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how did dracula become the world 's most famous vampire ? more than 100 years after his creator was laid to rest , dracula lives on as the most famous vampire in history . but this transylvanian noble , neither the first fictional vampire nor the most popular of his time , may have remained buried in obscurity if not for a twist of fate . dracula 's first appearance was in bram stoker 's 1897 novel of the same name . but that was far from the beginning of vampire myths . blood-sucking monsters had already been part of folklore for at least 800 years . it was slavic folklore that gave us the word vampire , or `` upir '' in old russian . the term 's first known written mention comes from the 11th century . vampire lore in the region predated christianity 's arrival and persisted despite the church 's efforts to eliminate pagan beliefs . stories of vampires originated from misinterpretations of diseases , such as rabies , and pellagra , and decomposition . in the case of the latter , gasses swelling the body and blood oozing from the mouth could make a corpse look like it had recently been alive and feeding . vampires were describe as bloated with overgrown teeth and nails . this gave rise to many rituals intended to prevent the dead from rising , such as burying bodies with garlic or poppyseeds , as well as having them staked , burned , or mutilated . vampire lore remained a local phenomenon until the 18th century when serbia was caught in the struggle between two great powers , the habsburg monarchy and ottoman empire . austrian soldiers and government officials observed and documented the strange local burial rituals , and their reports became widely publicized . the resulting vampire hysteria got so out of hand that in 1755 , the austrian empress was forced to dispatch her personal physician . he investigated and put an end to the rumors by publishing a thorough , scientific refutation . the panic subsided , but the vampire had already taken root in western europe 's imagination , spawning works like `` the vampyre '' in 1819 , and joseph sheridan le fanu 's `` carmilla '' in 1872 . this book would greatly influence a young irish drama critic named bram stoker . stoker , who was born in dublin in 1847 , was famously bedridden with an unknown illness until the age of seven . during that time , his mother told him folktales and true tales of horror , including her experiences during an outbreak of cholera in 1832 . there , she described victims buried alive in mass graves . later in his life , stoker went on to write fantasy , romance , adventure stories , and , in 1897 , `` dracula . '' although the book 's main villain and namesake is thought to be based on the historical figure of vlad iii dracula , or vlad the impaler , the association is mostly just that they share a name . other elements and characters were inspired directly and indirectly by various works in the victorian era , such as `` the mysterious stranger . '' the novel , upon release , was only a moderate success in its day , nor was it even stoker 's most well-known work , mentioned only briefly in a 1912 obituary . but a critical copyright battle would completely change dracula 's fate , and catapult the character into literary renown . in 1922 , a german studio adapted the novel into the now classic silent film `` nosferatu '' without paying royalties . despite changes in character names and minor plot points , the parallels were obvious , and the studio was sued into bankruptcy . to prevent more plagiarism attempts , stoker 's widow decided to establish copyright over the stage version of `` dracula '' by approving a production by family-friend hamilton deane . although deane 's adaptation made drastic cuts to the story , it became a classic , thanks largely to bela lugosi 's performance on broadway . lugosi would go on to star in the 1931 film version by universal , lending the character many of his signature characteristics . and since then , dracula has risen again in countless adaptations , finding eternal life far beyond the humble pages of his birth .

but this transylvanian noble , neither the first fictional vampire nor the most popular of his time , may have remained buried in obscurity if not for a twist of fate . dracula 's first appearance was in bram stoker 's 1897 novel of the same name . but that was far from the beginning of vampire myths .

many people incorrectly believe the vlad iii dracula was a huge inspiration for stoker in writing his novel , but actually he was only minor and tied primarily to his famous villain ’ s name . why do you think perceptions about this fact are often wrong ?

how does your smartphone know exactly where you are ? the answer lies 12,000 miles over your head in an orbiting satellite that keeps time to the beat of an atomic clock powered by quantum mechanics . phew . let 's break that down . first of all , why is it so important to know what time it is on a satellite when location is what we 're concerned about ? the first thing your phone needs to determine is how far it is from a satellite . each satellite constantly broadcasts radio signals that travel from space to your phone at the speed of light . your phone records the signal arrival time and uses it to calculate the distance to the satellite using the simple formula , distance = c x time , where c is the speed of light and time is how long the signal traveled . but there 's a problem . light is incredibly fast . if we were only able to calculate time to the nearest second , every location on earth , and far beyond , would seem to be the same distance from the satellite . so in order to calculate that distance to within a few dozen feet , we need the best clock ever invented . enter atomic clocks , some of which are so precise that they would not gain or lose a second even if they ran for the next 300 million years . atomic clocks work because of quantum physics . all clocks must have a constant frequency . in other words , a clock must carry out some repetitive action to mark off equivalent increments of time . just as a grandfather clock relies on the constant swinging back and forth of a pendulum under gravity , the tick tock of an atomic clock is maintained by the transition between two energy levels of an atom . this is where quantum physics comes into play . quantum mechanics says that atoms carry energy , but they ca n't take on just any arbitrary amount . instead , atomic energy is constrained to a precise set of levels . we call these quanta . as a simple analogy , think about driving a car onto a freeway . as you increase your speed , you would normally continuously go from , say , 20 miles/hour up to 70 miles/hour . now , if you had a quantum atomic car , you would n't accelerate in a linear fashion . instead , you would instantaneously jump , or transition , from one speed to the next . for an atom , when a transition occurs from one energy level to another , quantum mechanics says that the energy difference is equal to a characteristic frequency , multiplied by a constant , where the change in energy is equal to a number , called planck 's constant , times the frequency . that characteristic frequency is what we need to make our clock . gps satellites rely on cesium and rubidium atoms as frequency standards . in the case of cesium 133 , the characteristic clock frequency is 9,192,631,770 hz . that 's 9 billion cycles per second . that 's a really fast clock . no matter how skilled a clockmaker may be , every pendulum , wind-up mechanism and quartz crystal resonates at a slightly different frequency . however , every cesium 133 atom in the universe oscillates at the same exact frequency . so thanks to the atomic clock , we get a time reading accurate to within 1 billionth of a second , and a very precise measurement of the distance from that satellite . let 's ignore the fact that you 're almost definitely on earth . we now know that you 're at a fixed distance from the satellite . in other words , you 're somewhere on the surface of a sphere centered around the satellite . measure your distance from a second satellite and you get another overlapping sphere . keep doing that , and with just four measurements , and a little correction using einstein 's theory of relativity , you can pinpoint your location to exactly one point in space . so that 's all it takes : a multibillion-dollar network of satellites , oscillating cesium atoms , quantum mechanics , relativity , a smartphone , and you . no problem .

enter atomic clocks , some of which are so precise that they would not gain or lose a second even if they ran for the next 300 million years . atomic clocks work because of quantum physics . all clocks must have a constant frequency .

why are the elements cesium and rubidium used in many atomic clocks ?

