of the most famous executive orders have changed the course of american history . fdr issued an executive order to establish the works progress administration , which helped build thousands of roads , bridges , and parks throughout the country . the wpa also employed thousands of writers , painters , sculptors , and artists to create works of art in public spaces . additionally , harry truman used an executive order to desegregate the armed forces in 1948 . and in 1965 , lyndon johnson signed an executive order to establish requirements for nondiscriminatory practices in hiring and employment . executive orders have often been used in positive and inclusive ways , but they 've also been used to exclude and divide . one of the most notable examples being fdr 's 1942 executive order . he gave the military authority to target predominantly japanese-americans , as well as german-americans and italian-americans , in certain regions across the country . this executive order also removed any or all of those people into military zones , most commonly known as internment camps . beginning in the early 1960s , each president has issued roughly 300 executive orders , but fdr issued over 3,500 . at the other end of the spectrum , william henry harrison never issued an executive order , probably because his presidency only lasted 31 days . the u.s. constitution is somewhat ambiguous on the extent of the president 's power . that 's resulted in executive orders expanding over time . for instance , since lyndon johnson , presidents have begun issuing orders to create faith-based initiatives , establish federal agencies , and remove barriers for scientific research . there are checks and balances in the u.s. political system . congress can pass laws to counteract executive orders , and judges can halt them by deeming them unconstitutional . but in the time it takes for those things to happen , an executive order can go into effect and possibly change the course of history , for better or for worse .

they are , however , enforced like laws , and are subject to judicial review by the court system to make sure they 're within the limits of the constitution . that means the courts have the power to invalidate any executive decisions that they determine are an overreach of the president in trying to assert power . and once the president leaves office , if his or her successor wants to eliminate the executive order , they can do so .

many modern day presidents use executive orders in times of crisis or to expand programs they believe in . do you think presidents should have this sweeping power over the 320 million americans in the united states ? since recent presidents are usually elected by only half of the country , is the executive order too much power for one person ? in your opinion , if the voters decided to take this power away , what could they replace it with ? can we ever ensure that one person will not use this power for bad deeds instead of good ? how can congress , the courts , and voters make sure this does not happen ?

[ stories from the sea ] [ fish tale my secret life as plankton ] how did i get here ? well , it 's a stranger story than you might think . i came from a world of drifters , a place few humans have ever seen . the world of plankton . i came from a batch of a million eggs , and only a few of us survived . when i became a larva , i moved among other drifters . [ `` plankton '' comes from the greek `` planktos '' for wandering ] my fellow plankton came in all sizes , from tiny algae and bacteria to animals longer than a blue whale . i shared my nursery with other embryos and juveniles , from clams and crabs to sea urchins and anemones . ( high pitch sound ) we drifting animals are called zooplankton . the most common animals here are copepods and krill . ( buzzing ) you could search the world over , but you 'd never find a place more diverse than my childhood home . a teaspoon of seawater can contain more than a million living creatures . it can be a pretty tough existence , though . trillions are born here , but only a few make it to adulthood . he may be no larger than a pin head , but this crab larva is an arrow worm 's worst nightmare . ( bumping noises ) ( buzzing ) epic battles between carnivores like these are just one way to get food . but the real powers of this place come from phytoplankton . single-celled life that transforms sunlight and carbon dioxide into edible gold . phytoplankton are the base for the largest food web in the world . during the night , many animals like me would rise up from the depths to feed on this sun-powered feast . ( maraca sound ) i was part of the largest daily migration of life on earth . during the day , i 'd return to the darkness , where i 'd join my bizarre companions . ( high pitch buzz ) ( flapping noises ) cannibals , like this sea butterfly mollusk , that eats its next of kin . and comb jellies , that beat cilia like rainbowed eyelashes . some of these snare their prey with sticky tentacles , while others just take a bite out of their cousins . and siphonophores that catch prey with toxic fishing lures . but my favorite would have to be the crustacean phronima . its monstrous looks inspired the movie `` aliens . '' it can catch tiny bits in its bristles , but prefers larger prey like salps . with two sets of eyes , this female prowls the deeper water . prey in hand , she performs one of the strangest behaviors in the entire animal kingdom . with body parts from her victims , she delicately assembles a barrel-like home feeding her young until they can drift off and survive on their own . best of all , they make the perfect snack for a small fish like me . here among the plankton , the food web is so tangled and complex , even scientists do n't know who eats whom . but i do . at least now you know a bit of my story . there 's so much more to me than just a tasty meal .

he may be no larger than a pin head , but this crab larva is an arrow worm 's worst nightmare . ( bumping noises ) ( buzzing ) epic battles between carnivores like these are just one way to get food . but the real powers of this place come from phytoplankton .

describe some of the structural and behavioral adaptations that zooplankton use to get food .

translator : jenny zurawell i am awele . daughter of alice , granddaughter of ruth , great-granddaughter of big momma alice and madir corine , great-great-granddaughter of anna and zitii benyen . it is my hope to find my best possible self in the service of others . now , my daddy , he used to tell me stories . my daddy , he would say , `` i want you to know who you are and where you come from . that will guide you as you discover who you must be . now , you listen to this story , you hear me , baby girl ? it 's not going to be in a book . your teacher is not going to tell it , but you need to understand who you are . '' that became a guiding principle in the stories that i wanted to tell . stories about legacy of who we are . i used to hear all the time that children are the future , but what does that cliché really mean and how are we preparing them ? so i looked for narratives about young people and the legacy that they bring as agents of change . the power that you have right now . today , march 2 , 1955 -- the story that i want to share with you comes from 1955 , march 2 . it 's about a courageous 16-year-old girl , claudette colvin . and it comes full circle today because a week ago today , in san francisco , my middle school students , they performed a program that i had written , `` agents of change , '' starting with the reenactment of plessy v. ferguson from 1892 to 1896 , moving to brown v. board and a student-led strike by barbara rose johns , jumping to claudette colvin and the montgomery bus boycott and ending in 1960 with the sit-in movement , the non-violent movement led by students . so i 'm going to share the story , and i would like to also share the work i do with it , as a case study . i paid my dime at the front of the bus , and then i ran to the back door with the rest of the colored kids so the driver would n't take off before we got on . also , well , whites do n't want us walking down the aisle next to them . when i got back on the bus , colored section was full , so , i sat in the middle section . i took the last row seat on the left , it was right by the window , was n't thinking about anything in particular . `` hey . '' i did n't know the girl next to me either , this older girl . so i just looked out the window . driver went more stops , more people were getting on , colored and white . pretty soon , no more seats were available . `` give me those seats , '' the driver called out . colored folks just started getting up . white folks started taking their seats , but i stayed seated . girl next to me and the other two across -- they stayed seated . i knew it was n't the restricted area . `` make light on your feet ! '' girl next to me got up immediately . she stood in the aisle , then the other two girls . but i told myself , this is n't the restricted area . the driver , he looked up , looked in the window , that mirror . he pulled over . a pregnant lady , mrs. hamilton , got on the bus . she ran to the back and got on , not knowing he was trying to have me relinquish my seat . and she sat right next to me . `` the two of you need to get up so i can drive on . '' `` sir , i paid my dime , i paid my fare . it 's my right , you know , my constitutional -- '' `` constitutional ? ha-ha , let me get the police . '' well he got off and he flagged down two motormen , and they came . and those motormen , they came onto the bus . looked at mrs. hamilton . `` now the two of you need to get up so the driver can drive on . '' `` sir , i paid my dime . i 'm pregnant . if i were to move right now , i 'd be very sick , sir . '' `` sir , i paid my dime too , you know , and it 's my right , my constitutional right . i 'm a citizen of the united states . you just read the 13th and 14th amendment , it 'll tell you so . i know the law . my teacher , she taught it at school . '' you see , my teacher , she taught the constitution , the bill of rights , the declaration of independence , patrick henry 's speech -- i even memorized it . my teacher , she would prick our minds , trying to see what we thinking about . she would say , `` who are you ? hmm ? who are you , sitting right here right now ? the person that people think they see from your outside ? who are you on the inside ? how you think ? how you feel ? what you believe ? would you be willing to stand up for what you believe in even if someone wants to hold you back because you 're different ? do you love your beautiful brown skin , children ? hmm ? are you american ? what does it mean to be an american ? huh ? homework tonight , write me an essay : `` what does it mean to be an american ? '' you need to know who you are , children ! '' my teacher , she would teach us history and current events . she said that 's how we can understand everything that 's going on and we can do something about it . `` sir , all i know is i hate jim crow . i also know if i ai n't got nothing worth living for , i ai n't got nothing worth dying for . so give me liberty or give me death ! ouch ! i do n't care ! take me to jail . '' they dragged her off the bus . next thing , claudette colvin was in a car seat , backseat of the police car , handcuffed through the windows . the following year , may 11 , 1956 , claudette colvin was the star witness in the federal court case browder v. gayle . her , an 18-year-old teenager and two others , women , mrs. browder . their case , browder v. gayle , went up to the supreme court . on the heels of brown v. board of education , the 14th amendment and her powerful testimony that day , the rest is history . now , why is it we do n't know this story ? the montgomery bus boycott -- we hear rosa parks , martin luther king , they will forever be lifted up . but the role women played in that movement , the role of claudette , as an up-stander , it teaches us important lessons that challenge us today . what does it mean to be a participant ? a responsible citizen in a democracy ? and lessons of courage and of faith ? so i find freedom movement history that includes young people so that they can explore these big ideas of identity , your chosen identity , and the imposed identity . what does membership in society mean ? who has it ? how do we make amends ? race and violence in america , as well as participatory citizenship . so these stories allow me to have conversations , to speak the unspeakable , that many are afraid to have . once in eugene , oregon , a young , blond-haired , blue-eyed boy , middle schooler , at the end of a performance in the dialogue said , `` but ms. awele , racism 's over , right ? '' and not wanting to answer for him , i said , `` turn to the person sitting next to you . see if you can come up with evidence . '' and i gave them four minutes to talk . soon , they began to tell stories , evidence of racism in their community . a girl wrote to me , a high school student in san francisco : `` i was going to skip school but then i heard we had an assembly , so i came . and after listening to the students talk and seeing your performance , i thought i should organize my friends and we should go down to a board meeting and tell them that want to have advanced classes for a through g requirements . '' so , i tell you this story today in honor of the legacy of young people that have come before , so that they will have guideposts and signs to be the change that they want to see in this world , as claudette colvin was . because she struck down the constitutionality of segregated seats in montgomery , alabama . thank you . ( applause ) thank you . ( applause )

the power that you have right now . today , march 2 , 1955 -- the story that i want to share with you comes from 1955 , march 2 . it 's about a courageous 16-year-old girl , claudette colvin . and it comes full circle today because a week ago today , in san francisco , my middle school students , they performed a program that i had written , `` agents of change , '' starting with the reenactment of plessy v. ferguson from 1892 to 1896 , moving to brown v. board and a student-led strike by barbara rose johns , jumping to claudette colvin and the montgomery bus boycott and ending in 1960 with the sit-in movement , the non-violent movement led by students .

what happened to 16-year-old claudette colvin in march 1955 ?

in the mid-1970 ’ s , erno rubik invented the rubik ’ s cube . but that doesn ’ t mean knew how to solve it . it took him a few moths to figure it out . by the time the first world rubik ’ s cube championships were held in 1982 , the winner -- he could solve the cube in a little less than 23 seconds . and these days ? [ news montage of collin ’ s record ] this is world record holder collin burns , and today , we find out how he did it . [ titles ] “ it could last another day ; it could last another few years . the previous record lasted for just over 2 years . but with single solve , especially , you just need to get lucky . or at least that ’ s a big part of it. ” collin tends to downplay his skills but it ’ s worth noting there are two types of world records . the way speedcubing competitions work is that volunteers scramble the cubes according to instructions that are generated by a computer , so competitors all get the same scramble . they do 5 solves and their three middle scores are averaged . so collin holds the world record for a single solve . but the world record for an average score is held by a 19-year-old in australia . still , collin ’ s record is a huge deal . at the competition where we met up with him , kids were asking him for his autograph . he ’ s now being sponsored by a cube company and by a cube retailer , which are paying for him to travel internationally . and he wants people to know , you could do this too . “ the biggest misconception about cubing is that it ’ s difficult , which it really isn ’ t. ” pop culture treats the rubik ’ s cube like some sort of iq test , but it ’ s not . at least not anymore . “ generally average is much more impressive because you have to be consistently fast. ” still , collin ’ s record is a huge deal . at the competition where we met up with him , other kids were asking him for autographs . “ are you that famous cube guy ? ” i recently bought a cube online and it came with instructions for beginners . and if you memorize those , you can solve the cube in a couple minutes . it helps to understand the design of the puzzle . at first glance , it looks like a cube made out of cubes — right , three layers of nine . but if you look closer , you ’ ll see there aren ’ t actually any cubes here . so that tells you that the corners will always be corners , the edges will always be edges , and the middle pieces determine the color of that face . speedcubers will buy special cubes . they can lubricate them and adjust the tension . but the real key to their speed is efficiency - they ’ re looking several moves ahead , and they use fewer moves to get the same result . so there are 43 quintillion possible arrangements for the cube . a few years back , some researchers borrowed computing power from google to find out that any scramble can be solved in 20 moves or less . they call it god ’ s number . but humans just aren ’ t that good . the beginners ’ method that i learned uses 100 to 200 moves . speedcubers use more around 50 to 60 moves . and they can do that , in part , because of the knowledge gained by the previous generation of speedcubers . when the cube first spread around the world back in the 80s , people had to learn through trial and error . this was happening in a lot of math departments and campus clubs . people were discovering the cube at the same time , and they were sharing what they learned . the method collin uses was developed by jessica fridrich , an engineering professor who was a college student at the time . it starts with a cross on one of the faces . and that face becomes the bottom layer . then what they do is solve the corners of the bottom layer and the middle layer simultaneously . “ so , now you can see that all of this is solved. ” and for the final layer , they ’ re choosing from dozens of algorithms that they ’ ve memorized . and those are sequences of moves that mess up the cube temporarily to move certain pieces into place . and then put the rest of the cube back where it was . the rubik ’ s cube has made a comeback in recent years along with that same ethic of sharing tips and strategies . so all the resources you need are there , there ’ s just one other thing . practice ! this is collin nearly 5 years ago . world records are not built in a day .

so there are 43 quintillion possible arrangements for the cube . a few years back , some researchers borrowed computing power from google to find out that any scramble can be solved in 20 moves or less . they call it god ’ s number .

any scramble can be solved in ___ moves or less .

imagine you 're on a game show , and you can choose between two prizes : a diamond or a bottle of water . it 's an easy choice . the diamonds are clearly more valuable . now imagine being given the same choice again , only this time , you 're not on a game show , but dehydrated in the desert after wandering for days . do you choose differently ? why ? are n't diamonds still more valuable ? this is the paradox of value , famously described by pioneering economist adam smith . and what it tells us is that defining value is not as simple as it seems . on the game show , you were thinking about each item 's exchange value , what you could obtain for them at a later time , but in an emergency , like the desert scenario , what matters far more is their use value , how helpful they are in your current situation . and because we only get to choose one of the options , we also have to consider its opportunity cost , or what we lose by giving up the other choice . after all , it does n't matter how much you could get from selling the diamond if you never make it out of the desert . most modern economists deal with the paradox of value by attempting to unify these considerations under the concept of utility , how well something satisfies a person 's wants or needs . utility can apply to anything from the basic need for food to the pleasure of hearing a favorite song , and will naturally vary for different people and circumstances . a market economy provides us with an easy way to track utility . put simply , the utility something has to you is reflected by how much you 'd be willing to pay for it . now , imagine yourself back in the desert , only this time , you get offered a new diamond or a fresh bottle of water every five minutes . if you 're like most people , you 'll first choose enough water to last the trip , and then as many diamonds as you can carry . this is because of something called marginal utility , and it means that when you choose between diamonds and water , you compare utility obtained from every additional bottle of water to every additional diamond . and you do this each time an offer is made . the first bottle of water is worth more to you than any amount of diamonds , but eventually , you have all the water you need . after a while , every additional bottle becomes a burden . that 's when you begin to choose diamonds over water . and it 's not just necessities like water . when it comes to most things , the more of it you acquire , the less useful or enjoyable every additional bit becomes . this is the law of diminishing marginal utility . you might gladly buy two or three helpings of your favorite food , but the fourth would make you nauseated , and the hundredth would spoil before you could even get to it . or you could pay to see the same movie over and over until you got bored of it or spent all of your money . either way , you 'd eventually reach a point where the marginal utility for buying another movie ticket became zero . utility applies not just to buying things , but to all our decisions . and the intuitive way to maximize it and avoid diminishing returns is to vary the way we spend our time and resources . after our basic needs are met , we 'd theoretically decide to invest in choices only to the point they 're useful or enjoyable . of course , how effectively any of us manage to maximize utility in real life is another matter . but it helps to remember that the ultimate source of value comes from us , the needs we share , the things we enjoy , and the choices we make .

after a while , every additional bottle becomes a burden . that 's when you begin to choose diamonds over water . and it 's not just necessities like water .

who among the following economists wrote about the ‘ water and diamonds ’ paradox of value ?

translation - marie de hert in j.r.r . 's world , gandalf is one of five wizards sent by the valar to guide the inhabitants of middle earth in their struggles against the dark force of sauron . gandalf 's body was mortal , subject to the physical rules of middle earth , but his spirit was immortal , as seen when he died as gandalf the grey and resurrected as gandalf the white . according to the wachowski 's script , an awakened human only has to link up and hack the neon binary code of the matrix to learn how to fly a helicopter in a matter of seconds . or if you are the one , or one of the ones , you do n't even need a helicopter , you just need a cool pair of shades . cheshire cats can juggle their own heads . ipads are rudimentary . no quidditch match ends until the golden snitch is caught . and the answer to the ultimate question of life , the universe , and everything is most certainly 42 . just like real life , fictional worlds operate consistently within a spectrum of physical and societal rules . that 's what makes these intricate worlds believable , comprehensible , and worth exploring . in real life , the law of gravity holds seven book sets of `` harry potter '' to millions of bookshelves around the world . we know this to be true , but we also know that ever since j.k. typed the words wizard , wand , and `` wingardium leviosa , '' that law of gravity has ceased to exist on the trillions of pages resting between those bookends . authors of science fiction and fantasy literally build worlds . they make rules , maps , lineages , languages , cultures , universes , alternate universes within universes , and from those worlds sprout story , after story , after story . when it 's done well , readers can understand fictional worlds and their rules just as well as the characters that live in them do and sometimes , just as well or even better than the reader understands the world outside of the book . but how ? how can human-made squiggles on a page reflect lights into our eyes that send signals to our brains that we logically and emotionally decode as complex narratives that move us to fight , cry , sing , and think , that are strong enough not only to hold up a world that is completely invented by the author , but also to change the reader 's perspective on the real world that resumes only when the final squiggle is reached ? i 'm not sure anyone knows the answer to that question , yet fantastical , fictional worlds are created everyday in our minds , on computers , even on napkins at the restaurant down the street . the truth is your imagination and a willingness to , figuratively , live in your own world are all you need to get started writing a novel . i did n't dream up hogwarts or the star wars ' cantina , but i have written some science thrillers for kids and young adults . here are some questions and methods i 've used to help build the worlds in which those books take place . i start with a basic place and time . whether that 's a fantasy world or a futuristic setting in the real world , it 's important to know where you are and whether you 're working in the past , present , or future . i like to create a timeline showing how the world came to be . what past events have shaped the way it is now ? then i brainstorm answers to questions that draw out the details of my fictional world . what rules are in place here ? this covers everything from laws of gravity , or not , to the rules of society and the punishments for individuals who break them . what kind of government does this world have ? who has power , and who does n't ? what do people believe in here ? and what does this society value most ? then it 's time to think about day-to-day life . what 's the weather like in this world ? where do the inhabitants live and work and go to school ? what do they eat and how do they play ? how do they treat their young and their old ? what relationships do they have with the animals and plants of the world ? and what do those animals and plants look like ? what kind of technology exists ? transportation ? communication ? access to information ? there 's so much to think about ! so , spend some time living in those tasks and the answers to those questions , and you 're well on your way to building your own fictional world . once you know your world as well as you hope your reader will , set your characters free in it and see what happens . and ask yourself , `` how does this world you created shape the individuals who live in it ? and what kind of conflict is likely to emerge ? '' answer those questions , and you have your story . good luck , future world-builder !

and the answer to the ultimate question of life , the universe , and everything is most certainly 42 . just like real life , fictional worlds operate consistently within a spectrum of physical and societal rules . that 's what makes these intricate worlds believable , comprehensible , and worth exploring .

which of the following is true of fictional worlds ?

the biggest kidney stone on record weighed more than a kilogram and was 17 centimeters in diameter . the patient did n't actually swallow a stone the size of a coconut . kidney stones form inside the body , but unfortunately , they 're extremely painful to get out . a kidney stone is a hard mass of crystals that can form in the kidneys , ureters , bladder , or urethra . urine contains compounds that consist of calcium , sodium , potassium , oxalate , uric acid , and phosphate . if the levels of these particles get too high , or if urine becomes too acidic or basic , the particles can clump together and crystallize . unless the problem is addressed , the crystals will gradually grow over a few weeks , months , or even years , forming a detectable stone . calcium oxalate is the most common type of crystal to form this way , and accounts for about 80 % of kidney stones . less common kidney stones are made of calcium phosphate , or uric acid . a slightly different type of stone made of the minerals magnesium ammonium phosphate , or struvite , can be caused by bacterial infection . and even rarer stones can result from genetic disorders or certain medications . a kidney stone can go undetected until it starts to move . when a stone travels through the kidney and into the ureter , its sharp edges scratch the walls of the urinary tract . nerve endings embedded in this tissue transmit excruciating pain signals through the nervous system . and the scratches can send blood flowing into the urine . this can be accompanied by symptoms of nausea , vomiting , and a burning sensation while urinating . if a stone gets big enough to actually block the flow of urine , it can create an infection , or back flow , and damage the kidneys themselves . but most kidney stones do n't become this serious , or even require invasive treatment . masses less than five millimeters in diameter will usually pass out of the body on their own . a doctor will often simply recommend drinking large amounts of water to help speed the process along , and maybe taking some pain killers . if the stone is slightly larger , medications like alpha blockers can help by relaxing the muscles in the ureter and making it easier for the stone to get through . another medication called potassium citrate can help dissolve the stones by creating a less acidic urine . for medium-sized stones up to about ten millimeters , one option is pulverizing them with soundwaves . extracorporeal shock wave lithotripsy uses high-intensity pulses of focused ultrasonic energy aimed directly at the stone . the pulses create vibrations inside the stone itself and small bubbles jostle it . these combined forces crush the stone into smaller pieces that can pass out of the body more easily . but zapping a stone with sound does n't work as well if it 's simply too big . so sometimes , more invasive treatments are necessary . a rigid tube called a stent can be placed in the ureter to expand it . optical fibers can deliver laser pulses to break up the stone . stones can also be surgically removed through an incision in the patient 's back or groin . what about just avoiding kidney stones in the first place ? for people prone to them , their doctor may recommend drinking plenty of water , which dilutes the calcium oxalate and other compounds that eventually build up into painful stones . foods like potato chips , spinach , rhubarb , and beets are high in oxalate , so doctors might advise limiting them . even though calcium is often found in stones , calcium in foods and beverages can actually help by binding to oxalate in the digestive tract before it can be absorbed and reach the kidneys . if you do end up with a kidney stone , you 're not alone . data suggests that rates are rising , but that world record probably wo n't be broken any time soon .

stones can also be surgically removed through an incision in the patient 's back or groin . what about just avoiding kidney stones in the first place ? for people prone to them , their doctor may recommend drinking plenty of water , which dilutes the calcium oxalate and other compounds that eventually build up into painful stones .

list preventative measures a person can take to prevent the formation of kidney stones .

it 's easy to forget how vast and deep the ocean really is . about 60 % of it is actually a cold and dark region known as the deep ocean . and it reaches down to 11,000 meters . yet , this remote zone is also one of the greatest habitats on earth , harboring a huge diversity of life , from giant squids and goblin sharks to minuscule animals smaller than a millimeter . how do so many species thrive in this underwater world ? over the decades , intrepid scientists have ventured there to find out . traveling down through the water column , pressure increases and light begins to wane . at 200 meters , photosynthesis stops and temperature decreases from surface temperatures by up to 20 degrees celsius . by 1000 meters , normal sunlight has disappeared altogether . without light , life as we know it seems impossible . that 's why in 1844 , the naturalist edward forbes wrote his azoic theory , azoic , meaning without animals . forbes was sure that nothing could survive below 600 meters on account of the lack of light . of course , the discovery of deep-sea species proved him wrong . what forbes failed to take into account is something called marine snow , which sounds much nicer than it is . marine snow is basically organic matter , things like particles of dead algae , plants , and animals , drifting down into the depths and acting as food for deep-sea animals . largely thanks to that , abundant life forms exist in the darkness , adapting to a harsh reality where only the weird and wonderful can survive . fish with cavernous mouths , spiky teeth jutting from their jaws , and lamp-like structures protruding from their heads , like the anglerfish which entices prey with its misleading glow . several sea creatures have perfected this lightning technique known as bioluminescence , using it to lure prey , distract predators , or attract mates . some creatures use it for camoflauge . in parts of the water column where only faint blue light filters through , animals bioluminesce to match the glow . predators or prey looking up from below are deceived by this camoflauge , unable to see the creatures silhouette . such otherworldly adaptations also arise from the need to locate and snatch up food before it drifts away . some sea animals , like jellyfish , comb jellies and salps can migrate between depths partially because their 90 % water consistency allows them to withstand immense pressure . but they 're the exception . most deep-sea creatures are confined to a narrow range in the water column where nutrients are scarce since the food drifting downwards from the surface rapidly sinks to the sea floor . plunging all the way down , we find more exotic creatures . some take on dwarfism , a trait that transforms them into miniature versions of animals we see closer to the surface . it 's thought that reduced food availability causes the shrinkage . only a tiny fraction of the food produced at the surface reaches the sea floor , so being small gives animals a low energy requirement and an adaptive advantage . and yet , the sea is also the land of giants . here , gargantuan squids can reach 18 meters long . isopods scuttle around the sea floor like enormous wood lice . there are long-limbed japanese spider crabs , and oarfish , whose bodies stretch to 15 meters . this trait is known as gigantism , and it 's something of a mystery . it 's thought that high oxygen levels may drive extreme growth in some species , while the colder temperatures promote longer life spans , giving animals the opportunity to grow massive . many of these exotic sea beasts will never experience sunlight . some will venture up through the water column to feed , and a few will actually break the waves , reminding us at the surface about the incredible survival skills of the ocean 's deepest inhabitants . humans still have an astounding 95 % of the ocean left to explore . so those depths remain a great mystery . what other untold wonders lie far below , and which ones will we discover next ?

and it reaches down to 11,000 meters . yet , this remote zone is also one of the greatest habitats on earth , harboring a huge diversity of life , from giant squids and goblin sharks to minuscule animals smaller than a millimeter . how do so many species thrive in this underwater world ?

how big can a giant squid be ?

perfumers can learn to distinguish individual odors in a fragrance made of hundreds of scents . tea experts have been known to sniff out not just the location where a tea was from , but the season of harvest and whether it was planted by a plum tree . and the new york city transit authority once had an employee responsible only for sniffing out gas leaks in the subway system . can just anyone learn to smell with the sensitivity of those experts ? for most of us , what we smell is largely involuntary , whether it 's garbage behind a restaurant , the shampoo of the woman leaving an elevator as you enter , or a bakery 's fresh-made bread . with a few million olfactory receptors in our noses , we clearly do n't lack the ability to smell well . we just might not always pay close enough attention . that 's a shame because we may be missing opportunities to make strong emotional connections . smells are powerfully linked to emotions and can awaken memories of places we 've long ago left and people we 've loved . but fortunately , it is possible to train our brains to smell better . for example , helen keller was able to recognize a person 's work , and in her words , distinguish the carpenter from the iron worker , the artist from the mason or the chemist , by a simple inhale . follow these steps and you too can change the way the world smells to you . first , stick your nose in it . some animals that are known to be great smellers , like dogs who can sniff out explosives and pigs who can find truffles underground , put their noses right at the place they want to smell . human noses , meanwhile , are casting around in the middle of the air , giving us an anatomical disadvantage . so bring your nose close to the world around you . the ground , surfaces , objects , the food in your hand . get close to your dog , your partner , the book you 're reading . not only will your nose be closer to the odor source , but the warmth of your breath will make odors easier to smell . second , sniff like you mean it . smelling actually happens way up near the bridge of our noses in a postage stamp-sized square of tissue called the olfactory epithelium . when we sniff , odor molecules are sucked up into our nostrils until they hit this tissue where they combine to our olfactory , or scent , receptors . when we inhale normally , only a little air makes it there . but one or two solid sharp sniffs will ensure that more air gets to your smell receptors . after just a few more sniffs , the receptors , which are best at noticing new smells , turn off temporarily . so you can give your nose a rest and sniff again later . finally , dwell on the smell . most smells pass by us with little attention , but simply noticing what you 're smelling and by trying to describe it , name it , and locate its source , you can expand your vocabulary of smells . when an odor molecule binds to a scent receptor , it sends an electrical signal from the sensory neurons to our brain 's olfactory bulbs . the signal then continues to other areas of the brain , where it 's integrated with taste , memory , or emotional information before registering to us as a smell . fmri research shows that the extra time spent focusing on scent changes the brain of experienced smellers . for them , perceiving and imagining odors becomes more automatic than for non-experts . to get started yourself , take ingredients from your kitchen : spices , vanilla , or fruit , but never anything toxic . close your eyes and have someone bring them under your nose . sniff and try to name the source . over time , you 'll begin to appreciate nuances in familiar odors and recognize characteristics of new and unusual smells . the perfumer has practiced these steps enough to become an artist of odor , but even if you never pursue smelling to that degree , the spectacular result of an unspectacular action will change how you sense and experience your days .

not only will your nose be closer to the odor source , but the warmth of your breath will make odors easier to smell . second , sniff like you mean it . smelling actually happens way up near the bridge of our noses in a postage stamp-sized square of tissue called the olfactory epithelium .

why should you give a good , long sniff to something you would like to smell ?

take a moment to read the following . how was that ? frustrating ? slow ? what were those sentences about ? they 're actually a simulation of the experience of dyslexia , designed to make you decode each word . those with dyslexia experience that laborious pace every time they read . when most people think of dyslexia , they think of seeing letters and words backwards , like seeing `` b '' as `` d '' and vice versa , or they might think people with dyslexia see `` saw '' as `` was '' . the truth is people with dyslexia see things the same way as everyone else . dyslexia is caused by a phonological processing problem , meaning people affected by it have trouble not with seeing language but with manipulating it . for example , if you heard the word cat and then someone asked you , `` remove the 'c ' , '' what word would you have left ? at . this can be difficult for those with dyslexia . given a word in isolation , like fantastic , students with dyslexia need to break the word into parts to read it : fan , tas , tic . time spent decoding makes it hard to keep up with peers and gain sufficient comprehension . spelling words phonetically , like s-t-i-k for stick and f-r-e-n-s for friends is also common . these difficulties are more widespread and varied than commonly imagined . dyslexia affects up to one in five people . it occurs on a continuum . one person might have mild dyslexia while the next person has a profound case of it . dyslexia also runs in families . it 's common to see one family member who has trouble spelling while another family member has severe difficulty decoding even one syllable words , like catch . the continuum and distribution of dyslexia suggests a broader principle to bear in mind as we look at how the brains of those with dyslexia process language . neurodiversity is the idea that because all our brains show differences in structure and function , we should n't be so quick to label every deviation from `` the norm '' as a pathological disorder or dismiss people living with these variations as `` defective . '' people with neurobiological variations like dyslexia , including such creative and inventive individuals as picasso , muhammad ali , whoopi goldberg , steven spielberg , and cher , clearly have every capacity to be brilliant and successful in life . so , here 's the special way the brains of those with dyslexia work . the brain is divided into two hemispheres . the left hemisphere is generally in charge of language and , ultimately , reading , while the right typically handles spatial activities . fmri studies have found that the brains of those with dyslexia rely more on the right hemisphere and frontal lobe than the brains of those without it . this means , when they read a word , it takes a longer trip through their brain and can get delayed in the frontal lobe . because of this neurobiological glitch , they read with more difficulty . but those with dyslexia can physically change their brain and improve their reading with an intensive , multi-sensory intervention that breaks the language down and teaches the reader to decode based on syllable types and spelling rules . the brains of those with dyslexia begin using the left hemisphere more efficiently while reading , and their reading improves . the intervention works because it locates dyslexia appropriately as a functional variation in the brain , which , naturally , shows all sorts of variations from one person to another . neurodiversity emphasizes this spectrum of brain function in all humans and suggests that to better understand the perspectives of those around us , we should try not only to see the world through their eyes but understand it through their brains .

they 're actually a simulation of the experience of dyslexia , designed to make you decode each word . those with dyslexia experience that laborious pace every time they read . when most people think of dyslexia , they think of seeing letters and words backwards , like seeing `` b '' as `` d '' and vice versa , or they might think people with dyslexia see `` saw '' as `` was '' . the truth is people with dyslexia see things the same way as everyone else .

describe why you think a structured , multisensory , explicit intervention would be the most successful intervention for students with dyslexia ?

commas are tricky things , especially when subordinates and conjunctions are involved . if you can remember a few basic rules , a simple law of physics , and some common scenarios , you will be able to use commas correctly . i like to think of the different parts of our sentence as characters . let 's meet a few of them : the tiny conjunctions , the mighty subordinates , and the clever comma . conjunctions are small and nimble . they are words that connect clauses , words , and phrases . you can easily remember the conjunctions by remembering the acronym fanboys . the conjunctions are for , and , nor , but , or , yet , so . because they 're so small , more often than not , they require the help of a comma but not always . subordinates , on the other hand , are the wwe heavyweight champions of sentences . they are words that connect two unequal things , dependent and independent clauses . subordinates make it very clear what is being prioritized in a sentence . commonly used subordinates are although , because , before , however , unless , and even though . because subordinates are all about power , they can do a lot of heavy lifting by themselves . but , of course , sometimes even the strongest among us needs some help from our clever friends . because our clever comma is so nice , she often roams her neighborhood looking for some community service to do . today , as soon as she leaves her house , she sees a subordinate lifting the weight of two complete sentences , one on each arm . bartheleme loves engaging in political debate even though he usually loses . the comma asks the subordinate if he needs help . well , we know that subordinates are the wwe heavyweight champions of sentences . they can easily hold the weight of these two complete sentences because they are distributed evenly on both arms . so , when the comma asks if it can help , the subordinate is appalled at the idea of needing assistance . no thanks , maybe next time ! so , the comma continues on . soon , she seems a couple of subordinates attempting to lift the weight of sentences directly in front of themselves . even though bartheleme loves to sing , he never sings in front of others . the comma asks the subordinates if they need help . they might not want to admit it , but this time the subordinates do need help . complete sentences weigh quite a bit . simple physics tells us that it 's easier to balance heavy objects if the weight is evenly distributed . so , while the subordinates are quite capable of balancing two complete sentences when carrying the weight on both sides , they 're having trouble picking just one up . the comma rushes over to help the struggling subordinates , but how will she help ? when subordinates begin sentences , the comma will place herself directly after the first thought or complete sentence . after helping the subordinates , our comma heroine continues on and spots a conjunction holding the weight of two complete sentences . bartheleme was accepted into the university of chicago , and he is on the waitlist for stanford university . the comma asks the conjunction if he needs help . of course he does ! hurry ! the comma rushes and places itself before the conjunction . fanboys are n't as militant as subordinates . for this reason , the commas do n't have to fall in line behind the fanboys . fanboys are courteous creatures . they allow the comma to go ahead of them . helping others is hard work ! on her way home , our comma sees a conjunction holding up the weight of a complete sentence and a fragment sentence . bartheleme is going to major in molecular biology or interpretive dance . the now-exhausted comma asks the conjunction if he needs help lifting the items . this is one of the rare occassions where a conjunction does n't need the help of a comma . the conjunction assures the comma that help is n't needed , which is good for the comma because by now , all it wants to do is go home and rest up for another day of vigilant sentence constructing .

commas are tricky things , especially when subordinates and conjunctions are involved . if you can remember a few basic rules , a simple law of physics , and some common scenarios , you will be able to use commas correctly . i like to think of the different parts of our sentence as characters .

english is a difficult language to learn . the rules regarding the written word are vast . at times , the rules can be confusing . what value should be placed on punctuation ? should a person be judged by his or her ability ( or lack thereof ) to use commas correctly ? are there some professions where punctuation is more important ? would you hire someone who wasn ’ t a strong writer ?

where did russia come from , why is it so big , and what are the differences between it and its neighbors ? the answers lie in an epic story of seafaring warriors , nomadic invaders , and the rise and fall of a medieval state known as kievan rus . in the first millennium , a large group of tribes spread through the dense woodlands of eastern europe . because they had no writing system , much of what we know about them comes from three main sources : archaeological evidence , accounts from literate scholars of the roman empire and the middle east , and , lastly , an epic history called the primary chronicle compiled in the 12th century by a monk named nestor . what they tell us is that these tribes who shared a common slavic language and polytheistic religion had by the 7th century split into western , southern and eastern branches , the latter stretching from the dniester river to the volga and the baltic sea . as nestor 's story goes , after years of subjugation by vikings from the north , who , by the way , did not wear horned helmets in battle , the region 's tribes revolted and drove back the northmen , but left to their own devices , they turned on each other . such chaos ensued that , ironically , the tribes reached out to the foreigners they had just expelled , inviting them to return and establish order . the vikings accepted , sending a prince named rurik and his two brothers to rule . with rurik 's son , oleg , expanding his realm into the south , and moving the capitol to kiev , a former outpost of the khazar empire , the kievan rus was born , `` rus '' most likely deriving from an old norse word for `` the men who row . '' the new princedom had complex relations with its neighbors , alternating between alliance and warfare with the khazar and byzantine empires , as well as neighboring tribes . religion played an important role in politics , and as the legend goes , in 987 , the rus prince vladamir i decided it was time to abandon slavic paganism , and sent emissaries to explore neighboring faiths . put off by islam 's prohibition on alcohol and judaism 's expulsion from its holy land , the ruler settled on orthodox christianity after hearing odd accounts of its ceremonies . with vladimir 's conversion and marriage to the byzantine emperor 's sister , as well as continued trade along the volga route , the relationship between the two civilizations deepened . byzantine missionaries created an alphabet for slavic languages based on a modified greek script while rus viking warriors served as the byzantine emperor 's elite guard . for several generations , the kievan rus flourished from its rich resources and trade . its noblemen and noblewomen married prominent european rulers , while residents of some cities enjoyed great culture , literacy , and even democratic freedoms uncommon for the time . but nothing lasts forever . fratricidal disputes over succession began to erode central power as increasingly independent cities ruled by rival princes vied for control . the fourth crusade and decline of constantinople devastated the trade integral to rus wealth and power , while teutonic crusaders threatened northern territories . the final blow , however , would come from the east . consumed by their squabbles , rus princes paid little attention to the rumors of a mysterious unstoppable hoard until 1237 , when 35,000 mounted archers led by batu khan swept through the rus cities , sacking kiev before continuing on to hungary and poland . the age of kievan rus had come to an end , its people now divided . in the east , which remained under mongol rule , a remote trading post , known as moscow , would grow to challenge the power of the khans , conquering parts of their fragmenting empire , and , in many ways , succeeding it . as it absorbed other eastern rus territories , it reclaimed the old name in its greek form , ruscia . meanwhile , the western regions whose leaders had avoided destruction through political maneuvering until the hoard withdrew came under the influence of poland and lithuania . for the next few centuries , the former lands of kievan rus populated by slavs , ruled by vikings , taught by greeks , and split by mongols would develop differences in society , culture and language that remain to the present day .

byzantine missionaries created an alphabet for slavic languages based on a modified greek script while rus viking warriors served as the byzantine emperor 's elite guard . for several generations , the kievan rus flourished from its rich resources and trade . its noblemen and noblewomen married prominent european rulers , while residents of some cities enjoyed great culture , literacy , and even democratic freedoms uncommon for the time .

which of the following was not a major contributor to the decline of kievan rus ?

between the first europeans arriving in 1492 and the victorian age , the indigenous population of the new world dropped by at least 90 % . the cause ? not the conquistadors and company -- they killed lots of people but their death count is nothing compared to what they brought with them : small pox , typhus , tuberculosis , influenza , bubonic plague , cholera , mumps , measles and more leapt from those first explorers to the costal tribes , then onward the microscopic invaders spread through a hemisphere of people with no defenses against them . tens of millions died . these germs decided the fate of these battles long before the fighting started . now ask yourself : why did n't the europeans get sick ? if new-worlders were vulnerable to old-world diseases , then surely old-worlders would be vulnerable to new world diseases . yet , there was no americapox spreading eastward infecting europe and cutting the population from 90 million to 9 . had americapox existed it would have rather dampened european ability for transatlantic expansion . to answer why this did n't happen : we need first to distinguish regular diseases -- like the common cold -- from what we 'll call plagues . 1 . spread quickly between people . sneezes spread plagues faster than handshakes which are faster than closeness . plagues use more of this than this . 2 . they kill you quickly or you become immune . catch a plague and you 're dead within seven to thirty days ; survive and you 'll never get it again . your body has learned to fight it . you might still carry it -- the plague lives in you , you can still spread it -- but it ca n't hurt you . the surface answer to this question is n't that europeans had better immune systems to fight off new world plagues -- it 's that the new world did n't have plagues for them to catch . they had regular diseases but there was no americapox to carry . these are history 's biggest killers , and they all come from the old world . but why ? let 's dig deeper , and talk cholera : a plague that spreads if your civilization does a bad job of separating drinking water from pooping water . london was terrible at this , making it the cholera capital of the world . cholera can rip through dense neighborhoods , killing swaths of the population before moving onward . but that 's the key : it has to move on . in a small , isolated group , a plague like cholera can not survive -- it kills all available victims , leaving only the immune and then theres nowhere to go -- it 's a fire that burns through its fuel . but a city -- shining city on the hill -- to which rural migrants flock , where hundreds of babies are born a day : this is sanctuary for the fire of plague ; fresh kindling comes to it . the plague flares and smolders and flares and smolders again -- impossible to extinguish . historically , in city borders , plagues killed faster than people could breed . cities grew because more people moved to them than died inside of them . cities only started growing from their own population in the 1900s when medicine finally left its leaches and bloodletting phase and entered its soap and soup phase , giving humans some tools to slow death . but before that a city was an unintentional playground for plagues and a grim machine to sort the immune from the rest . so the deeper answer is that the new world did n't have plagues because the new world did n't have big , dense , terribly sanitized deeply interconnected cities for plagues to thrive . ok , but the new world was n't completely barren of cities , and tribes were n't completely isolated . otherwise the newly-arrived smallpox in the 1400s could n't have spread . cities are only part of the puzzle : they 're required for plagues , but cities do n't make the germs that start the plagues -- those germs come from the missing piece . now , most germs do n't want to kill you , for the same reason you do n't want to burn down your house ; germs live in you . chronic diseases like leprosy are terrible because they 're very good at living in you and not killing you . plague lethality is an accident , a misunderstanding , because the germs that cause them do n't know they 're in humans ; they think they 're in this . plagues come from animals . whooping cough comes from pigs , as does flu , as well as from birds . our friend the cow alone is responsible for measles , tuberculosis , and smallpox . for the cow these diseases are no big deal -- like colds for us . but when cow germs get in humans , the things they do to make a cow a little sick to spread make humans very sick . deadly sick . now , germs jumping species like this is extraordinarily rare . that 's why generations of humans can spend time around animals just fine . being the patient zero of a new animal-to-human plague is winning a terrible lottery . but a colonial-age city raises the odds : there used to be animals everywhere ; horses , herds of livestock in the streets , open slaughterhouses , meat markets pre-refrigeration , and rivers of human and animal excrement running through it all . a more perfect environment for diseases to jump species could hardly be imagined . so the deeper answer is that plagues come from animals , but so rarely that you have to raise the odds with many chances for infection and even then the new-born plague needs a fertile environment to grow . the old world had the necessary pieces in abundance . but why was a city like london filled with sheep and pigs and cows and tenochtitlan was n't ? this brings us to the final level , for this video anyway . some animals can be put to human use -- this is what domestication means : animals you can breed , not just hunt . forget for a the moment the modern world : go back to 10,000bc when tribes of humans reached just about everywhere . if you were in one of these tribes , what local animals could you capture , alive , and successfully pen to breed ? maybe you 're in north dakota and thinking about catching a buffalo : an unpredictable , violent tank on hooves , that can outrun you across the planes , leap over your head and travels in herds thousands strong . oh , and you have no horses to help you -- because there are no horses on the continent . horses live here -- and wo n't be brought over until too late . it 's just you , a couple buddies , and stone-based tools . american indians did n't fail to domesticate buffalo because they could n't figure it out . they failed because it 's a buffalo . no one could do it -- buffalo would have been amazing creatures to put to human work back in bc , but it 's not going to happen -- humans have only barely domesticated buffalo with all our modern tools . the new world did n't have good animal candidates for domestication . almost everything big enough to be useful is also too dangerous , or too agile . meanwhile the fertile crescent to central europe had cows and pigs and sheep and goats : easy-peasy animals comparatively begging to be domesticated . a wild boar is something to contend with if you only have stone tools but it 's possible to catch and pen and breed and feed to eat -- because pigs ca n't leap to the sky or crush all resistance beneath their hooves . in the new world the only native domestication contestant was : llamas . they 're better than nothing -- which is probably why the biggest cities existed in south america -- but they 're no cow . ever try to manage a heard of llamas in the mountains of peru ? yeah , you can do it , but it 's not fun . nothing but drama , these llamas . these might seem , cherry-picked examples , because are n't there hundreds of thousands of species of animals ? yes , but when you 're stuck at the bottom of the tech tree , almost none of them can be domesticated . from the dawn of man until this fateful meeting , humans domesticated ; maybe a baker 's dozen of unique species the world over . and even to get that high a number you need to stretch it to include honeybees and silkworms ; nice to have , but you ca n't build a civilization on a foundation of honey alone . these early tribes were n't smarter , or better at domestication . the old world had more valuable and easy animals . with dogs , herding sheep and cattle is easier . now humans have a buddy to keep an eye on the clothing factory , and the milk and cheeseburger machine , and the plow-puller . now farming is easier , which means there 's more benefit to staying put , which means more domestication , which means more food which means more people and more density and oh look where we 're going . citiesville : population : lots ; bring your animals ; plagues welcome . that is the full answer : the lack of new world animals to domesticate limited not only exposure to germs sources but also limited food production , which limited population growth , which limited cities , which made plagues in the new world an almost impossibility . in the old [ world ] , exactly the reverse , and thus a continent full of plague and a continent devoid of it . so when ships landed in the new world , there was no americapox to bring back . the game of civilization has nothing to do with the players , and everything to do with the map . access to domesticated animals in numbers and diversity is the key resource to bootstrapping a complex society from nothing -- and that complexity brings with it , unintentionally , a passive biological weaponry devastating to outsiders . start the game again but move the domesticable animals across the sea and history 's arrow of disease and death flows in the opposite direction . this still does leave one last question . just why are some animals domesticable and others not ? why could n't american indians domesticate deer ? why ca n't zebras be domesticated ? they look just like horses . and what does it mean to tame an animal ? to answer that , click here for part 2 . this video has been brought to you by audible.com and was a presentation of diamond 's theory as laid out in his book gun , germs and steel . if you found this video interesting you should go right now to audible.com/grey and get a copy of the book . there is so much more in this than could ever been explained in a short video -- guns , germs and steel is the history book to rule all history books . audible has over 180,000 things for you to listen to . it is an endless source of interestingness . so once again , please to go audible.com/grey get a 30-day free trial and let them know that you came from this channel . audiobooks are a big part of my life and i think they should be a big part of your life . why not get started today ?

plague lethality is an accident , a misunderstanding , because the germs that cause them do n't know they 're in humans ; they think they 're in this . plagues come from animals . whooping cough comes from pigs , as does flu , as well as from birds .

plagues come from animals but so rarely that in order for a plague to be created , the odds of infection have to be heightened . what can raise the odds of infection ?

many elements of traditional japanese culture , such as cuisine and martial arts , are well-known throughout the world . kabuki , a form of classical theater performance , may not be as well understood in the west but has evolved over 400 years to still maintain influence and popularity to this day . the word kabuki is derived from the japanese verb kabuku , meaning out of the ordinary or bizarre . its history began in early 17th century kyoto , where a shrine maiden named izumo no okuni would use the city 's dry kamo riverbed as a stage to perform unusual dances for passerby , who found her daring parodies of buddhist prayers both entertaining and mesmerizing . soon other troops began performing in the same style , and kabuki made history as japan 's first dramatic performance form catering to the common people . by relying on makeup , or keshou , and facial expressions instead of masks and focusing on historical events and everyday life rather than folk tales , kabuki set itself apart from the upper-class dance theater form known as noh and provided a unique commentary on society during the edo period . at first , the dance was practiced only by females and commonly referred to as onna-kabuki . it soon evolved to an ensemble performance and became a regular attraction at tea houses , drawing audiences from all social classes . at this point , onna-kabuki was often risque as geishas performed not only to show off their singing and dancing abilities but also to advertise their bodies to potential clients . a ban by the conservative tokugawa shogunate in 1629 led to the emergence of wakashu-kabuki with young boys as actors . but when this was also banned for similar reasons , there was a transition to yaro-kabuki , performed by men , necessitating elaborate costumes and makeup for those playing female roles , or onnagata . attempts by the government to control kabuki did n't end with bans on the gender or age of performers . the tokugawa military group , or bakufu , was fueled by confucian ideals and often enacted sanctions on costume fabrics , stage weaponry , and the subject matter of the plot . at the same time , kabuki became closely associated with and influenced by bunraku , an elaborate form of puppet theater . due to these influences , the once spontaneous , one-act dance evolved into a structured , five-act play often based on the tenets of confucian philosophy . before 1868 , when the tokugawa shogunate fell and emperor meiji was restored to power , japan had practiced isolation from other countries , or sakoku . and thus , the development of kabuki had mostly been shaped by domestic influences . but even before this period , european artists , such as claude monet , had become interested in and inspired by japanese art , such as woodblock prints , as well as live performance . after 1868 , others such as vincent van gogh and composer claude debussy began to incorporate kabuki influences in their work , while kabuki itself underwent much change and experimentation to adapt to the new modern era . like other traditional art forms , kabuki suffered in popularity in the wake of world war ii . but innovation by artists such as director tetsuji takechi led to a resurgence shortly after . indeed , kabuki was even considered a popular form of entertainment amongst american troops stationed in japan despite initial u.s. censorship of japanese traditions . today , kabuki still lives on as an integral part of japan 's rich cultural heritage , extending its influence beyond the stage to television , film , and anime . the art form pioneered by okuni continues to delight audiences with the actors ' elaborate makeup , extravagant and delicately embroidered costumes , and the unmistakable melodrama of the stories told on stage .

the tokugawa military group , or bakufu , was fueled by confucian ideals and often enacted sanctions on costume fabrics , stage weaponry , and the subject matter of the plot . at the same time , kabuki became closely associated with and influenced by bunraku , an elaborate form of puppet theater . due to these influences , the once spontaneous , one-act dance evolved into a structured , five-act play often based on the tenets of confucian philosophy . before 1868 , when the tokugawa shogunate fell and emperor meiji was restored to power , japan had practiced isolation from other countries , or sakoku .

due to the influence of the tokugawa military and bunraku , kabuki soon evolved into a structured _______ play .

so praseodymium is a very interesting element . it ’ s got a myriad of uses but perhaps the most interesting one is that it has been used to enable us to get within 1/1000th of a degree of absolute zero , which is minus 273 degrees c , which is pretty darn cold . it was just used in the components which they were using in the coils to get the temperature down . it ’ s also used in welder ’ s goggles because it ’ s quite good at filtering out harmful types of light to the human eye , so you find it ’ s in the goggle and it helps the welder be able to see what he ’ s doing . it ’ s also been used in a silicate which is being used to lower the speed of light down to a mere 300 metres per second , which is still pretty fast but not very fast compared to the normal speed of light .

it ’ s also used in welder ’ s goggles because it ’ s quite good at filtering out harmful types of light to the human eye , so you find it ’ s in the goggle and it helps the welder be able to see what he ’ s doing . it ’ s also been used in a silicate which is being used to lower the speed of light down to a mere 300 metres per second , which is still pretty fast but not very fast compared to the normal speed of light .

stephen said that praseodymium has also been used as a silicate to lower the speed of light down to a mere 300 m/s . but what is the approximate speed of light in a vacuum ?

when you think of natural history museums , you probably picture exhibits filled with ancient lifeless things , like dinosaurs meteroites , and gemstones . but behind that educational exterior , which only includes about 1 % of a museum 's collection , there are hidden laboratories where scientific breakthroughs are made . beyond the unmarked doors , and on the floors the elevators wo n't take you to , you 'd find windows into amazing worlds . this maze of halls and laboratories is a scientific sanctuary that houses a seemingly endless variety of specimens . here , researchers work to unravel mysteries of evolution , cosmic origins , and the history of our planet . one museum alone may have millions of specimens . the american museum of natural history in new york city has over 32,000,000 in its collection . let 's take a look at just one of them . scientists have logged exactly where and when it was found and used various dating techniques to pinpoint when it originated . repeat that a million times over , and these plants , animals , minerals , fossils , and artifacts present windows into times and places around the world and across billions of years of history . when a research problem emerges , scientists peer through these windows and test hypotheses about the past . for example , in the 1950s , populations of predatory birds , like peregrine falcons , owls , and eagles started to mysteriously crash , to the point where a number of species , including the bald eagle , were declared endangered . fortunately , scientists in the field museum in chicago had been collecting the eggs of these predatory birds for decades . they discovered that the egg shells used to be thicker and had started to thin around the time when an insecticide called ddt started being sprayed on crops . ddt worked very well to kill insects , but when birds came and ate those heaps of dead bugs , the ddt accumulated in their bodies . it worked its way up the food chain and was absorbed by apex predator birds in such high concentrations that it thinned their eggs so that they could n't support the nesting bird 's weight . there were omelettes everywhere until scientists from the field museum in chicago , and other institutions , helped solve the mystery and save the day . america thanks you , field museum . natural history museums windows into the past have solved many other scientific mysteries . museum scientists have used their collections to sequence the neanderthal genome , discover genes that gave mammoths red fur , and even pinpoint where ancient giant sharks gave birth . there are about 900 natural history museums in the world , and every year they make new discoveries and insights into the earth 's past , present and future . museum collections even help us understand how modern threats , such as global climate change , are impacting our world . for instance , naturalists have been collecting samples for over 100 years from walden pond , famously immortalized by henry david thoreau . thanks to those naturalists , who count thoreau among their number , we know that the plants around walden pond are blooming over three weeks earlier than they did 150 years ago . because these changes have taken place gradually , one person may not have noticed them over the span of a few decades , but thanks to museum collections , we have an uninterrupted record showing how our world is changing . so the next time you 're exploring a natural history museum , remember that what you 're seeing is just one gem of a colossal scientific treasure trove . behind those walls and under your feet are windows into forgotten worlds . and who knows ? one day some future scientist may peer through one and see you .

there are about 900 natural history museums in the world , and every year they make new discoveries and insights into the earth 's past , present and future . museum collections even help us understand how modern threats , such as global climate change , are impacting our world . for instance , naturalists have been collecting samples for over 100 years from walden pond , famously immortalized by henry david thoreau .

why would it be useful for a museum to have multiple examples of the same species in its collections ?

in 19 b.c. , the roman poet virgil was traveling from greece to rome with the emperor augustus . on the way , he stopped to go sightseeing in megara , a town in greece . out in the sun for too long , he suffered heatstroke and died on his journey back to italy . on his deathbed , virgil thought about the manuscript he had been working on for over ten years , an epic poem that he called the `` aeneid . '' unsatisfied with the final edit , he asked his friends to burn it , but they refused , and soon after virgil 's death , augustus ordered it to be published . why was augustus so interested in saving virgil 's poem ? the romans had little tradition of writing serious literature and virgil wanted to create a poem to rival the `` iliad '' and `` odyssey '' of ancient greece . the `` aeneid , '' a 9,896 line poem , spans twelve separate sections , or books , the first six of which mirror the structure of the `` odyssey '' and the last six echo the `` iliad . '' also like the greek epics , the `` aeneid '' is written entirely in dactylic hexameter . in this meter , each line has six syllable groups called feet made up of dactyls which go long , short , short , and spondees which go long , long . so the famous opening line in the original latin starts , `` arma virvmqve cano , '' which can be translated as `` i sing of arms and the man , '' arms , meaning battles and warfare , another `` iliad '' reference , and the man being the hero aeneas . to understand the `` aeneid , '' it 's necessary to examine the unsettled nature of roman politics in the second half of the 1st century b.c . in 49 b.c. , julius caesar , augustus 's great uncle , triggered nearly 20 years of civil war when he led his army against the roman republic . after introducing a dictatorship , he was assassinated . only after augustus 's victory over marc antony and cleopatra in 31 b.c . did peace return to rome and augustus became the emperor . virgil aimed to capture this sense of a new era and of the great sacrifices that the romans had endured . he wanted to give the romans a fresh sense of their origins , their past , and their potential . by connecting the founding of rome to the mythological stories that his audience knew so well , virgil was able to link his hero aeneas to the character of augustus . in the epic poem , aeneas is on a quest to establish a new home for his people . this duty , or pietas as the romans called it , faces all kinds of obstacles . aeneas risks destruction in the ruins of troy , agonizes over love when he meets the beautiful queen of carthage , dido , and in one of the most vivid passages in all of ancient literature , has to pass through the underworld . on top of all that , he must then fight to win a homeland for his people around the future sight of rome . virgil presents aeneas as a sort of model for augustus , and that 's probably one of the reasons the emperor was so eager to save the poem from destruction . but virgil did n't stop there . in some sections , aeneas even has visions of rome 's future and of augustus himself . virgil presents augustus as a victor , entering rome in triumph and shows him expanding the roman empire . perhaps most importantly , he 's hailed as only the third roman leader in 700 years to shut the doors of the temple of janus signifying the arrival of permanent peace . but there 's a twist . virgil only read augustus three selected extracts of the story and that was augustus 's entire exposure to it . some of the other sections could be seen as critical , if not subtly subversive about the emperor 's achievements . aeneas , again a model for augustus , struggles with his duty and often seems a reluctant hero . he does n't always live up to the behavior expected of a good roman leader . he struggles to balance mercy and justice . by the end , the reader is left wondering about the future of rome and the new government of augustus . perhaps in wanting the story published , augustus had been fooled by his own desire for self-promotion . as a result , virgil 's story has survived to ask questions about the nature of power and authority ever since .

unsatisfied with the final edit , he asked his friends to burn it , but they refused , and soon after virgil 's death , augustus ordered it to be published . why was augustus so interested in saving virgil 's poem ? the romans had little tradition of writing serious literature and virgil wanted to create a poem to rival the `` iliad '' and `` odyssey '' of ancient greece . the `` aeneid , '' a 9,896 line poem , spans twelve separate sections , or books , the first six of which mirror the structure of the `` odyssey '' and the last six echo the `` iliad . ''

which ancient country ’ s literature inspired virgil ’ s writing ?

beneath your ribs , you 'll find , among other things , the pancreas , an organ that works a lot like a personal health coach . this organ controls your sugar levels and produces a special juice that releases the nutrients from your food to help keep you in the best possible shape . the pancreas sits just behind your stomach , an appropriate home , as one of its jobs is to break down the food you eat . it aids digestion by producing a special tonic made of water , sodium bicarbonate , and digestive enzymes . sodium bicarbonate neutralizes the stomach 's natural acidity , so these digestive enzymes can perform their jobs . lipase breaks down fatty substances , protease splits up proteins , and amylase divides carbohydrates to create energy-rich sugars . most of those nutrients then get absorbed into the blood stream , and go on to enrich the body . while all this is happening , the pancreas works on another critical task , controlling the amount of sugar in your blood . it achieves this with the hormones insulin and glucagon , which are produced in special cells called the islets of langerhans . having too much or too little sugar can be life threatening , so the pancreas must stay on constant alert . after a big meal , the blood often becomes flushed with sugar . to bring us back to normal , the pancreas releases insulin , which makes the excess sugar move into cells , where it 's either used as an energy source , or stored for later . insulin also tells the liver to shut down sugar production . on the other hand , if blood sugar is low , the pancreas releases a hormone called glucagon that tells the body 's cells and liver to release stored sugars back into the bloodstream . the interplay between insulin and glucagon is what keeps our sugar levels balanced . but a faulty pancreas can no longer coach us like this , meaning that this healthy balance is destroyed . if it 's weakened by disease , the organ 's ability to produce insulin may be reduced , or even extinguished , which can trigger the condition known as diabetes . without regular insulin release , sugar steadily builds up in the blood , eventually hardening the blood vessels and causing heart attacks , kidney failure , and strokes . the same lack of insulin deprives cells of the energy-rich sugar they need to grow and function . people with diabetes also tend to have higher levels of glucagon , which makes even more sugar circulate . without this internal health coach , our sugar levels would go haywire , and we would n't be able to digest important nutrients . but like any coach , it 's not the pancreas ' job alone to keep us healthy . it needs our conscious participation , too .

the same lack of insulin deprives cells of the energy-rich sugar they need to grow and function . people with diabetes also tend to have higher levels of glucagon , which makes even more sugar circulate . without this internal health coach , our sugar levels would go haywire , and we would n't be able to digest important nutrients .

what are the disadvantages caused by having diabetes ?

it 's 4 a.m. , and the big test is in eight hours , followed by a piano recital . you 've been studying and playing for days , but you still do n't feel ready for either . so , what can you do ? well , you can drink another cup of coffee and spend the next few hours cramming and practicing , but believe it or not , you might be better off closing the books , putting away the music , and going to sleep . sleep occupies nearly a third of our lives , but many of us give surprisingly little attention and care to it . this neglect is often the result of a major misunderstanding . sleep is n't lost time , or just a way to rest when all our important work is done . instead , it 's a critical function , during which your body balances and regulates its vital systems , affecting respiration and regulating everything from circulation to growth and immune response . that 's great , but you can worry about all those things after this test , right ? well , not so fast . it turns out that sleep is also crucial for your brain , with a fifth of your body 's circulatory blood being channeled to it as you drift off . and what goes on in your brain while you sleep is an intensely active period of restructuring that 's crucial for how our memory works . at first glance , our ability to remember things does n't seem very impressive at all . 19th century psychologist herman ebbinghaus demonstrated that we normally forget 40 % of new material within the first twenty minutes , a phenomenon known as the forgetting curve . but this loss can be prevented through memory consolidation , the process by which information is moved from our fleeting short-term memory to our more durable long-term memory . this consolidation occurs with the help of a major part of the brain , known as the hippocampus . its role in long-term memory formation was demonstrated in the 1950s by brenda milner in her research with a patient known as h.m. after having his hippocampus removed , h.m. 's ability to form new short-term memories was damaged , but he was able to learn physical tasks through repetition . due to the removal of his hippocampus , h.m. 's ability to form long-term memories was also damaged . what this case revealed , among other things , was that the hippocampus was specifically involved in the consolidation of long-term declarative memory , such as the facts and concepts you need to remember for that test , rather than procedural memory , such as the finger movements you need to master for that recital . milner 's findings , along with work by eric kandel in the 90 's , have given us our current model of how this consolidation process works . sensory data is initially transcribed and temporarily recorded in the neurons as short-term memory . from there , it travels to the hippocampus , which strengthens and enhances the neurons in that cortical area . thanks to the phenomenon of neuroplasticity , new synaptic buds are formed , allowing new connections between neurons , and strengthening the neural network where the information will be returned as long-term memory . so why do we remember some things and not others ? well , there are a few ways to influence the extent and effectiveness of memory retention . for example , memories that are formed in times of heightened feeling , or even stress , will be better recorded due to the hippocampus ' link with emotion . but one of the major factors contributing to memory consolidation is , you guessed it , a good night 's sleep . sleep is composed of four stages , the deepest of which are known as slow-wave sleep and rapid eye movement . eeg machines monitoring people during these stages have shown electrical impulses moving between the brainstem , hippocampus , thalamus , and cortex , which serve as relay stations of memory formation . and the different stages of sleep have been shown to help consolidate different types of memories . during the non-rem slow-wave sleep , declarative memory is encoded into a temporary store in the anterior part of the hippocampus . through a continuing dialogue between the cortex and hippocampus , it is then repeatedly reactivated , driving its gradual redistribution to long-term storage in the cortex . rem sleep , on the other hand , with its similarity to waking brain activity , is associated with the consolidation of procedural memory . so based on the studies , going to sleep three hours after memorizing your formulas and one hour after practicing your scales would be the most ideal . so hopefully you can see now that skimping on sleep not only harms your long-term health , but actually makes it less likely that you 'll retain all that knowledge and practice from the previous night , all of which just goes to affirm the wisdom of the phrase , `` sleep on it . '' when you think about all the internal restructuring and forming of new connections that occurs while you slumber , you could even say that proper sleep will have you waking up every morning with a new and improved brain , ready to face the challenges ahead .

it 's 4 a.m. , and the big test is in eight hours , followed by a piano recital . you 've been studying and playing for days , but you still do n't feel ready for either .

which is correct ?

let 's start with day and night . life evolved under conditions of light and darkness , light and then darkness . and so plants and animals developed their own internal clocks so that they would be ready for these changes in light . these are chemical clocks , and they 're found in every known being that has two or more cells and in some that only have one cell . i 'll give you an example -- if you take a horseshoe crab off the beach , and you fly it all the way across the continent , and you drop it into a sloped cage , it will scramble up the floor of the cage as the tide is rising on its home shores , and it 'll skitter down again right as the water is receding thousands of miles away . it 'll do this for weeks , until it kind of gradually loses the plot . and it 's incredible to watch , but there 's nothing psychic or paranormal going on ; it 's simply that these crabs have internal cycles that correspond , usually , with what 's going on around it . so , we have this ability as well . and in humans , we call it the `` body clock . '' you can see this most clearly when you take away someone 's watch and you shut them into a bunker , deep underground , for a couple of months . ( laughter ) people actually volunteer for this , and they usually come out kind of raving about their productive time in the hole . so , no matter how atypical these subjects would have to be , they all show the same thing . they get up just a little bit later every day -- say 15 minutes or so -- and they kind of drift all the way around the clock like this over the course of the weeks . and so , in this way we know that they are working on their own internal clocks , rather than somehow sensing the day outside . so fine , we have a body clock , and it turns out that it 's incredibly important in our lives . it 's a huge driver for culture and i think that it 's the most underrated force on our behavior . we evolved as a species near the equator , and so we 're very well-equipped to deal with 12 hours of daylight and 12 hours of darkness . but of course , we 've spread to every corner of the globe and in arctic canada , where i live , we have perpetual daylight in summer and 24 hours of darkness in winter . so the culture , the northern aboriginal culture , traditionally has been highly seasonal . in winter , there 's a lot of sleeping going on ; you enjoy your family life inside . and in summer , it 's almost manic hunting and working activity very long hours , very active . so , what would our natural rhythm look like ? what would our sleeping patterns be in the sort of ideal sense ? well , it turns out that when people are living without any sort of artificial light at all , they sleep twice every night . they go to bed around 8:00 p.m. until midnight and then again , they sleep from about 2:00 a.m. until sunrise . and in-between , they have a couple of hours of sort of meditative quiet in bed . and during this time , there 's a surge of prolactin , the likes of which a modern day never sees . the people in these studies report feeling so awake during the daytime , that they realize they 're experiencing true wakefulness for the first time in their lives . so , cut to the modern day . we 're living in a culture of jet lag , global travel , 24-hour business , shift work . and you know , our modern ways of doing things have their advantages , but i believe we should understand the costs . thank you . ( applause )

and in summer , it 's almost manic hunting and working activity very long hours , very active . so , what would our natural rhythm look like ? what would our sleeping patterns be in the sort of ideal sense ?

describe the natural sleep patterns that were discovered in this study .

if you ask people whether they think stealing is wrong , most of them would answer , `` yes . '' and yet , in 2013 , organizations all over the world lost an estimated total of 3.7 trillion dollars to fraud , which includes crimes like embezzlement , pyramid schemes , and false insurance claims . this was n't just the work of a few bad apples . the truth is that many people are susceptible not only to the temptation to commit fraud but to convincing themselves that they 've done nothing wrong . so why does fraud happen ? while individual motivations may differ from case to case , the fraud triangle , a model developed by criminologist donald cressey , shows three conditions that make fraud likely : pressure , opportunity , and rationalization . pressure is often what motivates someone to engage in fraud to begin with . it could be a personal debt , an addiction , an earnings quota , a sudden job loss , or an illness in the family . as for opportunity , many people in both public and private sectors have access to tools that enable them to commit and conceal fraud : corporate credit cards , internal company data , or control over the budget . the combination of pressure and being exposed to such opportunities on a daily basis can create a strong temptation . but even with these two elements , most fraud still requires rationalization . many fraudsters are first time offenders , so in order to commit an act most would regard as wrong , they need to justify it to themselves . some feel entitled to the money because they are underpaid and overworked and others believe their fraud is victimless , perhaps even planning to return the money once their crisis is resolved . some of the most common types of fraud do n't even register as such to the perpetrator . examples include employees fudging time sheets or expense reports , taxpayers failing to report cash earnings , or service providers overbilling insurance companies . though these may seem small , and can sometimes only involve hundreds of dollars , they all contribute to the big picture . and then there 's fraud on a massive scale . in 2003 , italian dairy food giant parmalat went bankrupt after it was found to have fabricated a 4 billion dollar bank account and falsified financial statements to hide the fact that its subsidiaries had been losing money . because it was family controlled , corporate governance and regulator supervision were difficult , and the company likely hoped that the losses could be recouped before anyone found out . and it 's not just corporate greed . governments and non-profits are also susceptible to fraud . during her time as city comptroller for dixon , illinois , rita crundwell embezzled over 53 million dollars . rita was one of the country 's leading quarter horse breeders and winner of 52 world championships . but the cost of maintaining the herd ran to 200,000 dollars per month . because her position gave her complete control over city finances , she was easily able to divert money to an account she used for private expenses , and the scheme went unnoticed for 20 years . it is believed that crundwell felt entitled to a lavish lifestyle based on her position , and the notoriety her winnings brought to the city . it 's tempting to think of fraud as a victimless crime because corporations and civic institutions are n't people . but fraud harms real people in virtually every case : the employees of parmalat who lost their jobs , the citizens of dixon whose taxes subsidized horse breeding , the customers of companies which raise their prices to offset losses . sometimes the effects are obvious and devestating , like when bernie madoff caused thousands of people to lose their life savings . but often they 're subtle and not easy to untangle . yet someone , somewhere is left holding the bill .

some of the most common types of fraud do n't even register as such to the perpetrator . examples include employees fudging time sheets or expense reports , taxpayers failing to report cash earnings , or service providers overbilling insurance companies . though these may seem small , and can sometimes only involve hundreds of dollars , they all contribute to the big picture .

discuss how fraudulently making higher insurance claims or falsifying time sheets could be harmful to you or your community .

you 've probably heard of the human genome , the huge collection of genes inside each and every one of your cells . you probably also know that we 've sequenced the human genome , but what does that actually mean ? how do you sequence someone 's genome ? let 's back up a bit . what is a genome ? well , a genome is all the genes plus some extra that make up an organism . genes are made up of dna , and dna is made up of long , paired strands of a 's , t 's , c 's , and g 's . your genome is the code that your cells use to know how to behave . cells interacting together make tissues . tissues cooperating with each other make organs . organs cooperating with each other make an organism , you ! so , you are who you are in large part because of your genome . the first human genome was sequenced ten years ago and was no easy task . it took two decades to complete , required the effort of hundreds of scientists across dozens of countries , and cost over three billion dollars . but some day very soon , it will be possible to know the sequence of letters that make up your own personal genome all in a matter of minutes and for less than the cost of a pretty nice birthday present . how is that possible ? let 's take a closer look . knowing the sequence of the billions of letters that make up your genome is the goal of genome sequencing . a genome is both really , really big and very , very small . the individual letters of dna , the a 's , t 's , g 's , and c 's , are only eight or ten atoms wide , and they 're all packed together into a clump , like a ball of yarn . so , to get all that information out of that tiny space , scientists first have to break the long string of dna down into smaller pieces . each of these pieces is then separated in space and sequenced individually , but how ? it 's helpful to remember that dna binds to other dna if the sequences are the exact opposite of each other . a 's bind to t 's , and t 's bind to a 's . g 's bind to c 's , and c 's to g 's . if the a-t-g-c sequence of two pieces of dna are exact opposites , they stick together . because the genome pieces are so very small , we need some way to increase the signal we can detect from each of the individual letters . in the most common method , scientists use enzymes to make thousands of copies of each genome piece . so , we now have thousands of replicas of each of the genome pieces , all with the same sequence of a 's , t 's , g 's , and c 's . but we have to read them all somehow . to do this , we need to make a batch of special letters , each with a distinct color . a mixture of these special colored letters and enzymes are then added to the genome we 're trying to read . at each spot on the genome , one of the special letters binds to its opposite letter , so we now have a double-stranded piece of dna with a colorful spot at each letter . scientists then take pictures of each snippet of genome . seeing the order of the colors allows us to read the sequence . the sequences of each of these millions of pieces of dna are stitched together using computer programs to create a complete sequence of the entire genome . this is n't the only way to read the letter sequences of pieces of dna , but it 's one of the most common . of course , just reading the letters in the genome does n't tell us much . it 's kind of like looking through a book written in a language you do n't speak . you can recognize all the letters but still have no idea what 's going on . so , the next step is to decipher what the sequence means , how your genome and my genome are different . interpreting the genes of the genome is the part scientists are still working on . while not every difference is consequential , the sum of these differences is responsible for differences in how we look , what we like , how we act , and even how likely we are to get sick or respond to specific medicines . better understanding of how disparities between our genomes account for these differences is sure to change the way we think not only about how doctors treat their patients , but also how we treat each other .

because the genome pieces are so very small , we need some way to increase the signal we can detect from each of the individual letters . in the most common method , scientists use enzymes to make thousands of copies of each genome piece . so , we now have thousands of replicas of each of the genome pieces , all with the same sequence of a 's , t 's , g 's , and c 's .

once we have the sequences for each piece of dna from a genome , scientists ________ .

many of us have hundreds of things on our minds at any moment , often struggling to keep track of everything we need to do . but fortunately , there 's one important thing we do n't have to worry about remembering : breathing . when you breathe , you transport oxygen to the body 's cells to keep them working and clear your system of the carbon dioxide that this work generates . breathing , in other words , keeps the body alive . so , how do we accomplish this crucial and complex task without even thinking about it ? the answer lies in our body 's respiratory system . like any machinery , it consists of specialized components , and requires a trigger to start functioning . here , the components are the structures and tissues making up the lungs , as well as the various other respiratory organs connected to them . and to get this machine moving , we need the autonomic nervous system , our brain 's unconscious control center for the vital functions . as the body prepares to take in oxygen-rich air , this system sends a signal to the muscles around your lungs , flattening the diaphragm and contracting the intercostal muscles between your ribs to create more space for the lungs to expand . air then wooshes into your nose and mouth , through your trachea , and into the bronchi that split at the trachea 's base , with one entering each lung . like tree branches , these small tubes divide into thousands of tinier passages called bronchioles . it 's tempting to think of the lungs as huge balloons , but instead of being hollow , they 're actually spongy inside , with the bronchioles running throughout the parenchyma tissue . at the end of each bronchiole is a little air sack called an alveolus , wrapped in capillaries full of red blood cells containing special proteins called hemoglobin . the air you 've breathed in fills these sacks , causing the lungs to inflate . here is where the vital exchange occurs . at this point , the capillaries are packed with carbon dioxide , and the air sacks are full of oxygen . but due to the basic process of diffusion , the molecules of each gas want to move to a place where there 's a lower concentration of their kind . so as oxygen crosses over to the capillaries , the hemoglobin grabs it up , while the carbon dioxide is unloaded into the lungs . the oxygen-rich hemoglobin is then transported throughout the body via the bloodstream . but what do our lungs do with all that carbon dioxide ? exhale it , of course . the autonomic nervous system kicks in again , causing the diaphragm to ball up , and the intercostal muscles to relax , making the chest cavities smaller and forcing the lungs to compress . the carbon dioxide-rich air is expelled , and the cycle begins again . so that 's how these spongy organs keep our bodies efficiently supplied with air . lungs inhale and exhale between 15 and 25 times a minute , which amounts to an incredible 10,000 liters of air each day . that 's a lot of work , but do n't sweat it . your lungs and your autonomic nervous system have got it covered .

it 's tempting to think of the lungs as huge balloons , but instead of being hollow , they 're actually spongy inside , with the bronchioles running throughout the parenchyma tissue . at the end of each bronchiole is a little air sack called an alveolus , wrapped in capillaries full of red blood cells containing special proteins called hemoglobin . the air you 've breathed in fills these sacks , causing the lungs to inflate . here is where the vital exchange occurs .