so , well , astatine is an element which most chemists , including me , know little about them except its name . in fact most of our students have difficulty even remembering the name . and , again , like many radioactive materials , because it ’ s highly radioactive not only is the chemistry not studied much but the compounds themselves tend to decompose very easily .

so , well , astatine is an element which most chemists , including me , know little about them except its name . in fact most of our students have difficulty even remembering the name .

why have only a few chemists come into contact with astatine ?

if you line up the entire text of `` moby dick , '' which was published in 1851 , into a giant rectangle , you may notice some peculiar patterns , like these words , which seem to predict the assassination of martin luther king , or these references to the 1997 death of princess di . so , was herman melville a secret prophet ? the answer is no , and we know that thanks to a mathematical principle called ramsey theory . it 's the reason we can find geometric shapes in the night sky , it 's why we can know without checking that at least two people in london have exactly the same number of hairs on their head , and it explains why patterns can be found in just about any text , even vanilla ice lyrics . so what is ramsey theory ? simply put , it states that given enough elements in a set or structure , some particular interesting pattern among them is guaranteed to emerge . as a simple example , let 's look at what 's called the party problem , a classic illustration of ramsey theory . suppose there are at least six people at a party . amazingly enough , we can say for sure that some group of three of them either all know each other , or have never met before , without knowing a single thing about them . we can demonstrate that by graphing out all the possibilities . each point represents a person , and a line indicates that the pair know each other . every pair only has two possibilities : they either know each other or they do n't . there are a lot of possibilities , but every single one has the property that we 're looking for . six is the lowest number of guests where that 's guaranteed to be the case , which we can express like this . ramsey theory gives us a guarantee that such a minimum number exists for certain patterns , but no easy way to find it . in this case , as the total number of guests grows higher , the combinations get out of control . for instance , say you 're trying to find out the minimum size of a party where there 's a group of five people who all know each other or all do n't . despite five being a small number , the answer is virtually impossible to discover through an exhaustive search like this . that 's because of the sheer volume of possibilities . a party with 48 guests has 2^ ( 1128 ) possible configurations , more than the number of atoms in the universe . even with the help of computers , the best we know is that the answer to this question is somewhere between 43 and 49 guests . what this shows us is that specific patterns with seemingly astronomical odds can emerge from a relatively small set . and with a very large set , the possibilities are almost endless . any four stars where no three lie in a straight line will form some quadrilateral shape . expand that to the thousands of stars we can see in the sky , and it 's no surprise that we can find all sorts of familiar shapes , and even creatures if we look for them . so what are the chances of a text concealing a prophecy ? well , when you factor in the number of letters , the variety of possible related words , and all their abbreviations and alternate spellings , they 're pretty high . you can try it yourself . just pick a favorite text , arrange the letters in a grid , and see what you can find . the mathematician t.s . motzkin once remarked that , `` while disorder is more probable in general , complete disorder is impossible . '' the sheer size of the universe guarantees that some of its random elements will fall into specific arrangements , and because we evolved to notice patterns and pick out signals among the noise , we are often tempted to find intentional meaning where there may not be any . so while we may be awed by hidden messages in everything from books , to pieces of toast , to the night sky , their real origin is usually our own minds .

it 's the reason we can find geometric shapes in the night sky , it 's why we can know without checking that at least two people in london have exactly the same number of hairs on their head , and it explains why patterns can be found in just about any text , even vanilla ice lyrics . so what is ramsey theory ? simply put , it states that given enough elements in a set or structure , some particular interesting pattern among them is guaranteed to emerge .

does ramsey theory tell us how to find a particular structure in a given system ? in the case of random letters for instance , does ramsey theory tell you how to find a particular word or phrase ?

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 ?

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 ?

are there any types of surfaces for which the pythagorean theorem would not be valid ? if so , which ones ?

you may know that it takes light a zippy eight minutes to reach us from the surface of the sun , so how long do you think it takes light to travel from the sun 's core to its surface ? a few seconds or a minute at most ? well , oddly enough , the answer is many thousands of years . here 's why . photons are produced by the nuclear reactions deep in the core of our sun . as the photons flow out of the core , they interact with matter and lose energy , becoming longer wavelength forms of light . they start out as gamma rays in the core , but end up as x-rays , ultraviolet or visible light as they near the surface . however , that journey is neither simple nor direct . upon being born , each photon travels at a speed of 300,000 kilometers per second until it collides with a proton and is diverted in another direction , acting like a bullet ricocheting off of every charged particle it strikes . the question of how far this photon gets from the center of the sun after each collision is known as the random walk problem . the answer is given by this formula : distance equals step size times the square root of the number of steps . so if you were taking a random walk from your front door with a one meter stride each second , it would take you a million steps and eleven days just to travel one kilometer . so then how long does it take for a photon generated in the center of the sun to reach you ? we know the mass of the sun and can use that to calculate the number of protons within it . let 's assume for a second that all the sun 's protons are evenly spread out , making the average distance between them about 1.0 x 10^-10 meters . to random walk the 690,000 kilometers from the core to the solar surface would then require 3.9 x 10^37 steps , giving a total travel time of 400 billion years . hmm , that ca n't be right . the sun is only 4.6 billion years old , so what went wrong ? two things : the sun is n't actually of uniform density and photons will miss quite a few protons between every collision . in actuality , a photon 's energy , which changes over the course of its journey , determines how likely it is to interact with a proton . on the density question , our models show that the sun has a hot core , where the fusion reactions occur . surrounding that is the radiative zone , followed by the convective zone , which extends all the way to the surface . the material in the core is much denser than lead , while the hot plasma near the surface is a million times less dense with a continuum of densities in between . and here 's the photon-energy relationship . for a photon that carries a small amount of energy , a proton is effectively huge , and it 's much more likely to cause the photon to ricochet . and for a high-energy photon , the opposite is true . protons are effectively tiny . photons start off at very high energies compared to when they 're finally radiated from the sun 's surface . now when we use a computer and a sophisticated solar interior model to calculate the random walk equation with these changing quantities , it spits out the following number : 170,000 years . future discoveries about the sun may refine this number further , but for now , to the best of our understanding , the light that 's hitting your eyes today spent 170,000 years pinballing its way towards the sun 's surface , plus eight miniscule minutes in space . in other words , that photon began its journey two ice ages ago , around the same time when humans first started wearing clothes .

you may know that it takes light a zippy eight minutes to reach us from the surface of the sun , so how long do you think it takes light to travel from the sun 's core to its surface ? a few seconds or a minute at most ?

compare the travel time of light from the sun to you versus the travel time of the light from the core of the sun to its surface .

here 's a conundrum : identical twins originate from the same dna , so how can they turn out so different even in traits that have a significant genetic component ? for instance , why might one twin get heart disease at 55 , while her sister runs marathons in perfect health ? nature versus nurture has a lot to do with it , but a deeper related answer can be found within something called epigenetics . that 's the study of how dna interacts with the multitude of smaller molecules found within cells , which can activate and deactivate genes . if you think of dna as a recipe book , those molecules are largely what determine what gets cooked when . they are n't making any conscious choices themselves , rather their presence and concentration within cells makes the difference . so how does that work ? genes in dna are expressed when they 're read and transcribed into rna , which is translated into proteins by structures called ribosomes . and proteins are much of what determines a cell 's characteristics and function . epigenetic changes can boost or interfere with the transcription of specific genes . the most common way interference happens is that dna , or the proteins it 's wrapped around , gets labeled with small chemical tags . the set of all of the chemical tags that are attached to the genome of a given cell is called the epigenome . some of these , like a methyl group , inhibit gene expression by derailing the cellular transcription machinery or causing the dna to coil more tightly , making it inaccessible . the gene is still there , but it 's silent . boosting transcription is essentially the opposite . some chemical tags will unwind the dna , making it easier to transcribe , which ramps up production of the associated protein . epigenetic changes can survive cell division , which means they could affect an organism for its entire life . sometimes that 's a good thing . epigenetic changes are part of normal development . the cells in an embryo start with one master genome . as the cells divide , some genes are activated and others inhibited . over time , through this epigenetic reprogramming , some cells develop into heart cells , and others into liver cells . each of the approximately 200 cell types in your body has essentially the same genome but its own distinct epigenome . the epigenome also mediates a lifelong dialogue between genes and the environment . the chemical tags that turn genes on and off can be influenced by factors including diet , chemical exposure , and medication . the resulting epigenetic changes can eventually lead to disease , if , for example , they turn off a gene that makes a tumor-suppressing protein . environmentally-induced epigenetic changes are part of the reason why genetically identical twins can grow up to have very different lives . as twins get older , their epigenomes diverge , affecting the way they age and their susceptibility to disease . even social experiences can cause epigenetic changes . in one famous experiment , when mother rats were n't attentive enough to their pups , genes in the babies that helped them manage stress were methylated and turned off . and it might not stop with that generation . most epigenetic marks are erased when egg and sperm cells are formed . but now researchers think that some of those imprints survive , passing those epigenetic traits on to the next generation . your mother 's or your father 's experiences as a child , or choices as adults , could actually shape your own epigenome . but even though epigenetic changes are sticky , they 're not necessarily permanent . a balanced lifestyle that includes a healthy diet , exercise , and avoiding exposure to contaminants may in the long run create a healthy epigenome . it 's an exciting time to be studying this . scientists are just beginning to understand how epigenetics could explain mechanisms of human development and aging , as well as the origins of cancer , heart disease , mental illness , addiction , and many other conditions . meanwhile , new genome editing techniques are making it much easier to identify which epigenetic changes really matter for health and disease . once we understand how our epigenome influences us , we might be able to influence it , too .

it 's an exciting time to be studying this . scientists are just beginning to understand how epigenetics could explain mechanisms of human development and aging , as well as the origins of cancer , heart disease , mental illness , addiction , and many other conditions . meanwhile , new genome editing techniques are making it much easier to identify which epigenetic changes really matter for health and disease . once we understand how our epigenome influences us , we might be able to influence it , too .

epigenetics shows us that your phenotype is not completely written in your genome . what implications could this have for evolutionary biology ?