_____ drives o2 and co2 across the capillaries and air sacs in the lungs .

living with her family high above the ground in the northern tropical forests of colombia , you will find shakira , a cotton-top tamarin with a penchant for conversation . say , `` hola ! '' though you may not realize it , this one pound monkey communicates in a highly sophisticated language of 38 distinct calls based on variations of chirps and whistles . the response she just gave is known as a `` b chirp '' , a call often directed at humans . to appreciate the complexities of shakira 's language , let 's learn a few chirps and whistles , then examine how their combinations form grammatically structured sequences . the chirp shakira used to greet us comes from a class of calls known as single frequency modulated syllables . this class is made up of short duration calls , or chirps , and long duration calls , like screams and squeals . researchers have determined that there are eight different types of chirps categorized by stem upsweep , duration , peak frequency , and frequency change . in addition , each chirp has its own unique meaning . for example , shakira 's `` c chirp '' is used when she is approaching food , where as her `` d chirp '' is only used when she has the food in hand . single whistles also exhibit a unique intention with each call and just as there are eight different chirps , there are five different whistles . based on frequency modulation , single whistles are subdivided into four categories : squeaks , initially modulated whistles , terminally modulated whistles , and flat whistles . the language 's quality of unique intention is wonderfully exemplified by the category of initially modulated whistles . these whistles change based on the proximity of shakira to other members of her family . if shakira is greater than .6 meters from her family , she 'll sound a large initally modulated whistle . but if she 's less than .6 meters from her family , she 'll sound a small initially modulated whistle . now that we 've learned a few chirps and whistles , shakira wants to show off by taking you through a quick day in her life with these calls . while heading towards a feeding tree for her first meal of the day , she says , ( monkey noise ) , a call most often used in relaxed investigations . however , suddenly she spots the shadow of a hawk . `` e chirp '' for alarm . this call alerts her family to the presence of this predator , and shakira jumps to the safety of an inner branch . the coast seems clear , so shakira makes her way towards her dad . wait , wait . who is that ? ah , it 's her younger brother , carlos . cotton-top tamarins often squeal during play wrestling . uh-oh . he 's playing a little too roughly , and shakira screams , alerting her parents to help her . her dad makes his way towards the ball of rolling fur and her brother stops . shakira shakes herself and scratches herself to get the hair on her head back in place . then shakira spots another group of unfamiliar tamarins and hears their normal long call . she turns to her family . ( monkey noise ) did you catch that ? first there was a chirp , then a whistle . this is what 's known as a combination vocalization , a phrase that contains both a chirp and a whistle . these are two calls strung together to convey a message . the combination of these two elements alerts her family to the presence of another group , the `` f chirp '' , and the distance they are away , the normal long call whistle . in other words , shakira just said a sentence . her simple demonstration is just the tip of the iceberg . she 's got trills , chatters , multiple whistle calls , more combination vocalizations , even twitters . yet sadly enough , we may not get to hear everything she has to say . mixed in with chirping sonatas from high above is the constant thud of a machete chopping trees . shakira 's habitat in colombia is being cut down , piece by piece , and if we do n't work to protect the critically endangered cotton-top tamarin , it will become extinct in our lifetime . if the chirp from one tamarin to the next has proven to be more than just idle chit chat , imagine what else we have left to discover . imagine what else shakira can tell us .

ah , it 's her younger brother , carlos . cotton-top tamarins often squeal during play wrestling . uh-oh .

cotton-top tamarins can communicate using ________ .

is she turning towards you or away from you ? no one can agree . she 's the mysterious subject of dutch master johannes vermeer 's `` girl with the pearl earring , '' a painting often referred to as the 'mona lisa of the north . ' belonging to a dutch style of idealized , sometimes overly expressive paintings known as tronies , the `` girl with the pearl earring '' has the allure and subtlety characteristic of vermeer 's work . but this painting stands apart from the quiet narrative scenes that we observe from afar in many of vermeer 's paintings . a girl reading a letter . a piano lesson . a portrait artist at work . these paintings give us a sense of intimacy while retaining their distance , a drawn curtain often emphasizes the separation . we can witness a milkmaid serenely pouring a bowl of milk , but that milk is n't for us . we 're only onlookers . the studied composition in vermeer 's paintings invokes a balanced harmony . with the checkered floor in many of his works , vermeer demonstrates his command of perspective and foreshortening . that 's a technique that uses distortion to give the illusion of an object receding into the distance . other elements , like sight lines , mirrors , and light sources describe the moment through space and position . the woman reading a letter by an open window is precisely placed so the window can reflect her image back to the viewer . vermeer would even hide the leg of an easel for the sake of composition . the absence of these very elements brings the `` girl with the pearl earring '' to life . vermeer 's treatment of light and shadow , or chiaroscuro , uses a dark , flat background to further spotlight her three-dimensionality . instead of being like a set piece in a theatrical narrative scene , she becomes a psychological subject . her eye contact and slightly parted lips , as if she is about to say something , draw us into her gaze . traditional subjects of portraiture were often nobility or religious figures . so why was vermeer painting an anonymous girl ? in the 17th century , the city of delft , like the netherlands in general , had turned against ruling aristocracy and the catholic church . after eight decades of rebellion against spanish power , the dutch came to favor the idea of self-rule and a political republic . cities like delft were unsupervised by kings or bishops , so many artists like vermeer were left without traditional patrons . fortunately , business innovation spearheaded by the dutch east india company transformed the economic landscape in the netherlands . it created a merchant class and new type of patron . wishing to be represented in the paintings they financed , these merchants preferred middle class subjects depicted in spaces that looked like their own homes surrounded by familiar objects . the maps that appear in vermeer 's paintings , for example , were considered fashionable and worldly by the merchant class of what is known as the dutch golden age . the oriental turban worn by the `` girl with the pearl earring '' also emphasizes the worldliness of the merchant class , and the pearl itself , a symbol of wealth , is actually an exaggeration . vermeer could n't have afforded a real pearl of its size . it was likely just a glass or tin drop varnished to look like a pearl . this mirage of wealth is mirrored in the painting itself . in greater context , the pearl appears round and heavy , but a detailed view shows that it 's just a floating smudge of paint . upon close inspection , we are reminded of vermeer 's power as an illusion maker . while we may never know the real identity of the `` girl with the pearl earring , '' we can engage with her portrait in a way that is unforgettable . as she hangs in her permanent home in the mauritshuis museum in the hague , her presence is simultaneously penetrating and subtle . in her enigmatic way , she represents the birth of a modern perspective on economics , politics , and love .

the absence of these very elements brings the `` girl with the pearl earring '' to life . vermeer 's treatment of light and shadow , or chiaroscuro , uses a dark , flat background to further spotlight her three-dimensionality . instead of being like a set piece in a theatrical narrative scene , she becomes a psychological subject .

what does chiaroscuro refer to ?

translator : ido dekkers reviewer : emma gon ( music ) every movie you 've ever seen , every tv show , every magazine , every time you surf the internet , you 're absorbing information , a bit like a sponge absorbs water . the words on the screen , the images , the colors , the sounds , the angle of the camera , every detail is designed to make you think , act or feel a certain way . your brain is subconsciously decoding images and sounds , and just by being alive today , by interacting with and reading all these different types of media , you 're already an expert at decoding and understanding these hidden messages . a set of codes and conventions that work together to make you feel happy , angry , afraid , excited . to make you want to buy a particular product -- a refreshing drink , a new phone . to style your hair a certain way . to cheer for the hero or boo the villain . welcome to the family tree of technical codes . so what constitutes a code ? first of all , it has to be recognized by all who read it . imagine a busy city where motorists do n't know how to read the traffic signals . we all have to know red equals stop , green means go , for the system to work . otherwise it would be chaos . secondly , codes are made meaningful by their context . we ca n't fully interpret or decipher a code until we see how it relates to other signs and symbols . look at these two intersecting lines . without any context , things around the code to help you understand or make meaning from it , it 's hard to know exactly what these lines represent . they could be a cross , symbolizing religion , an add sign , symbolizing a mathematical concept , the letter t from the alphabet , or they could just be two lines intersecting . if we add a crescent moon shape , and a circle with a line on it in front , the two lines now have a context , a relationship to their surroundings , and are magically revealed as the letter t. by adding additional information around the code , we 've changed its context , and therefore given it a concrete meaning . let 's meet the family . technical codes , senior has three sons : symbolic codes , written codes and technical codes , junior . symbolic codes has three sons : symbolic color , symbolic objects and symbolic animals . this branch of the family is all about representation . red represents hot or stop or danger , depending on its context . so if you see a red light above a yellow and a green light on a pole above the road , you know by this context that the light represents stop . written codes has three sons : you and only you , buzzwords and catchphrase . these guys are all about saying a lot with a little , or planting a word in your subconscious that triggers a response whenever you hear or read it . have you noticed how many times i 've said the word `` you ? '' you should feel like it 's directed specifically at you , and only you , that it 's addressing your needs and desire to learn about your world . if i tell you that all the cool , fresh and hip people are buying a new drink or wearing a particular brand , the buzzwords `` new , '' `` fresh '' or `` free '' make the product seem more interesting and appealing . if i wrap that product or idea in a simple phrase that 's easy to remember and becomes part of your everyday speech , then every time you hear or say those few words , your brain connects them to the product . so just do it , think different , and enjoy the power of the catchphrase . and technical codes , junior has three sons : camera angles , framing and lighting . for these boys , it 's all about how the camera is placed , how objects , people and places are shot , and what we see on screen -- or just as importantly , what we do n't see . when the camera is placed high above the subject , it makes you look small , insignificant and powerless . and the reverse is also true , when the camera is below . so is this video trying to manipulate you to buy something ? yes , an idea . the idea that understanding the relationship between technical codes and the role they play in shaping your understanding of the world around us through the media we consume is fun and interesting . is it trying to make you feel a certain way ? absolutely . every image , every word , has been carefully crafted to work together to make you feel positive about the idea that you need to be educated to engage with what you read , watch and listen to in movies , tv shows , magazines and on the internet . by understanding these codes , and how they work together to subconsciously change the way you think , feel and act towards products and ideas , you 'll be aware of these techniques and able to identify their impact on you . one of the most powerful advertising mediums in the world is word of mouth . if you 've ever recommended a product or movie , a service , or even a video online , then you 've played your part in passing the message . so soak all this information up . recognize how the family tree of technical codes works on you , and those around you , to make an impact find excellent examples , and spread the word .

if i wrap that product or idea in a simple phrase that 's easy to remember and becomes part of your everyday speech , then every time you hear or say those few words , your brain connects them to the product . so just do it , think different , and enjoy the power of the catchphrase . and technical codes , junior has three sons : camera angles , framing and lighting .

why do companies invest billions of dollars in advertising ? do you think it makes a big difference ?

can you read in the car ? if so , consider yourself pretty lucky . for one-third of the population , looking at a book while moving along in a car or a boat or train or plane quickly makes them sick to their stomach . but why do we get motion sickness in the first place ? well , believe it or not , scientists are n't exactly sure . the most common theory has to do with mismatched sensory signals . when you travel in a car , your body gets two different messages . your eyes are seeing the inside of a vehicle , which does n't seem to be moving . meanwhile , your ear is telling your brain you 're accelerating . wait , your ear ? your ear has another important function besides hearing . in its innermost part lies a group of structures known as the vestibular system , which gives us our sense of balance and movement . inside there are three semicircular tubules that can sense rotation , one for each dimension of space . and there are also two hair-lined sacks filled with fluid . when you move , the fluid shifts and tickles the hairs , telling your brain if you 're moving horizontally or vertically . all this tells your body which direction you 're moving in , how much you 've accelerated , even at what angle . in a car , your vestibular system correctly senses your movement , but your eyes do n't see it , especially when glued to a book . the opposite can happen . you 're at the movies , and the camera makes a sweeping move . this time , your eyes think you 're moving while your ear knows you 're sitting still . but why does this conflicting information make us feel so terrible ? scientists are n't sure , but they think there 's an evolutionary explanation . fast moving vehicles and video recordings have only existed in the last couple of centuries , a blink in evolutionary time . for most of our history , there was n't that much that could cause this sensory mix-up , except for poisons . and because poisons are not the best thing for survival , our bodies evolved a direct but unpleasant way to get rid of what we ate that was causing the confusion . it 's a pretty reasonable theory , but it leaves things unexplained , like why women are more affected by motion sickness than men , or why passengers get more nauseous than drivers . another theory suggests that the cause is more about the way some unfamiliar situations make it harder to maintain our natural body posture . studies show that being immersed in water or just changing your stance can greatly reduce the effects of motion sickness . but we do n't really know what 's going on . we know the more common remedies for car queasiness -- looking at the horizon , over-the-counter pills , chewing gum , but none are totally reliable nor can they handle intense motion sickness and sometimes the stakes are far higher than just not being bored during a long car ride . at nasa , where astronauts are hurled into space at 17,000 miles per hour , motion sickness is a serious problem . in addition to researching the latest space-age technologies , nasa also spends a lot of time figuring out how to keep astronauts from vomiting up their space rations . like understanding the mysteries of sleep or curing the common cold , motion sickness is one of those seemingly simple problems that , despite amazing scientific progress , we still know very little about . perhaps one day the exact cause of motion sickness will be found , and with it , a completely effective way to prevent it , but that day is still on the horizon .

another theory suggests that the cause is more about the way some unfamiliar situations make it harder to maintain our natural body posture . studies show that being immersed in water or just changing your stance can greatly reduce the effects of motion sickness . but we do n't really know what 's going on .

which of the following can not help you remedy the effects of motion sickness ?

the dna in just one of your cells gets damaged tens of thousands of times per day . multiply that by your body 's hundred trillion or so cells , and you 've got a quintillion dna errors everyday . and because dna provides the blueprint for the proteins your cells need to function , damage causes serious problems , such as cancer . the errors come in different forms . sometimes nucleotides , dna 's building blocks , get damaged , other times nucleotides get matched up incorrectly , causing mutations , and nicks in one or both strands can interfere with dna replication , or even cause sections of dna to get mixed up . fortunately , your cells have ways of fixing most of these problems most of the time . these repair pathways all rely on specialized enzymes . different ones respond to different types of damage . one common error is base mismatches . each nucleotide contains a base , and during dna replication , the enzyme dna polymerase is supposed to bring in the right partner to pair with every base on each template strand . adenine with thymine , and guanine with cytosine . but about once every hundred thousand additions , it makes a mistake . the enzyme catches most of these right away , and cuts off a few nucleotides and replaces them with the correct ones . and just in case it missed a few , a second set of proteins comes behind it to check . if they find a mismatch , they cut out the incorrect nucleotide and replace it . this is called mismatch repair . together , these two systems reduce the number of base mismatch errors to about one in one billion . but dna can get damaged after replication , too . lots of different molecules can cause chemical changes to nucleotides . some of these come from environmental exposure , like certain compounds in tobacco smoke . but others are molecules that are found in cells naturally , like hydrogen peroxide . certain chemical changes are so common that they have specific enzymes assigned to reverse the damage . but the cell also has more general repair pathways . if just one base is damaged , it can usually be fixed by a process called base excision repair . one enzyme snips out the damaged base , and other enzymes come in to trim around the site and replace the nucleotides . uv light can cause damage that 's a little harder to fix . sometimes , it causes two adjacent nucleotides to stick together , distorting the dna 's double helix shape . damage like this requires a more complex process called nucleotide excision repair . a team of proteins removes a long strand of 24 or so nucleotides , and replaces them with fresh ones . very high frequency radiation , like gamma rays and x-rays , cause a different kind of damage . they can actually sever one or both strands of the dna backbone . double strand breaks are the most dangerous . even one can cause cell death . the two most common pathways for repairing double strand breaks are called homologous recombination and non-homologous end joining . homologous recombination uses an undamaged section of similar dna as a template . enzymes interlace the damaged and undamgaed strands , get them to exchange sequences of nucleotides , and finally fill in the missing gaps to end up with two complete double-stranded segments . non-homologous end joining , on the other hand , does n't rely on a template . instead , a series of proteins trims off a few nucleotides and then fuses the broken ends back together . this process is n't as accurate . it can cause genes to get mixed up , or moved around . but it 's useful when sister dna is n't available . of course , changes to dna are n't always bad . beneficial mutations can allow a species to evolve . but most of the time , we want dna to stay the same . defects in dna repair are associated with premature aging and many kinds of cancer . so if you 're looking for a fountain of youth , it 's already operating in your cells , billions and billions of times a day .

if they find a mismatch , they cut out the incorrect nucleotide and replace it . this is called mismatch repair . together , these two systems reduce the number of base mismatch errors to about one in one billion . but dna can get damaged after replication , too .

base mismatch is due to :

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 .

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 .

two friends ride skateboards in opposite directions . the speed of the first skateboarder is 5 miles per hour faster than the second . after 2 hours , they are 70 miles apart . what are their rates ?

throughout the history of mankind , three little words have sent poets to the blank page , philosophers to the agora , and seekers to the oracles : `` who am i ? '' from the ancient greek aphorism inscribed on the temple of apollo , `` know thyself , '' to the who 's rock anthem , `` who are you ? '' philosophers , psychologists , academics , scientists , artists , theologians and politicians have all tackled the subject of identity . their hypotheses are widely varied and lack significant consensus . these are smart , creative people , so what 's so hard about coming up with the right answer ? one challenge certainly lies with the complex concept of the persistence of identity . which you is who ? the person you are today ? five years ago ? who you 'll be in 50 years ? and when is `` am '' ? this week ? today ? this hour ? this second ? and which aspect of you is `` i '' ? are you your physical body ? your thoughts and feelings ? your actions ? these murky waters of abstract logic are tricky to navigate , and so it 's probably fitting that to demonstrate the complexity , the greek historian plutarch used the story of a ship . how are you `` i '' ? as the tale goes , theseus , the mythical founder king of athens , single-handedly slayed the evil minotaur at crete , then returned home on a ship . to honor this heroic feat , for 1000 years athenians painstakingly maintained his ship in the harbor , and annually reenacted his voyage . whenever a part of the ship was worn or damaged , it was replaced with an identical piece of the same material until , at some point , no original parts remained . plutarch noted the ship of theseus was an example of the philosophical paradox revolving around the persistence of identity . how can every single part of something be replaced , yet it still remains the same thing ? let 's imagine there are two ships : the ship that theseus docked in athens , ship a , and the ship sailed by the athenians 1000 years later , ship b . very simply , our question is this : does a equal b ? some would say that for 1000 years there has been only one ship of theseus , and because the changes made to it happened gradually , it never at any point in time stopped being the legendary ship . though they have absolutely no parts in common , the two ships are numerically identical , meaning one and the same , so a equals b . however , others could argue that theseus never set foot on ship b , and his presence on the ship is an essential qualitative property of the ship of theseus . it can not survive without him . so , though the two ships are numerically identical , they are not qualitatively identical . thus , a does not equal b . but what happens when we consider this twist ? what if , as each piece of the original ship was cast off , somebody collected them all , and rebuilt the entire original ship ? when it was finished , undeniably two physical ships would exist : the one that 's docked in athens , and the one in some guy 's backyard . each could lay claim to the title , `` the ship of theseus , '' but only would could actually be the real thing . so which one is it , and more importantly , what does this have to do with you ? like the ship of theseus , you are a collection of constantly changing parts : your physical body , mind , emotions , circumstances , and even your quirks , always changing , but still in an amazing and sometimes illogical way , you stay the same , too . this is one of the reasons that the question , `` who am i ? '' is so complex . and in order to answer it , like so many great minds before you , you must be willing to dive into the bottomless ocean of philosophical paradox . or maybe you could just answer , `` i am a legendary hero sailing a powerful ship on an epic journey . '' that could work , too .

how can every single part of something be replaced , yet it still remains the same thing ? let 's imagine there are two ships : the ship that theseus docked in athens , ship a , and the ship sailed by the athenians 1000 years later , ship b . very simply , our question is this : does a equal b ?

how long did the athenians maintain the ship of theseus in the harbor ?

we read fiction for many reasons . to be entertained , to find out who done it , to travel to strange , new planets , to be scared , to laugh , to cry , to think , to feel , to be so absorbed that for a while we forget where we are . so , how about writing fiction ? how do you suck your readers into your stories ? with an exciting plot ? maybe . fascinating characters ? probably . beautiful language ? perhaps . `` billie 's legs are noodles . the ends of her hair are poison needles . her tongue is a bristly sponge , and her eyes are bags of bleach . '' did that description almost make you feel as queasy as billie ? we grasp that billie 's legs are n't actually noodles . to billie , they feel as limp as cooked noodles . it 's an implied comparison , a metaphor . so , why not simply write it like this ? `` billie feels nauseated and weak . '' chances are the second description was n't as vivid to you as the first . the point of fiction is to cast a spell , a momentary illusion that you are living in the world of the story . fiction engages the senses , helps us create vivid mental simulacra of the experiences the characters are having . stage and screen engage some of our senses directly . we see and hear the interactions of the characters and the setting . but with prose fiction , all you have is static symbols on a contrasting background . if you describe the story in matter of fact , non-tactile language , the spell risks being a weak one . your reader may not get much beyond interpreting the squiggles . she will understand what billie feels like , but she wo n't feel what billie feels . she 'll be reading , not immersed in the world of the story , discovering the truths of billie 's life at the same time that billie herself does . fiction plays with our senses : taste , smell , touch , hearing , sight , and the sense of motion . it also plays with our ability to abstract and make complex associations . look at the following sentence . `` the world was ghost-quiet , except for the crack of sails and the burbling of water against hull . '' the words , `` quiet , '' `` crack , '' and `` burbling , '' engage the sense of hearing . notice that buckell does n't use the generic word sound . each word he chooses evokes a particular quality of sound . then , like an artist laying on washes of color to give the sense of texture to a painting , he adds anoter layer , motion , `` the crack of sails , '' and touch , `` the burbling of water against hull . '' finally , he gives us an abstract connection by linking the word quiet with the word ghost . not `` quiet as a ghost , '' which would put a distancing layer of simile between the reader and the experience . instead , buckell creates the metaphor `` ghost-quiet '' for an implied , rather than overt , comparison . writers are always told to avoid cliches because there 's very little engagement for the reader in an overused image , such as `` red as a rose . '' but give them , `` love ... began on a beach . it began that day when jacob saw anette in her stewed-cherry dress , '' and their brains engage in the absorbing task of figuring out what a stewed-cherry dress is like . suddenly , they 're on a beach about to fall in love . they 're experiencing the story at both a visceral and a conceptual level , meeting the writer halfway in the imaginative play of creating a dynamic world of the senses . so when you write , use well-chosen words to engage sound , sight , taste , touch , smell , and movement . then create unexpected connotations among your story elements , and set your readers ' brushfire imaginations alight .

it 's an implied comparison , a metaphor . so , why not simply write it like this ? `` billie feels nauseated and weak . ''

what does the lesson suggest you do when you write ? list some hints it gives that could help you write better fiction .

translator : andrea mcdonough reviewer : bedirhan cinar i like to think of life science as one big pyramid . let 's call the pyramid , `` biological organization '' . let 's work our way from very small and specific concepts to very large and complex topics . so let 's start at the tip of the pyramid , with something so small , it ca n't be seen by the human eye , a single cell . a cell by itself is the most basic component of life . a single cell , which is capable of living on its own , is called a unicellular organism , organisms like bacteria or protists . these organisms are everywhere you look , you just ca n't see them . but , when cells join together , with more than one cell like itself to perform a similar function , it 's no longer a unicellular organism . it 's then called a tissue . no , not that kind of tissue . there are four types of tissues found in the human body : connective , muscle , nervous , and epithelial . bone tissue is a type of connective tissue and it 's not flimsy like a kleenex at all . blood is also an example of the same cells working together to perform the same job , but it 's a liquid , again , not like a kleenex at all . no matter what the consistency is , a tissue is a group of the same cells , working together to perform a similar function . any time there are different tissues working together , we then call it an organ . that 's the next level of the pyramid . animals are n't the only ones with organs ; plants have organs too . when we find multiple different organs working together to perform the same job , we then call it an organ system . take the digestive system , for example . it 's made up of a mouth , esophagus , stomach , pancreas , liver , gall bladder , small intestine , and large intestine , also known as your colon . although each individual organ in this organ system does a very different job , together , these organs work to achieve the one goal of taking all the nutrients out of the food we eat and getting rid of what we do n't need . an organ system , by definition , can only do one job , like get the nutrients from our food , send and receive electrical signals , or exchange oxygen for carbon dioxide . regardless of their individual function , all organ systems rely on one another to do the vital jobs which they ca n't do themselves . if one organ system does n't work , the others will shut down , too . an organism is a complicated , living thing , which requires the proper functioning of multiple organ systems to maintain stability . this stability is called homeostasis . when all organ systems are working together and maintaining homeostasis , then it results in a happy , living organism . organisms are incredibly diverse and can be as simple as a bacteria or as complex as you . when a group of the same organisms , also known as a species , live together in the same environment , we then call it a population . often there are several populations all living in one environment . that is what we call a community . each time you look out the window , you 're seeing a community . when we look at multiple communities , along with how all of the organisms interact with the physical environment , then we refer to it as an ecosystem . when you look at all the ecosystems of earth together , you 're looking at the earth . the earth is a big , round circle of life . that 's why we call it a biosphere - bio , meaning life and sphere , meaning circle . and there you go ! when you break it down to each level , a very complex concept and phrase becomes easy to understand . all life starts with a single cell . when cells join together , they are called a tissue . a group of different tissues are called an organ , and a group of different organs are an organ system . a group of organ systems working together make up an organism , and a group of the same organisms are a population . combining several different populations together give us a community . and several different communities in a large area is an ecosystem . and every ecosystem together makes up our biosphere . and that , my friends , is biological organization , the pyramid of life .

there are four types of tissues found in the human body : connective , muscle , nervous , and epithelial . bone tissue is a type of connective tissue and it 's not flimsy like a kleenex at all . blood is also an example of the same cells working together to perform the same job , but it 's a liquid , again , not like a kleenex at all .

an example of a tissue is :

so , you 're thinking of moving to mars . have you picked out a spot for your new home ? no ? well , i 'm here to help . first things first , here are some of the things you 'll need to bring to the red planet : a high tolerance for cold , loneliness , and radiation ; a lifetime supply of breathable air and food ; a multibillion dollar spaceship ; a desire to just get away from it all ; and water . you 're definitely going to need water . so what sort of real estate are you looking for ? how about a mansion in the maze-like noctis labyrinthus ? a hideaway in the happy face crater ? a fortress on the face mesa ? an oceanview ? uh , bad news on the last one . you 're about 4 billion years late . we 're pretty sure that mars used to have oceans , lakes , rivers , the whole package . but over time , almost all of it froze beneath the surface , or evaporated off into space . there 's probably still some trapped beneath the seasonally expanding and contracting carbon dioxide ice caps , though . so what might mars look like today if it had surface water ? that , of course , depends on how much we 're talking about , but maybe something like this . the relatively flat northern hemisphere is below the average elevation , so it would become one giant ocean , while the crater-ridden southern hemisphere would stay mostly high and dry . that difference between hemispheres is a bit bizarre , and we do n't know why it 's like that . the southern half is probably much older , judging by features like the number of craters , and the evidence of increased volcanic activity in the north . okay , so who knows ? maybe one day mars will have oceans again , but for now , what we 've got is essentially one giant dusty desert . in fact , it 's similar enough to deserts on earth , that we 've been able to learn a great deal about mars on our home planet . for instance , martian sand dunes form and behave similarly to our sand dunes , though the martian versions often grow twice as large thanks to a gravitational pull that 's about a third as strong as ours . and mars has some features you wo n't see on earth , like tars , which are crestless sand dunes up to fifteen meters tall , whose formations we have yet to understand . you 're probably wondering , `` what do you get when you combine a planet-wide desert with an atmosphere that , like ours , is subject to wind-generating pressure differentials , dust storms ? '' these will be your main weather hazards on the red planet . they play a large part in making the planet red by distributing rusted iron particles across the surface and into the air . thanks to the low gravity and lack of moisture , these dust storms can last for months and cover the planet . so , you might want to build your home as high as possible . well , look no further . this is olympus mons , the largest volcano in the solar system . even if mars had a breathable atmosphere , you 'd find the views from the 25 kilometer summit breathtaking . or are volcanos not your thing ? then how about valles marineris , the largest canyon in the solar system ? it 's so wide that from one side , the opposite rim would be below the curve of the horizon . still , you 'll catch some spectacular blue sunsets in the normally red sky , which gets its color from the dust absorbing most of the blue light , and the way sunlight is scattered by the atmosphere . have you got spirit , curiosity , or are you just looking for opportunity ? then stop stalling and make the move to mars today . mars : redder than ever .

then stop stalling and make the move to mars today . mars : redder than ever .

mars one is a mission with the goal of establishing a permanent human settlement on mars . the project managers plan to land the first humans on mars and establish a permanent human colony there by 2027. they can not come back to earth . many people applied to go for this strange mission . the majority of the applicants are under 36 and well-educated . what do you think about them ? do you think they are normal people with normal lives ? what is the first and last problem that they may challenge during this life ? what do you do if planners send you to this mission ?

it 's estimated that for every 10,000 bills in the u.s. , one of those bills is fake . that may not sound like much , but it adds up to millions of dollars in cold hard cash . counterfeit money has the potential to cause all sorts of problems , from leaving you short $ 20 to destabilizing national economies . but do n't worry . you can help catch the counterfeits . all you need are some simple tools and a bit of chemistry . first up , the anti-counterfeit detection pen . the pen looks like a highlighter and contains a solution of potassium iodide and elemental iodine . it reveals of the presence of starch , which is commonly used to strengthen regular printer paper , but wo n't be found in real money . that 's because authentic bills are made of cotton and linen and are threaded with tiny red and blue fibers . that material is made by a single , highly-guarded company called crane and company , which has been printing currency since paul revere asked them to help finance the revolutionary war . the starch in many counterfeit bills , on the other hand , is made of two molecules : amylopectin and amylose . it 's amylose that gives the fake away . its long chain of sugar molecules connected by oxygen atoms forms a helical structure , like dna . iodide likes to squeeze inside this coil , forming a new compound that leaves a dark mark on the paper . however , in the absence of starch , there is no chemical reaction and the mark will look light yellow . so if the fake is n't printed on starchy paper , iodine solutions ca n't help you . that 's one of the reasons u.s. bills printed since 1996 have been chemically enhanced to include another counterfeit countermeasure : a strip that fluoresces under uv light . that 's the same kind of light used at black light parties and airport security lines . the polyester strip printed with invisble ink is just one millimeter wide and is found in different positions depending on a bill 's value . if you hold your dollar up to natural light , you can see the amount and the word usa printed on the band . but under uv light , these strips really shine . they contain molecules that can be excited by absorbing certain amounts of energy , specifically , that given off by common uv light sources . as these excited molecules return to their original states , they lose a bit of energy as heat and then radiate the rest as light . energy is inversely related to wavelength , which means that the longer wavelengths have lower energy . so the lower energy light given off by the strip means longer wavelengths that fall in the visible range , and suddenly we can see that which had been invisible . and if a glowing strip does n't show up on a recent bill , you have a fake on your hands . for times when you 're not dealing with counterfeit masterminds , looking for simple visual cues will do . make sure the portrait looks lifelike and not flat , the seal has perfectly even sawtooth points , the inked border is unbroken , and the serial number has precisely equal spacing between each number . so the next time you come across some dubious dough , have a closer look , pull out your iodine solution , or take it to a rave and you just might catch a counterfeit .

that 's one of the reasons u.s. bills printed since 1996 have been chemically enhanced to include another counterfeit countermeasure : a strip that fluoresces under uv light . that 's the same kind of light used at black light parties and airport security lines . the polyester strip printed with invisble ink is just one millimeter wide and is found in different positions depending on a bill 's value .

fluorescent ink absorbs ultraviolet light , loses some energy as heat then radiates _____ that appear in the visible light range .

translator : andrea mcdonough reviewer : jessica ruby so two guys walk into a bar . really ? no , seriously . two guys walk into a bar , an ice cream bar : dave , a physicist working on the large hadron collider at cern , the european laboratory for particle physics , and steve , a blues singer . `` dave , how 's it going ? '' `` steve , good to see you ! '' `` two scoops of chocolate almond for me . '' `` vanilla shake . '' `` hey , i just saw something about the lhc on tv . you guys found bozo in your detector ? '' `` well , not exactly . we found a boson , probably the higgs boson . '' `` what 's that ? '' `` it 's a particle . '' `` do n't you find particles all the time ? '' `` yes , but this one means that the higgs field might really exist . '' `` field ? what field ? '' `` the higgs field . it 's named after peter higgs , although many others contributed to the idea . it is n't a field , like where you grow corn , but a hypothetical , invisible kind of force field that pervades the whole universe . '' `` hmmmm , okay . if it pervades the whole universe , how come i 've never seen it ? that 's a bit strange . '' `` well , actually , it 's not that strange . think of the air around us . we ca n't see it or smell it . well , perhaps in some places we can . but we can detect its presence with sophisticated equipment , like our own bodies . so the fact that we ca n't see something just makes it a bit harder to determine whether its really there or not . '' `` alright , go on . '' `` so , we believe this higgs field is all around us , everywhere in the universe . and what it does is rather special - it gives mass to elementary particles . '' `` what 's an elementary particle ? '' `` an elementary particle is what we call particles that have no structure , they ca n't be divided , they 're the basic building blocks of the universe . '' `` i thought those were atoms . '' `` well , atoms are actually made of smaller components , protons , neutrons , and electrons . while electrons are fundamental particles , neutrons and protons are not . they are made up of other fundamental particles called quarks . '' `` sounds like russian dolls . does it ever end ? '' `` actually , we do n't really know . but our current understanding is called the standard model . in it , there are two types of fundamental particles : the fermions , that make up matter , and the bosons , that carry forces . we often order these particles according to their properties , such as mass . we can measure the masses of the particles , but we never really knew where this mass came from or why they have the masses they do . '' `` so how does this higgs field thing explain mass ? '' `` well , when a particle passes through the higgs field , it interacts and gets mass . the more it interacts , the more mass it has . '' `` ok , i kind of get that , but is it really that important ? i mean , what if there were no higgs field ? '' `` if there were no higgs field , the world would n't exist at all . there would be no stars , no planets , no air , no anything , not even that spoon or the ice cream you 're eating . '' `` oh , that would be bad . okay , but where does this higgs boson fit into things ? '' `` alright , now , you see the cherry in my shake ? '' `` can i have it ? '' `` no , not yet . we have to use it as an analogy first . '' `` oh , right , the cherry 's the higgs boson . '' `` no , not quite . the cherry is a particle moving through the higgs field , the shake . the shake gives the cherry its mass . '' `` i get it . okay , so the molecules of the shake are the higgs bosons ! '' `` well , you 're getting closer . it takes an excitation of the higgs field to produce the higgs boson . so , for example , if i were to add energy by , say , dropping this cherry in the shake , '' `` ah , then the drops that spill on the bar are the higgs bosons . '' `` almost ! the splash itself is the higgs boson . '' `` are you serious ? '' `` well , that 's what quantum mechanics teaches us . in fact , all particles are excitations of fields . '' `` okay , right . well , i kind of see why you like particle physics , it 's quite cool , strange , but cool . '' `` yeah , you could call it a bit strange , it 's not like everyday life . the higgs boson is an excitation of the higgs field . by finding the higgs boson , we know that the higgs field exists . '' `` right . so now you found it , we know this higgs field exists . you must be done . is there anything left of particle physics ? '' `` actually , we 've just begun . it 's a bit like , you know , when columbus thought he had found a new route to india . he 'd , indeed , found something new , but not quite what he was expecting . so , first , we need to make sure that the boson we found is actually the higgs boson . it seems to fit , but we need to measure its properties to be sure . '' `` how 'd you do that ? '' `` take a lot more data . this new boson lives for only a very short time before it breaks down or decays into lighter , more stable particles . by measuring these particles , you learn about the properties of the boson . '' `` and what exactly are you looking for ? '' `` well , the standard model predicts how often and in what ways the higgs boson would decay to the various , lighter particles . so we want to see if the particle we have found is the one predicted by the standard model or if it fits into other possible theoretical models . '' `` and if it fits a different model ? '' `` that would be even more exciting ! in fact , that 's how science advances . we replace old models with new ones if they better explain our observations . '' `` right , so it seems like finding this higgs boson gives a direction for exploration , a bit like that columbus guy heading west . '' `` exactly ! and this is really just the beginning . ''