hi i ’ m john green , this is crash course us history , and today we 're going to tell the story of how a group of plucky english people struck a blow for religious freedom , and founded the greatest , freest and fattest nation the world has ever seen . [ libertage ] these brits entered a barren land containing no people , and quickly invented the automobile , baseball and star trek and we all lived happily ever after . mr. green , mr. green , if it is really that simple , i am so getting an a in this class . oh , me from the past , you 're just a delight . [ theme music ] so most americans grew up hearing that the united states was founded by pasty english people who came here to escape religious persecution . and that 's true of the small proportion of people who settled in the massachusetts bay and created what we now know is new england . but these pilgrims and puritans , there 's a difference , weren ’ t the first people or even the first europeans to come to the only part of the globe we did n't paint over . in fact they weren ’ t the first english people . the first english people came to virginia . off topic but how weird is it that the first permanent english colony in the americas was named not for queen elizabeth ’ s epicness but for her supposed chastity . right anyway , those first english settlers were n't looking for religious freedom , they wanted to get rich . so the first successful english colony in america was founded in jamestown , virginia in 1607 . i say `` successful '' because there were two previous attempts to colonize the region . they were both epic failures . the more famous of which was the colony of roanoke island set up by sir walter raleigh , which is famous because all the colonists disappeared leaving only the word `` croatoan '' on carved into a tree . jamestown was a project of the virginia company , which existed to make money for its investors , something it never did . the hope was that they would find gold in the chesapeake region like the spanish had in south america , so there were a disproportionate number of goldsmiths and jewelers there to fancy up that gold which of course did not exist . anyway , it turns out that jewelers dislike farming -- so much so , that captain john smith who soon took over control of the island once said that they would rather starve than farm . so in the first year , half of the colonists died . 400 replacements came , but , by 1610 , after a gruesome winter called `` the starving time , '' the number of colonists had dwindled to 65 . and eventually word got out that the new world ’ s 1 year survival rate was like 20 % and it became harder to find new colonists . but 1618 , a virginia company hit upon a recruiting strategy called the headright system which offered 50 acres of land for each person that a settler paid to bring over . and this enabled the creation of a number of large estates , which were mostly worked on and populated by indentured servants . indentured servants were n't quite slaves , but they were kind of temporary slaves . like they could be bought and sold and they had to do what their masters commanded . but after seven to ten years of that , if they were n't dead , they were paid their freedom dues which they hoped would allow them to buy farms of their own . sometimes that worked out , but often either the money was n't enough to buy a farm , or else they were too dead to collect it . even more ominously in 1619 , just 12 years after the founding of jamestown , the first shipment of african slaves arrived in virginia . so the colony probably would have continued to struggle along , if they had n't found something that people really loved : tobacco . tobacco had been grown in mexico since at least 1000 bce , but the europeans had never seen it and it proved to be kind of a `` thank you for the small pox ; here 's some lung cancer ” gift from the natives . interestingly king james hated smoking . he called it “ a custom loathsome to the eye and hateful to the nose '' but he loved him some tax revenue , and nothing sells like drugs . by 1624 virginia was producing more than 200,000 pounds of tobacco per year . by the 1680s , more than 30 million pounds per year . tobacco was so profitable the colonists created huge plantations with very little in the way of towns or infrastructure to hold the social order together , a strategy that always works out brilliantly . the industry also structured virginian society . first off , most of the people who came in the 17th century , three-quarters of them , were servants . so virginia became a microcosm of england : a small class of wealthy landowners sitting atop a mass of servants . that sounds kind of dirty but it was mostly just sad . the society was also overwhelmingly male , because male servants were more useful in the tobacco fields , they were the greatest proportion of immigrants . in fact they outnumbered women 5 to 1 . the women who did come over were mostly indentured servants , and if they were to marry , which they often did because they were in great demand , they had to wait until their term of service was up . this meant delayed marriage which meant fewer children which further reduced the number of females . life was pretty tough for these women , but on the upside virginia was kind of a swamp of pestilence , so their husbands often died , and that created a small class of widows or even unmarried women who , because of their special status , could make contracts and own property , so that was good , sort of . ok. a quick word about maryland . maryland was the second chesapeake colony , founded in 1632 , and by now there was no messing around with joint stock companies . maryland was a proprietorship : a massive land grant to a single individual named cecilius calvert . calvert wanted to turn maryland into like a medieval feudal kingdom to benefit himself and his family , and he was no fan of the representational institutions that were developing in virginia . also calvert was catholic , and catholics were welcome in maryland which was n't always the case elsewhere . speaking of which , let 's talk about massachusetts . so jamestown might have been the first english colony , but massachusetts bay is probably better known . this is largely because the colonists who came there were so recognizable for their beliefs and also for their hats . that ’ s right . i ’ m talking about the pilgrims and the puritans . and no , i will not be talking about thanksgiving ... is a lie . i can ’ t help myself . but only to clear up the difference between pilgrims and puritans and also to talk about squanto . god i love me some squanto . let 's go to the thought bubble . most of the english men and women who settled in new england were uber-protestant puritans who believed the protestant church of england was still too catholic-y with its kneeling and incense and extravagantly-hatted archbishops . the particular puritans who , by the way did not call themselves that -- other people did , who settled in new england were called congregationalists because they thought congregations should determine leadership and worship structures , not bishops . the pilgrims were even more extreme . they wanted to separate more or less completely from the church of england . so first they fled to the netherlands , but the dutch were apparently too corrupt for them , so they rounded up investors and financed a new colony in 1620 . they were supposed to land in virginia , but in what perhaps should have been taken as an omen , they were blown wildly off course and ended up in what 's now massachusetts , founding a colony called plymouth . while still on board their ship the mayflower , 41 of the 150 or so colonists wrote and signed an agreement called the mayflower compact , in which they all bound themselves to follow `` just and equal laws '' that their chosen representatives would write-up . since this was the first written framework for government in the us , it 's kind of a big deal . but anyway , the pilgrims had the excellent fortune of landing in massachusetts with 6 weeks before winter , and they had the good sense not to bring very much food with them or any farm animals . half of them died before winter was out . the only reason they did n't all die was that local indians led by squanto gave them food and saved them . a year later , grateful that they had survived mainly due to the help of an alliance with the local chief massasoit , and because the indians had taught them how to plant corn and where to catch fish , the pilgrims held a big feast : the first thanksgiving . thanks thought bubble ! and by the way , that feast was on the fourth thursday in november , not mid-october as is celebrated in some of these green areas we call not america . anyway squanto was a pretty amazing character and not only because he helped save the pilgrims . he found that almost all of his tribe , the patuxet had been wiped out by disease and eventually settled with the pilgrims on the site of his former village and then died ... of disease because it is always ruining everything . so the pilgrims struggled on until 1691 when their colony was subsumed by the larger and much more successful massachusetts bay colony . the massachusetts bay colony was chartered in 1629 by london merchants who , like the founders of the virginia company , hoped to make money . but unlike virginia , the board of directors relocated from england to america , which meant that in massachusetts they had a greater degree of autonomy and self-government than they did in virginia . social unity was also much more important in massachusetts than it was in virginia . the puritans ' religious mission meant that the common good was , at least at first , put above the needs or the rights of the individual . those different ideas in the north and south about the role of government would continue ... until now . oh god . it 's time for the mystery document ? the rules are simple . i read the mystery document which i have not seen before . if i get it right , then i do not get shocked with the shock pen , and if i get it wrong i do . all right . `` we must be knit together in this work as one man , we must entertain each other in brotherly affection , we must be willing to abridge ourselves of our superfluities ( su-per-fluities ? i do n't know ) , for the supply of others necessities , we must uphold a familiar commerce together in all meekness , gentleness , patience and liberality , ... for we must consider that we shall be as a city upon a hill , the eyes of all people are upon us ; so that if we shall deal falsely with our god in this work we have undertaken and so cause him to withdraw his present help from us , we shall be made a story and a byword through the world . '' alright , first thing i noticed : the author of this document is a terrible speller or possibly wrote this before english was standardized . also , a pretty religious individual . and the community in question seems to embrace something near socialism : abridging the superfluous for others ' necessities . also it says that the community should be like a city upon a hill , like a model for everybody . and because of that metaphor , i know exactly where it comes from : the sermon `` a model of christian charity '' by john winthrop . yes ! yes ! no punishment ! this is one of the most important sermons in american history . it shows us just how religious the puritans were , but it also shows us that their religious mission was n't really one of individualism but of collective effort . in other words , the needs of the many outweigh the needs of the few or the one . but this city on a hill metaphor is the basis for one kind of american exceptionalism : the idea that we are so special and so godly that we will be a model to other nations , at least as long , according to winthrop , as we act together . lest you think winthrop ’ s words were forgotten , they did become the centerpiece of ronald reagan ’ s 1989 farewell address . okay so new england towns were governed democratically , but that does n't mean that the puritans were big on equality or that everybody was able to participate in government because no . the only people who could vote or hold office were church members , and to be a full church member you had to be a “ visible saint '' , so really , power stayed in the hands of the church elite . the same went for equality . while it was better than in the chesapeake colonies or england , as equality went ... eh , pretty unequal . as john winthrop declared , `` some must be rich , and some poor . some high , an eminent in power , and dignity ; others mean and in subjection . '' or as historian eric foner put it `` inequality was considered an expression of god 's will and while some liberties applied to all inhabitants , there were separate lists of rights for freemen , women , children and servants . '' there was also slavery in massachusetts . the first slaves were recorded in the colony in 1640 . however , puritans really did foster equality in one sense . they wanted everyone to be able to read the bible . in fact , parents could be punished by the town councils for not properly instructing their children in making them literate . but when roger williams called for citizens to be able to practice any religion they chose , he was banished from the colonies . so was ann hutchinson who argued the church membership should be based on inner grace and not on outward manifestations like church attendance . williams went on to found rhode island , so that worked out fine for him , but hutchinson , who was doubly threatening to massachusetts because she was a woman preaching unorthodox ideas , was too radical and was further banished to westchester , new york where she and her family were killed by indians . finally , somebody who does n't die of disease or starvation . so americans like to think of their country as being founded by pioneers of religious freedom who were seeking liberty from the oppressive english . we 've already seen that 's only partly true . for one thing , puritan ideas of equality and representation were n't particularly equitable or representational . in truth , america was also founded by indigenous people and by spanish settlers , and the earliest english colonies were n't about religion ; they were about money . we 'll see this tension between american mythology and american history again next week and also every week . thanks for watching ; i ’ ll see you next time . crash course is produced and directed by stan muller , our script supervisor is meredith danko , the associate producer is danica johnson , the show is written by my high school history teacher , raoul meyer and myself , and our graphics team is thought bubble . if you have questions about today 's video or really about anything about american history , ask them in comments ; the entire crash course team and many history professionals are there to help you . thanks for watching crash course . please make sure you are subscribed and , as we say in my home town , `` do n't forget to be awesome . ''

they were both epic failures . the more famous of which was the colony of roanoke island set up by sir walter raleigh , which is famous because all the colonists disappeared leaving only the word `` croatoan '' on carved into a tree . jamestown was a project of the virginia company , which existed to make money for its investors , something it never did .