`` well , not exactly . we found a boson , probably the higgs boson . '' `` what 's that ? ''

if the thing that atlas and cms have discovered turns out not to be the higgs boson predicted by the standard model , what could be the consequences ? what might it be signs of ?

on september 6 , 1522 , the `` victoria '' sailed into harbor in southern spain . the battered vessel and its 18 sailors were all that remained of a fleet that had departed three years before . yet her voyage was considered a success for the `` victoria '' had achieved something unprecedented : the first circumnavigation of the globe . but this story really begins in 1494 , two years after columbus 's voyage on behalf of spain . columbus 's discovery had prompted the catholic spanish rulers to turn to the pope to preempt any claims by portugal to the new lands . the pope resolved this dispute by drawing an imaginary line on the world map . spain had the right to claim territories west of the divide , and portugal to the east . spain and portugal , the two major seafaring super powers at the time , agreed to these terms in what came to be called the treaty of tordesillas . at the time , these nations had their eyes on the same prize : trade routes to the spice islands in today 's indonesia . the spices found there , which were used as seasonings , food preservatives , and aphrodisiacs , were worth many times their weight in gold . but because of portugal 's control over eastern sea routes , spain 's only viable option was to sail west . so when a portuguese defector named ferdinand magellan claimed that a westward route to the spice islands existed , king charles made him captain of a spanish armada , and gave him all the resources he would need . along with a share in the voyage 's profits , he granted magellan five ships and about 260 men . the crew included a young slave named enrique , captured by magellan on a previous journey to malacca , and antonio pigafetta , a venetian nobleman seeking adventure . on september 20 , 1519 , the fleet weighed anchor and headed southwest . after making landfall in what is now brazil , it proceeded along the coast , exploring any water way leading inland . they were looking for the fabled passage linking east and west . as the weather worsened , the spaniards resentment at having a portuguese captain escalated . a full-blown mutiny soon erupted , which magellan crushed with unspeakable cruelty . but his problems were only just beginning . during a reconnaissance mission , the `` santiago '' was wrecked by a storm . then while exploring a narrow waterway , the captain of the `` san antonio '' took the first opportunity to slip away and sail back home . magellan pressed forward , and on october 21 , he started exploring a navigable sea way . 27 freezing days later , the three remaining ships emerged from what we now call the strait of magellan into the mar pacifico . the fleet never expected the new ocean to be so vast . after 98 days at sea , dozens of sailors had succumbed to scurvy and famine . when they finally reached land again , enrique , the young slave , proved able to communicate with the natives . their goal could n't be far . sailing further west , magellan was warmly received by rajah humabon of cebu . so when the ruler asked him to help subdue and convert the rebellious chief of mactan , the captain readily agreed . the adventure would be his last . overconfident and severely outnumbered , magellan 's force was overwhelmed , and the native 's bamboo spears ended the captain 's life . yet the voyage had to continue . magellan 's will specified that enrique should be freed , but the expedition still needed an interpreter . with his freedom at stake , enrique is believed to have plotted with the rajah to have about 30 of the spaniards killed at a feast on the beach . enrique was never heard from again , but if he ever made it back to malacca , he may have been the first person to actually circumnavigate the globe . meanwhile , the survivors burned the concepcion and proceeded onward . they finally reached the spice islands in november of 1521 and loaded up on precious cargo . but they still had to return to spain . the `` trinidad '' sank shortly after being captured by the portuguese . the `` victoria '' continued west , piloted by juan sebastián elcano , one of the pardoned mutineers . against all odds , the small vessel made it back to spain with a full cargo of cloves and cinnamon , enough to cover the expedition and turn a profit . an obsessive chronicler , pigafetta described the lands and people they encountered . with the help of a humble slave , he also compiled the world 's first phrase book of native languages . his journal is the reason we can tell this story . magellan 's legacy lingers . he had galaxies and space programs named after him . elcano , too , was celebrated in spain with a coat of arms and his face on currency and stamps . united by fate , the survivors and the hundreds who sacrificed their lives challenged conventional wisdom and completed a historic journey once thought impossible .

his journal is the reason we can tell this story . magellan 's legacy lingers . he had galaxies and space programs named after him .

which of the assertions below is not true with regard to ferdinand magellan ?

you might have seen this symbol before , whether it 's as a temporary tattoo or at a chinese temple . it 's called the yin-yang symbol . it comes from taoism , a religion born in china and it has far more meaning than you probably realize . the yin is the dark swirl , and the yang is the light one , and each side has a dot of the opposite color , which gives a clue to the meaning of yin and yang . everything contains the seed of its opposite . darth vadar has the seed of goodness , and luke has the potential to follow his father to the dark side . like luke and his father , yin and yang are not total opposites , they are relative to each other . taoists believe that the universe is made up of energies , vibrations , and matter , which behave differently in different contexts . something can be yin or yang depending on , well , depending on lots of things . so , while wheat that 's growing is yang , when it 's being reaped , it 's yin . a wave 's crest is yang , and the trough is yin . villages on the sunny side of a valley in china have names like liuyang or shiyang , but on the shady side , for example , of the yangtze river valley , there 's jiangyin . the brake is yin to the gas pedal 's yang . an eggshell is yang , the egg inside is yin . you think you 're getting it ? yang is harder , stronger , brighter , and faster , but one can turn into the other or are two sides of the same coin . the sunbeams are yang in comparison to the shadows . the pitch is yang , the catch is yin . the yang starts an action , and the yin receives it , completes it . yin is the inside space of a cup ; it would n't be a cup without it . yang is the cup . the coffee 's heat , however , is yang , and its blackness is yin . yang goes berserk sometimes , but there 's some very powerful yins , too , if they do n't quite go berserk . yin is the darker swirl , the female , but there is a white dot in it . and yang is the lighter , the male , but it has a black dot . water flowing calmly in a river is yin , but when it goes over the waterfall , it 's very yang . toothpicks are yin compared with a telephone pole . the back of a person is more yin than the front . the top of a person is the yang end . taoism teaches that there is a power in the universe . it 's higher , deeper , and truer than any other force . they call it the tao . it means the way . like the force in star wars , the tao has two sides . unlike other religions where the higher power is all good , and perhaps has an all-evil rival , taoism teaches that we need to learn from both yin and yang . and unlike religions with gods that are personal , the higher power in taoism is not . taoists believe that living in harmony with the way , a person will not have to fight against the universe 's natural flow . so , for example , listen more , argue less . be ready to back up or undo something , and you will make even faster progress . do n't worry about being the best , be who you are . live simply . complications take you away from the tao . `` the wise person is flexible , '' taoists say . learning to use the tao is what taoism is all about , and that 's why you should know your yin from your yang .

water flowing calmly in a river is yin , but when it goes over the waterfall , it 's very yang . toothpicks are yin compared with a telephone pole . the back of a person is more yin than the front . the top of a person is the yang end . taoism teaches that there is a power in the universe .

compared to a person with too much yin energy , a person with too much yang energy would probably

do you remember when you first realized that your computer was more than just a monitor and keyboard ? that between the mouse click and the video playing , there was something that captured your intention , understood it , and made it real ? what is that something ? is it gremlins ? let 's imagine that we can shrink down to the size of an electron and inject ourselves into a click of a mouse . if you took your mouse apart , you 'd see that it 's really a very simple machine . it has a couple buttons and a system for detecting motion and distance . you might have an optical mouse that makes these measurements with lights and sensors , but older ones did this with a hard rubber ball and some plastic wheels . same concept . when you click the button on your mouse , it sends a message to the computer with information about its position . when your mouse click is received , it 's handled by the basic input/output subsystem . this subsystem acts like the eyes and ears and mouth and hands of the computer . basically , it provides a way for the computer to interact with its environment . but it also acts like a buffer to keep the cpu from being overwhelmed by distractions . in this case , the i/o subsystem decides that your mouse click is pretty important so it generates an interrupt to the cpu . `` hey , cpu ! got a click here . '' the cpu , or central processing unit , is the brains of the whole computer . just like your brain does n't take up your whole body , the cpu does n't take up the whole computer , but it runs the show all the same . and the cpu 's job , its whole job , is fetching instructions from memory and executing them . so , while you 're typing , typing , typing , maybe really fast , like 60 words a minute , the cpu is fetching and executing billions of instructions a second . yes , billions every second : instructions to move your mouse around on the screen , to run that clock widget on your desktop , play your internet radio , manage the files you 're editing on the hard drive , and much , much more . your computer 's cpu is one heck of a multitasker ! `` but oh my gosh there 's a very important mouse click coming through now ! let 's drop everything now and deal with that ! '' there are programs for everything that the cpu does . a special program for the mouse , for the clock widget , for the internet radio , and for dealing with letters sent by the keyboard . each program was initially written by a human in a human-readable programming language , like java , c++ , or python . but human programs take up a lot of space and contain a lot of unnecessary information to a computer , so they are compiled and made smaller and stored in bits of ones and zeros in memory . the cpu realizes that it needs instructions for how to deal with this mouse click , so it looks up the address for the mouse program and sends a request to the memory subsystem for instructions stored there . each instruction in the mouse device driver is duly fetched and executed . and that 's not nearly the end of the story ! because the cpu learns that the mouse was clicked when the cursor was over a picture of a button on the monitor screen , and so , the cpu asks memory for the monitor program to find out what that button is . and then the cpu has to ask memory for the program for the button , which means that the cpu needs the monitor program again to show the video associated with the button , and so it goes . and let 's just say there are a lot of programs involved before you even see the button on the screen light up when you clicked it . so , just the simple task of clicking your mouse means visiting all of the critical components of your computer 's architecture : peripherals , the basic input-output system , the cpu , programs , and memory , and not one gremlin .

in this case , the i/o subsystem decides that your mouse click is pretty important so it generates an interrupt to the cpu . `` hey , cpu ! got a click here . ''

the cpu can handle ________ of instructions a second

we check the time every day , all day long . but did you ever wonder - where did telling time come from ? why does it matter what time it is ? who determined the clock and why in the world are there so many different time zones ? the first form of telling time was the sundial and the earliest sundials known from the archaeological record are obelisks from nearly 5,000 years ago . sundials indicate the time by casting a shadow onto a surface . the object that casts the shadow is a stick in the center known as a gnomon . a well-constructed sundial can measure time with remarkable accuracy , and sundials were used to monitor the performance of clocks until the modern era . but sundials have their limitations too . obviously they require the sun to shine , so they do n't work at all during the night when it 's dark . many different devices have been used over the years to estimate the passage of time : candles and sticks of incense that burn down at fairly predictable speeds have been used , along with the hourglass . hourglasses are devices in which fine sand pours through a tiny hole at a constant rate and indicates a predetermined passage of an arbitrary period of time . the origin of the hourglass is uncertain , although beginning in the 14th century , the hourglass was used commonly , especially on board ships . the motion of the boat on the water did not affect the hourglass , unlike other time-measuring devices . the mechanical clock was invented in the 13th century which sparked a big change in traditional timekeeping methods . this modern clock relied on the swing of a pendulum or the vibration of a quartz crystal , which was far more accurate than sand or candles . today , the basis for scientific time is a continuous count of seconds based on atomic clocks all around the world , known as the international atomic time . why does it matter that we keep track of time ? well , time regulates our daily lives and makes it possible to accurately communicate with people all over the world . without a time system , we would have many challenges in farming , social structures , communication , and business . take the american railroad system , for example . in the mid-19th century , each railroad used its own standard time generally based on the local time of its headquarters , and the railroad 's train schedules were published using its own time . some major railroad junctions served by several different railroads had a separate clock for each railroad , each showing a different time . the distance between new york and boston is about 2 degrees , or 8 minutes , which can be the difference between making or missing your train connection . if the difference between new york and boston is 8 minutes , imagine the difference between boston and australia . the use of time zones irons out these differences and makes communication significantly smoother . a time zone is a region on earth that has a uniform standard time . there are 40 time zones on land because the earliest and latest time zones are 26 hours apart . any given calendar date exists at some point on the globe for 50 hours . so the next time someone asks you `` what time is it ? '' your answer may be a whole lot more complicated than it used to be .

a time zone is a region on earth that has a uniform standard time . there are 40 time zones on land because the earliest and latest time zones are 26 hours apart . any given calendar date exists at some point on the globe for 50 hours .

do you think time zones are necessary ? couldn ’ t we just adjust to the differences in other parts of the country or world ? why or why not ?

( music ) i want everyone to put their hands on top of their head . yeah , yeah , yeah . put your hands on top of your head . just relax . just stay calm . everything will be nice and smooth if you just participate and just relax , okay ? yeah . all right , now put your hands down . do n't be no hero . put your hands down . okay ? all right . now . cool . good . i want you to run all that financial aid . yeah , sucka , put the scholarships in the bag , yeah , yeah . put the scholarships in the bag . yeah , you too , yeah , yeah , yeah . yeah , you . yeah , yeah . you over there , go put the pell grants in the bag . put the pell grants in there too . yeah , you . go . yeah , yeah , yeah . you , go over to that booth and get me some of them subsidized , some of them subsidized loans . it ai n't a game no more . i know you 're hiding the money somewhere here . with all this tuition you got me and my homies payin ' -- woo ! -- i 'm about to get gangster-scholar up in here . up in here . i 'm about to go n.w.a . meets beastie boys if i do n't see the cash , man . cause we 're not gon na take it . ♪ oh ... oh , you thought i was playing . oh , you thought this was a game . back up , back up . mind your business , that 's all . what do you , think this is a game ? what ? huh ? you do n't even know me . i 'll say something else . do n't call me crazy . do not call me -- rives , tell 'em do n't call me crazy before i go crazy . i 'm telling you , now i 'm about to go crazy . i 'm about to go tupac thug life in here . like , `` i ai n't a killer but do n't push me . revenge is like the sweetest joy -- '' woo ! i 'm about to go biggie smalls brooklyn type , like , `` super nintendo , sega genesis . when i was dead broke -- '' woo ! i 'm about to go krs-one cuckoo for cocoa puffs-type wild . like , `` wa da da dang , wa da da da dang , listen to my nine millimeter go bang . '' you know what ? you are dumb . you are really dumb . hide your kids , hide your wife , 'cause we gettin ' financial aid all up and in and around here . you think this is a game ? you think i want to be out here doing this ? do you know how hard it was to find these guns ? all right , i 'm sorry . you understand ? i 'm just trying to get my education . you know what i mean ? i 'm just trying to fight for the opportunity that my great-great-great-grandfather died for , you know what i 'm saying ? you know how my ancestors did sit-ins , just so i can sit in a classroom . and all these years , all y'all been doing is strangling the life out of my bank statement , leaving my pockets as vacant as parking lots . professor willie lynch taught you well , huh ? keep the body , take the money . force feed my people deception and failure . condition our brains to malfunction at the sight of success . just keep the cycle going . make us pay for an education that will end up failing us . put us in debt so we 're giving back the money we earned from our back-breaking work . this seems all too familiar . sounds like the rust of shackles locking their way onto my degree . sounds like the thirteenth amendment in reverse . lecture halls should n't feel like cotton fields , should n't sound like muffled freedom songs trapped in the jaws of a generation 's dreams . oho ! oh , it all makes sense . give us enough to get by but not enough to provide for ourselves . keep us psychologically feeble so we lose our purpose in the process . stop thieving our aspirations out of our sleep . do n't call it financial aid if you 're not helping anyone with it . we have fought . we have fought way too hard to let green paper build a barricade in front of our futures . i will not let you potentially rob food out of my children 's stomach . best believe i 'm going out blasting . i ai n't no killer , but do n't push me . i wish it did n't come to this , but i have to for my cousins in haiti who do n't even know what a college looks like , for my best friend raymond sitting in cell block nine instead of a university , for the nooses hanging my gpa by its neck . there is no other option . there is no other way . just , please , put the money in the bag . put the money in the bag . i just want to go to school , man . i just want to get my education . i just want to learn . i just want to grow . put the money in the bag , please . just put the money in the bag .

just keep the cycle going . make us pay for an education that will end up failing us . put us in debt so we 're giving back the money we earned from our back-breaking work .

in this piece , lissaint is staging a robbery to pay for

the story of the buddha ’ s life , like all of buddhism , is a story about confronting suffering . he was born between the sixth and fourth century b.c. , the son of a wealthy king in the himalayan foothills of nepal . it was prophesied that the young buddha — then called siddhartha gautama — would either become the emperor of india or a very holy man . since siddhartha ’ s father desperately wanted him to become the former , he kept the child isolated in a palace . young gautama had every imaginable luxury : jewels , servants , lotus ponds , even beautiful dancing women . for 29 years , gautama lived in bliss , protected from the smallest misfortunes of the outside world but then , he left the palace for short excursions . what he saw amazed him : first he met a sick man , then an aging man , and then a dying man . show these kind of people in india—add them to the same image one by one he was astounded to discover that these unfortunate people represented normal—indeed , inevitable—parts of the human condition that would one day touch him , too . horrified and fascinated , gautama made a fourth trip outside the palace walls—and encountered a holy man , who had learned to seek spiritual life in the midst of the vastness of human suffering . inspired by the holy man , gautama left the palace for good . he tried to learn from other holy men . he almost starved himself to death by avoiding all physical comforts and pleasures , as they did . perhaps unsurprisingly , it did not bring him solace from suffering . then he thought of a moment when he was a small boy : sitting by the river , he ’ d noticed that when the grass was cut , the insects and their eggs were trampled and destroyed . as a child , he ’ d felt a deep compassion for the tiny insects . reflecting on his childhood compassion , gautama felt a profound sense of peace . he ate , meditated , and finally reached the highest state of enlightenment : nirvana it refers to the “ blowing out ” of the flames of desire . with this , gautama had become the buddha , “ the awakened one ” . the buddha awoke by recognising that all of creation , from distraught ants to dying human beings , is unified by suffering . recognising this , the buddha discovered how to best approach suffering . first , one shouldn ’ t bathe in luxury , nor abstain from food and comforts altogether . instead , one ought to live in moderation . the buddha called this the middle way this allows for maximal concentration on cultivating compassion for others and seeking enlightenment next , the buddha described a path to transcending suffering called the four noble truths the first noble truth is the realisation that first prompted the buddha ’ s journey : that there is suffering and constant dissatisfaction in the world . the second is that this suffering is caused by our desires . as the buddha said , “ attachment is the root of all suffering. ” the third truth is that we can transcend suffering by removing or managing these desires . the buddha thus made the remarkable claim that we must change our outlook , not our circumstances . we are unhappy not because we don ’ t have enough money , love or status but because we are greedy , vain , and insecure . by re-orienting our mind we can grow to be content . the people become happier—superimpose smiles or use a second image of their face with the correct behaviour and what we now term a mindful attitude , we can also become better people . we can invert negative emotions and states of mind , turning ignorance into wisdom , anger into compassion , and greed into generosity . the fourth and final noble truth the buddha uncovered is that we can learn to move beyond suffering through what he termed the noble eightfold path . the eightfold path involves a series of aspects of behaving “ right ” and wisely : right view , right intention , right speech , right action , right livelihood , right effort , right mindfulness , and right concentration . what strikes the western observer is the notion that wisdom is a habit , not merely an intellectual realisation . one must exercise one ’ s nobler impulses on a regular basis , as one would train a limb . the moment of understanding is only one part of becoming a better person . after his death , the buddha ’ s followers collected his “ sutras ” ( sermons or sayings ) into scripture , and developed texts to guide followers in meditation , ethics , and mindful living . the monasteries that had developed during the buddha ’ s lifetime grew and multiplied , throughout china and east asia . for a time , buddhism was particularly uncommon in india itself , and only a few quiet groups of yellow-clad monks and nuns roamed the countryside , meditating quietly in nature . but then , in the 3rd century b.c. , an indian king named ashoka grew troubled by the wars he had fought and converted to buddhism . he sent monks and nuns far and wide to spread the practice . buddhist spiritual tradition spread across asia and eventually throughout the world . buddha ’ s followers divided into two main schools : theravada buddhism which colonised southeast asia , and mahayana buddhism which took hold in china and northeast asia . today , there are between a half and one and a half billion buddhists in both east and west following the buddha ’ s teachings and seeking a more enlightened and compassionate state of mind . intriguingly , the buddha ’ s teachings are important regardless of our spiritual identification . like the buddha , we are all born into the world not realising how much suffering it contains , and unable to fully comprehend that misfortune , sickness , and death will come to us too . as we grow older , this reality often feels overwhelming , and we may seek to avoid it altogether . but the buddha ’ s teachings remind us of the importance of facing suffering directly . we must do our best to liberate ourselves from the grip of our own desires , and recognise that suffering can be viewed as part of our common connection with others , spurring us to compassion and gentleness .

we can invert negative emotions and states of mind , turning ignorance into wisdom , anger into compassion , and greed into generosity . the fourth and final noble truth the buddha uncovered is that we can learn to move beyond suffering through what he termed the noble eightfold path . the eightfold path involves a series of aspects of behaving “ right ” and wisely : right view , right intention , right speech , right action , right livelihood , right effort , right mindfulness , and right concentration .

what is the noble eightfold path ?

hendrix , cobain and page . they can all shred , but how exactly do the iconic contraptions in their hands produce notes , rhythm , melody and music . when you pluck a guitar string , you create a vibration called a standing wave . some points on the string , called nodes , do n't move at all , while other points , anti-nodes , oscillate back and forth . the vibration translates through the neck and bridge to the guitar 's body , where the thin and flexible wood vibrates , jostling the surrounding air molecules together and apart . these sequential compressions create sound waves , and the ones inside the guitar mostly escape through the hole . they eventually propagate to your ear , which translates them into electrical impulses that your brain interprets as sound . the pitch of that sound depends on the frequency of the compressions . a quickly vibrating string will cause a lot of compressions close together , making a high-pitched sound , and a slow vibration produces a low-pitched sound . four things affect the frequency of a vibrating string : the length , the tension , the density and the thickness . typical guitar strings are all the same length , and have similar tension , but vary in thickness and density . thicker strings vibrate more slowly , producing lower notes . each time you pluck a string , you actually create several standing waves . there 's the first fundamental wave , which determines the pitch of the note , but there are also waves called overtones , whose frequencies are multiples of the first one . all these standing waves combine to form a complex wave with a rich sound . changing the way you pluck the string affects which overtones you get . if you pluck it near the middle , you get mainly the fundamental and the odd multiple overtones , which have anti-nodes in the middle of the string . if you pluck it near the bridge , you get mainly even multiple overtones and a twangier sound . the familiar western scale is based on the overtone series of a vibrating string . when we hear one note played with another that has exactly twice its frequency , its first overtone , they sound so harmonious that we assign them the same letter , and define the difference between them as an octave . the rest of the scale is squeezed into that octave divided into twelve half steps whose frequency is each 2^ ( 1/12 ) higher than the one before . that factor determines the fret spacing . each fret divides the string 's remaining length by 2^ ( 1/12 ) , making the frequencies increase by half steps . fretless instruments , like violins , make it easier to produce the infinite frequencies between each note , but add to the challenge of playing intune . the number of strings and their tuning are custom tailored to the chords we like to play and the physiology of our hands . guitar shapes and materials can also vary , and both change the nature and sound of the vibrations . playing two or more strings at the same time allows you to create new wave patterns like chords and other sound effects . for example , when you play two notes whose frequencies are close together , they add together to create a sound wave whose amplitude rises and falls , producing a throbbing effect , which guitarists call the beats . and electric guitars give you even more to play with . the vibrations still start in the strings , but then they 're translated into electrical signals by pickups and transmitted to speakers that create the sound waves . between the pickups and speakers , it 's possible to process the wave in various ways , to create effects like distortion , overdrive , wah-wah , delay and flanger . and lest you think that the physics of music is only useful for entertainment , consider this . some physicists think that everything in the universe is created by the harmonic series of very tiny , very tense strings . so might our entire reality be the extended solo of some cosmic jimi hendrix ? clearly , there 's a lot more to strings than meets the ear .

if you pluck it near the bridge , you get mainly even multiple overtones and a twangier sound . the familiar western scale is based on the overtone series of a vibrating string . when we hear one note played with another that has exactly twice its frequency , its first overtone , they sound so harmonious that we assign them the same letter , and define the difference between them as an octave .

western scale is based on the overtone series of a vibrating string which contains 12 notes in between octaves ( chromatic scale : c , c # , d , d # , e , f , f # , g , g # , a , a # , b , c ) . design another possible scale .

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 .

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 .

describe the process of wave shoaling and why you can ’ t see tsunamis far from shore .

behold the human brain , it 's lumpy landscape visibly split into a left and right side . this structure has inspired one of the most pervasive ideas about the brain , that the left side controls logic and the right , creativity . and yet , this is a myth unsupported by scientific evidence . so how did this misleading idea come about , and what does it get wrong ? it 's true that the brain has a right and a left side . this is most apparent with the outer layer , or the cortex . internal regions , like the striatum , hypothalamus , thalamus , and brain stem appear to be made from continuous tissue , but in fact , they 're also organized with left and right sides . the left and the right sides of the brain do control different body functions , such as movement and sight . the brain 's right side controls the motion of the left arm and leg and vice versa . the visual system is even more complex . each eye has a left and right visual field . both left visual fields are sent to the right side of the brain , and both right fields are sent to the left side . so the brain uses both sides to make a complete image of the world . scientists do n't know for sure why we have that crossing over . one theory is it began soon after animals developed more complex nervous systems because it gave the survival advantage of quicker reflexes . if an animal sees a predator coming from its left side , it 's best off escaping to the right . so we can say that vision and movement control are two systems that rely on this left-right structure , but problems arise when we over-extend that idea to logic and creativity . this misconception began in the mid-1800s when two neurologists , broca and wernicke , examined patients who had problems communicating due to injuries . the researchers found damage to the patients ' left temporal lobes , so they suggested that language is controlled by the left side of the brain . that captured the popular imagination . author robert louis stevenson then introduced the idea of a logical left hemisphere competing with an emotional right hemisphere represented by his characters dr. jekyll and mr. hyde . but this idea did n't hold up when doctors and scientists examined patients who were missing a hemisphere or had their two hemispheres separated . these patients showed a complete range of behaviors , both logical and creative . later research showed that one side of the brain is more active than the other for some functions . language is more localized to the left and attention to the right . so one side of the brain may do more work , but this varies by system rather than by person . there is n't any evidence to suggest that individuals have dominant sides of the brain , or to support the idea of a left-right split between logic and creativity . some people may be particularly logical or creative , but that has nothing to do with the sides of their brains . and even the idea of logic and creativity being at odds with each other does n't hold up well . solving complex math problems requires inspired creativity and many vibrant works of art have intricate logical frameworks . almost every feat of creativity and logic carries the mark of the whole brain functioning as one .

the left and the right sides of the brain do control different body functions , such as movement and sight . the brain 's right side controls the motion of the left arm and leg and vice versa . the visual system is even more complex .

the right side of the brain controls the movement of the :

translator : andrea mcdonough reviewer : jessica ruby these are grizzly bears . as you can see , they have big teeth and giant claws . but once you get to know them better , they 're not as ferocious as you might think . they play a critical role in the function of our ecosystems , but , unfortunately , their habitat is dwindling fast . in order to protect them , it 's important to know why do grizzlies choose certain areas to inhabit in the first place ? let 's look at a threatened population of bears living in the rocky mountains of canada . remember those giant claws ? well , they 're not for what you might think . they have evolved specifically for digging up energy-rich roots . it turns out that grizzlies eat a lot of plants . the ones that live here are almost vegetarians . you see , unlike other predators , grizzlies have diverse diets that can include up to 90 % vegetation . however , maintaining a diet of plants can be difficult . in these northern latitudes , you have distinct seasons where it 's really nice and green for part of the year and really cold for the other part . if you eat plants , you have almost nothing to eat for the cold part of the year . so , you either have to migrate like geese or hibernate like ground squirrels . grizzly bears hibernate . their behaviors are closely synchronized with the seasons . during the summer , they have to pack on enough body fat to survive the winter . without it , they would either starve or not have enough energy to successfully produce offspring . but when you eat mostly plants , it 's hard to gain a lot of weight . you need to be a highly effective forager . so , bears tightly follow the schedule of the plants and harvest them like crops at the point in time when they are at the most nutritious . this will happen in different places at different times . in autumn , a large male grizzly can eat up to 200,000 berries in a single day . therefore , to protect these bears , researchers want to take a closer look at the seasonal interaction between grizzlies and plants to identify areas of the highest quality habitat . this begins 700 kilometers up in space . up here , two nasa satellites carry sensors that are sensitive to the light reflected by vegetation . every species of plant reflects a unique combination of wave lengths , called spectral signatures that act like different chords on a piano but use light instead of sound . these signatures are recorded by the satellites every day and are combined like frames in a movie so you can watch the vegetation grow over an entire summer . simultaneously , the movements of bears wearing gps collars are monitored to see how they respond to the ebb and flow of nutrition throughout their habitat . now , instead of ordinary , static habitat maps , these dynamic , time-lapse habitat maps could be used for grizzly bear conservation in a number of ways . first , they help calculate the carrying capacity of the study area . in other words , how many bears can the remaining habitat support ? is there enough food to go around ? second , the maps show where bears will be foraging at specific times . we can prevent disturbing the bears and stressing them out by avoiding these areas during important feeding periods . finally , the maps can be used to predict the effects of climate change , where shifting annual temperatures will alter the rate of plant growth , throwing the bears ' precise foraging schedule out of whack . this provides less food and increases competition between bears . grizzlies are charismatic symbols of the wilderness . these habitat maps made from satellite imagery can not only help conserve grizzly bears but all sorts of different species . they aid us in understanding how ecosystems function , where they are threatened , and how we can try to keep our fragile , amazing planet intact .

simultaneously , the movements of bears wearing gps collars are monitored to see how they respond to the ebb and flow of nutrition throughout their habitat . now , instead of ordinary , static habitat maps , these dynamic , time-lapse habitat maps could be used for grizzly bear conservation in a number of ways . first , they help calculate the carrying capacity of the study area .

satellite images are used to create habitat maps that show the best areas for bears to dwell . what are some other ways these maps can be used to help conserve grizzly bear populations ?

the story goes something like this : a royal , rich or righteous individual , who otherwise happens to be a lot like us , makes a mistake that sends his life , and the lives of those around him , spiraling into ruin . sound familiar ? this is the classic story pattern for greek tragedy . for thousands of years , we 've spun spellbinding tales that fit this pattern , and modern storytellers around the world continue to do so . three critical story components influenced by aristotle 's `` poetics '' help us understand the allure . first , the tragic hero should be elevated in rank and ability , but also relatable . perhaps he is a king , or extraordinary in some other way . but because you and i are neither unusually good nor unusually bad , neither is the hero . and he has one particular tragic flaw , or hamartia , something like ambition , tyranny , stubbornness , or excess pride that causes him to make a critical mistake . and from that mistake comes disaster and downfall . as an example of these elements in action , let 's look to sophocles 's `` oedipus rex , '' about a man who does n't know he was adopted , and is warned by an oracle that he 's destined to murder his father and marry his mother . in trying to escape this fate , he kills a man who wo n't get out of his way at a crossroad . he then cleverly answers the riddle of the monstrous sphynx , freeing the kingdom of thebes from a plague . he marries the widowed queen and becomes king . but after he finds out that the murdered man was his father , and the queen he married is his mother , oedipus gouges out his eyes and retreats into the wilderness . at the beginning of his story , oedipus is elevated in ability , and he 's elevated in rank . he 's neither unusually evil nor saintly . he 's relatable . notice the height of the fall . once a king , but now homeless and blind . it 's more tragic , after all , if a king falls from a tall throne than if a jester falls off his step stool . oedipus 's tragic flaw is hubris , or excessive pride , and it causes him to attempt to avoid the fate prophesied for him , which is exactly what makes it happen . he 's a particularly unlucky soul because his mistake of killing his father and marrying his mother is done in complete ignorance . of course , these narrative principles transcend classic greek tragedy . in shakespeare 's canon , we see hamlet 's indecisiveness lead to a series of bad decisions , or perhaps non-decisions , that culminate in the death of almost every character in the play , and macbeth 's ambition catapults him to the top before sending him careening to his grave . even modern pop culture staples like `` game of thrones '' and `` the dark knight '' resonate with the tropes aristotle identified over 2000 years ago . so what 's the point of all of this suffering ? according to aristotle , and many scholars since , a good tragedy can evoke fear and pity in the audience : fear of falling victim to the same or similar catastrophe , and pity for the height of the hero 's downfall . ideally , after watching these tragic events unfold , we experience catharsis , a feeling of relief and emotional purification . not everyone agrees why this happens . it may be that empathizing with the hero allows us to experience and release strong emotions that we keep bottled up , or maybe it just lets us forget about our own problems for a little while . but regardless of how you feel when you watch poor oedipus , never has there been a more salient reminder that no matter how bad things get , at least you did n't kill your father and marry your mother .

so what 's the point of all of this suffering ? according to aristotle , and many scholars since , a good tragedy can evoke fear and pity in the audience : fear of falling victim to the same or similar catastrophe , and pity for the height of the hero 's downfall . ideally , after watching these tragic events unfold , we experience catharsis , a feeling of relief and emotional purification .

a good tragedy evokes fear in the audience , specifically fear of _____ ?

immortality . in movies , kings are always searching for the secret to immortality . but is immortality really a good thing ? to a ten-year-old boy , one year is the same as 10 % of his life . to his forty-year-old mother , one year is merely 2.5 % of her life . the same year , 365 days , can feel differently to different people . if we live until we 're 82 , that 's about 30,000 days . if this boy lives for 30,000 years , a year to him could feel like a day . and if this boy 's emotions sustain through the potential boredom of living for millions of years , he might become extremely lonely and sad , knowing he has and always will outlive everyone he has ever loved . but what if everyone were immortal ? well , first off , earth is only so big . so , where would we all live ? ( grunts ) `` excuse me ! '' `` that 's my face ! '' `` stop it ! '' `` pardon me . '' `` tight in here ! '' do you remember what you did last year or when you were five ? how much of your past have you forgotten ? if you have trouble remembering what you did when you were five , how will you remember what happened if you were alive a thousand years ago ? a million years ago ? we do n't remember every single detail of our past because our brains have a limited capacity and we replace useless memories , like middle school locker combinations , with relevant information . if this immortal boy finds a companion to fall in love with once every hundred years , he would have ten thousand girlfriends in a million years . and how many of those ten thousand girls ' names will he be able to remember ? this changes what a meaningful relationship means , does n't it ? another tricky thing about immortality : human beings have not always looked the same . this can be explained by darwin 's theory of evolution . for instance , if women find taller men more attractive , then more tall men would mate and have children , putting more tall genes in the gene pool . that means , in the next generation , more children will have the genes to be taller . repeat that process for a million years and the average height will be a lot taller than the average height today , assuming there 's no natural disaster that wipes out all the tall people . our ancestors were short , hairy apes . we still have body hair , but we do n't look like apes any more . if you 're the only person who is immortal , while everyone else keeps evolving , generation after generation , you will eventually look quite different than the people who surround you . `` hi , how you doing ? '' if one of our ancestors , apes , is still alive today , how many people will make friends with it instead of calling the museum of natural history ? and one more physical consideration for immortality : scars . after all , immortality does n't automatically translate to invincibility , it just means you can not die . but it does n't guarantee what condition you 'll be alive in . look at your body and count how many scars you have . if you have made this many permanent scars within your life , imagine how much damage you would have if you were one thousand years old ! now , there are approximately 185,000 amputation-related hospital discharges every year in the u.s . these injuries are due to accidents or illnesses . certainly the percentage is low comparing to the total population if you only live for a hundred years . however , if you 've been alive for over one million years , the odds of still having all your limbs are pretty slim . what about little accessories , like your eyes , your nose , your ears , fingers or toes ? what about your teeth ? what are the odds of you keeping your dental health for a hundred years ? a thousand years ? one million years ? you might end up looking like a horribly scuffed-up mr . potato head with missing pieces and dentures . so , are you sure you want to live forever ? now , which superpower physics lesson will you explore next ? shifting body size and content , super speed , flight , super strength , immortality , and -- invisibility .

but it does n't guarantee what condition you 'll be alive in . look at your body and count how many scars you have . if you have made this many permanent scars within your life , imagine how much damage you would have if you were one thousand years old !

which of these body parts can grow back if it is cut off ?

what do euclid , twelve-year-old einstein , and american president james garfield have in common ? they all came up with elegant proofs for the famous pythagorean theorem , the rule that says for a right triangle , the square of one side plus the square of the other side is equal to the square of the hypotenuse . in other words , a²+b²=c² . this statement is one of the most fundamental rules of geometry , and the basis for practical applications , like constructing stable buildings and triangulating gps coordinates . the theorem is named for pythagoras , a greek philosopher and mathematician in the 6th century b.c. , but it was known more than a thousand years earlier . a babylonian tablet from around 1800 b.c . lists 15 sets of numbers that satisfy the theorem . some historians speculate that ancient egyptian surveyors used one such set of numbers , 3 , 4 , 5 , to make square corners . the theory is that surveyors could stretch a knotted rope with twelve equal segments to form a triangle with sides of length 3 , 4 and 5 . according to the converse of the pythagorean theorem , that has to make a right triangle , and , therefore , a square corner . and the earliest known indian mathematical texts written between 800 and 600 b.c . state that a rope stretched across the diagonal of a square produces a square twice as large as the original one . that relationship can be derived from the pythagorean theorem . but how do we know that the theorem is true for every right triangle on a flat surface , not just the ones these mathematicians and surveyors knew about ? because we can prove it . proofs use existing mathematical rules and logic to demonstrate that a theorem must hold true all the time . one classic proof often attributed to pythagoras himself uses a strategy called proof by rearrangement . take four identical right triangles with side lengths a and b and hypotenuse length c. arrange them so that their hypotenuses form a tilted square . the area of that square is c² . now rearrange the triangles into two rectangles , leaving smaller squares on either side . the areas of those squares are a² and b² . here 's the key . the total area of the figure did n't change , and the areas of the triangles did n't change . so the empty space in one , c² must be equal to the empty space in the other , a² + b² . another proof comes from a fellow greek mathematician euclid and was also stumbled upon almost 2,000 years later by twelve-year-old einstein . this proof divides one right triangle into two others and uses the principle that if the corresponding angles of two triangles are the same , the ratio of their sides is the same , too . so for these three similar triangles , you can write these expressions for their sides . next , rearrange the terms . and finally , add the two equations together and simplify to get ab²+ac²=bc² , or a²+b²=c² . here 's one that uses tessellation , a repeating geometric pattern for a more visual proof . can you see how it works ? pause the video if you 'd like some time to think about it . here 's the answer . the dark gray square is a² and the light gray one is b² . the one outlined in blue is c² . each blue outlined square contains the pieces of exactly one dark and one light gray square , proving the pythagorean theorem again . and if you 'd really like to convince yourself , you could build a turntable with three square boxes of equal depth connected to each other around a right triangle . if you fill the largest square with water and spin the turntable , the water from the large square will perfectly fill the two smaller ones . the pythagorean theorem has more than 350 proofs , and counting , ranging from brilliant to obscure . can you add your own to the mix ?

some historians speculate that ancient egyptian surveyors used one such set of numbers , 3 , 4 , 5 , to make square corners . the theory is that surveyors could stretch a knotted rope with twelve equal segments to form a triangle with sides of length 3 , 4 and 5 . according to the converse of the pythagorean theorem , that has to make a right triangle , and , therefore , a square corner .

according to the converse of the pythagorean theorem , stretching a rope knotted into 12 equal segments to form a 3-4-5-segmented triangle would ensure which of the following is created ?

when you hear the word art , what comes to mind ? a painting , like the mona lisa , or a famous sculpture or a building ? what about a vase or a quilt or a violin ? are those things art , too , or are they craft ? and what 's the difference anyway ? it turns out that the answer is not so simple . a spoon or a saddle may be finely wrought , while a monument may be , well , uninspired . just as not every musical instrument is utilitarian , not every painting or statue is made for its own sake . but if it 's so tricky to separate art from craft , then why do we distinguish objects in this way ? you could say it 's the result of a dramatic historical turn of events . it might seem obvious to us today to view people , such as da vinci or michelangelo , as legendary artists , and , of course , they possessed extraordinary talents , but they also happened to live in the right place at the right time , because shortly before their lifetimes the concept of artists hardly existed . if you had chanced to step into a medieval european workshop , you would have witnessed a similar scene , no matter whether the place belonged to a stonemason , a goldsmith , a hatmaker , or a fresco painter . the master , following a strict set of guild statutes , insured that apprentices and journeymen worked their way up the ranks over many years of practice and well-defined stages of accomplishment , passing established traditions to the next generation . patrons regarded these makers collectively rather than individually , and their works from murano glass goblets , to flemish lace , were valued as symbols of social status , not only for their beauty , but their adherence to a particular tradition . and the customer who commissioned and paid for the work , whether it was a fine chair , a stone sculpture , a gold necklace , or an entire building , was more likely to get credit than those who designed or constructed it . it was n't until around 1400 that people began to draw a line between art and craft . in florence , italy , a new cultural ideal that would later be called renaissance humanism was beginning to take form . florentine intellectuals began to spread the idea of reformulating classical greek and roman works , while placing greater value on individual creativity than collective production . a few brave painters , who for many centuries , had been paid by the square foot , successfully petitioned their patrons to pay them on the basis of merit instead . within a single generation , people 's attitudes about objects and their makers would shift dramatically , such that in 1550 , giorgio vasari , not incidentally a friend of michelangelo , published an influential book called , `` lives of the most excellent painters , sculptors and architects , '' elevating these types of creators to rock star status by sharing juicy biographical details . in the mind of the public , painting , sculpture and architecture were now considered art , and their makers creative masterminds : artists . meanwhile , those who maintained guild traditions and faithfully produced candelsticks , ceramic vessels , gold jewelery or wrought iron gates , would be known communally as artisans , and their works considered minor or decorative arts , connoting an inferior status and solidifying the distinction between art and craft that still persists in the western world . so , if we consider a painting by rembrandt or picasso art , then where does that leave an african mask ? a chinese porclein vase ? a navajo rug ? it turns out that in the history of art , the value placed on innovation is the exception rather than the rule . in many cultures of the world , the distinction between art and craft has never existed . in fact , some works that might be considered craft , a peruvian rug , a ming dynasty vase , a totem pole , are considered the cultures ' preeminent visual forms . when art historians of the 19th century saw that the art of some non-western cultures did not change for thousands of years , they classified the works as primitive , suggesting that their makers were incapable of innovating and therefore were not really artists . what they did n't realize was that these makers were not seeking to innovate at all . the value of their works lay precisely in preserving visual traditions , rather than in changing them . in the last few decades , works such as quilts , ceramics and wood carvings have become more prominently included in art history textbooks and displayed in museums alongside paintings and sculpture . so maybe it 's time to dispense with vague terms like art and craft in favor of a word like visual arts that encompasses a wider array of aesthetic production . after all , if our appreciation of objects and their makers is so conditioned by our culture and history , then art and its definition are truly in the eye of the beholder .

in fact , some works that might be considered craft , a peruvian rug , a ming dynasty vase , a totem pole , are considered the cultures ' preeminent visual forms . when art historians of the 19th century saw that the art of some non-western cultures did not change for thousands of years , they classified the works as primitive , suggesting that their makers were incapable of innovating and therefore were not really artists . what they did n't realize was that these makers were not seeking to innovate at all .

when art historians of the nineteenth century saw that the art of some non-western cultures did not change for thousands of years , they classified the works as ________ .

we have historical records that allow us to know how the ancient greeks dressed , how they lived , how they fought ... but how did they think ? one natural idea is that the deepest aspects of human thought -- our ability to imagine , to be conscious , to dream -- have always been the same . another possibility is that the social transformations that have shaped our culture may have also changed the structural columns of human thought . we may all have different opinions about this . actually , it 's a long-standing philosophical debate . but is this question even amenable to science ? here i 'd like to propose that in the same way we can reconstruct how the ancient greek cities looked just based on a few bricks , that the writings of a culture are the archaeological records , the fossils , of human thought . and in fact , doing some form of psychological analysis of some of the most ancient books of human culture , julian jaynes came up in the '70s with a very wild and radical hypothesis : that only 3,000 years ago , humans were what today we would call schizophrenics . and he made this claim based on the fact that the first humans described in these books behaved consistently , in different traditions and in different places of the world , as if they were hearing and obeying voices that they perceived as coming from the gods , or from the muses ... what today we would call hallucinations . and only then , as time went on , they began to recognize that they were the creators , the owners of these inner voices . and with this , they gained introspection : the ability to think about their own thoughts . so jaynes 's theory is that consciousness , at least in the way we perceive it today , where we feel that we are the pilots of our own existence -- is a quite recent cultural development . and this theory is quite spectacular , but it has an obvious problem which is that it 's built on just a few and very specific examples . so the question is whether the theory that introspection built up in human history only about 3,000 years ago can be examined in a quantitative and objective manner . and the problem of how to go about this is quite obvious . it 's not like plato woke up one day and then he wrote , `` hello , i 'm plato , and as of today , i have a fully introspective consciousness . '' ( laughter ) and this tells us actually what is the essence of the problem . we need to find the emergence of a concept that 's never said . the word introspection does not appear a single time in the books we want to analyze . so our way to solve this is to build the space of words . this is a huge space that contains all words in such a way that the distance between any two of them is indicative of how closely related they are . so for instance , you want the words `` dog '' and `` cat '' to be very close together , but the words `` grapefruit '' and `` logarithm '' to be very far away . and this has to be true for any two words within the space . and there are different ways that we can construct the space of words . one is just asking the experts , a bit like we do with dictionaries . another possibility is following the simple assumption that when two words are related , they tend to appear in the same sentences , in the same paragraphs , in the same documents , more often than would be expected just by pure chance . and this simple hypothesis , this simple method , with some computational tricks that have to do with the fact that this is a very complex and high-dimensional space , turns out to be quite effective . and just to give you a flavor of how well this works , this is the result we get when we analyze this for some familiar words . and you can see first that words automatically organize into semantic neighborhoods . so you get the fruits , the body parts , the computer parts , the scientific terms and so on . the algorithm also identifies that we organize concepts in a hierarchy . so for instance , you can see that the scientific terms break down into two subcategories of the astronomic and the physics terms . and then there are very fine things . for instance , the word astronomy , which seems a bit bizarre where it is , is actually exactly where it should be , between what it is , an actual science , and between what it describes , the astronomical terms . and we could go on and on with this . actually , if you stare at this for a while , and you just build random trajectories , you will see that it actually feels a bit like doing poetry . and this is because , in a way , walking in this space is like walking in the mind . and the last thing is that this algorithm also identifies what are our intuitions , of which words should lead in the neighborhood of introspection . so for instance , words such as `` self , '' `` guilt , '' `` reason , '' `` emotion , '' are very close to `` introspection , '' but other words , such as `` red , '' `` football , '' `` candle , '' `` banana , '' are just very far away . and so once we 've built the space , the question of the history of introspection , or of the history of any concept which before could seem abstract and somehow vague , becomes concrete -- becomes amenable to quantitative science . all that we have to do is take the books , we digitize them , and we take this stream of words as a trajectory and project them into the space , and then we ask whether this trajectory spends significant time circling closely to the concept of introspection . and with this , we could analyze the history of introspection in the ancient greek tradition , for which we have the best available written record . so what we did is we took all the books -- we just ordered them by time -- for each book we take the words and we project them to the space , and then we ask for each word how close it is to introspection , and we just average that . and then we ask whether , as time goes on and on , these books get closer , and closer and closer to the concept of introspection . and this is exactly what happens in the ancient greek tradition . so you can see that for the oldest books in the homeric tradition , there is a small increase with books getting closer to introspection . but about four centuries before christ , this starts ramping up very rapidly to an almost five-fold increase of books getting closer , and closer and closer to the concept of introspection . and one of the nice things about this is that now we can ask whether this is also true in a different , independent tradition . so we just ran this same analysis on the judeo-christian tradition , and we got virtually the same pattern . again , you see a small increase for the oldest books in the old testament , and then it increases much more rapidly in the new books of the new testament . and then we get the peak of introspection in `` the confessions of saint augustine , '' about four centuries after christ . and this was very important , because saint augustine had been recognized by scholars , philologists , historians , as one of the founders of introspection . actually , some believe him to be the father of modern psychology . so our algorithm , which has the virtue of being quantitative , of being objective , and of course of being extremely fast -- it just runs in a fraction of a second -- can capture some of the most important conclusions of this long tradition of investigation . and this is in a way one of the beauties of science , which is that now this idea can be translated and generalized to a whole lot of different domains . so in the same way that we asked about the past of human consciousness , maybe the most challenging question we can pose to ourselves is whether this can tell us something about the future of our own consciousness . to put it more precisely , whether the words we say today can tell us something of where our minds will be in a few days , in a few months or a few years from now . and in the same way many of us are now wearing sensors that detect our heart rate , our respiration , our genes , on the hopes that this may help us prevent diseases , we can ask whether monitoring and analyzing the words we speak , we tweet , we email , we write , can tell us ahead of time whether something may go wrong with our minds . and with guillermo cecchi , who has been my brother in this adventure , we took on this task . and we did so by analyzing the recorded speech of 34 young people who were at a high risk of developing schizophrenia . and so what we did is , we measured speech at day one , and then we asked whether the properties of the speech could predict , within a window of almost three years , the future development of psychosis . but despite our hopes , we got failure after failure . there was just not enough information in semantics to predict the future organization of the mind . it was good enough to distinguish between a group of schizophrenics and a control group , a bit like we had done for the ancient texts , but not to predict the future onset of psychosis . but then we realized that maybe the most important thing was not so much what they were saying , but how they were saying it . more specifically , it was not in which semantic neighborhoods the words were , but how far and fast they jumped from one semantic neighborhood to the other one . and so we came up with this measure , which we termed semantic coherence , which essentially measures the persistence of speech within one semantic topic , within one semantic category . and it turned out to be that for this group of 34 people , the algorithm based on semantic coherence could predict , with 100 percent accuracy , who developed psychosis and who will not . and this was something that could not be achieved -- not even close -- with all the other existing clinical measures . and i remember vividly , while i was working on this , i was sitting at my computer and i saw a bunch of tweets by polo -- polo had been my first student back in buenos aires , and at the time he was living in new york . and there was something in this tweets -- i could not tell exactly what because nothing was said explicitly -- but i got this strong hunch , this strong intuition , that something was going wrong . so i picked up the phone , and i called polo , and in fact he was not feeling well . and this simple fact , that reading in between the lines , i could sense , through words , his feelings , was a simple , but very effective way to help . what i tell you today is that we 're getting close to understanding how we can convert this intuition that we all have , that we all share , into an algorithm . and in doing so , we may be seeing in the future a very different form of mental health , based on objective , quantitative and automated analysis of the words we write , of the words we say . gracias . ( applause )

so for instance , you want the words `` dog '' and `` cat '' to be very close together , but the words `` grapefruit '' and `` logarithm '' to be very far away . and this has to be true for any two words within the space . and there are different ways that we can construct the space of words . one is just asking the experts , a bit like we do with dictionaries .

define mariano sigman 's concept of 'a space of words . '

the area surrounding the north pole may seem like a frozen and desolate environment where nothing ever changes . but it is actually a complex and finely balanced natural system , and its extreme location makes it vulnerable to feedback processes that can magnify even tiny changes in the atmosphere . in fact , scientists often describe the arctic as the canary in the coal mine when it comes to predicting the impact of climate change . one major type of climate feedback involves reflectivity . white surfaces , like snow and ice , are very effective at reflecting the sun 's energy back into space , while darker land and water surfaces absorb much more incoming sunlight . when the arctic warms just a little , some of the snow and ice melts , exposing the ground and ocean underneath . the increased heat absorbed by these surfaces causes even more melting , and so on . and although the current situation in the arctic follows the warming pattern , the opposite is also possible . a small drop in temperatures would cause more freezing , increasing the amount of reflective snow and ice . this would result in less sunlight being absorbed , and lead to a cycle of cooling , as in previous ice ages . arctic sea ice is also responsible for another feedback mechanism through insulation . by forming a layer on the ocean 's surface , the ice acts as a buffer between the frigid arctic air and the relatively warmer water underneath . but when it thins , breaks , or melts in any spot , heat escapes from the ocean , warming the atmosphere and causing more ice to melt in turn . both of these are examples of positive feedback loops , not because they do something good , but because the initial change is amplified in the same direction . a negative feedback loop , on the other hand , is when the initial change leads to effects that work in the opposite direction . melting ice also causes a type of negative feedback by releasing moisture into the atmosphere . this increases the amount and thickness of clouds present , which can cool the atmosphere by blocking more sunlight . but this negative feedback loop is short-lived , due to the brief arctic summers . for the rest of the year , when sunlight is scarce , the increased moisture and clouds actually warm the surface by trapping the earth 's heat , turning the feedback loop positive for all but a couple of months . while negative feedback loops encourage stability by pushing a system towards equilibrium , positive feedback loops destabilize it by enabling larger and larger deviations . and the recently increased impact of positive feedbacks may have consequences far beyond the arctic . on a warming planet , these feedbacks ensure that the north pole warms at a faster rate than the equator . the reduced temperature differences between the two regions may lead to slower jet stream winds and less linear atmospheric circulation in the middle latitudes , where most of the world 's population lives . many scientists are concerned that shifts in weather patterns will last longer and be more extreme , with short term fluctuations becoming persistent cold snaps , heat waves , droughts and floods . so the arctic sensitivity does n't just serve as an early warning alarm for climate change for the rest of the planet . its feedback loops can affect us in much more direct and immediate ways . as climate scientists often warn , what happens in the arctic does n't always stay in the arctic .

while negative feedback loops encourage stability by pushing a system towards equilibrium , positive feedback loops destabilize it by enabling larger and larger deviations . and the recently increased impact of positive feedbacks may have consequences far beyond the arctic . on a warming planet , these feedbacks ensure that the north pole warms at a faster rate than the equator .

albedo feedbacks are strongest when :

so , i think all good tornado talks need to start with an awesome tornado shot . and this is not that awesome tornado shot . that was the first tornado i ever saw , it was really cool , really scary , and i 'm showing it to you guys because that 's why i got into the field in the first place . so even though it 's a bad photograph , it was really cool to be out there the first time . but now i 'm taking real tornado footage . fast forward a few years . this is a few years ago , during a field project called vortex2 , where myself and a bunch of other scientists were out there , surrounding tornadoes with different types of instrumentation and trying to figure out how tornadoes form . it 's a big question we 're trying to answer . it sounds like a very basic one , but it 's something we 're still trying to figure out . we 're also still trying to figure out what the winds are like near the surface . we know what the winds are like above building level , but we really do n't know what they 're like at the surface and how that relates to what we 're seeing above building level . most tornadoes form from what we call supercell thunderstorms . supercell thunderstorms are what you commonly think of as tornado-raising storms . they 're big , rotating thunderstorms that happen a lot of times in the midsection of the united states . but the problem is that even though they 're rotating up above , it does n't mean they 're rotating at the surface . and when we look at these storms and at these pictures and at the data we have , they all kind of look the same . and it 's really problematic if we 're trying to make tornado forecasts or warnings , because we only want to warn or forecast about the storms that are going to actually make a tornado . one of the big , critical distinguishing features , we think , between these storms , is something about the rear-flank downdraft . so these big rotating thunderstorms have this downdraft that wraps around the rear edge of it , hence the `` rear-flank '' downdraft . but we think how warm that is , how buoyant that air is , and then also how strong the updraft it 's wrapping into , makes a big difference on whether or not it 's going to make a tornado . there 's a lot more that goes into it -- i 'll tell you about that in a second . once you actually get a tornado , again , the problem that we have is getting measurements near the surface . it 's really hard to get measurements near the surface -- most people do n't want to drive into tornadoes . there are a few exceptions ; you might have seen them on tv shows . but most people do n't want to do that . even getting instrumentation in the path of the tornado is pretty tricky , too . because , again , you do n't want to be that close to a tornado because sometimes the winds around the tornado are strong as well . so getting information , that critical location , is key for us because , again , we do n't know if the winds that we 're seeing above ground level , way above building level , actually map to the surface , if they 're stronger , weaker , or about the same as what we 're seeing above buildings . the way we get at answering a lot of these questions -- and i 'm an observationalist ; i love to get out in the field , and collect data on tornadoes -- we compile a lot of observations . i work with this group who operates mobile radars , and they 're exactly what they say -- basically , a radar on the back of a big blue truck , and we drive up really close to tornadoes to map out the winds . we map out the precipitation . we map out all these different things that are going on in order to better understand the processes in these storms . and that bottom there , that 's what a tornado looks like when you 're looking at it with a mobile radar , and really close . also , what we do is a lot of modeling , so we do a lot of computer models and simulations , because the atmosphere is governed by the laws of physics . so we can model the laws of physics and see where the tornado might go , where the storm might go , how strong the winds are near the surface and not actually have to go out in the field . but of course , we want to have both observations and modeling to move forward with the science . so , i showed you that video earlier that went real quick , too . this is what it looks like , looking at it with a radar . so you saw it visually , but this is what i get really excited about when i see now in the field , stuff that looks like this . the really exciting thing about looking at stuff like this is that we caught this storm from when it did n't make a tornado to when it made a tornado and intensified and when it dissipated . this is the one of the rare data sets that we have out there that were able to study the entire life cycle of a tornado . i talked about how we think that rear-flank downdraft is important because it tilts , there 's a lot of spin in the atmosphere , but the problem with all this spin in the atmosphere is it needs to be oriented vertically , because that 's what tornadoes are doing , and it needs to orientated vertically near the ground . so we think this rear-flank downdraft just pulses . and these pulses in this rear-flank downdraft , we think , are very important for converging that rotation , but also getting that rotation into the right place . other things we 've learned is that we have gotten a bunch of fortuitous measurements in the path of the tornadoes and very near the surface . and we found out that the winds near the surface are actually pretty comparable to what we 're seeing 30 , 40 meters above ground level . so there 's not a big reduction in what we 're seeing above the surface to what we 're seeing at house level . and that was a pretty surprising finding for us , because we kind of assumed that the winds decrease pretty substantially near the surface . i 'm going to end with this real quick . and this is not my last tornado i ever saw , but i really like this image , because this was taken with one of those mobile radars i was talking about . this is a tornado , not a hurricane , and this is what it looks like when you 're really close to it . and i find this amazing , that we can actually take technology this close to these types of storms and see these inner workings . and for those of you who look at tornado images often , you can see there 's a lot going on -- there 's rain spiraling , and you can actually see the debris cloud associated with this tornado . i look forward to the future and future technologies and being able to learn a lot more about these storms , as the world advances , as you guys contribute to the science and we 're able to really learn more about how tornadoes form . thank you . ( applause )

so , i think all good tornado talks need to start with an awesome tornado shot . and this is not that awesome tornado shot . that was the first tornado i ever saw , it was really cool , really scary , and i 'm showing it to you guys because that 's why i got into the field in the first place .

what are the current theories on tornado formation ? describe how these theories can be tested . what additional data is needed to test these theories ?

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 .

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 .

all of the following scientists were involved in the history of aspirin , except which one ?

if you lined up all the blood vessels in your body , they 'd be 95,000 kilometers long and everyday , they carry the equivalent of over 7,500 liters of blood , though that 's actually the same four or five liters recycled over and over , delivering oxygen , and precious nutrients like glucose and amino acids to the body 's tissues . all that blood exerts a force on the muscular walls of the blood vessels . that force is called blood pressure , and it rises and falls with the phases of the heartbeat . it 's highest during systole , when the heart contracts to force blood through the arteries . this is your systolic blood pressure . when the heart is at rest between beats , blood pressure falls to its lowest value , the diastolic pressure . a typical healthy individual produces a systolic pressure between 90 and 120 millimeters of mercury , and diastolic pressure between 60 and 80 . taken together , a normal reading is a bit less than 120 over 80 . the blood traverses the landscape of the body through the pipes of the circulatory system . in any plumbing system , several things can increase the force on the walls of the pipes : the properties of the fluid , extra fluid , or narrower pipes . so if the blood thickens , a higher pressure is needed to push it , so the heart will pump harder . a high-salt diet will lead to a similar result . the salt promotes water retention , and the extra fluid increases the blood volume and blood pressure , and stress , like the fight or flight response , releases hormones , like epinephrine and norepinephrine that constrict key vessels , increasing the resistance to flow and raising the pressure upstream . blood vessels can usually handle these fluctuations easily . elastic fibers embedded in their walls make them resilient , but if your blood pressure regularly rises above about 140 over 90 , what we call hypertension , and stays there , it can cause serious problems . that 's because the extra strain on the arterial wall can produce small tears . when the injured tissue swells up , substances that respond to the inflammation , like white blood cells , collect around the tears . fat and cholesterol floating in the blood latch on , too , eventually building up to form a plaque that stiffens and thickens the inner arterial wall . this condition is called atherosclerosis , and it can have dangerous consequences . if the plaque ruptures , a blood clot forms on top of the tear , clogging the already narrowed pipe . if the clot is big enough , it can completely block the flow of oxygen and nutrients to cells downstream . in vessels that feed the heart , that will cause a heart attack , when oxygen-deprived cardiac muscle cells start to die . if the clot cuts off blood flow to the brain , it causes a stroke . dangerously clogged blood vessels can be widened by a procedure called an angioplasty . there , doctors thread a wire through the vessel to the obstructed site , and then place a deflated balloon catheter over the wire . when the balloon is inflated , it forces the passageway open again . sometimes a rigid tube called a stent is placed in a vessel to held hold it open , letting the blood flow freely to replenish the oxygen-starved cells downstream . staying flexible under pressure is a tough job for arteries . the fluid they pump is composed of substances that can get sticky and clog them , and your typical healthy heart beats about 70 times a minute , and at least 2.5 billion times during an average lifetime . that may sound like an insurmountable amount of pressure , but do n't worry , your arteries are well suited for the challenge .

if the clot cuts off blood flow to the brain , it causes a stroke . dangerously clogged blood vessels can be widened by a procedure called an angioplasty . there , doctors thread a wire through the vessel to the obstructed site , and then place a deflated balloon catheter over the wire .

dangerously-clogged blood vessels can be widened by a procedure called a ( n ) _____ .

space : it 's where things happen . time : it 's when things happen . we can measure where things are and when things take place , but in modern physics , we realize when and where are actually part of the same question . because when it comes to understanding the universe , we need to replace three-dimensional space plus time with a single concept : four-dimensional space-time . we 'll explore and explain space-time in this series of animations . animations ? yeah . well , we 're not very animated are we ? sure we are ! look , i can go from here to here . whoa ! how 'd you get from here to there ? how fast did you go ? did you run ? walk ? did you even go in a straight line ? ah ! to answer that , you 'll need to make our cartoon physics look more like physics physics . you 'll need more panels . more panels , please ! okay , in each panel , andrew 's in a slightly different place . so i can see each one records where andrew is at a different time . that 's great . but it would be easier to see what 's going on if we could cut out all the hundreds of panels and stack them up like a flip book . right , now let 's flip through the book so that we can see one panel after another getting through 24 in every second . see ! i told you it was an animation . now you can see me walking along . drawing all those panels and putting them into a flip book is just one way of recording the way i 'm moving . it 's how animation , or even movies , work . as it turns out , at my walking speed , it takes two seconds to get past each fence post , and they 're spaced four meters apart . so we can calculate my velocity -- how fast i 'm moving through space - - is two meters per second . but i could 've worked that out from the panels without flipping through them . from the edge of the flip book , you can see all of the copies of the fence posts and all of the copies of andrew and he 's in a slightly different place in each one . now we can predict everything that will happen to andrew when we flip through 24 pages every second , including his speed of motion , just by looking . no need to flip through at all . the edge of this flip book is known as a space-time diagram of andrew 's journey through , you guessed it , space and time . we call the line that represents andrew 's journey his world line . if i jog instead of walking , i might be able to get past a fence post every second . he 's not very athletic . anyway , when we look at this new flip book from the edge , we can do the same analysis as before . the world line for andrew jogging is more tilted over than the world line for andrew walking . we can tell he 's going twice as fast as before without flipping the panels . but here 's the clever bit . in physics , it 's always good to view things from other perspectives . after all , the laws of physics should be the same for everyone or no one will obey them . so let 's rethink our cartoon and have the camera follow andrew jogging along as the fence posts approach and pass behind him . still viewing it as a flip book of panels , we do n't need to redraw anything . we simply move all of the cutout frames slightly until andrew 's tilted world line becomes completely vertical . to see why , let 's flip it . yes , now i 'm stationery , just jogging on the spot , in the center of the panel . on the edge of the flip book , my world line was going straight upwards . the fence posts are coming past me . it 's now their world lines that are tilted . this rearrangement of the panels is known as a galilean transformation , and it lets us analyze physics from someeone else 's perspective . in this case , mine . after all , it 's always good to see things from other points of view , especially when the viewers are moving at different speeds . so long as the speeds are n't too high . if you 're a cosmic ray moving at the speed of light , our flip book of your point of view falls apart . to stop that from happening , we 'll have to glue panels together . instead of a stack of separate panels , we 'll need a solid block of space-time , which we 'll come to in the next animation .

space : it 's where things happen . time : it 's when things happen . we can measure where things are and when things take place , but in modern physics , we realize when and where are actually part of the same question .

things that happen later will therefore appear :

`` war and peace , '' a tome , a slog , the sort of book you should n't read in bed because if you fall asleep , it could give you a concussion , right ? only partly . `` war and peace '' is a long book , sure , but it 's also a thrilling examination of history , populated with some of the deepest , most realistic characters you 'll find anywhere . and if its length intimidates you , just image how poor tolstoy felt . in 1863 , he set out to write a short novel about a political dissident returning from exile in siberia . five years later , he had produced a 1,200 page epic featuring love stories , battlefields , bankruptcies , firing squads , religious visions , the burning of moscow , and a semi-domesticated bear , but no exile and no political dissidents . here 's how it happened . tolstoy , a volcanic soul , was born to a famously eccentric aristocratic family in 1828 . by the time he was 30 , he had already dropped out of kazan university , gambled away the family fortune , joined the army , written memoirs , and rejected the literary establishment to travel europe . he then settled into yasnaya polyana , his ancestral mansion , to write about the return of the decembrists , a band of well-born revolutionaries pardoned in 1856 after 30 years in exile . but , tolstoy thought , how could he tell the story of the decembrists return from exile without telling the story of 1825 , when they revolted against the conservative tsar nicholas i ? and how could he do that without telling the story of 1812 , when napoleon 's disastrous invasion of russia helped trigger the authoritarianism the decembrists were rebelling against ? and how could he tell the story of 1812 without talking about 1805 , when the russians first learned of the threat napoleon posed after their defeat at the battle of austerlitz ? so tolstoy began writing , both about the big events of history and the small lives that inhabit those events . he focused on aristocrats , the class he knew best . the book only occasionally touches on the lives of the vast majority of the russian population , who were peasants , or even serfs , farmers bound to serve the owners of the land on which they lived . `` war and peace '' opens on the eve of war between france and russia . aristocrats at a cocktail party fret about the looming violence , but then change the topic to those things aristocrats always seem to care about : money , sex , and death . this first scene is indicative of the way the book bounces between the political and personal over an ever-widening canvas . there are no main characters in `` war and peace . '' instead , readers enter a vast interlocking web of relationships and questions . will the hapless and illegitimate son of a count marry a beautiful but conniving princess ? will his only friend survive the battlefields of austria ? and what about that nice young girl falling in love with both men at once ? real historical figures mix and mingle with all these fictional folk , napoleon appears several times , and even one of tolstoy 's ancestors plays a background part . but while the characters and their psychologies are gripping , tolstoy is not afraid to interrupt the narrative to pose insightful questions about history . why do wars start ? what are good battlefield tactics ? do nations rise and fall on the actions of so-called great men like napoleon , or are there larger cultural and economic forces at play ? these extended digressions are part of what make `` war and peace '' so panoramic in scope . but for some 19th century critics , this meant `` war and peace '' barely felt like a novel at all . it was a `` large , loose , baggy monster , '' in the words of henry james . tolstoy , in fact , agreed . to him , novels were a western european form . russian writers had to write differently because russian people lived differently . `` what is 'war and peace ' ? '' he asked . `` it is not a novel . still less an epic poem . still less a historical chronicle . 'war and peace ' is what the author wanted and was able to express in the form in which it was expressed . '' it is , in other words , the sum total of tolstoy 's imaginative powers , and nothing less . by the time `` war and peace '' ends , tolstoy has brought his characters to the year 1820 , 36 years before the events he originally hoped to write about . in trying to understand his own times , he had become immersed in the years piled up behind him . the result is a grand interrogation into history , culture , philosophy , psychology , and the human response to war .

russian writers had to write differently because russian people lived differently . `` what is 'war and peace ' ? '' he asked .

henry james thought `` war and peace '' ’ s mix of philosophical essays and fiction narrative made it :

if you 've had surgery , you might remember starting to count backwards from ten , nine , eight , and then waking up with the surgery already over before you even got to five . and it might seem like you were asleep , but you were n't . you were under anesthesia , which is much more complicated . you were unconscious , but you also could n't move , form memories , or , hopefully , feel pain . without being able to block all those processes at once , many surgeries would be way too traumatic to perform . ancient medical texts from egypt , asia and the middle east all describe early anesthetics containing things like opium poppy , mandrake fruit , and alcohol . today , anesthesiologists often combine regional , inhalational and intravenous agents to get the right balance for a surgery . regional anesthesia blocks pain signals from a specific part of the body from getting to the brain . pain and other messages travel through the nervous system as electrical impulses . regional anesthetics work by setting up and electrical baracade . they bind to the proteins in neurons ' cell membranes that let charged particles in and out , and lock out positively charged particles . one compound that does this is cocaine , whose painkilling effects were discovered by accident when an ophthalmology intern got some on his tongue . it 's still occasionally used as an anesthetic , but many of the more common regional anesthetics have a similar chemical structure and work the same way . but for major surgeries where you need to be unconscious , you 'll want something that acts on the entire nervous system , including the brain . that 's what inhalational anesthetics do . in western medicine , diethyl ether was the first common one . it was best known as a recreational drug until doctors started to realize that people sometimes did n't notice injuries they received under the influence . in the 1840s , they started sedating patients with ether during dental extractions and surgeries . nitrous oxide became popular in the decades that followed and is still used today . although ether derivatives , like sevoflurane , are more common . inhalational anesthesia is usually supplemented with intravenous anesthesia , which was developed in the 1870s . common intravenous agents include sedatives , like propofol , which induce unconsciousness , and opioids , like fentanyl , which reduce pain . these general anesthetics also seem to work by affecting electrical signals in the nervous system . normally , the brain 's electrical signals are a chaotic chorus as different parts of the brain communicate with each other . that connectivity keeps you awake and aware . but as someone becomes anesthetized , those signals become calmer and more organized , suggesting that different parts of the brain are n't talking to each other anymore . there 's a lot we still do n't know about exactly how this happens . several common anesthetics bind to the gaba-a receptor in the brain 's neurons . they hold the gateway open , letting negatively charged particles flow into the cell . negative charge builds up and acts like a log jam , keeping the neuron from transmitting electrical signals . the nervous system has lots of these gated channels , controlling pathways for movement , memory , and consciousness . most anesthetics probably act on more than one , and they do n't act on just the nervous system . many anesthetics also affect the heart , lungs , and other vital organs . just like early anesthetics , which included familiar poisons like hemlock and aconite , modern drugs can have serious side effects . so an anesthesiologist has to mix just the right balance of drugs to create all the features of anesthesia , while carefully monitoring the patient 's vital signs , and adjusting the drug mixture as needed . anesthesia is complicated , but figuring out how to use it allowed for the development of new and better surgical techniques . surgeons could learn how to routinely and safely perform c-sections , reopen blocked arteries , replace damaged livers and kidneys , and many other life-saving operations . and each year , new anesthesia techniques are developed that will ensure more and more patients survive the trauma of surgery .

there 's a lot we still do n't know about exactly how this happens . several common anesthetics bind to the gaba-a receptor in the brain 's neurons . they hold the gateway open , letting negatively charged particles flow into the cell .