which colony was set up by sir walter riley ?

feldspar mineral ... from the ytterby quarry . how many elements does it contain ? shall we take it home ? so terbium , just like europium , is often used in television screens and various types of displays and where it comes in is that it gives green and yellow colours , which in contrast to the red and blue which europium gives you , gives you the full selection that you need to give colour images . so ytterby gruva , ytterby mine , what a great place , the snow is falling . this is designated ytterby mine , a historical landmark for the discovery of four periodic elements : yttrium , terbium , erbium , and ytterbium . terbium was eventually discovered or eventually isolated by the chemist mosander in 1843 . it was from an earth called itrea which was originated in this quarry where we are right now in ytterby in sweden . terbium is a really unusual element . it ’ s a metal ; moderate abundance . it ’ s called a rare earth element , which is really quite ironic because it ’ s not as rare as its name would suggest . the abundance is something like 20 to 30 times that of silver , so i don ’ t think it ’ s really rare . it doesn ’ t really have much biological activity but we do find terbium within the bones in the human body and in animals but also within the kidneys so you do find small concentrations but it doesn ’ t really have a perceived biological activity . terbium is also used in certain magnetic devices and when you include it in certain alloys it forms magnetic devices which increase or decrease in size depending on the strength or type of magnetic field which they are placed into which has various technological applications . so terbium alloys are really quite interesting because they have what ’ s called magnetostrictive behaviour . so what that means is that the size of the crystal or the size of the structure of the alloy itself gets either larger or smaller when it ’ s exposed to a large or strong magnetic field . so , there ’ s much research going into these terbium alloys for small motors or small switches perhaps and also to use as strain gauges and other types of really quite elaborate instruments . so these may well provide us a lot of new research in the areas of nano-science and nano-machines . also , because of its fluorescence nature it ’ s often used as a marker in biochemistry so if you want to stain cells and determine whether certain types are present then you can use it for that too . so in terms of day-to-day life , where do we find terbium ? well we find it in unusual devices like energy-saving light-bulbs because it stimulates or it increases the yield of light in the mercury discharge that we use to run fluorescent strips . so we found it around us in shops and houses , in factories , street-lighting , everywhere . but what i think is a really quite nice and important application of terbium is the fact that it ’ s used to make phosphorescent materials . so these are materials which generate light or allow us to develop pictures if we irradiate them with something like an x-ray . and , in fact , terbium is used to make very , very high light yielding phosphors for use in screens and visualisation screens for x- rays . so what this means is that if i go into the hospital for diagnostic x- ray i no longer have to be exposed to long periods of x-rays because the terbium screen allows the generation of the pictures at much , much lower dose of x-ray . so it ’ s really quite a significant advance . it ’ s really quite nice chemistry as well .

so terbium , just like europium , is often used in television screens and various types of displays and where it comes in is that it gives green and yellow colours , which in contrast to the red and blue which europium gives you , gives you the full selection that you need to give colour images . so ytterby gruva , ytterby mine , what a great place , the snow is falling . this is designated ytterby mine , a historical landmark for the discovery of four periodic elements : yttrium , terbium , erbium , and ytterbium .

as pete explained from snow-covered ytterby , how can the phosphorescence of terbium be applied to make safer hospital diagnoses ?

packed inside every cell in your body is a set of genetic instructions , 3.2 billion base pairs long . deciphering these directions would be a monumental task but could offer unprecedented insight about the human body . in 1990 , a consortium of 20 international research centers embarked on the world 's largest biological collaboration to accomplish this mission . the human genome project proposed to sequence the entire human genome over 15 years with $ 3 billion of public funds . then , seven years before its scheduled completion , a private company called celera announced that they could accomplish the same goal in just three years and at a fraction of the cost . the two camps discussed a joint venture , but talks quickly fell apart as disagreements arose over legal and ethical issues of genetic property . and so the race began . though both teams used the same technology to sequence the entire human genome , it was their strategies that made all the difference . their paths diverged in the most critical of steps : the first one . in the human genome project 's approach , the genome was first divided into smaller , more manageable chunks about 150,000 base pairs long that overlapped each other a little bit on both ends . each of these fragments of dna was inserted inside a bacterial artificial chromosome where they were cloned and fingerprinted . the fingerprints showed scientists where the fragments overlapped without knowing the actual sequence . using the overlapping bits as a guide , the researchers marked each fragment 's place in the genome to create a contiguous map , a process that took about six years . the cloned fragments were sequenced in labs around the world following one of the project 's two major principles : that collaboration on our shared heritage was open to all nations . in each case , the fragments were arbitrarily broken up into small , overlapping pieces about 1,000 base pairs long . then , using a technology called the sanger method , each piece was sequenced letter by letter . this rigorous map-based approach called hierarchical shotgun sequencing minimized the risk of misassembly , a huge hazard of sequencing genomes with many repetitive portions , like the human genome . the consortium 's `` better safe than sorry '' approach contrasted starkly with celera 's strategy called whole genome shotgun sequencing . it hinged on skipping the mapping phase entirely , a faster , though foolhardy , approach according to some . the entire genome was directly chopped up into a giant heap of small , overlapping bits . once these bits were sequenced via the sanger method , celera would take the formidable risk of reconstructing the genome using just the overlaps . but perhaps their decision was n't such a gamble because guess whose freshly completed map was available online for free ? the human genome consortium , in accordance with the project 's second major principle which held that all of the project 's data would be shared publicly within 24 hours of collection . so in 1998 , scientists around the world were furiously sequencing lines of genetic code using the tried and true , yet laborious , sanger method . finally , after three exhausting years of continuous sequencing and assembling , the verdict was in . in february 2001 , both groups simultaneously published working drafts of more than 90 % of the human genome , several years ahead of the consortium 's schedule . the race ended in a tie . the human genome project 's practice of immediately sharing its data was an unusual one . it is more typical for scientists to closely guard their data until they are able to analyze it and publish their conclusions . instead , the human genome project accelerated the pace of research and created an international collaboration on an unprecedented scale . since then , robust investment in both the public and private sector has led to the identification of many disease related genes and remarkable advances in sequencing technology . today , a person 's genome can be sequenced in just a few days . however , reading the genome is only the first step . we 're a long way away from understanding what most of our genes do and how they are controlled . those are some of the challenges for the next generation of ambitious research initiatives .