several common anesthetics bind to this receptor in the brain to cause sedation

is there a disease that makes us love cats , and do you have it ? maybe , and it 's more likely than you 'd think . we 're talking about toxoplasmosis , a disease caused by toxoplasma gondii . like all parasites , toxoplasma lives at the expense of its host , and needs its host to produce offspring . to do that , toxo orchestrates a brain manipulation scheme involving cats , their rodent prey , and virtually all other birds and mammals , including humans . documented human infections go as far back as ancient egypt . we found samples in mummies . today , about a third of the world 's population is infected , and most of them never even know it . in healthy people , symptoms often do n't show up at all . when they do , they 're mild and flu-like . but those are just the physical symptoms . toxoplasma also nestles into our brains and meddles with our behavior behind the scenes . to understand why , let 's take a look at the parasite 's life cycle . while the parasite can multiply in practically any host , it can only reproduce sexually in the intestines of cats . the offspring , called oocysts , are shed in the cat 's feces . a single cat can shed up to a hundred million oocysts . if another animal , like a mouse , accidentally ingests them , they 'll invade the mouse 's tissues and mature to form tissue cysts . if the mouse gets eaten by a cat , the tissue cysts become active and release offspring that mate to form new oocysts , completing the cycle . but there 's a problem . a mouse 's natural desire to avoid a cat makes it tough to close this loop . toxoplasma has a solution for that . the parasites invade white blood cells to hitch a ride to the brain where they seem to override the innate fear of predators . infected rodents are more reckless and have slower reaction times . strangest of all , they 're actually attracted to feline urine , which probably makes them more likely to cross paths with a cat and help the parasite complete its life cycle . how does the parasite pull this off ? although the exact mechanism is n't known , toxo appears to increase dopamine , a brain neurotransmitter that is involved in novelty-seeking behavior . thus , one idea is that toxo tinkers with neurotransmitters , the chemical signals that modulate emotions . the result ? fatal attraction . but mice are n't the only animals that end up with these parasites , and that 's where humans , and all of toxo 's other hosts , come in . we can accidentally ingest oocysts in contaminated water , or unwashed produce , or from playing in sandboxes , or cleaning out litter boxes . this is behind the common recommendation that pregnant women not change cat litter . toxo can cause serious birth defects . we can also get toxo from eating undercooked meat from other animals that picked up some oocysts . and it turns out that toxo can mess with our brains , too . studies have found connections between toxo and schizophrenia , biopolar disorder , obsessive compulsive disorder , and aggression . it also slows reactions and decreases concentration , which may be why one study found that people involved in traffic accidents were almost three times more likely to have toxoplasma . so is toxo manipulating our brains as an evolutionary strategy to get predatory cats to eat us ? or are our brains just similar enough to a rodent 's that the same neurological tricks that lure them in catch us in the net , too ? and is toxo the reason so many people love cats and keep them as pets ? well , the jury 's still out on that one . some recent studies even contradict the idea . regardless , toxoplasma has definitely benefited from humans to become one of the world 's most successful parasites . it 's not just our willingness to let cats on our dining room tables or in our beds . raising livestock and building cities which attract rodents has provided billions of new hosts , and you and your cat may be two of them .

some recent studies even contradict the idea . regardless , toxoplasma has definitely benefited from humans to become one of the world 's most successful parasites . it 's not just our willingness to let cats on our dining room tables or in our beds .

when are humans at risk of becoming infected with toxoplasma ?

say two people are walking down the street , and they bump into each other . they 'll just shake it off and walk on . sometimes that happens with molecules too . they just bounce off each other , and that 's that . but what if two people were to bump into each other , and during that collision , one person 's arm got severed and reattached to the other person 's face ? now that sounds really weird , but it 's similar to one of the many ways that molecules can react with each other . two molecules can join and become one . one can split apart and become two . molecules can switch parts . all these changes are chemical reactions , and we can see them happening around us . for example , when fireworks explode , or iron rusts , or milk goes bad , or people are born , grow old , die , and then decompose . but chemical reactions do n't just happen willy nilly ! everything has to be right . first , the molecules have to hit each other in the right orientation . and second , they have to hit each other hard enough , in other words , with enough energy . now you 're probably thinking that a reaction just happens in one direction and that 's it . sometimes that 's true . for example , things ca n't unburn or unexplode . but most reactions can happen in both directions , forward and reverse . there 's no reason that our face-arm guy ca n't bump into armless girl , reattaching that arm back to its original socket . now let 's zoom out a bit . now let 's say that you 've got a thousand people on the street , and all of them start with their limbs normally attached . at the beginning , every collision is a chance for person a to transfer an arm to person b 's face . and so at the beginning , more and more people end up with arms attached to their faces or arms missing . but as the number of people with arm-faces and missing arms grows , collisions between those people become more likely . and when they bump into each other , guess what ? normal-appendage people are reproduced . now the number of limb transfers per second forward will start high and then fall , and the number of limb transfers per second backward will start at zero and then rise . eventually they 'll meet , they 'll be the same . and when that happens , the number of people in each state stops changing , even though people are still bumping into each other and exchanging limbs . now how many people do you think there are in each state ? half and half , right ? no , well , maybe . it depends . it could be 50/50 , but it could be 60/40 or 15/85 , or anything . we chemists have to get our little , gloved hands dirty - ah , well , we 're in a lab so not really dirty - to figure out what the actual distribution of molecules is . even though each of limb transfers is a pretty dramatic event for the people involved , if we zoom out , we see population numbers that do n't change . we call this nirvana equilibrium , and it does n't just happen with chemical reactions . things like gene pools and highway traffic show the same pattern . it looks pretty still from 30,000 feet , but there is lots of crazy stuff happening on the ground , you just need to zoom in to see it .

now you 're probably thinking that a reaction just happens in one direction and that 's it . sometimes that 's true . for example , things ca n't unburn or unexplode .

which of the following statements is true :

picture warm , gooey cookies , crunchy candies , velvety cakes , waffle cones piled high with ice cream . is your mouth watering ? are you craving dessert ? why ? what happens in the brain that makes sugary foods so hard to resist ? sugar is a general term used to describe a class of molecules called carbohydrates , and it 's found in a wide variety of food and drink . just check the labels on sweet products you buy . glucose , fructose , sucrose , maltose , lactose , dextrose , and starch are all forms of sugar . so are high-fructose corn syrup , fruit juice , raw sugar , and honey . and sugar is n't just in candies and desserts , it 's also added to tomato sauce , yogurt , dried fruit , flavored waters , or granola bars . since sugar is everywhere , it 's important to understand how it affects the brain . what happens when sugar hits your tongue ? and does eating a little bit of sugar make you crave more ? you take a bite of cereal . the sugars it contains activate the sweet-taste receptors , part of the taste buds on the tongue . these receptors send a signal up to the brain stem , and from there , it forks off into many areas of the forebrain , one of which is the cerebral cortex . different sections of the cerebral cortex process different tastes : bitter , salty , umami , and , in our case , sweet . from here , the signal activates the brain 's reward system . this reward system is a series of electrical and chemical pathways across several different regions of the brain . it 's a complicated network , but it helps answer a single , subconscious question : should i do that again ? that warm , fuzzy feeling you get when you taste grandma 's chocolate cake ? that 's your reward system saying , `` mmm , yes ! '' and it 's not just activated by food . socializing , sexual behavior , and drugs are just a few examples of things and experiences that also activate the reward system . but overactivating this reward system kickstarts a series of unfortunate events : loss of control , craving , and increased tolerance to sugar . let 's get back to our bite of cereal . it travels down into your stomach and eventually into your gut . and guess what ? there are sugar receptors here , too . they are not taste buds , but they do send signals telling your brain that you 're full or that your body should produce more insulin to deal with the extra sugar you 're eating . the major currency of our reward system is dopamine , an important chemical or neurotransmitter . there are many dopamine receptors in the forebrain , but they 're not evenly distributed . certain areas contain dense clusters of receptors , and these dopamine hot spots are a part of our reward system . drugs like alcohol , nicotine , or heroin send dopamine into overdrive , leading some people to constantly seek that high , in other words , to be addicted . sugar also causes dopamine to be released , though not as violently as drugs . and sugar is rare among dopamine-inducing foods . broccoli , for example , has no effect , which probably explains why it 's so hard to get kids to eat their veggies . speaking of healthy foods , let 's say you 're hungry and decide to eat a balanced meal . you do , and dopamine levels spike in the reward system hot spots . but if you eat that same dish many days in a row , dopamine levels will spike less and less , eventually leveling out . that 's because when it comes to food , the brain evolved to pay special attention to new or different tastes . why ? two reasons : first , to detect food that 's gone bad . and second , because the more variety we have in our diet , the more likely we are to get all the nutrients we need . to keep that variety up , we need to be able to recognize a new food , and more importantly , we need to want to keep eating new foods . and that 's why the dopamine levels off when a food becomes boring . now , back to that meal . what happens if in place of the healthy , balanced dish , you eat sugar-rich food instead ? if you rarely eat sugar or do n't eat much at a time , the effect is similar to that of the balanced meal . but if you eat too much , the dopamine response does not level out . in other words , eating lots of sugar will continue to feel rewarding . in this way , sugar behaves a little bit like a drug . it 's one reason people seem to be hooked on sugary foods . so , think back to all those different kinds of sugar . each one is unique , but every time any sugar is consumed , it kickstarts a domino effect in the brain that sparks a rewarding feeling . too much , too often , and things can go into overdrive . so , yes , overconsumption of sugar can have addictive effects on the brain , but a wedge of cake once in a while wo n't hurt you .

what happens if in place of the healthy , balanced dish , you eat sugar-rich food instead ? if you rarely eat sugar or do n't eat much at a time , the effect is similar to that of the balanced meal . but if you eat too much , the dopamine response does not level out .

what kind of diet has an effect in the brain that is similar to eating a balanced meal ?

translator : andrea mcdonough reviewer : bedirhan cinar nameste . i 'm from india , and india is one of the oldest civilizations in the world . it has contributed to the world concepts such as yoga , ayurveda , spicy chicken tikka , and vedic math . vedic math is one of the world 's easiest and simplest way to do math . we are going to combine together and do some number crunching today . so what we are going to first do is multiply by 11 . we 're going to do it together , so if you blink , you 're going to miss it . so just watch it , ok . so we 're going to do 32 times 11 , ok . so we split 3 , and we split 2 , and we add 3 and 2 and paste it on top , and we get the answer as 352 . that 's it . let 's try another sum . 45 times 11 . let 's hear it . exactly , that 's 495 . and 75 times 11 . so it gives you 7,125 , 1 gets carried over and it becomes 825 . that 's how simple it is . ok , this is the principle behind it where a is the coefficient . let 's move on . ok , now what we 're going to do is the base method . ok , this is used to multiply numbers very close to the powers of 10 , like 10 , 100 , 1,000 , and so on . so we have a sum here , say 99 times 97 . ok , now tell me , is 99 more than 100 or less than 100 ? less by how much ? so we write minus 01 . and 97 is less than 100 by how much ? so we write minus 03 . so what we 're going to do is we 're going to cross subtract and get the first part of the answer , like this . we 're going to do cross subtraction . 97 minus 01 would give us 96. and we multiply 03 times 01 vertically , and we get an answer of 03 . let 's check another sum . try and do it yourselves . we got 98 , which is , is it more than a 100 , less than 100 ? by how much ? and 97 is 3 . so we got 98 , we go crosswise , we got 98 minus 3 , or we can do 97 minus 2 , they 'll all give you the same answer . so that would give us 95 . and the second part would be 06 . so that 's our answer . ok , let 's take a bigger number . let 's try this one . here the base is 1,000 . so we got -004 , and 997 would be -003 . we go crosswise like this , and we get 996 minus 003 would give us 993 , and 004 times 003 would give us 012 . and that 's our answer . thank you . 14 times 12 . ok , here the base is 10 . ok , so is 14 more than 10 or less than 10 ? more , so we got plus 4 , and 12 , we got plus 2 . again , we apply the same rule , so we do 12 plus 4 , which gives us 16 , like this . and we multiply 2 and 4 , that gives us 8 . so now , all of us here , we 're going to do mental squaring , ok. everybody is going to participate here , and we 're going to do squares of numbers more than 100 mentally right now . so we got 101 , ok , now visualize on the board , what 's going to be on the right hand side . plus 01 , so we got that . ok , now we add plus sides , right ? yes ? no ? so we got 101 plus 01 , that would give us 102 , and , see here , like this . and 01 is getting squared , right ? so that would give us 01 , and that 's your answer . try the next one . let 's try 102 squared . let 's try , everybody . so 100 , so 102 would be 10404 . ok , now the next one , try it everybody together . i 'll give you 5 seconds . ok , let 's say it together , let 's say it together , ok. [ 10609 ] 10609 and that 's the answer . woo ! 104 squared , how much would that be ? calculate it , 5 seconds . come on , girls in the back . ok , so the answer would be 10816 . ok , let 's do the next one : 105 squared . oh , no , no , no , no , we 're going to try over , we 're going to try over , ok ? ok . i 'll give you 5 seconds , just think about it . ok , now we 're going to go , ok ? 11025 . ok , let 's going to do the next one , 106 squared . try it , come one , everybody , it 's simple and easy . [ 11236 ] ok , let 's do it one more time . 11236 . now 107 , think , hold on , do n't say anything out loud , just think mentally , 107 squared . ok , now let 's say it out loud . 11449 . and 108 squared . [ 11664 ] fantastic , give yourself a round of applause , come on ! and this is the principle behind this , where a and b are the excesses or the deficiency from the base . i 'm going to teach you in vedic math , there are 16 sutras , or word formulas , ok . they are very visual and one of them is called , `` vertically and crosswise , '' through which you can multiply any number by any number in a single line . so i 'm going to do a two-digit by a two-digit multiplication . let 's do this . so we got 31 times 12 . ok , so we 're going to apply the vertically and crosswise sutra . so we 're going to do like this : vertically , and then we 're going to go crosswise , and then we 're going to do vertical again . so , 2 times 1 gives us [ 2 ] , 2 times 3 gives us [ 6 ] , and 1 times 1 gives us [ 1 ] . 6 plus 1 , [ 7 ] . 1 times 3 gives us [ 3 ] . and that 's it , and that 's our answer . no more tedious calculations , no more going through the rough work , it 's simple in one line . i want to show you a sum again , this time with carry-overs . the same formula , all of us here can do this , ok . same formula . so let 's get started . 4 times 2 gives us [ 8 ] . ok , now we go crosswise like this , so we 're going to multiply 4 times 1 , [ 4 ] , and 3 times 2 , [ 6 ] 4 plus 6 gives us [ 10 ] . so we put down 0 , carry the 1 . and 3 times 1 gives us [ 3 ] , plus 1 , [ 4 ] . exactly , that 's our answer , 408 . ok , thank you for being such a participative audience , and we had a great time number crunching . now i want to end with a question : whether you 'd like math to be dull or boring , or fun and interesting ? the choice is yours .

it has contributed to the world concepts such as yoga , ayurveda , spicy chicken tikka , and vedic math . vedic math is one of the world 's easiest and simplest way to do math . we are going to combine together and do some number crunching today .

what is not part of the principle behind vedic math ?

what you 're looking at is n't some weird x-ray . it 's actually a baby yellow tang surgeonfish at two months old . and you thought your childhood was awkward . but here is the same fish as an adult , a beautiful inhabitant of the indian and pacific oceans ' coral reefs and one of the most popular captive fish for salt water aquariums . of the 27,000 known fish species , over a quarter live on coral reefs that make up less than 1 % of the earth 's surface . but prior to settling down in this diverse tropical environment , baby coral reef fish face the difficult process of growing up on their own , undergoing drastic changes , and the journey of a lifetime before they find that reef to call home . the life cycle for most of these fish begins when their parents spew sperm and eggs into the water column . this can happen daily , seasonally , or yearly depending on the species , generally following lunar or seasonal tidal patterns . left to their fate , the fertilized eggs drift with the currents , and millions of baby larvae hatch into the world . when they first emerge , the larvae are tiny and vulnerable . some do n't even have gills yet and must absorb oxygen directly from the water through their tissue-thin skin . they may float in the water column anywhere from minutes to months , sometimes drifting thousands of miles across vast oceans , far from the reefs where they were born . along the way , they must successfully avoid predators , obtain food , and ride the right currents to find their way to a suitable adult habitat , which might as well be a needle in vast haystack of ocean . so , how did they accomplish this feat ? until recently , marine biologists thought of larval fish as largely passive drifters , dispersed by ocean currents to distant locales . but in the last 20 years , new research has suggested that larvae may not be as helpless as they seem , and are capable of taking their fate in their own fins to maximize their chances of survival . the larvae of many species are unexpectedly strong swimmers , and can move vertically in the water column to place themselves in different water masses and preferentially ride certain currents . these fish may be choosing the best routes to their eventual homes . when searching for these homes , evidence suggests that larvae navigate via a complex suite of sensory systems , detecting both sound and smell . odor , in particular , allows larvae to distinguish between different environments , even adjacent reefs , helping guide them toward their preferred adult habitats . many will head for far-flung locales miles away from their birth place . but some will use smell and other sensory cues to navigate back to the reefs where they were born , even if they remain in the larval stage for months . so , what happens when larvae do find a suitable coral reef ? do they risk it all in one jump from the water column , hoping to land in exactly the right spot to settle down and metamorphose into adults ? not exactly . instead , larvae appear to have more of a bungee system . larvae will drop down in the water column to check out a reef below . if conditions are n't right , they can jump back up into higher water masses and ride on , chancing that the next reef they find will be a better fit . but this is the point where our knowledge ends . we do n't know the geographic movements of individual larva for most species . nor do we know which exact environmental cues and behaviors they use to navigate to the reefs they will call home . but we do know that these tiny trekkers are more than the fragile and helpless creatures science once believed them to be . the secret lives of baby fish remain largely mysterious to us , unknown adventures waiting to be told .

so , how did they accomplish this feat ? until recently , marine biologists thought of larval fish as largely passive drifters , dispersed by ocean currents to distant locales . but in the last 20 years , new research has suggested that larvae may not be as helpless as they seem , and are capable of taking their fate in their own fins to maximize their chances of survival .

how long can the larval phase last ?

translator : ido dekkers reviewer : ariana bleau lugo say you 're at the beach , and you get sand in your eyes . how do you know the sand is there ? you obviously ca n't see it , but if you are a normal , healthy human , you can feel it , that sensation of extreme discomfort , also known as pain . now , pain makes you do something , in this case , rinse your eyes until the sand is gone . and how do you know the sand is gone ? exactly . because there 's no more pain . there are people who do n't feel pain . now , that might sound cool , but it 's not . if you ca n't feel pain , you could get hurt , or even hurt yourself and never know it . pain is your body 's early warning system . it protects you from the world around you , and from yourself . as we grow , we install pain detectors in most areas of our body . these detectors are specialized nerve cells called nociceptors that stretch from your spinal cord to your skin , your muscles , your joints , your teeth and some of your internal organs . just like all nerve cells , they conduct electrical signals , sending information from wherever they 're located back to your brain . but , unlike other nerve cells , nociceptors only fire if something happens that could cause or is causing damage . so , gently touch the tip of a needle . you 'll feel the metal , and those are your regular nerve cells . but you wo n't feel any pain . now , the harder you push against the needle , the closer you get to the nociceptor threshold . push hard enough , and you 'll cross that threshold and the nociceptors fire , telling your body to stop doing whatever you 're doing . but the pain threshold is n't set in stone . certain chemicals can tune nociceptors , lowering their threshold for pain . when cells are damaged , they and other nearby cells start producing these tuning chemicals like crazy , lowering the nociceptors ' threshold to the point where just touch can cause pain . and this is where over-the-counter painkillers come in . aspirin and ibuprofen block production of one class of these tuning chemicals , called prostaglandins . let 's take a look at how they do that . when cells are damaged , they release a chemical called arachidonic acid . and two enzymes called cox-1 and cox-2 convert this arachidonic acid into prostaglandin h2 , which is then converted into a bunch of other chemicals that do a bunch of things , including raise your body temperature , cause inflammation and lower the pain threshold . now , all enzymes have an active site . that 's the place in the enzyme where the reaction happens . the active sites of cox-1 and cox-2 fit arachidonic acid very cozily . as you can see , there is no room to spare . now , it 's in this active site that aspirin and ibuprofen do their work . so , they work differently . aspirin acts like a spine from a porcupine . it enters the active site and then breaks off , leaving half of itself in there , totally blocking that channel and making it impossible for the arachidonic acid to fit . this permanently deactivates cox-1 and cox-2 . ibuprofen , on the other hand , enters the active site , but does n't break apart or change the enzyme . cox-1 and cox-2 are free to spit it out again , but for the time that that ibuprofen is in there , the enzyme ca n't bind arachidonic acid , and ca n't do its normal chemistry . but how do aspirin and ibuprofen know where the pain is ? well , they do n't . once the drugs are in your bloodstream , they are carried throughout your body , and they go to painful areas just the same as normal ones . so that 's how aspirin and ibuprofen work . but there are other dimensions to pain . neuropathic pain , for example , is pain caused by damage to our nervous system itself ; there does n't need to be any sort of outside stimulus . and scientists are discovering that the brain controls how we respond to pain signals . for example , how much pain you feel can depend on whether you 're paying attention to the pain , or even your mood . pain is an area of active research . if we can understand it better , maybe we can help people manage it better .

exactly . because there 's no more pain . there are people who do n't feel pain . now , that might sound cool , but it 's not . if you ca n't feel pain , you could get hurt , or even hurt yourself and never know it .

why might cursing very loudly ( or yelling without cursing ) after a painful event help alleviate pain ?

they 're everywhere , but you will never see one . trillions of them are flying through you right this second , but you ca n't feel them . these ghost particles are called neutrinos and if we can catch them , they can tell us about the furthest reaches and most extreme environments of the universe . neutrinos are elementary particles , meaning that they ca n't be subdivided into other particles the way atoms can . elementary particles are the smallest known building blocks of everything in the universe , and the neutrino is one of the smallest of the small . a million times less massive than an electron , neutrinos fly easily through matter , unaffected by magnetic fields . in fact , they hardly ever interact with anything . that means that they can travel through the universe in a straight line for millions , or even billions , of years , safely carrying information about where they came from . so where do they come from ? pretty much everywhere . they 're produced in your body from the radioactive decay of potassium . cosmic rays hitting atoms in the earth 's atmosphere create showers of them . they 're produced by nuclear reactions inside the sun and by radioactive decay inside the earth . and we can generate them in nuclear reactors and particle accelerators . but the highest energy neutrinos are born far out in space in environments that we know very little about . something out there , maybe supermassive black holes , or maybe some cosmic dynamo we 've yet to discover , accelerates cosmic rays to energies over a million times greater than anything human-built accelerators have achieved . these cosmic rays , most of which are protons , interact violently with the matter and radiation around them , producing high-energy neutrinos , which propagate out like cosmic breadcrumbs that can tell us about the locations and interiors of the universe 's most powerful cosmic engines . that is , if we can catch them . neutrinos ' limited interactions with other matter might make them great messengers , but it also makes them extremely hard to detect . one way to do so is to put a huge volume of pure transparent material in their path and wait for a neutrino to reveal itself by colliding with the nucleus of an atom . that 's what 's happening in antarctica at icecube , the world 's largest neutrino telescope . it 's set up within a cubic kilometer of ice that has been purified by the pressure of thousands of years of accumulated ice and snow , to the point where it 's one of the clearest solids on earth . and even though it 's shot through with boreholes holding over 5,000 detectors , most of the cosmic neutrinos racing through icecube will never leave a trace . but about ten times a year , a single high-energy neutrino collides with a molecule of ice , shooting off sparks of charged subatomic particles that travel faster through the ice than light does . in a similar way to how a jet that exceeds the speed of sound produces a sonic boom , these superluminal charged particles leave behind a cone of blue light , kind of a photonic boom . this light spreads through icecube , hitting some of its detectors located over a mile beneath the surface . photomultiplier tubes amplify the signal , which contains information about the charged particles ' paths and energies . the data are beamed to astrophysicists around the world who look at the patterns of light for clues about the neutrinos that produced them . these super energetic collisions are so rare that icecube 's scientists give each neutrino nicknames , like big bird and dr. strangepork . icecube has already observed the highest energy cosmic neutrinos ever seen . the neutrinos it detects should finally tell us where cosmic rays come from and how they reached such extreme energies . light , from infrared , to x-rays , to gamma rays , has given us increasingly energetic and continuously surprising views of the universe . we are now at the dawn of the age of neutrino astronomy , and we have no idea what revelations icecube and other neutrino telescopes may bring us about the universe 's most violent , most energetic phenomena .

icecube has already observed the highest energy cosmic neutrinos ever seen . the neutrinos it detects should finally tell us where cosmic rays come from and how they reached such extreme energies . light , from infrared , to x-rays , to gamma rays , has given us increasingly energetic and continuously surprising views of the universe . we are now at the dawn of the age of neutrino astronomy , and we have no idea what revelations icecube and other neutrino telescopes may bring us about the universe 's most violent , most energetic phenomena .

for many years , light has been the main tool for exploring the universe . what do you think neutrinos can tell us that light can not ?

as far as we know , medieval england was never invaded by ice zombies , or terrorized by dragons , but it was shaken by a power struggle between two noble families spanning generations and involving a massive cast of characters with complex motives and shifting loyalties . if that sounds familiar , it 's because the historical conflicts known as the wars of the roses served as the basis for much of the drama in game of thrones . the real-life seeds of war were sewn by the death of king edward iii in 1377 . edward 's oldest son had died before his father , but his ten-year-old son , richard ii , succeeded to the throne ahead of edward 's three surviving sons . this skipping of an entire generation left lingering claims to the throne among their various offspring , particularly the lancasters , descended from edward 's third son , and the yorks , descended from his fourth son . the name of the ensuing wars comes from the symbols associated with the two families , the white rose of york and the red rose of lancaster . the lancasters first gained the throne when richard ii was deposed by his cousin henry iv in 1399 . despite sporadic unrest , their reign remained secure until 1422 , when henry v 's death in a military campaign left an infant henry vi as king . weak-willed and dominated by advisors , henry was eventually convinced to marry margaret of anjou to gain french support . margaret was beautiful , ambitious , and ruthless in persecuting any threat to her power , and she distrusted richard of york , most of all . york had been the king 's close advisor and loyal general , but was increasingly sidelined by the queen , who promoted her favorite supporters , like the earls of suffolk and somerset . york 's criticism of their inept handling of the war against france led to his exclusion from court and transfer to ireland . meanwhile , mounting military failures , and corrupt rule by margaret and her allies caused widespread discontent , and in the midst of this chaos , richard of york returned with an army to arrest somerset and reform the court . initially unsuccessful , he soon got his chance when he was appointed protector of the realm after henry suffered a mental breakdown . however , less than a year later , henry suddendly recovered and the queen convinced him to reverse york 's reforms . york fled and raised an army once more . though he was unable to directly seize the throne , he managed to be reinstated as protector and have himself and his heirs designated to succeed henry . but instead of a crown , york 's head acquired a pike after he was killed in battle with the queen 's loyalists . his young son took up the claim and was crowned edward iv . edward enjoyed great military success against the lancasters . henry was captured , while margaret fled into exile with their reportedly cruel son , edward of westminster . but the newly crowned king made a tragic political mistake by backing out of his arranged marriage with a french princess to secretly marry the widow of a minor noble . this alienated his most powerful ally , the earl of warwick . warwick allied with the lancasters , turned edward 's jealous younger brother , george , against him , and even briefly managed to restore henry as king , but it did n't last . edward recaptured the throne , the lancaster prince was killed in battle , and henry himself died in captivity not long after . the rest of edward iv 's reign was peaceful , but upon his death in 1483 , the bloodshed resumed . though his twelve-year-old son was due to succeed him , edward 's younger brother richard iii declared his nephews illegitimate due to their father 's secret marriage . he assumed the regency himself and threw the boys in prison . though no one knows what ultimately became of them , after a while , the princes disappeared and richard 's power seemed secure . but his downfall would come only two years later from across the narrow sea of the english channel . henry tudor was a direct descendant of the first duke of lancaster , raised in exile after his father 's death in a previous rebellion . with richard iii 's power grab causing a split in the york faction , henry won support for his royal claim . raising an army in france , he crossed the channel in 1485 and quickly defeated richard 's forces . and by marrying elizabeth of york , elder sister of the disappeared princes , the newly crowned henry vii joined the two roses , finally ending nearly a century of war . we often think of historical wars as decisive conflicts with clearly defined winners and losers . but the wars of the roses , like the fiction they inspired , show us that victories can be uncertain , alliances unstable , and even the power of kings as fleeting as the seasons .

this alienated his most powerful ally , the earl of warwick . warwick allied with the lancasters , turned edward 's jealous younger brother , george , against him , and even briefly managed to restore henry as king , but it did n't last . edward recaptured the throne , the lancaster prince was killed in battle , and henry himself died in captivity not long after .

what was the ultimate fate of edward v and his brother -- the 'princes in the tower ' ?

pick a card , any card . actually , just pick up all of them and take a look . this standard 52-card deck has been used for centuries . everyday , thousands just like it are shuffled in casinos all over the world , the order rearranged each time . and yet , every time you pick up a well-shuffled deck like this one , you are almost certainly holding an arrangement of cards that has never before existed in all of history . how can this be ? the answer lies in how many different arrangements of 52 cards , or any objects , are possible . now , 52 may not seem like such a high number , but let 's start with an even smaller one . say we have four people trying to sit in four numbered chairs . how many ways can they be seated ? to start off , any of the four people can sit in the first chair . one this choice is made , only three people remain standing . after the second person sits down , only two people are left as candidates for the third chair . and after the third person has sat down , the last person standing has no choice but to sit in the fourth chair . if we manually write out all the possible arrangements , or permutations , it turns out that there are 24 ways that four people can be seated into four chairs , but when dealing with larger numbers , this can take quite a while . so let 's see if there 's a quicker way . going from the beginning again , you can see that each of the four initial choices for the first chair leads to three more possible choices for the second chair , and each of those choices leads to two more for the third chair . so instead of counting each final scenario individually , we can multiply the number of choices for each chair : four times three times two times one to achieve the same result of 24 . an interesting pattern emerges . we start with the number of objects we 're arranging , four in this case , and multiply it by consecutively smaller integers until we reach one . this is an exciting discovery . so exciting that mathematicians have chosen to symbolize this kind of calculation , known as a factorial , with an exclamation mark . as a general rule , the factorial of any positive integer is calculated as the product of that same integer and all smaller integers down to one . in our simple example , the number of ways four people can be arranged into chairs is written as four factorial , which equals 24 . so let 's go back to our deck . just as there were four factorial ways of arranging four people , there are 52 factorial ways of arranging 52 cards . fortunately , we do n't have to calculate this by hand . just enter the function into a calculator , and it will show you that the number of possible arrangements is 8.07 x 10^67 , or roughly eight followed by 67 zeros . just how big is this number ? well , if a new permutation of 52 cards were written out every second starting 13.8 billion years ago , when the big bang is thought to have occurred , the writing would still be continuing today and for millions of years to come . in fact , there are more possible ways to arrange this simple deck of cards than there are atoms on earth . so the next time it 's your turn to shuffle , take a moment to remember that you 're holding something that may have never before existed and may never exist again .

how can this be ? the answer lies in how many different arrangements of 52 cards , or any objects , are possible . now , 52 may not seem like such a high number , but let 's start with an even smaller one .

besides a deck of cards , have you ever encountered a situation where objects can be rearranged ? describe the situation , and calculate the number of possible rearrangements -- or permutations -- that these objects possess .

what is love ? seriously , though , what is it ? what is love ? a verb ? a noun ? a universal truth ? an ideal ? a common thread of all religions ? a cult ? a neurological phenomenon ? there 's no shortage of answers . some are all-encompassing . it conquers all . it 's all you need . it 's all there is . these are all comparisons , though , ways of defining it by contrast , by saying it 's more important than all other things , but is it ? sure , love matters more than your standard turkey sandwich , but does it matter more than shelter ? or sanity ? or an exceptional turkey sandwich ? no matter your answer , you 're just ranking it , not defining it . another challenge to defining love is we often try to do so while falling into it or out of it . would you trust someone who just won the lottery to accurately define the concept of currency ? or , i do n't know , ask a guy to define bears while he 's fending them off ? or is romance not like winning the lottery ? are break ups not like bear attacks ? bad comparisons ? that 's my point . i 'm not thinking right because i 'm in love , so ha ! taking a step back , or taking a cold shower , whatever , love is potentially the most intensely thought about thing in all of human history . and despite centuries upon centuries of obsession , it still overwhelms us . some say it 's a feeling , a magical emotion , a feeling for someone like you 've never felt before . but feelings are fluid , not very concrete foundation for a definition . sometimes you hate the person you love . plus , come on , you 've felt feelings like it before , sort of in miniature . your relationships with your family shape your relationships with partners . and your love for your partner may be in its own dynamic relationship , healthy or totally weird , with the love of your parents and siblings . love is also a set of behaviors we associate with the feeling : holding hands , kissing , hugging , public displays of affection , dating , marriage , having kids , or just sex . but these loving actions can be subjective or culturally relative . you may love or be someone who ca n't have kids or does n't want to , who believes in marriage but also in divorce , who 's from a culture where people do n't really date the way we think of dating , or who just does n't want to make out on the bus . but if love is a thing that we can define , then how can it mean opposite things for so many people ? so , maybe love 's just all in your head , a personal mystery winding through your neural pathways and lighting up pleasing , natural rewards in your nervous system . perhaps these rewards are addictive . perhaps love is a temporary or permanent addiction to a person , just like a person can be addicted to a drug . i do n't mean to be edgy like some pop song . evidence shows that chemicals in your brain stimulated by another person can make you develop a habit for that person . the person comes to satisfy a physiological craving , and you want more . but then sometimes , slowly or suddenly , you do n't . you 've fallen out of love , become unaddicted , for a spell . what happened ? does one develop a tolerance or hit a limit ? why do some lovers stay addicted to each other their entire lives ? perhaps to create new lives , to proliferate their species ? maybe love is just human dna 's optimal method for bringing about its own replication . there are evolutionary arguments regarding every human mating behavior , from how we display ourselves to potential mates , to how we treat each other in relationships , to how we raise kids . thus , some argue that the feeling you think you feel in your soul is just biology 's way to make you continue our species . nature has selected you to have crushes on hotties , just like it makes monkeys have crushes on hot monkeys , and biology marches on . but is that all love is ? or , perhaps worse , is it just a construct , some fake concept we all convince each other to try to live up to for a fake sense of purpose ? maybe it is a construct , but let 's be more precise about what a construct is because love is constructed from reality : our experiences , feelings , brain chemistry , cultural expectations , our lives . and this edifice can be viewed through countless dimensions : scientific , emotional , historical , spiritual , legal , or just personal . if no two people are the same , no two people 's love is the same either . so , in every loving relationship , there 's a lot to talk about and partners should be open to that , or the relationship probably wo n't last . love is always up for discussion and , sure , under construction . so , if we ca n't define it , that 's a good sign . it means we 're all still making it . wait , i did n't mean , you know what i meant .

and this edifice can be viewed through countless dimensions : scientific , emotional , historical , spiritual , legal , or just personal . if no two people are the same , no two people 's love is the same either . so , in every loving relationship , there 's a lot to talk about and partners should be open to that , or the relationship probably wo n't last .

love is the same for all people .

i must look rather strange to you , all covered in spines , without even a face . but i 've taken many forms during my life . i started out just like you : a tiny egg in a watery world . my parents never knew each other . one moonlit night before a storm , thousands of urchins , clams and corals released trillions of sperm and eggs into the open sea . my father 's sperm somehow met my mother 's egg , and they fused . fertilization . instantly , i became an embryo the size of a speck of dust . after a few hours of drifting , i cleaved in two , then four , then eight cells . then so many , i lost count . in less than a day , i developed a gut and a skeleton . i became a rocket ship , a pluteus larva . i floated through the world of plankton , searching for tiny algae to eat . for weeks , i was surrounded by all kinds of organisms , larvae of all sorts . most are so different from their adult form that biologists have a tough time figuring out who they are . try matching these youngsters to their parents . this veliger larvae will turn into a snail ; this zoea , into a crab ; and this planula , into a clytia jelly . some of my young companions are easier to picture as grown-ups . these baby jellies , known as ephyrae , already resemble their beautiful but deadly parents . here in the plankton , there 's more than one way to get your genes into the next generation . most medusa jellies make special structures called polyps , that simply bud off babies with no need for sex . salps are similar . when food is abundant , they just clone themselves into long chains . the plankton is full of surprises when it comes to sex . meet the hermaphrodites . these comb jellies and arrow worms produce , store and release both sperm and eggs . they can fertilize themselves , or another . when you 're floating in a vast sea , with little control over who you may meet , it can pay to play both sides of the field . the majority of species here , however , never mate , nor form any sort of lasting bonds . that was my parents ' strategy . there were so many of us pluteus larvae , i just hid in the crowd , while most of my kin were devoured . not all parents leave the survival of their offspring to chance . some have far fewer young and take much better care of them , brooding their precious cargo for days , even months . this speedy copepod totes her beautifully packaged eggs for days . this phronima crustacean carries her babies on her chest , then carefully places them in a gelatinous barrel . but the black-eyed squid takes the prize . she cradles her eggs in long arms for nine months , the same time it takes to gestate a human infant . eventually , all youngsters have to make it on their own in this drifting world . some will spend their whole lives in the plankton , but others , like me , move on . a few weeks after i was conceived , i decided to settle down , and metamorphosed into a recognizable urchin . so now you know a bit of my story . i may just be a slow-moving ball of spines , but do n't let my calm adult exterior fool you . i was a rocket ship . i was a wild child .

fertilization . instantly , i became an embryo the size of a speck of dust . after a few hours of drifting , i cleaved in two , then four , then eight cells .

how big was the embryo ?

in the past few months , i 've been traveling for weeks at a time with only one suitcase of clothes . one day , i was invited to an important event , and i wanted to wear something special and new for it . so i looked through my suitcase and i could n't find anything to wear . i was lucky to be at the technology conference on that day , and i had access to 3d printers . so i quickly designed a skirt on my computer , and i loaded the file on the printer . it just printed the pieces overnight . the next morning , i just took all the pieces , assembled them together in my hotel room , and this is actually the skirt that i 'm wearing right now . ( applause ) so it was n't the first time that i printed clothes . for my senior collection at fashion design school , i decided to try and 3d print an entire fashion collection from my home . the problem was that i barely knew anything about 3d printing , and i had only nine months to figure out how to print five fashionable looks . i always felt most creative when i worked from home . i loved experimenting with new materials , and i always tried to develop new techniques to make the most unique textiles for my fashion projects . i loved going to old factories and weird stores in search of leftovers of strange powders and weird materials , and then bring them home to experiment on . as you can probably imagine , my roommates did n't like that at all . ( laughter ) so i decided to move on to working with big machines , ones that did n't fit in my living room . i love the exact and the custom work i can do with all kinds of fashion technologies , like knitting machines and laser cutting and silk printing . one summer break , i came here to new york for an internship at a fashion house in chinatown . we worked on two incredible dresses that were 3d printed . they were amazing -- like you can see here . but i had a few issues with them . they were made from hard plastics and that 's why they were very breakable . the models could n't sit in them , and they even got scratched from the plastics under their arms . with 3d printing , the designers had so much freedom to make the dresses look exactly like they wanted , but still , they were very dependent on big and expensive industrial printers that were located in a lab far from their studio . later that year , a friend gave me a 3d printed necklace , printed using a home printer . i knew that these printers were much cheaper and much more accessible than the ones we used at my internship . so i looked at the necklace , and then i thought , `` if i can print a necklace from home , why not print my clothes from home , too ? '' i really liked the idea that i would n't have to go to the market and pick fabrics that someone else chose to sell -- i could just design them and print them directly from home . i found a small makerspace , where i learned everything i know about 3d printing . right away , they literally gave me the key to the lab , so i could experiment into the night , every night . the main challenge was to find the right filament for printing clothes with . so what is a filament ? filament is the material you feed the printer with . and i spent a month or so experimenting with pla , which is a hard and scratchy , breakable material . the breakthrough came when i was introduced to filaflex , which is a new kind of filament . it 's strong , yet very flexible . and with it , i was able to print the first garment , the red jacket that had the word `` liberté '' -- `` freedom '' in french -- embedded into it . i chose this word because i felt so empowered and free when i could just design a garment from my home and then print it by myself . and actually , you can easily download this jacket , and easily change the word to something else . for example , your name or your sweetheart 's name . ( laughter ) so the printer plates are small , so i had to piece the garment together , just like a puzzle . and i wanted to solve another challenge . i wanted to print textiles that i would use just like regular fabrics . that 's when i found an open-source file from an architect who designed a pattern that i love . and with it , i was able to print a beautiful textile that i would use just like a regular fabric . and it actually even looks a little bit like lace . so i took his file and i modified it , and changed it , played with it -- many kinds of versions out of it . and i needed to print another 1,500 more hours to complete printing my collection . so i brought six printers to my home and just printed 24-7 . and this is actually a really slow process , but let 's remember the internet was significantly slower 20 years ago , so 3d printing will also accelerate and in no time you 'll be able to print a t-shirt in your home in just a couple of hours , or even minutes . so you guys , you want to see what it looks like ? audience : yeah ! ( applause ) danit peleg : rebecca is wearing one of my five outfits . almost everything here she 's wearing , i printed from my home . even her shoes are printed . audience : wow ! audience : cool ! ( applause ) danit peleg : thank you , rebecca . ( to audience ) thank you , guys . so i think in the future , materials will evolve , and they will look and feel like fabrics we know today , like cotton or silk . imagine personalized clothes that fit exactly to your measurements . music was once a very physical thing . you would have to go to the record shop and buy cds , but now you can just download the music -- digital music -- directly to your phone . fashion is also a very physical thing . and i wonder what our world will look like when our clothes will be digital , just like this skirt is . thank you so much . ( applause ) [ thank you ] ( applause )

it 's strong , yet very flexible . and with it , i was able to print the first garment , the red jacket that had the word `` liberté '' -- `` freedom '' in french -- embedded into it . i chose this word because i felt so empowered and free when i could just design a garment from my home and then print it by myself .

why was the word “ liberte ” embedded into her first 3d printed jacket ?

translator : andrea mcdonough reviewer : jessica ruby when i was a kid , my understanding of the seasons was that december and january were cold and covered with snow , april and may were bursting with flowers , july and august were hot and sunshiny , and september and october were a kaleidoscope of colorful leaves . it was just the way the world worked , and it was magical . if you had told me back then that one-third of earth 's population had never seen snow or that july 4th was most definitely not a beach day , i would have thought you were crazy . but in reality , seasonal change with four distinct seasons only happens in two regions on the planet . and , even in those two , the seasons are reversed . but why ? a lot of people have heard of an astronomer called johannes kepler and how he proved that planetary orbits are elliptical and that the sun is not at the center of the orbit . it was a big deal when he figured this out several hundred years ago . his discovery solved a lot of mathematical problems that astronomers were having with planetary orbit measurements . while it 's true that our orbit 's not perfectly circular , those pictures in our science books , on tv , and in the movies give an exaggerated impression of how elongated our orbit is . in fact , earth 's orbit is very nearly a perfect circle . however , because earth 's orbit is technically an ellipse , even though it does n't look like one , and the sun is n't quite exactly at the center , it means that our distance from the sun does change through the year . ah-ha ! so , winter happens when the earth is further away from the sun ! well , no , not so fast . the earth is actually closer to the sun in january than we are in july by 5 million kilometers . january is smack-dab in the middle of the coldest season of the year for those of us up north . still not convinced ? how about this : summer and winter occur simultaneously on the surface of our planet . when it 's winter in connecticut , it 's summer in new zealand . so , if it 's not the distance from the sun , what else could it be ? well , we need to also need to know that the earth does n't sit straight up . it actually tilts . and that axial tilt of the earth is one of the main reasons for the seasons . the earth spins on an axis that 's tilted 23.5 degrees from vertical . at the same time , the earth revolves around the sun with the axis always pointing in the same direction in space . together with the tilt , the spinning and revolving causes the number of hours of daylight in a region to change as the year goes by , with more hours in summer and fewer in winter . so , when the sun is shining on the earth , it warms up . after the sun sets , it has time to cool down . so , in the summer , any location that 's about 40 degrees north of the equator , like hartford , connecticut , will get 15 hours of daylight each day and 9 hours of darkness . it warms up for longer than it cools . this happens day after day , so there is an overall warming effect . remember this fact for later ! in the winter , the opposite happens . there are many more hours of cooling time than warming time , and day after day , this results in a cooling effect . the interesting thing is , as you move north , the number of daylight hours in summer increases . so , juneau , alaska would get about 19 hours of daylight on the same summer day that tallahassee , florida gets about 14 . in fact , in the summertime at the north pole , the sun never sets . ok , then , it 's all about daylight hours , i 've got it ! well , no , there 's another important piece to this puzzle . if daylight hours were the only thing that determined average temperature , would n't the north pole be the hottest place on earth in northern summer because it receives 24 hours of daylight in the months surrounding the summer solstice ? but it 's the north pole . there 's still icebergs in the water and snow on the ground . so , what 's going on ? the earth is a sphere and so the amount of solar energy an area receives changes based on how high the sun is in the sky , which , as you know , changes during the day between sunrise and sunset . but , the maximum height also changes during the year , with the greatest solar height during the summer months and highest of all at noon on the summer solstice , which is june 21st in the northern hemisphere and december 21st in the southern hemisphere . this is because as the earth revolves , the northern hemisphere ends up tilted away from the sun in the winter and toward the sun in summer , which puts the sun more directly overhead for longer amounts of time . remember those increased summer time daylight hours ? and solar energy per square kilometer increases as the sun gets higher in the sky . so , when the sun 's at an angle , the amount of energy delivered to each square of the sunlit area is less . therefore , even though the north pole is getting 24 hours of daylight to warm up , the sunlight it receives is very spread out and delivers less energy than a place further south , where the sun is higher in the sky because it 's more tilted toward the sun . besides , the north pole has a lot to make up for . it was cooling down without any sunlight at all for 6 months straight . so , as the seasons change , wherever you are , you can now appreciate not just the beauty of each new season but the astronomical complexity that brings them to you .

ah-ha ! so , winter happens when the earth is further away from the sun ! well , no , not so fast .

the earth is closest to the sun during the month of :

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 .

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 .

if i exercise 30 minutes a daily , the negative effects of sitting at work will be diminished .

meet our chemist , harriet . she has a chemical reaction that needs to occur more quickly . a chemist has some processes at her disposal that can help her speed up her reaction , and she knows of five ways . and to remember them , she thinks back to her days as a high school student , and the day she got a date for the dance . harriet was in high school , studying between classes . she had lost track of time and was going to be late to class . unbeknownst to her , harold , who was just around the corner , was running late , too . they both sprinted to class and , as it happened , sprinted directly into one another . now , this was no small collision . they ran squarely into one another in such a way that he knocked the books right out of her hand . `` i 'm sorry , '' he said . `` let me help you with your books . '' he kindly helped her re-collect her belongings , and politely offered to walk her to class . and you 'll never guess who went together to the dance later that year . yup , those two . so as we can see from this example , the key to getting a date for the dance is to collide with someone and knock the books out of their hands . now , you 're probably already aware that not all collisions lead to dates for the dance , thankfully . the collisions must have two important characteristics : one , correct orientation that allows books to be knocked from one 's hands ; and two , enough energy to knock the books out . shortly after this incident , harriet decided to tell me , her chemistry teacher , all about it . i noticed some interesting parallels between her story and chemical reaction rates , which happened to be what she was studying in the hallway the day of the collision . together , we decided to set out on two missions . harriet wanted to help all chemistry students and chemists remember how to speed up the rate of chemical reactions and i , being the nice guy that i am , decided to make it my mission to help create educational environments in which more book-dropping collisions can take place to increase future chemists ' chances of getting a date for the dance . in order to facilitate this improved dance-date-getting process , i propose five changes to all schools that parallel harriet 's five ways to increase chemical reaction rates . first , i propose that we shrink the size of the hallways . this will make it more difficult to safely navigate the hallways and will cause more collisions than in larger hallways . and by increasing the number of collisions , we increase the likelihood that some of those collisions will have the correct alignment and enough energy to create a date to the dance . now , chemically speaking , this is equivalent to lowering the volume of a reaction vessel or a reaction mixture . in doing so , the individual particles are closer together , and more collisions will occur . more collisions means a greater likelihood that collisions with the appropriate energy and configuration will happen . second , i propose increasing the overall population of the school . more students equals more collisions . by increasing the number of particles available for collision , we create an environment where more collisions can take place . third , we must reduce the time allowed between classes -- heck , let 's just cut it in half . in doing so , students will need to move more quickly to get from one class to the next . this increase in velocity will help make sure collisions have the appropriate amount of energy necessary to ensure book-dropping . this is analogous to increasing the temperature of the reaction mixture . higher temperature means particles are moving faster . faster-moving particles means more energy , and a greater likelihood of the reaction-causing collision . fourth , students must stop traveling in packs . by traveling in packs , the students on the outside of the pack insulate those in the middle from undergoing any collisions . by splitting up , each student has more area exposed that is available for a collision from a passing student . when particles travel in packs , the surface area is very small , and only the outside particles can collide . however , by breaking up the clumps into individual particles , the total surface area is increased , and each particle has an exposed surface that can react . fifth and finally , we hire a matchmaker . is this colliding and book-dropping too violent ? is there an easier way to get a date that requires less initial energy ? then a matchmaker will help with this . the matchmaker makes it easier for a couple to get together , by coordinating the match . our matchmaker is like a catalyst . chemical catalysts function by lowering the activation energy -- in other words , by lowering the energy required to start a reaction . they do this by bringing two particles together and orienting them correctly in space so that the two can meet at the correct configuration and allow a reaction to take place . so , to sum up : if a future chemist wants a date for the dance , he must collide with another person and knock the books out of their hands . and if a chemist wants to make a chemical reaction occur , the particles must collide in the correct orientation with an appropriate amount of energy . and both of these processes can be accelerated , using the five methods i 've described .

this increase in velocity will help make sure collisions have the appropriate amount of energy necessary to ensure book-dropping . this is analogous to increasing the temperature of the reaction mixture . higher temperature means particles are moving faster .

in this analogy , shortening the passing periods is analogous to :

when the next general election rolls around , who will be eligible to show up at the polls and vote for the president of the united states ? it 's really pretty simple . if you are at least 18 years old , a citizen of the u.s. , and a resident of a state , you can vote , assuming , that is , you are not a felon . seems about right . after all , the united states prides itself on being a democracy , or a government in which the ultimate authority lies with the citizens of the nation . but it was not always this way . in 1789 , george washington won the electoral college with 100 % of the vote , but whose vote was it ? probably not yours . only 6 % of the entire united states population was allowed to vote at all . voting was a right that only white , male property owners were allowed to exercise . by the 1820s and 1830s , the american population was booming from the east coast into the western frontier . frontier farmers were resilient , self-reliant , and mostly ineligible to vote because they did not own land . as these new areas of the nation became states , they typically left out the property requirement for voting . leaders such as andrew jackson , the united state 's first common man president , promoted what he called universal suffrage . of course , by universal suffrage , jackson really meant universal white , male suffrage . all he emphasized was getting rid of the property requirement for voting , not expanding the vote beyond white men . by the 1850s , about 55 % of the adult population was eligible to vote in the u.s. , much better than 6 % , but far from everybody . then , in 1861 , the american civil war began largely over the issue of slavery and states ' rights in the united states . when it was all over , the u.s. ratified the 15th amendment , which promised that a person 's right to vote could not be denied based on race , color , or previous condition as a slave . this meant that black men , newly affirmed as citizens of the u.s. , would now be allowed to vote . of course , laws are far from reality . despite the promise of the 15th amendment , intimidation kept african-americans from exercising their voting rights . states passed laws that limited the rights of african-americans to vote , including things like literacy tests , which were rigged so that not even literate african-americans were allowed to pass , and poll taxes . so , despite the 15th amendment , by 1892 , only about 6 % of black men in mississippi were registered to vote . by 1960 , it was only 1 % . and , of course , women were still totally out of the national voting picture . it was n't until 1920 that the women 's suffrage movement won their 30-year battle , and the 19th amendment finally gave women the vote , well , white women . the restrictions on african-americans , including african-american women , remained . after world war ii , many americans began to question the state of u.s. democracy . how could a nation that fought for freedom and human rights abroad come home and deny suffrage based on race ? the modern civil rights movement began in the 1940s with those questions in mind . after years of sacrifice , bloodshed , and pain , the united states passed the voting rights act of 1965 , finally eliminating restrictions such as literacy tests and protecting the voting rights promised under the 15th amendment to the constitution . now , any citizen over the age of 21 could vote . all seemed well until the united states went to war . when the vietnam war called up all men age 18 and over for the draft , many wondered whether it was fair to send men who could n't vote to war . in 1971 , the 26th amendment to the constitution made all citizens 18 and older eligible to vote , the last major expansion of voting rights in the united states . today , the pool of eligible voters in the u.s. is far broader and more inclusive than ever before in u.s. history . but , of course , it 's not perfect . there are still active efforts to suppress some groups from voting , and only about 60 % of those who can vote do . now that you know all the hard work that went into securing the right to vote , what do you think ? do enough citizens have the right to vote now ? and among those who can vote , why do n't more of them do it ?

the modern civil rights movement began in the 1940s with those questions in mind . after years of sacrifice , bloodshed , and pain , the united states passed the voting rights act of 1965 , finally eliminating restrictions such as literacy tests and protecting the voting rights promised under the 15th amendment to the constitution . now , any citizen over the age of 21 could vote .

what was the voting rights act of 1965 ?

translator : andrea mcdonough reviewer : bedirhan cinar what does `` going viral '' on the internet really mean , and why does it happen so quickly ? why is a financial institution too big to fail ? how does a virus in africa end up in the united states in a matter of hours ? why are facebook and google such powerful companies at creating global connections ? well , in a word : networks . but what are networks ? everyone knows about their social network , but there are all different kinds of networks you probably have n't thought about . networks are collections of links which combine by specific rules and behaviors if they are alive . we say that networks are alive because they are in constant change . over time , the connections within a network migrate and concentrate in new places , forming evolving structures . how the evolution and concentration of constantly changing connections occurs is the subject of a whole discipline called network theory . we can think of networks as neighborhoods . neighborhoods are defined by maps . a google map demonstrates the relationship between locations in exactly the same fashion a network connects hubs and nodes , using streets as links to connect neighborhoods . the reason a network can expand and evolve so quickly is based upon a mathematical concept called power functions . a power function is a mathematical amplification mechanism , which over specific and very small ranges , accelerates changes logarithmically . that is , a very small change in one parameter produces a huge change in another over a very specific range of values . an example of how network structure emerges is the algorithm used by google . as the number of links around a search term , say `` friends '' , increases , connections begin to form among millions of different searches using the term `` friend '' . what google has cleverly accomplished is a real-time mathematical model for how to predict the emergence of growing connections among billions of search terms . the algorithm google derived collects the number of references to any search object . as references to a search object increase , the number of links also increases , creating a node . as the node increases in size , it eventually becomes a hub , which links to many nodes . networks will continue to emerge as new ways of connecting and creating neighborhoods are defined . perhaps you can begin to see why networks are so powerful . as google continues to collect the billions of daily searches , new clusters of links will rapidly emerge , forming additional and growing networks . despite the logarithmic expansion of your network , the laws of six degrees of separation still apply . therefore , if you explore a close friend or acquaintances in you facebook network , everyone on average will be separated by six individuals or less and a map of your social network will create neighborhoods linked by common connections among friends .

why are facebook and google such powerful companies at creating global connections ? well , in a word : networks . but what are networks ? everyone knows about their social network , but there are all different kinds of networks you probably have n't thought about .

what law applies to our social networks ?

this is the story of three plastic bottles , empty and discarded . their journeys are about to diverge with outcomes that impact nothing less than the fate of the planet . but they were n't always this way . to understand where these bottles end up , we must first explore their origins . the heroes of our story were conceived in this oil refinery . the plastic in their bodies was formed by chemically bonding oil and gas molecules together to make monomers . in turn , these monomers were bonded into long polymer chains to make plastic in the form of millions of pellets . those were melted at manufacturing plants and reformed in molds to create the resilient material that makes up the triplets ' bodies . machines filled the bottles with sweet bubbily liquid and they were then wrapped , shipped , bought , opened , consumed and unceremoniously discarded . and now here they lie , poised at the edge of the unknown . bottle one , like hundreds of millions of tons of his plastic brethren , ends up in a landfill . this huge dump expands each day as more trash comes in and continues to take up space . as plastics sit there being compressed amongst layers of other junk , rainwater flows through the waste and absorbs the water-soluble compounds it contains , and some of those are highly toxic . together , they create a harmful stew called leachate , which can move into groundwater , soil and streams , poisoning ecosystems and harming wildlife . it can take bottle one an agonizing 1,000 years to decompose . bottle two 's journey is stranger but , unfortunately , no happier . he floats on a trickle that reaches a stream , a stream that flows into a river , and a river that reaches the ocean . after months lost at sea , he 's slowly drawn into a massive vortex , where trash accumulates , a place known as the great pacific garbage patch . here the ocean 's currents have trapped millions of pieces of plastic debris . this is one of five plastic-filled gyres in the world 's seas . places where the pollutants turn the water into a cloudy plastic soup . some animals , like seabirds , get entangled in the mess . they , and others , mistake the brightly colored plastic bits for food . plastic makes them feel full when they 're not , so they starve to death and pass the toxins from the plastic up the food chain . for example , it 's eaten by lanternfish , the lanternfish are eaten by squid , the squid are eaten by tuna , and the tuna are eaten by us . and most plastics do n't biodegrade , which means they 're destined to break down into smaller and smaller pieces called micro plastics , which might rotate in the sea eternally . but bottle three is spared the cruel purgatories of his brothers . a truck brings him to a plant where he and his companions are squeezed flat and compressed into a block . okay , this sounds pretty bad , too , but hang in there . it gets better . the blocks are shredded into tiny pieces , which are washed and melted , so they become the raw materials that can be used again . as if by magic , bottle three is now ready to be reborn as something completely new . for this bit of plastic with such humble origins , suddenly the sky is the limit .

the plastic in their bodies was formed by chemically bonding oil and gas molecules together to make monomers . in turn , these monomers were bonded into long polymer chains to make plastic in the form of millions of pellets . those were melted at manufacturing plants and reformed in molds to create the resilient material that makes up the triplets ' bodies .

the chains that ultimately form plastic are known as :

humans have observed comets for thousands of years as their orbits have brought them within visible distance of earth . appearing throughout historical records , these mysterious lights that came out of nowhere and disappeared after a short while were thought to be ill omens of war and famine , or the wrath of gods . but recent research has revealed that comets may be even more deeply connected to humanity and our presence on earth than any of these mythical explanations suggested . when you think of our solar system , you probably imagine the nine , sorry eight , planets orbiting the sun . but beyond neptune , far from the heat of the sun , there is a sparse ring found formed by icy chunks ranging from the size of marbles to that of small planets . and thousands of times farther at the outer reaches of the solar system lies a spherical cloud of small fragments and gases . many of these ancient clumps of stardust are leftovers from the formation of the solar system 4.6 billion years ago , while some of the most distant may even come from a neighboring system . but sometimes the gravity from passing planets or stars pulls them toward our sun , beginning a journey that can take up to millions of years . as the frozen object travels further into the solar system , the sun grows from a distant spark to an inferno , melting the ice for the first time in billions of years . gas and steam eject dust into space , forming a bright surrounding cloud , called a coma , that can grow even larger than the sun itself . meanwhile , the intense stream of high-energy particles constantly emitted by the sun , known as the solar wind , blows particles away from the comet 's core , forming a trail of debris up to millions of miles long . the ice , gas and dust reflect light glowing brightly . a comet is born , now orbiting the sun along with the rest of the objects in our solar system . but as the comet travels through the solar system , the solar wind tears apart and recombines molecules into various compounds . in some of the compounds that scientists found , first in the rubble left by a meteorite that disintegrated above northern canada , and then in samples collected by a space craft from a passing comet 's tail , were nothing less important than amino acids . coming together to form proteins according to the instructs encoded in dna , these are the main active components in all living cells , from bacteria to blue whales . if comets are where these building blocks of life were first formed , then they are the ultimate source of life on earth , and , perhaps , some of the other places they visited as well . we know that planets orbit nearly every star in the night sky , with one in five having a planet similar to earth in size and temperature . if earth-like planets and the molecules found in dna are not anomalies , we may be only one example of what 's possible when a planet under the right conditions is seeded with organic molecules by a passing comet . so , rather than an omen of death , the comet that first brought amino acids to earth could have been a portent of life , a prediction of a distant future , where creatures of stardust would return to space to find the mysteries of where they came from .

coming together to form proteins according to the instructs encoded in dna , these are the main active components in all living cells , from bacteria to blue whales . if comets are where these building blocks of life were first formed , then they are the ultimate source of life on earth , and , perhaps , some of the other places they visited as well . we know that planets orbit nearly every star in the night sky , with one in five having a planet similar to earth in size and temperature . if earth-like planets and the molecules found in dna are not anomalies , we may be only one example of what 's possible when a planet under the right conditions is seeded with organic molecules by a passing comet .

for the first time in history earth-like planets are known to orbit one of every five stars in the galaxy . organic molecules are sprinkled throughout solar systems in comets and asteroids . given these new discoveries , do you think life exists on other planets ?

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 . ''

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 .

shakespeare ’ s audiences would have been worried about kings being overthrown because :

i was walking my mountain the other day , and i was feeling really at home with the forest . and i was so grateful to it for showing me that forests are built on relationships which form networks , like these beautiful river networks . and i thought , `` wow , forests are just like human families . '' and i was so taken by the beauty of this idea that i fell and i crashed down on the ground , and i hit my head on this new stump . and i was so angry ! then , i was so heartbroken because there was a whole family of trees cut down . thing is , where i 'm from in western canada , there 's clearcuts like this hidden everywhere , and it was n't until google earth starting sending images , like this , that we realized the whole world was wiping its noses on our old-growth forests . did you know that deforestation like this around the world causes more greenhouse gas emissions than all the trains , planes and automobiles combined ? yeah , i 'm really upset about this , but i 'm also really hopeful because i 've also discovered in my research that forest networks are organized in the same way as our own neural networks and our social networks . and i believe that if we can learn to integrate these into a whole that we can change this dangerous pathway of global warming because i believe we are wired for healing . so , here 's the science : the most ancient of these networks is this below-ground fungal network , or mushroom network . and it evolved over a billion years ago to allow organisms to migrate from the ocean onto the land . and eventually , they got together with plants in this symbiosis . and this allowed plants to photosynthesize , pulling co2 , which is our biggest greenhouse gas , out of the atmosphere and giving off oxygen , which allows us to breathe and actually allowed humans to eventually evolve . now , we call this symbiosis a mycorrhiza , myco for fungus , rrhiza for root . so , the fungus and root get together , and they trade for mutual benefit . now , all trees in all forests all over the world depend on these mycorrhizas for their very survival . they ca n't live without them . and the way it works is that a seed falls on the forest floor , it germinates , it sends a root down into the soil , and it starts sending out chemical signals to the fungi to grow towards the root . and the fungus communicates back with its own signals , and it says to the root , 'you need to grow towards me and branch and soften . ' and so by this communication , they grow together into this magical symbiosis . and the way that symbiosis works is the plant takes its hard-earned carbon from photosynthesis and brings it to the fungus because the fungus ca n't photosynthesize . and the fungus takes nutrients and water it gathers from the soil , where plant roots ca n't grow , and they give it to the plant . and so they 're both benefiting in this cooperation . now , as the fungus grows through the soil , it starts linking plant and plant and tree and tree together until the whole forest is linked together . did you know that a single tree can be literally linked up to hundreds of other trees as far as the eye can see ? and as you 're walking through the forest , what you see , the trees , the roots , the mushrooms , are just the tip of the iceberg . under a single footstep , there are 300 miles of fungal cells stacked end on end moving stuff around . and if you could look down into the ground , it would be like this super highway with cars going everywhere . now , all networks are made of nodes and links . in forests , those nodes would be trees and the links fungi . it 's kind of like in your facebook network , where nodes would be friends and links would be your friendships . now , we all know that some of those nodes , or friends , are busier than others , like that friend who is always sending out group messages . well , it 's the same in forests , and these nodes in forests , we call them hubs , they 're the big trees in the forests with roots going everywhere . now , we also have learned that the systems organized around these hubs , these big old trees , so in forests , that 's where the regeneration occurs . in your facebook network , that might be how parties are organized , around that hub that 's always sending out the group messages . we call those hubs in forests mother trees ; they 're the big old trees in the forest . and they fix the carbon in their leaves , and they send it down through their massive trunks and into the networks all around them that are linked up to all the other trees and seedlings , the young ones , and they start sending that carbon everywhere . the more those seedlings are stressed out , maybe from drought or shade , the more the mother tree sends to them . it 's kind of like in your families , where if you 're kind of stressed out , mom and dad kick in and help you out a bit more , right ? well , it 's the same in forests . the other thing that we 've recently discovered is that mother trees will preferentially send more signals to her own kids , her own children . and then , this way she helps them do better , and then they survive more , and then they can pass their genes on to future generations . so , how natural selection works . now , the way these forests are organized makes them both resilient and vulnerable . they 're resilient because there 's many mother trees , and there 's many fungal species linking them together . and that network is really hard to break . it 's pretty darn tough . but of course , we humans have figured out how to do that . and what we do is we take out the mother trees . and maybe taking one out wo n't make much difference but when you take more and more and more and clearcut and more and more and more that it can cause the system to collapse and fall down , like dominoes . and we can cross tipping points and cause more forest death and more global warming , and we 're doing that . so what we do , our choices we make , can lead us towards global heatlh or global sickness . we do have choices . and i 'm going to leave you with four ideas that i think are worth spreading . first one : to love the forest you have to go spend time in it . go be in the forest , connect with it . and then you 'll fight hard enough to protect them . second : learn how they work . learn how those networks link things together in organized forests . and to do that , you got ta go out there take risks , make mistakes . third : protect forests . they need you to do that because they ca n't do it themselves . they 're stuck in one spot . they ca n't run away from humans , and they ca n't run away from global warming . they need you . and finally , and most importantly , use your own very clever , brilliant , neural and social networks to create amazing messages , and spread the word that forests are worth saving because you 're worth saving , and i believe that together we 're all wired for healing .

in your facebook network , that might be how parties are organized , around that hub that 's always sending out the group messages . we call those hubs in forests mother trees ; they 're the big old trees in the forest . and they fix the carbon in their leaves , and they send it down through their massive trunks and into the networks all around them that are linked up to all the other trees and seedlings , the young ones , and they start sending that carbon everywhere .

mother trees serve as hubs in the forest , where kin seedlings establish in their vast mycorrhizal networks . what are some ways we can use this knowledge to ensure healthy regeneration of disturbed ( e.g. , logged ) forest ?

in islamic culture , geometry is everywhere . you can find it in mosques , madrasas , palaces and private homes . this tradition began in the 8th century ce during the early history of islam , when craftsman took preexisting motifs from roman and persian cultures and developed them into new forms of visual expression . this period of history was a golden age of islamic culture , during which many achievements of previous civilizations were preserved and further developed , resulting in fundamental advancements in scientific study and mathematics . accompanying this was an increasingly sophisticated use of abstraction and complex geometry in islamic art , from intricate floral motifs adorning carpets and textiles , to patterns of tilework that seemed to repeat infinitely , inspiring wonder and contemplation of eternal order . despite the remarkable complexity of these designs , they can be created with just a compass to draw circles and a ruler to make lines within them , and from these simple tools emerges a kaleidoscope multiplicity of patterns . so how does that work ? well , everything starts with a circle . the first major decision is how will you divide it up ? most patterns split the circle into four , five or six equal sections . and each division gives rise to distinctive patterns . there 's an easy way to determine whether any pattern is based on fourfold , fivefold , or sixfold symmetry . most contain stars surrounded by petal shapes . counting the number of rays on a starburst , or the number of petals around it , tells us what category the pattern falls into . a star with six rays , or surrounded by six petals , belongs in the sixfold category . one with eight petals is part of the fourfold category , and so on . there 's another secret ingredient in these designs : an underlying grid . invisible , but essential to every pattern , the grid helps determine the scale of the composition before work begins , keeps the pattern accurate , and facilitates the invention of incredible new patterns . let 's look at an example of how these elements come together . we 'll start with a circle within a square , and divide it into eight equal parts . we can then draw a pair of criss-crossing lines and overlay them with another two . these lines are called construction lines , and by choosing a set of their segments , we 'll form the basis of our repeating pattern . many different designs are possible from the same construction lines just by picking different segments . and the full pattern finally emerges when we create a grid with many repetitions of this one tile in a process called tessellation . by choosing a different set of construction lines , we might have created this pattern , or this one . the possibilities are virtually endless . we can follow the same steps to create sixfold patterns by drawing construction lines over a circle divided into six parts , and then tessellating it , we can make something like this . here 's another sixfold pattern that has appeared across the centuries and all over the islamic world , including marrakesh , agra , konya and the alhambra . fourfold patterns fit in a square grid , and sixfold patterns in a hexagonal grid . fivefold patterns , however , are more challenging to tessellate because pentagons do n't neatly fill a surface , so instead of just creating a pattern in a pentagon , other shapes have to be added to make something that is repeatable , resulting in patterns that may seem confoundingly complex , but are still relatively simple to create . also , tessellation is not constrained to simple geometric shapes , as m.c . escher 's work demonstrates . and while the islamic geometric design tradition does n't tend to employ elements like fish and faces , it does sometimes make use of multiple shapes to craft complex patterns . this more than 1,000-year-old tradition has wielded basic geometry to produce works that are intricate , decorative and pleasing to the eye . and these craftsman prove just how much is possible with some artistic intuition , creativity , dedication and a great compass and ruler .

in islamic culture , geometry is everywhere . you can find it in mosques , madrasas , palaces and private homes .

geometry is everywhere in the natural world . can you find of examples of fourfold , fivefold and sixfold geometry in nature ?

translator : tom carter reviewer : bedirhan cinar why are gas stations always built right next to other gas stations ? why can i drive for a mile without finding a coffee shop and then stumble across three on the same corner ? why do grocery stores , auto repair shops and restaurants always seem to exist in groups instead of being spread evenly throughout a community ? while there are several factors that might go into deciding where to place your business , clusters of similar companies can be explained by a very simple story called hotelling 's model of spatial competition . imagine that you sell ice cream at the beach . your beach is one mile long and you have no competition . where would you place your cart in order to sell the most product ? in the middle . the one-half-mile walk may be too far for some people at each end of the beach , but your cart serves as many people as possible . one day you show up at work just as your cousin teddy is arriving at the beach with his own ice cream cart . in fact , he 's selling exactly the same type of ice cream as you are . you agree that you will split the beach in half . in order to ensure that customers do n't have to walk too far you set up your cart a quarter mile south of the beach center , right in the middle of your territory . teddy sets up a quarter mile north of the center , in the middle of teddy territory . with this agreement , everyone south of you buys ice cream from you . everyone north of teddy buys from him , and the 50 % of beachgoers in between walk to the closest cart . no one walks more than a quarter of a mile , and both vendors sell to half of the beachgoers . game theorists consider this a socially optimal solution . it minimizes the maximum number of steps any visitor must take in order to reach an ice cream cart . the next day , when you arrive at work , teddy has set up his cart in the middle of the beach . you return to your location a quarter mile south of center and get the 25 % of customers to the south of you . teddy still gets all of the customers north in teddy territory , but now you split the 25 % of people in between the two carts . day three of the ice cream wars , you get to the beach early , and set up right in the center of teddy territory , assuming you 'll serve the 75 % of beachgoers to your south , leaving your cousin to sell to the 25 % of customers to the north . when teddy arrives , he sets up just south of you stealing all of the southerly customers , and leaving you with a small group of people to the north . not to be outdone , you move 10 paces south of teddy to regain your customers . when you take a mid-day break , teddy shuffles 10 paces south of you , and again , steals back all the customers to the far end of the beach . throughout the course of the day , both of you continue to periodically move south towards the bulk of the ice cream buyers , until both of you eventually end up at the center of the beach , back to back , each serving 50 % of the ice-cream-hungry beachgoers . at this point , you and your competitive cousin have reached what game theorists call a nash equilibrium - the point where neither of you can improve your position by deviating from your current strategy . your original strategy , where you were each a quarter mile from the middle of the beach , did n't last , because it was n't a nash equilibrium . either of you could move your cart towards the other to sell more ice cream . with both of you now in the center of the beach , you ca n't reposition your cart closer to your furthest customers without making your current customers worse off . however , you no longer have a socially optimal solution , since customers at either end of the beach have to walk further than necessary to get a sweet treat . think about all the fast food chains , clothing boutiques , or mobile phone kiosks at the mall . customers may be better served by distributing services throughout a community , but this leaves businesses vulnerable to aggressive competition . in the real world , customers come from more than one direction , and businesses are free to compete with marketing strategies , by differentiating their product line , and with price cuts , but at the heart of their strategy , companies like to keep their competition as close as possible .

think about all the fast food chains , clothing boutiques , or mobile phone kiosks at the mall . customers may be better served by distributing services throughout a community , but this leaves businesses vulnerable to aggressive competition . in the real world , customers come from more than one direction , and businesses are free to compete with marketing strategies , by differentiating their product line , and with price cuts , but at the heart of their strategy , companies like to keep their competition as close as possible .

if you started a retail business , would you prefer to be in a community with no competition or a community with several other retail businesses just like yours ? why ?

it 's midnight and all is still , except for the soft skittering of a gecko hunting a spider . geckos seem to defy gravity , scaling vertical surfaces and walking upside down without claws , adhesive glues or super-powered spiderwebs . instead , they take advantage of a simple principle : that positive and negative charges attract . that attraction binds together compounds , like table salt , which is made of positively charged sodium ions stuck to negatively charged chloride ions . but a gecko 's feet are n't charged and neither are the surfaces they 're walking on . so , what makes them stick ? the answer lies in a clever combination of intermolecular forces and stuctural engineering . all the elements in the periodic table have a different affinity for electrons . elements like oxygen and fluorine really , really want electrons , while elements like hydrogen and lithium do n't attract them as strongly . an atom 's relative greed for electrons is called its electronegativity . electrons are moving around all the time and can easily relocate to wherever they 're wanted most . so when there are atoms with different electronegativities in the same molecule , the molecules cloud of electrons gets pulled towards the more electronegative atom . that creates a thin spot in the electron cloud where positive charge from the atomic nuclei shines through , as well as a negatively charged lump of electrons somewhere else . so the molecule itself is n't charged , but it does have positively and negatively charged patches . these patchy charges can attract neighboring molecules to each other . they 'll line up so that the positive spots on one are next to the negative spots on the other . there does n't even have to be a strongly electronegative atom to create these attractive forces . electrons are always on the move , and sometimes they pile up temporarily in one spot . that flicker of charge is enough to attract molecules to each other . such interactions between uncharged molecules are called van der waals forces . they 're not as strong as the interactions between charged particles , but if you have enough of them , they can really add up . that 's the gecko 's secret . gecko toes are padded with flexible ridges . those ridges are covered in tiny hair-like structures , much thinner than human hair , called setae . and each of the setae is covered in even tinier bristles called spatulae . their tiny spatula-like shape is perfect for what the gecko needs them to do : stick and release on command . when the gecko unfurls its flexible toes onto the ceiling , the spatulae hit at the perfect angle for the van der waals force to engage . the spatulae flatten , creating lots of surface area for their positively and negatively charged patches to find complimentary patches on the ceiling . each spatula only contributes a minuscule amount of that van der waals stickiness . but a gecko has about two billion of them , creating enough combined force to support its weight . in fact , the whole gecko could dangle from a single one of its toes . that super stickiness can be broken , though , by changing the angle just a little bit . so , the gecko can peel its foot back off , scurrying towards a meal or away from a predator . this strategy , using a forest of specially shaped bristles to maximize the van der waals forces between ordinary molecules has inspired man-made materials designed to imitate the gecko 's amazing adhesive ability . artificial versions are n't as strong as gecko toes quite yet , but they 're good enough to allow a full-grown man to climb 25 feet up a glass wall . in fact , our gecko 's prey is also using van der waals forces to stick to the ceiling . so , the gecko peels up its toes and the chase is back on .