then , using a technology called the sanger method , each piece was sequenced letter by letter . this rigorous map-based approach called hierarchical shotgun sequencing minimized the risk of misassembly , a huge hazard of sequencing genomes with many repetitive portions , like the human genome . the consortium 's `` better safe than sorry '' approach contrasted starkly with celera 's strategy called whole genome shotgun sequencing . it hinged on skipping the mapping phase entirely , a faster , though foolhardy , approach according to some .

why was celera 's whole-genome sequencing approach considered more risky than the human genome project 's approach ?

water is virtually eveywhere , from soil moisture and ice caps , to the cells inside our own bodies . depending on factors like location , fat index , age , and sex , the average human is between 55-60 % water . at birth , human babies are even wetter . being 75 % water , they are swimmingly similar to fish . but their water composition drops to 65 % by their first birthday . so what role does water play in our bodies , and how much do we actually need to drink to stay healthy ? the h20 in our bodies works to cushion and lubricate joints , regulate temperature , and to nourish the brain and spinal cord . water is n't only in our blood . an adult 's brain and heart are almost three quarters water . that 's roughly equivalent to the amount of moisture in a banana . lungs are more similar to an apple at 83 % . and even seemingly dry human bones are 31 % water . if we are essentially made of water , and surrounded by water , why do we still need to drink so much ? well , each day we lose two to three liters through our sweat , urine , and bowel movements , and even just from breathing . while these functions are essential to our survival , we need to compensate for the fluid loss . maintaining a balanced water level is essential to avoid dehydration or over-hydration , both of which can have devastating effects on overall health . at first detection of low water levels , sensory receptors in the brain 's hypothalamus signal the release of antidiuretic hormone . when it reached the kidneys , it creates aquaporins , special channels that enable blood to absorb and retain more water , leading to concentrated , dark urine . increased dehydration can cause notable drops in energy , mood , skin moisture , and blood pressure , as well as signs of cognitive impairment . a dehydrated brain works harder to accomplish the same amount as a normal brain , and it even temporarily shrinks because of its lack of water . over-hydration , or hyponatremia , is usually caused by overconsumption of water in a short amount of time . athletes are often the victims of over-hydration because of complications in regulating water levels in extreme physical conditions . whereas the dehydrated brain amps up the production of antidiuretic hormone , the over-hydrated brain slows , or even stops , releasing it into the blood . sodium electrolytes in the body become diluted , causing cells to swell . in severe cases , the kidneys ca n't keep up with the resulting volumes of dilute urine . water intoxication then occurs , possibly causing headache , vomiting , and , in rare instances , seizures or death . but that 's a pretty extreme situation . on a normal , day-to-day basis , maintaining a well-hydrated system is easy to manage for those of us fortunate enough to have access to clean drinking water . for a long time , conventional wisdom said that we should drink eight glasses a day . that estimate has since been fine-tuned . now , the consensus is that the amount of water we need to imbibe depends largely on our weight and environment . the recommended daily intake varies from between 2.5-3.7 liters of water for men , and about 2-2.7 liters for women , a range that is pushed up or down if we are healthy , active , old , or overheating . while water is the healthiest hydrator , other beverages , even those with caffeine like coffee or tea , replenish fluids as well . and water within food makes up about a fifth of our daily h20 intake . fruits and vegetables like strawberries , cucumbers , and even broccoli are over 90 % water , and can supplement liquid intake while providing valuable nutrients and fiber . drinking well might also have various long-term benefits . studies have shown that optimal hydration can lower the chance of stroke , help manage diabetes , and potentially reduce the risk of certain types of cancer . no matter what , getting the right amount of liquid makes a world of difference in how you 'll feel , think , and function day to day .

water is virtually eveywhere , from soil moisture and ice caps , to the cells inside our own bodies . depending on factors like location , fat index , age , and sex , the average human is between 55-60 % water . at birth , human babies are even wetter . being 75 % water , they are swimmingly similar to fish .

at birth , what percentage of a human baby is comprised of water ?

i am in the coffee room where element 109 , meitnerium was named . in here , imagine it : 20 people sitting round arguing “ what are we going to call this new element ? ” writing the names on the blackboard…they rubbed it off ! but there , they had the whole choice of what the elements were called . like many others of these very heavy elements , meitnerium was made by taking a nucleus of a heavy element and banging into it a lighter element . in the case of this one you have lead with atomic number 82 and bang into it cobalt , or alternatively you can have bismuth which has atomic number 83 and bang in iron which has atomic number one less than cobalt so you have 2 different ways of making the same element . i was just told by sigurd hofmann , one of the discoverers , they chose the name , mietnerium because lisa mietner who was the co-discoverer of fission of atoms never got the nobel prize , her collaborator otto hahn got the nobel prize she didn ’ t . now she has got an element named after her , and he hasn ’ t , so her name will live longer than his . i think it would be really exciting to choose the name of an element . well professor , you are sitting next to a man who does get to name elements , this is your one chance to tell him what you think he should call any future elements that he might get to have a say in , let ’ s see what you are going to suggest to him . i think , i still think that it would be nice to honour max planck and i also think that planckium is a nice name it rolls off the tongue . what do you think ? planckium , will you bear that one in mind for us next time you have to name an element ? i think now , planckium , we can write in bold letters because he already was on our list . ok there you go ! planckium might be in the running next time , are you happy ? yes , thankyou . ok. lisa mietner was the first woman ever to get a phd , a doctorate in physics , in austria and then she moved to berlin . during the first world war she worked on a mobile x-ray unit for x-raying wounded soldiers and then she worked in berlin with max planck . and there is a very nice story that rutherford sent radioactive samples to them by post from cambridge and she could tell when a parcel was coming to her from cambridge before looking at it , while the postman was still holding it , because her geiger-counter started detecting radioactivity coming out of the parcel . people were not quite so careful when they sent radioactive samples in those days as they are now .

i am in the coffee room where element 109 , meitnerium was named . in here , imagine it : 20 people sitting round arguing “ what are we going to call this new element ? ” writing the names on the blackboard…they rubbed it off !

after which great scientist was meitnerium named ?