that flicker of charge is enough to attract molecules to each other . such interactions between uncharged molecules are called van der waals forces . they 're not as strong as the interactions between charged particles , but if you have enough of them , they can really add up .

a gecko ’ s skin is largely made of proteins , very long molecules which contain atoms of different electronegativities . explain how van der waals forces within proteins can cause them to fold into complex shapes .

translator : tom carter reviewer : bedirhan cinar as you can imagine , 400 years ago , navigating the open ocean was difficult . the winds and currents pushed and pulled ships off course , and so sailors based their directions on the port they left , attempting to maintain an accurate record of the ship 's direction and the distance sailed . this process was known as dead reckoning , because being just half a degree off could result in sailing right past the island that lay several miles just over the horizon . this was an easy mistake to make . thankfully , three inventions made modern navigation possible : sextants , clocks and the mathematics necessary to perform the required calculations quickly and easily . all are important . without the right tools , many sailors would be reluctant to sail too far from the sight of land . john bird , an instrument maker in london , made the first device that could measure the angle between the sun and the horizon during the day , called a sextant . knowing this angle was important , because it could be compared to the angle back in england at the exact same time . comparing these two angles was necessary to determine the longitude of the ship . clocks came next . in 1761 , john harrison , an english clockmaker and carpenter , built a clock that could keep accurate time at sea . the timepiece that could maintain accurate time while on a pitching , yawing deck in harsh conditions was necessary in order to know the time back in england . there was one catch though : since such a timepiece was handmade , it was very expensive . so an alternate method using lunar measurements and intense calculations was often used to cut costs . the calculations to determine a ship 's location for each measurement could take hours . but sextants and clocks were n't useful unless sailors could use these tools to determine their position . fortunately , in the 1600s , an amateur mathematician had invented the missing piece . john napier toiled for more than 20 years in his castle in scotland to develop logarithms , a calculation device . napier 's ideas on logarithms involved the form of one over e and the constant 10 to the seventh power . algebra in the early 1600s was not fully developed , and napier 's logarithm of one did not equal zero . this made the calculations much less convenient than logarithms with a base of 10 . henry briggs , a famous mathematician at gresham college in london , read napier 's work in 1614 , and the following year made the long journey to edinburgh to meet napier . briggs showed up unannounced at napier 's castle door and suggested that john switch the base and form of his logarithms into something much simpler . they both agreed that a base of 10 with the log of one equal to zero would greatly simplify everyday calculations . today we remember these as briggs common logarithms . until the development of electric calculating machines in the 20th century , any calculations involving multiplication , division , powers , and extraction of roots with large and small numbers were done using logarithms . the history of logarithms is n't just a lesson in math . there were many players responsible for successful navigation . instrument makers , astronomers , mathematicians , and of course sailors . creativity is n't only about going deep into one 's field of work , it 's about cross-pollination between disciplines too .

until the development of electric calculating machines in the 20th century , any calculations involving multiplication , division , powers , and extraction of roots with large and small numbers were done using logarithms . the history of logarithms is n't just a lesson in math . there were many players responsible for successful navigation . instrument makers , astronomers , mathematicians , and of course sailors .

this history of logarithms is n't just a lesson in math . there were many players responsible for successful navigation . which kind of person helped transform navigation ?

somewhere out there in that vast universe , there must surely be countless other planets teeming with life , but why do n't we see any evidence of it ? well , this is the famous question asked by enrico fermi in 1950 : `` where is everybody ? '' conspiracy theorists claim that ufos are visiting all the time and the reports are just being covered up , but honestly , they are n't very convincing . but that leaves a real riddle . in the past year , the kepler space observatory has found hundreds of planets just around nearby stars , and if you extrapolate that data , it looks like there could be half a trillion planets just in our own galaxy . if any one in 10,000 has conditions that might support a form of life , that 's still 50 million possible life-harboring planets right here in the milky way . so here 's the riddle . our earth did n't form until about 9 billion years after the big bang . countless other planets in our galaxy should have formed earlier and given life a chance to get underway billions or certainly many millions of years earlier than happened on earth . if just a few of them had spawned intelligent life and started creating technologies , those technologies would have had millions of years to grow in complexity and power . on earth , we 've seen how dramatically technology can accelerate in just 100 years . in millions of years , an intelligent alien civilization could easily have spread out across the galaxy , perhaps creating giant energy-harvesting artifacts , or fleets of colonizing spaceships , or glorious works of art that fill the night sky . at the very least , you 'd think they 'd be revealing their presence , deliberately or otherwise , through electromagnetic signals of one kind or another . and yet we see no convincing evidence of any of it . why ? well , there are numerous possible answers , some of them quite dark . maybe a single , superintelligent civilization has indeed taken over the galaxy , and has imposed strict radio silence because it 's paranoid of any potential competitors . it 's just sitting there ready to obliterate anything that becomes a threat . or maybe they 're not that intelligent . or perhaps , the evolution of an intelligence capable of creating sophisticated technology is far rarer than we 've assumed . after all , it 's only happened once on earth in 4 billion years . maybe even that was incredibly lucky . maybe we are the first such civilization in our galaxy . or , perhaps , civilization carries with it the seeds of its own destruction through the inability to control the technologies it creates . but there are numerous more hopeful answers . for a start , we 're not looking that hard , and we 're spending a pitiful amount of money on it . only a tiny fraction of the stars in our galaxy have really been looked at closely for signs of interesting signals . and perhaps , we 're not looking the right way . maybe as civilizations develop , they quickly discover communication technologies far more sophisticated and useful than electromagnetic waves . maybe all the action takes place inside the mysterious recently discovered dark matter , or dark energy , that appear to account for most of the universe 's mass . or maybe we 're looking at the wrong scale . perhaps intelligent civilizations come to realize that life is ultimately just complex patterns of information interacting with each other in a beautiful way , and that can happen more efficiently at a small scale . so just as on earth , clunky stereo systems have shrunk to beautiful , tiny ipods , maybe intelligent life itself , in order to reduce its footprint on the environment , has turned itself microscopic , so the solar system might be teeming with aliens , and we 're just not noticing them . maybe the very ideas in our heads are a form of alien life . well , okay , that 's a crazy thought . the aliens made me say it . but it is cool that ideas do seem to have a life all of their own , and that they outlive their creators . maybe biological life is just a passing phase . well , within the next 15 years , we could start seeing real spectroscopic information from promising nearby planets that will reveal just how life-friendly they might be . and meanwhile seti , the search for extra-terrestrial intelligence , is now releasing its data to the public so that millions of citizen scientists , maybe including you , can bring the power of the crowd to join the search . and here on earth , amazing experiments are being done to try to create life from scratch , life that might be very different from the dna forms we know . all of this will help us understand whether the universe is teeming with life or , whether indeed , it 's just us . either answer , in its own way , is awe-inspiring , because even if we are alone , the fact that we think and dream , and ask these questions might yet turn out to be one of the most important facts about the universe . and i have one more piece of good news for you . the quest for knowledge and understanding never gets dull . it does n't . it 's actually the opposite . the more you know , the more amazing the world seems . and it 's the crazy possibilities , the unanswered questions , that pull us forward . so , stay curious .

so just as on earth , clunky stereo systems have shrunk to beautiful , tiny ipods , maybe intelligent life itself , in order to reduce its footprint on the environment , has turned itself microscopic , so the solar system might be teeming with aliens , and we 're just not noticing them . maybe the very ideas in our heads are a form of alien life . well , okay , that 's a crazy thought .

our planet formed relatively recently , compared with the age of the universe . why does this raise a riddle , when it comes to the search for alien life ?

in 1984 , an enterprising australian doctor named barry marshall decided to take a risk . too many of his patients were complaining of severe abdominal pain due to stomach ulcers , which are sores in the lining of the upper intestinal tract . at the time , few effective treatments for ulcers existed , and many sufferers required hospitalization or even surgery . desperate for answers , dr. marshall swallowed a cloudy broth of bacteria collected from the stomach of one of his patients . soon , dr. marshall was experiencing the same abdominal pain , bloating , and vomiting . ten days later , a camera called an endoscope peered inside his insides . marshall 's stomach was teeming with the same bacteria as his patient . he 'd also developed gastritis , or severe inflammation of the stomach , the hallmark precursor of ulcers . dr. marshall 's idea challenged a misconception that still persists to this day : that ulcers are caused by stress , food , or too much stomach acid . marshall thought the culprit was bacterial infections . initially , his idea was considered crazy by the brightest medical minds on the planet . but in 2005 , he and dr. robin warren received the ultimate validation when they were awarded the nobel prize for medicine . our stomachs are j-shaped organs with surprisingly intricate ecosystems awash in hormones and chemicals . the stomach is under constant attack by digestive enzymes , bile , proteins , microbes , and the stomach 's own acid . in response , it produces bicarbonate , mucus , and phospholipids called prostaglandins to maintain the integrity of its own lining . this delicate balance is constantly regulated and referred to as mucosal defense . since the mid-1800s , doctors thought stress alone caused most stomach ulcers . patients were given antidepressants or tranquilizers and told to visit health spas . this belief eventually shifted to the related notion of spicy foods and stress as culprits . yet no convincing study has ever demonstrated that emotional upset , psychological distress , or spicy food directly causes ulcer disease . by the mid-20th century , it was widely accepted that excess hydrochloric acid prompted the stomach to eat itself . fervent proponents of this idea were referred to as the acid mafia . the biggest hole in this theory was that antiacids only provide temporary relief . we now know that some rare ulcers are indeed caused by too much hydrochloric acid . but they make up less than 1 % of all cases . dr. marshall and dr. warren pinpointed a spiral-shaped bacteria called helicobacter pylori , or h. pylori , as the real offender . h. pylori is one of humanity 's oldest and most frequent companions , having joined us at least 50,000 years ago , and now found in 50 % of people . previously , we thought the stomach was sterile on account of it being such an acidic , hostile environment . yet h. pylori survives the acidic turmoil of the stomach with a variety of features that disrupt mucosal defense in its favor . for example , it produces an enzyme called urease that helps protect it from the surrounding gastric acid . h. pylori can make over 1,500 proteins , many of which are dedicated to maximizing its virulence . we still have unanswered questions , like why specific people develop ulcers at particular times . however , we do know individual genetics , other medical problems , use of certain medications , smoking , and the genetic diversity of helicobacter strains all play a role . in particular , certain pain medications used to reduce inflammation in joints have been discovered to work with h. pylori to create more severe stomach ulcers . dr. marshall ended up being fine after his famous , albeit dangerous , experiment . he ingested a course of antibiotics similar to the ones taken now for ulcers . to be treated by simple antibiotics is a modern triumph for a disease that previously needed surgery . marshall 's work also reminded us that scientific progress is not always smooth . but there 's value in trusting your proverbial , and sometimes literal , gut .

our stomachs are j-shaped organs with surprisingly intricate ecosystems awash in hormones and chemicals . the stomach is under constant attack by digestive enzymes , bile , proteins , microbes , and the stomach 's own acid . in response , it produces bicarbonate , mucus , and phospholipids called prostaglandins to maintain the integrity of its own lining .

which is the primary acid in the stomach ?

in 2010 , $ 30 billion worth of fruits and vegetables were wasted by american retailers and shoppers in part because of cosmetic problems and perceived spoilage . that 's a poor use of about 30 % of the produce on the market , not to mention the water and energy required to grow and transport it , and the landfill space getting used up by rotting fruit . so what are those cosmetic problems ? you 've probably passed over a spotty apple in the grocery store , or accidentally sunk your thumb into a mushy patch on a tomato . these blemishes can doom produce to the trash can . but what are they anyway , and are they actually bad for you ? those spots are evidence of an epic battle between plants and microbes . like humans , plants coexist with billions of fungi and bacteria . some of these microbes are beneficial to the plant , suppressing disease and helping it extract nutrients . others are pathogens , attacking the produce , still alive as it sits in a store display or your refrigerator and siphoning off molecules they can use themselves . the good news is they 're almost never bad for you . these fungi and bacteria have spent millions of years developing strategies to overcome a plant 's immune system . but healthy human immune systems are different enough that those strategies just do n't work on us . so in a plant , what does this process look like ? microbes can reach plants in a number of ways , like getting splashed onto it during watering or fertilization . under the right conditions , the microbes grow into large enough colonies to attack the waxy outer layer of fruit or leaves . their target : the delicious sugars and nutrients inside . this type of pathogen often makes spots like this . a clump of bacteria drains the nutrients and color from the fruit 's cells making that yellow halo . it then moves outward , leaving a black spot of dead cells in its wake . each spot , which could contain hundreds of thousands of microbes is actually caused by a combination of microbial attack and the host defending itself . for example , this is the bacterial pathogen pseudomonas syringae . once on a tomato , it enters the fruit and leaves , multiplies in the space between the cells , and produces toxins and proteins that allow it to disrupt the plant 's immune response . one toxin coronatine makes plants ' stomata open up , allowing bacteria to enter more freely . coronatine also activates pathways leading to chlorophyll degradation , which you can see as yellow spots . as the bacteria continue to feed and multiply , they start to kill off the plant cells . that explains spots , but what about mushy blemishes ? those are usually caused when the fruit is attacked by microbes after it 's detached from the plant . if the plant is wounded during transport , necrotic fungi can infiltrate through the wound , kill the cells , absorb their nutrients , and leave your food looking mushy or brown . those spots in particular can taste pretty bad . you 're eating dead and decomposing tissue , after all . but you can usually salvage the rest of the fruit . the non-mushy spots , like the ones you typically see on apples or tomatoes , are just on the surface and do n't usually affect flavor . of course , microbes that do make us sick , like e. coli and salmonella , can hitch a ride on vegetables , too . but because they 're not plant pathogens , they do n't typically cause spots . they just hang out invisibly on the surface . so it 's washing fruit and veggies , not avoiding the spotty ones , that will help you avoid getting sick . so the next time you 're at the grocery store , do n't be afraid to pick up funky-looking fruit . some stores will even give you a discount . wash them well and store them properly , as some produce like apples and cabbages will keep in the fridge for weeks . the spotty ones may not be eye candy , but they 're safe and just as delicious .

a clump of bacteria drains the nutrients and color from the fruit 's cells making that yellow halo . it then moves outward , leaving a black spot of dead cells in its wake . each spot , which could contain hundreds of thousands of microbes is actually caused by a combination of microbial attack and the host defending itself . for example , this is the bacterial pathogen pseudomonas syringae .

when you see a strawberry with a fluffy , mushy spot you know that this spot is probably caused by a :

this image of the vitruvian man , taken from leonardo 's sketches , has become one of the most recognizable symbols of the renaissance . but why ? it 's a simple pen and ink drawing , right ? wrong ! let 's start to answer this question with a math problem . i know how to calculate the area of a circle . i take the value for pi and multiply it by the radius squared . i also know how to take the area of a square . i multiply the base by itself . but how can i take the area of a circle and create a square with an equal area ? this is a problem often called `` squaring a circle '' that was first proposed in the ancient world . and like many ideas of the ancient world , it was given new life during the renaissance . as it turns out , this problem is impossible to solve because of the nature of pi , but that 's another story . leonardo 's sketch , which is influenced by the writings of the roman architect , vitruvius , places a man firmly at the center of a circle and a square . vitruvius claimed the navel is the center of the human body and that if one takes a compass and places the fixed point on the navel , a circle can be drawn perfectly around the body . additionally , vitruvius recognized that arm span and height have a nearly perfect correspondence in the human body , thus placing the body perfectly inside a square as well . leonardo used the ideas of vitruvius to solve the problem of squaring a circle metaphorically using mankind as the area for both shapes . leonardo was n't just thinking about vitruvius , though . there was an intellectual movement in italy at the time called neoplatonism . this movement took an old concept from the 4th century developed by plato and aristotle , called `` the great chain of being . '' this belief holds that the universe has a hierarchy resembling a chain , and that chain starts at the top with god , then travels down through the angels , planets , stars , and all lifeforms before ending with demons and devils . early in this philosophic movement , it was thought that mankind 's place in this chain was exactly in the center . because humans have a mortal body accompanied by an immortal soul , we divide the universe nicely in half . around the time leonardo sketched the vitruvian man , however , a neoplatonist named pico della mirandola had a different idea . he pried mankind off the chain and claimed that humans have a unique ability to take any position they want . pico claimed that god desired a being capable of comprehending the beautiful and complicated universe he had created . this led to the creation of mankind , which he placed at the center of the universe with the ability to take whatever form he pleases . mankind , according to pico , could crawl down the chain and behave like an animal or crawl up the chain and behave like a god , it 's our choice . looking back at the sketch , we can see that by changing the position of the man , he can fill the irreconcilable areas of a circle and a square . if geometry is the language the universe is written in , then this sketch seems to say we can exist within all its elements . mankind can fill whatever shape he pleases geometrically and philosophically as well . in this one sketch , leonardo was able to combine the mathematics , religion , philosophy , architecture , and artistic skill of his age . no wonder it has become such an icon for the entire time period .

there was an intellectual movement in italy at the time called neoplatonism . this movement took an old concept from the 4th century developed by plato and aristotle , called `` the great chain of being . '' this belief holds that the universe has a hierarchy resembling a chain , and that chain starts at the top with god , then travels down through the angels , planets , stars , and all lifeforms before ending with demons and devils . early in this philosophic movement , it was thought that mankind 's place in this chain was exactly in the center .

what can be found at the top of the great chain of being ?

so how many of you have ever been in a cave before ? okay , a few of you . when you think of a cave , most of you think of a tunnel going through solid rock . in fact , that 's how most caves are . around this half of the country , most of your caves are made of limestone . back where i 'm from , most of our caves are made from lava rock because we have a lot of volcanoes out there . but the caves i want to share with you today are made completely of ice , specifically glacier ice as formed in the side of the tallest mountain in the state of oregon called mount hood . now , mount hood 's only one hour 's drive from portland , the largest city in oregon where over two million people live . now , the most exciting thing for a cave explorer is to find a new cave and be the first human to ever go into it . the second most exciting thing for a cave explorer is to be the first one to make a map of a cave . now , these days , with so many people hiking around , it 's pretty hard to find a new cave , so you can imagine how excited we were to find three new caves within sight of oregon 's largest city and realize that they have never been explored or mapped before . it was kind of like being an astronaut because we were getting to see things and go places that no one had ever seen or gone before . so , what is a glacier ? well , those of you that have ever seen or touched snow , you know that it 's really light because it 's just a bunch of tiny ice crystals clumped together and it 's mostly air . if you squish a handful of snow to make a snowball , it gets really small , hard , and dense . well , in a mountain like hood where it snows over twenty feet a year , it crushes the air out of it and gradually forms it into hard , blue ice . now , each year more and more ice stacks up on top of it and eventually gets so heavy that it starts to slide down the mountain under its own weight , forming a slow-moving river of ice . when an ice pack like that starts to move , we call it a glacier and we give it a name . the name of the glacier these caves were formed is the sandy glacier . now , each year as new snow lands on the glacier , it melts in the summer sun , and it forms little rivers of water on the flow along the ice and they start to melt and bore their way down through the glacier , forming big networks of caves , sometimes going all the way down to the underlying bedrock . now , the crazy thing about glacier caves is that each year new tunnels form , different waterfalls pop up or move around from place to place inside the cave . warm water from the top of the ice is boring its way down , and warm air from below the mountain actually rises up , gets into the cave , and melts the ceilings back taller and taller . but the weirdest thing about glacier caves is that the entire cave is moving because it 's formed inside a block of ice the size of a small city that 's slowly sliding down the mountain . now , this is brent mcgregor , my cave exploration partner . he and i have both been exploring caves a long time and we 've been climbing mountains a long time , but neither of us have ever really explored a glacier cave before . back in 2011 , brent saw a youtube video of a couple of hikers that stumbled across the entrance to one of these caves . there were no gps coordinates for it , and all we knew was that it was somewhere out on the sandy glacier . so , in july of that year , we went out on the glacier , and we found a big crack in the ice . we had to build snow and ice anchors , so we could tie off ropes and repel down into the hole . this is me looking into the entrance crevasse . at the end of this hole , we found a huge tunnel going right up the mountain underneath thousands of tons of glacier ice . we followed this cave back for about a half mile until it came to an end . and then with the help of our survey tools , we made a three-dimensional map of the cave on our way back out . so , how do you map a cave ? well , cave maps are n't like trail maps or road maps because they have pits and holes going to overlapping levels . to make a cave map , you have to set up survey stations every few feet inside the cave , and you use a laser to measure the distance between those stations . and you use a compass and an inclinometer to measure the direction the cave is headed and measure the slope of the floor and the ceilings . now , those of you taking trigonometry , that particular type of math is very useful for making maps like this because it allows you to measure heights and distances without actually having to go there . in fact , the more i mapped and studied caves , the more useful i found all that math that i originally hated in school to be . so , when you 're done surveying , you take all this data , you punch it into the computer , and you find someone that can draw really well , and you have them draft up a map that looks something like this . and it will show you both a bird 's eye view of the passage as well as a profile view of the passage , kind of like an ant farm view . we named this cave snow dragon cave because it was like a big dragon sleeping under the snow . now , later this summer as more snow melted off the glacier , we found more caves , and we realized they were all connected . not long after we mapped snow dragon , brent discovered this new cave not very far away . the inside of it was coated with ice so we had to wear big spikes in our feet called crampons , so we could walk around without slipping . this cave was amazing ! the ice in the ceiling was glowing blue and green because the sunlight from far above was shining through the ice and lighting it all up . now , we could n't understand why this cave was so much colder than snow dragon until we got to the end , and we found out why . there was a huge pit or shaft called a moulin going a 130 feet straight up to the surface of the glacier . cold air from the top of the mountain was flowing down this hole , blasting through the cave , freezing everything inside of it . and we were so excited about finding this new pit , we actually came back in january the following year so we could be the first ones to explore it . it was so cold outside , we actually had to sleep inside the cave . here 's our camp on the left side of this entrance room . the next morning we climbed out of the cave and hiked all the way to the top of the glacier where we finally rigged and repelled this pit for the very first time . brent named this cave pure imagination , i think , because the beautiful sights we saw in there were beyond what we could have ever imagined . so , besides really cool ice , what else is inside these caves ? well , not too much lives in them because they 're so cold , and the entrance is actually covered up with snow for about eight months of the year , but there are some really cool things in there . there 's weird bacteria living in the water that actually eat and digest rocks to make their own food to live under this ice . in fact , this past summer scientists collected samples of water and ice specifically to see if things called extremophiles , tiny lifeforms that have evolved to live in a completely hostile conditions , might be living under the ice , kind of like what they hope to find in the polar ice caps of mars some day . another really cool thing is that as seeds and birds land on the surface of the glacier and die , they get buried in the snow and gradually become part of the glacier , sinking deeper and deeper into the ice . as these caves form and melt their way up into the ice , they make these artifacts rain down from the ceiling and fall into the cave floor where we end up finding them . for example , this is a nodal first seed we found . it 's been frozen in ice for over a hundred years , and it 's just now starting to sprout . this mallard duck feather was found over 1800 feet in the back of snow dragon cave . this duck died on the surface of the glacier long , long ago , and its feathers have finally made it down through over a hundred feet of ice before falling inside the cave . and this beautiful quartz crystal was also found in the back of snow dragon . even now brent and i find it hard to believe that all these discoveries were essentially in our own backyard , hidden away just waiting to be found . like i said earlier , the idea of discovery in this busy world we live in kind of seems like something you can only do with space travel now , but that 's not true . every year new caves get discovered that no one has ever been in before . so , it 's actually not too late for one of you to become a discoverer yourself . you just have to be willing to look and go where people do n't often go and focus your eyes and your mind to recognize the discovery when you see it because it might be in your own backyard . thank you very much .

but the caves i want to share with you today are made completely of ice , specifically glacier ice as formed in the side of the tallest mountain in the state of oregon called mount hood . now , mount hood 's only one hour 's drive from portland , the largest city in oregon where over two million people live . now , the most exciting thing for a cave explorer is to find a new cave and be the first human to ever go into it .

mount hood ________ .

the idea of human rights is that each one of us , no matter who we are or where we are born , is entitled to the same basic rights and freedoms . human rights are not privileges , and they can not be granted or revoked . they are inalienable and universal . that may sound straighforward enough , but it gets incredibly complicated as soon as anyone tries to put the idea into practice . what exactly are the basic human rights ? who gets to pick them ? who enforces them , and how ? the history behind the concept of human rights is a long one . throughout the centuries and across societies , religions , and cultures we have struggled with defining notions of rightfulness , justice , and rights . but one of the most modern affirmations of universal human rights emerged from the ruins of world war ii with the creation of the united nations . the treaty that established the un gives as one of its purposes to reaffirm faith in fundamental human rights . and with the same spirit , in 1948 , the un general assembly adopted the universal declaration of human rights . this document , written by an international committee chaired by eleanor roosevelt , lays the basis for modern international human rights law . the declaration is based on the principle that all human beings are born free and equal in dignity and rights . it lists 30 articles recognizing , among other things , the principle of nondiscrimination and the right to life and liberty . it refers to negative freedoms , like the freedom from torture or slavery , as well as positive freedoms , such as the freedom of movement and residence . it encompasses basic civil and political rights , such as freedom of expression , religion , or peaceful assembly , as well as social , economic , and cultural rights , such as the right to education and the right to freely choose one 's occupation and be paid and treated fairly . the declaration takes no sides as to which rights are more important , insisting on their universality , indivisibility , and interdependence . and in the past decades , international human rights law has grown , deepening and expanding our understanding of what human rights are , and how to better protect them . so if these principles are so well-developed , then why are human rights abused and ignored time and time again all over the world ? the problem in general is that it is not at all easy to universally enforce these rights or to punish transgressors . the udhr itself , despite being highly authoritative and respected , is a declaration , not a hard law . so when individual countries violate it , the mechanisms to address those violations are weak . for example , the main bodies within the un in charge of protecting human rights mostly monitor and investigate violations , but they can not force states to , say , change a policy or compensate a victim . that 's why some critics say it 's naive to consider human rights a given in a world where state interests wield so much power . critics also question the universality of human rights and emphasize that their development has been heavily guided by a small number of mostly western nations to the detriment of inclusiveness . the result ? a general bias in favor of civil policital liberties over sociopolitical rights and of individual over collective or groups rights . others defend universal human rights laws and point at the positive role they have on setting international standards and helping activists in their campaigns . they also point out that not all international human rights instruments are powerless . for example , the european convention on human rights establishes a court where the 47 member countries and their citizens can bring cases . the court issues binding decisions that each member state must comply with . human rights law is constantly evolving as are our views and definitions of what the basic human rights should be . for example , how basic or important is the right to democracy or to development ? and as our lives are increasingly digital , should there be a right to access the internet ? a right to digital privacy ? what do you think ?

that may sound straighforward enough , but it gets incredibly complicated as soon as anyone tries to put the idea into practice . what exactly are the basic human rights ? who gets to pick them ?

explain in a nutshell the concept of human rights—provide your own definition and offer a few examples of basic human rights .

translator : andrea mcdonough reviewer : bedirhan cinar ever wonder where most of the food you eat every day comes from ? well , about 60 % of the food you eat is carbohydrates . as you can probably tell from its name , carbohydrates contain carbon , hydrogen , and oxygen . but where do these atoms originally come from and how do they join together to make delicious foods like fruits and pasta ? it actually all starts with the air you are exhaling this very minute , specifically the carbon dioxide molecules . plants are going to breath in this very same carbon dioxide through pores in their skin , called stomata . plants drink in water from their roots to get the needed oxygen and hydrogen atoms , and their electrons , in order to build carbohydrates . what is that thing ? well , that 's a special plant organelle inside the leaves of plants called a chloroplast . it 's green beceause of a special light-absorbing pigment called chlorophyll . each leaf has about 44,000 cells and every cell can have anywhere between 20 to 100 chloroplasts . that 's up to 4,400,000 chloroplasts ! by now , you 've probably guessed that we 're talking about the process of photosynthesis and you might be wondering when the sun is going to make its entrance . let 's go back to that original molecule of water . the plant has to split this molecule of water so it can get electrons from it . but , the plant ca n't pull that water apart by itself . it needs help from the high-energy rays of the sun . so now that the chloroplast has all the building blocks - carbon , hydrogen , oxygen , and electrons - it can use them to go through the rest of the steps of photosynthesis to transform that original carbon dioxide gas into a simple carbohydrate called glucose , c-6-h-12-o-6 . that little glucose molecule then helps to build bigger and better carbohydrates like cellulose . cellulose is a type of carbohydrate found in plants that our body can not break down . we call it fiber and we eat it in vegetables like lettuce , broccoli , and celery . plants use cellulose to keep themselves strong . the plant could also turn that glucose into starch , a large molecule that stores energy for the plant . we love eating starch from plants like potatoes , corn , and rice . so you see , when you eat plants , we 're actually benefiting from photosynthesis . the plant makes things like starch , which we eat and then break back down into glucose , the first form the plant made . then , the mitochondria in our cells , powered by the oxygen we breath , can turn glucose into pure energy molecules called atp . atp powers all work done by each and every one of your cells , things like communication , movement , and transport . but why do we have to turn that glucose into atp ? well , think of it like this . you 're excited to start your summer job at the local ice cream stand , but your boss has just told you that she is going to pay you in ice cream cones . what are you going to be able to do with those ice cream cones ? nothing , which is why you kindly asked to be paid in dollars . atp is just like dollars . it is the currency that all cells of life use while glucose is , well , kind of like ice cream . even plants have mitochondria in their cells to break down the glucose they make into atp . so as you can see , humans and plants are intricately connected . the air we breath out is used by plants to make the carbohydrates we enjoy so much . and , in the process , they are releasing the very same oxygen molecules we need to breath in in order that our mitochondria can break down our delicous carbohydrate meal .

translator : andrea mcdonough reviewer : bedirhan cinar ever wonder where most of the food you eat every day comes from ? well , about 60 % of the food you eat is carbohydrates . as you can probably tell from its name , carbohydrates contain carbon , hydrogen , and oxygen .

on average , what percentage of the food we eat on a daily basis comes from carbohydrates ?

in ancient greece , violent internal conflict between bordering neighbors and war with foreign invaders was a way of life , and greeks were considered premier warriors . most greek city-states surrounded themselves with massive defensive walls for added protection . sparta in its prime was a different story , finding walls unnecessary when it had an army of the most feared warriors in the ancient world . so what was sparta doing differently than everyone else to produce such fierce soldiers ? to answer that question , we turn to the written accounts of that time . there are no surviving written accounts from spartans themselves , as it was forbidden for spartans to keep records , so we have to rely on those of non-spartan ancient historians , like herodotus , thucydides , and plutarch . these stories may be embellished and depict sparta at the apex of its power , so take them with a grain of salt . for spartans , the purpose for their existence was simple : to serve sparta . on the day of their birth , elder spartan leaders examined every newborn . the strong healthy babies were considered capable of fulfilling this purpose , and the others may have been left on mount taygetus to die . every spartan , boy or girl , was expected to be physically strong , mentally sharp , and emotionally resilient . and it was their absolute duty to defend and promote sparta at all costs . so in the first years of their lives , children were raised to understand that their loyalty belonged first to sparta , and then to family . this mindset probably made it easier for the spartan boys , who upon turning seven , were sent to the agoge , a place with one main purpose : to turn a boy into a spartan warrior through thirteen years of relentless , harsh , and often brutal training . the spartans prized physical perfection above all else , and so the students spent a great deal of their time learning how to fight . to ensure resilience in battle , boys were encouraged to fight among themselves , and bullying , unlike today , was acceptable . in order to better prepare the boys for the conditions of war , the boys were poorly fed , sometimes even going days without eating . they also were given little in the way of clothing so that they could learn to deal with different temperatures . spartan boys were encouraged to steal in order to survive , but if they were caught , they would be disciplined , not because they stole , but because they were caught in the act . during the annual contest of endurance in a religious ritual known as the diamastigosis , teenage boys were whipped in front of an altar at the sanctuary of artemis orthia . it was common for boys to die on the altar of the goddess . fortunately , not everything was as brutal as that . young spartans were also taught how to read , write , and dance , which taught them graceful control of their movements and helped them in combat . while the responsibilities for the girls of sparta were different , the high standards of excellence and expectation to serve sparta with their lives remained the same . spartan girls lived at home with their mothers as they attended school . their curriculum included the arts , music , dance , reading , and writing . and to stay in peak physical condition , they learned a variety of sports , such as discus , javelin , and horseback riding . in sparta , it was believed that only strong and capable women could bear children that would one day become strong and capable warriors . to all spartans , men and women , perhaps the most important lesson from spartan school was allegiance to sparta . to die for their city-state was seen as the completion of one 's duty to sparta . upon their death , only men who died in battle and women who died in childbirth were given tombstones . in the eyes of their countrymen , both died so that sparta could live .

and to stay in peak physical condition , they learned a variety of sports , such as discus , javelin , and horseback riding . in sparta , it was believed that only strong and capable women could bear children that would one day become strong and capable warriors . to all spartans , men and women , perhaps the most important lesson from spartan school was allegiance to sparta .

in 1859 , scientist charles darwin presented the idea that nature had a natural selection to keep the better adapted organisms thriving and get rid of poorer adapted ones . soon after reading darwin ’ s work , herbert spencer , an english philosopher , coined a phrase “ survival of the fittest ” meaning only the strong survive . do you think sparta proves this theory to be true ? how or how not ?

grammatical tense is how languages talk about time without explicitly naming time periods by , instead , modifying verbs to specify when action occurs . so how many different tenses are there in a language like english ? at first , the answer seems obvious : there 's past , present , and future . but thanks to something called grammatical aspect , each of those time periods actually divides further . there are four kinds of aspect . in the continuous or progressive aspect , the actions are still happening at the time of reference . the perfect aspect describes actions that are finished . the perfect progressive aspect is a combination , describing a completed part of a continuous action . and finally , there 's the simple aspect , the basic form of the past , present , and future tense where an action is not specified as continuous or discreet . that 's all a little hard to follow , so let 's see how it works in action . let 's say your friends tell you they went on a secret naval mission to collect evidence of a mysterious sea creature . the tense sets the overall frame of reference in the past , but within that , there are many options . your friends might say a creature attacked their boat , that 's the past simple , the most general aspect , which gives no further clarification . they were sleeping when it happened , a continuous process underway at that point . they might also tell you they had departed from nantucket to describe an action completed even earlier . that 's an example of the past perfect . or that they had been sailing for three weeks , something that was ongoing up until that point . in the present , they tell you that they still search for the creature today , their present simple activity . perhaps they are preparing for their next mission continuously as they speak . and they have built a special submarine for it , a completed achievement . plus , if they have been researching possible sightings of the creature , it 's something they 've been doing for a while and are still doing now making it present perfect progressive . so what does this next mission hold ? you know it still has n't happened because they will depart next week , the future simple . your friends will be searching for the elusive creature , an extended continuous undertaking . they tell you the submarine will have reached uncharted depths a month from now . that 's a confident prediction about what will be achieved by a specific point in the future , a point at which they will have been voyaging for three weeks in the future perfect progressive . the key insight to all these different tenses is that each sentence takes place in a specific moment , whether it 's past , present , or future . the point of aspects is that they tell you as of that moment the status of the action . in total , they give us twelve possibilities in english . what about other languages ? some , like french , swahili , and russian take a similar approach to english . others describe and divide time differently . some have fewer grammatical tenses , like japanese , which only distinguishes past from non-past , buli and tukang basi , which only distinguish future from non-future , and mandarin chinese with no verb tenses at all , only aspect . on the other hand , languages like yagwa split past tense into multiple degrees , like whether something happened hours , weeks , or years ago . in others , tenses are intertwined with moods that can convey urgency , necessity , or probability of events . this makes translation difficult but not impossible . speakers of most languages without certain tenses can express the same ideas with auxiliary words , like would or did , or by specifying the time they mean . are the variations from language to language just differents ways of describing the same fundamental reality ? or do their diverse structures reflect different ways of thinking about the world and even time itself ? and if so , what other ways of conceiving time may be out there ?

grammatical tense is how languages talk about time without explicitly naming time periods by , instead , modifying verbs to specify when action occurs . so how many different tenses are there in a language like english ?

do you think the way we speak about time in our mother-tongue influences the way we experience time ? why or why not ?