have you ever heard the sound of frogs calling at night ? for hundreds of millions of years , this croaking lullaby has filled the nighttime air . but recent studies suggest that these frogs are in danger of playing their final note . over the past few decades , amphibian populations have been rapidly disappearing worldwide . nearly one-third of the world 's amphibian species are endanger of extinction , and over 100 species have already disappeared . but do n't worry , there 's still hope . before we get into how to save the frogs , let 's start by taking a look at why they 're disappearing and why it 's important to keep them around . habitat destruction is the number one problem for frog populations around the world . there are seven billion humans on the planet , and we compete with frogs for habitat . we build cities , suburbs , and farms on top of frog habitat and chop forests and drain the wetlands that serve as home for numerous amphibian populations . climate change alters precipitation levels , drying up ponds , streams , and cloud forests . as the earth 's human population continues to grow , so will the threats amphibians face . there are a variety of other factors contributing to the frogs ' decline . over-harvesting for the pet and food trade results in millions of frogs being taken out of the wild each year . invasive species , such as non-native trout and crawfish , eat native frogs . humans are facilitating the spread of infectious diseases by shipping over 100 million amphibians around the world each year for use as food , pets , bait , and in laboratories and zoos , with few regulations or quarantines . one of these diseases , chytridiomycosis , has driven stream-dwelling amphibian populations to extinction in africa , australia , europe , and north , central , and south america . on top of all these problems , we add hundreds of millions of kilograms of pesticides to our ecosystems each year . and these chemicals are easily absorbed through amphibians ' permeable skin , causing immunosuppression , or a weakened immune system , and developmental deformities . okay , so why are these little green guys worth keeping around ? frogs are important for a multitude of reasons . they 're an integral part of the food web , eating flies , ticks , mosquitoes , and other disease vectors , thus , protecting us against malaria , dengue fever , and other illnesses . tadpoles keep waterways clean by feeding on algae , reducing the demand on our community 's filtration systems and keeping our cost of water low . frogs serve as a source of food for birds , fish , snakes , dragonflies , and even monkeys . when frogs disappear , the food web is disturbed , and other animals can disappear as well . amphibians are also extremely important in human medicine . over ten percent of the nobel prizes in physiology and medicine have gone to researchers whose work depended on amphibians . some of the antimicrobial peptides on frog skin can kill hiv , some act as pain killers , and others serve as natural mosquito repellents . many discoveries await us if we can save the frogs , but when a frog species disappears , so does any promise it holds for improving human health . fortunately , there are lots of ways you can help , and the best place to start is by improving your ecological footprint and day-to-day actions . the next time you listen to that nighttime lullaby , do n't think of it as just another background noise , hear it as a call for help , sung in perfect croaking harmony .

when frogs disappear , the food web is disturbed , and other animals can disappear as well . amphibians are also extremely important in human medicine . over ten percent of the nobel prizes in physiology and medicine have gone to researchers whose work depended on amphibians .

amphibians are under threat from which of the following factors ?

mysteries of vernacular : lady , woman . lady is tied to a number of words that seem at first glance etymologically unrelated . she traces her roots back to the old english words hlaf , which referred to a loaf of bread and is the direct ancestor of our modern word loaf , and daege , which meant maid and is the root of our word dairy , the place where the dairymaid works . together , hlaf and daege became hlafdige , literally loaf maid , or , more figuratively , kneader of bread . as early as the ninth century , hlafdige was the name for a mistress of servants , or the female head of the household . the old english word for a male head of household was hlafweard , a compound of hlaf , loaf , and weard , which meant keeper and is the word of modern words like ward and warden . both hlafweard , the breadwinner , and hlafdige , the bread kneader , came to be titles of respect , referring to citizens of higher social standing . through a process known as syncopation , both words lost their internal sounds to become lord and lady , respectively . though still an expression of courtesy , lady has since moved down the ladder of social standing and is now often used to mean simply a woman .

as early as the ninth century , hlafdige was the name for a mistress of servants , or the female head of the household . the old english word for a male head of household was hlafweard , a compound of hlaf , loaf , and weard , which meant keeper and is the word of modern words like ward and warden . both hlafweard , the breadwinner , and hlafdige , the bread kneader , came to be titles of respect , referring to citizens of higher social standing .

what is the relationship between the old english word hlafweard ( bread keeper ) and the modern english word breadwinner ?

would you believe that walruses , rattlesnakes , and parakeets all once lived in the same house ? let 's go back about 350 million years . look around . steamy swamps and rain forests of horsetails and ferns cover the region . amphibians are the dominant land vertebrates . they range in size from newts to crocodiles . and all require water to do their egg laying . if they do n't go to the water , their shell-less , jelly-like eggs will dry out . because of this hazard , they spend most of their time living in or near fresh water . that is , until a breakthrough in evolution changes everything : the amniotic egg . the amniotic egg is shelled , waterproof , and can be laid on dry land . it is produced by the amniotes , a new group of animals named after their revolutionary egg . the first amniote is a tetrapod , a four-legged animal , resembling a small lizard . while some amphibians can walk around on land and bury their eggs in wet soil or highly humid areas , nothing before the amniotes has the ability to lay its eggs on completely dry land . because of this evolved egg , the amniotes are the first animals with the ability to live a fully terrestrial life . but , despite their move inland , the amniotes have not abandoned their pond-dwelling upbringing . in fact , the amniotic egg brings the pond with them by enclosing the aquatic environment within its shell . this is achieved by four main upgrades that are unique to amniotic eggs . let 's take a closer look . the first development is the most obvious : the egg 's protective shell . it 's tough but flexible , and has a leathery surface , still seen in reptile eggs today . the shell protects the eggs from predators , bacteria , damage , and drying out . but , unlike the walls of a fish tank , the shell of the amniotic egg is porous , allowing oxygen to pass through so that the growing amniote inside does n't suffocate . the next two developments are two separate membranes that work together like a pair of lungs . they bring oxygen into the embryo while removing carbon dioxide . the first is the chorion , which is the protective layer that oxygen passes through after entering the shell 's tiny pores . you may recognize the chorion as the thin skin you peel away on a hard boiled egg . think of this waterproof membrane as the in and out doors of the egg . it 's the entrance for oxygen and exit for carbon dioxide . the membrane working with the chorion is the allantois . if the chorion is the doors , then the allantois is essentially the lobby of the building . it directs the oxygen and carbon dioxide while simultaneously storing unneeded waste from the embryo . the chorion and the allantois make sure the embryo has everything it needs and gets rid of anything it does n't . the last and perhaps the most important development is the amnion , the membrane for which the egg is named . the amnion is also contained within the chroion and holds the fluid in which the embryo floats . because it has left the watery world of the amphibians , the amnion is necessary for preventing the embryo from drying out . it is the transportable pond that allows the amniote to lay the egg on dry land . its fluid also protects the embryo from any collisions or rough landings , like a shock absorber on your bike or car . together , the shell and these four membranes create a safe , watery environment for the embryo to grow and develop . the new amniote offspring will continue the process of vertebrate evolution as it explores new land away from the water . they will spend the next million years splitting into two distinct groups : the synapsids and sauropsids . synapsida is the group of animals that contain mammals , while sauropsida is the group that contains reptiles , birds , and dinosaurs . these two amniotic groups collectively contain the walruses , rattlesnakes , and parakeets we know today . like a family reunion , with relatives of every shape and size , coming together from different corners of the earth , these animals can all call one place home : the amniotic egg .

but , despite their move inland , the amniotes have not abandoned their pond-dwelling upbringing . in fact , the amniotic egg brings the pond with them by enclosing the aquatic environment within its shell . this is achieved by four main upgrades that are unique to amniotic eggs . let 's take a closer look .

why is the amniotic egg compared to a traveling pond ?

have you ever noticed that it 's harder to start pedaling your bicycle than it is to ride at a constant speed ? or wondered what causes your bicycle to move ? or thought about why it goes forward instead of backwards or sideways ? perhaps not , and you would n't be alone . it was n't until the 17th century that isaac newton described the fundamental laws of motion and we understood the answer to these three questions . what newton recognized was that things tend to keep on doing what they are already doing . so when your bicycle is stopped , it stays stopped , and when it is going , it stays going . objects in motion tend to stay in motion and objects at rest tend to stay at rest . that 's newton 's first law . physicists call it the law of inertia , which is a fancy way of saying that moving objects do n't spontaneously speed up , slow down , or change direction . it is this inertia that you must overcome to get your bicycle moving . now you know that you have to overcome inertia to get your bicycle moving , but what is it that allows you to overcome it ? well , the answer is explained by newton 's second law . in mathematical terms , newton 's second law says that force is the product of mass times acceleration . to cause an object to accelerate , or speed up , a force must be applied . the more force you apply , the quicker you accelerate . and the more mass your bicycle has , and the more mass you have too , the more force you have to use to accelerate at the same rate . this is why it would be really difficult to pedal a 10,000 pound bicycle . and it is this force , which is applied by your legs pushing down on the pedals , that allows you to overcome newton 's law of inertia . the harder you push down on the pedals , the bigger the force and the quicker you accelerate . now on to the final question : when you do get your bike moving , why does it go forward ? according to newton 's third law , for every action , there is an equal and opposite reaction . to understand this , think about what happens when you drop a bouncy ball . as the bouncy ball hits the floor , it causes a downward force on the floor . this is the action . the floor reacts by pushing on the ball with the same force , but in the opposite direction , upward , causing it to bounce back up to you . together , the floor and the ball form what 's called the action/reaction pair . when it comes to your bicycle , it is a little more complicated . as your bicycle wheels spin clockwise , the parts of each tire touching the ground push backwards against the earth : the actions . the ground pushes forward with the same force against each of your tires : the reactions . since you have two bicycle tires , each one forms an action/reaction pair with the ground . and since the earth is really , really , really big compared to your bicycle , it barely moves from the force caused by your bicycle tires pushing backwards , but you are propelled forward .

since you have two bicycle tires , each one forms an action/reaction pair with the ground . and since the earth is really , really , really big compared to your bicycle , it barely moves from the force caused by your bicycle tires pushing backwards , but you are propelled forward .

in the last sentence of the talk i mention that the earth barely moves backwards as your bicycle wheel pushes against it . does the earth really move backwards ? explain , using your understanding of newton ’ s second law , how this could be true .

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

that 's part of sally struthers ' famine campaign . some of it is very familiar ; it 's the madonna and child . women and children are very effective in terms of ngo campaigns . we 've been looking at this imagery for a long time , for hundreds and hundreds of years ; the madonna and child . here is [ duccio ] , and here is michelangelo .

dodson ’ s concern about how reporters and ngo ’ s use “ madonna and child ” imagery is :

all year long , researchers at hundreds of hospitals around the world collect samples from flu patients and send them to top virology experts with one goal : to design the vaccine for the next flu season . but why do we need a new one every year ? vaccines for diseases like mumps and rubella offer a lifetime of protection with two shots early in life . what 's so special about the flu ? two factors make the flu a tough target . first , there are more than 100 subtypes of the influenza virus , and the ones in circulation change from season to season . and second , the flu 's genetic code allows it to mutate more quickly than many other viruses . the flu spreads by turning a host 's own cells into viral production factories . when the virus is engulfed by a host cell , it expels its genetic material , which makes its way to the nucleus . there , cellular machinery that normally copies the host 's genes starts replicating viral genes instead , creating more and more copies of the virus . new viruses are repackaged and crammed into the cell until it bursts , sending freshly minted influenza viruses out to infect additional cells . most viruses follow this script . the trick with the flu is that its genetic material is n't dna but a similar compound called rna . and rna viruses can mutate much faster . when cells synthesize dna , a built-in proofreader recognizes and corrects mistakes , but the rna synthesis mechanism does n't have this fail-safe . if errors creep in , they stick around creating new variants of the virus . why is this a problem ? because vaccines depend on recognition . the flu vaccine includes some of the same substances , called antigens , found on the surface of the virus itself . the body identifies those fragments as foreign and responds by producing compounds called antibodies , tailor-made to match the antigens . when a vaccinated person encounters the actual virus , the preprogrammed antibodies help the immune system identify the threat and mobilize quickly to prevent an infection . those antigens are different for every strain of influenza . if vaccination has prepared the immune system for one strain , a different one may still be able to sneak by . even within the same strain of flu , those rapid genetic mutations can change the surface compounds enough that the antibodies may not recognize them . to make things even more complicated , sometimes two different strains combine to create an entirely new hybrid virus . all of this makes vaccinating for the flu like trying to hit a moving transforming target . that 's why scientists are constantly collecting data about which strains are circulating and checking to see how much those strains have mutated from previous years ' versions . twice annually , the world health organization pulls together experts to analyze all that data , holding one meeting for each hemisphere . the scientists determine which strains to include in that season 's vaccine , picking four for the quadrivalent vaccine in use today . in spite of the flu 's evasive maneuvers , in recent years , the group 's predictions have been almost always correct . even when flu strains mutate further , the vaccine is often close enough that a vaccinated person who catches the flu anyway will have a milder and shorter illness than they would otherwise . vaccination also helps protect other people in the community who may not be medically eligible for the shot by preventing those around them from carrying the virus . this is called herd immunity . the flu shot ca n't give you the flu . it contains an inactivated virus that is n't capable of making you sick . you might feel tired and achy after getting it , but that 's not an infection . it 's your normal immune response to the vaccine . some parts of the world use , instead of a shot , an inhaled vaccine that contains a weakened live virus . this is also safe for the vast majority of people . only those with impaired immune systems would be at risk , but they 're typically not given live vaccines . meanwhile , scientists are working to develop a universal flu vaccine that would protect against any strain , even mutated ones . but until then , the hunt for next year 's vaccine is on .

most viruses follow this script . the trick with the flu is that its genetic material is n't dna but a similar compound called rna . and rna viruses can mutate much faster .

what is the genetic material of the flu virus ?

it 's a common saying that elephants never forget , but these magnificent animals are more than giant walking hard drives . the more we learn about elephants , the more it appears that their impressive memory is only one aspect of an incredible intelligence that makes them some of the most social , creative , and benevolent creatures on earth . unlike many proverbs , the one about elephant memory is scientifically accurate . elephants know every member in their herd , able to recognize as many as 30 companions by sight or smell . this is a great help when migrating or encountering other potentially hostile elephants . they also remember and distinguish particular cues that signal danger and can recall important locations long after their last visit . but it 's the memories unrelated to survival that are the most fascinating . elephants remember not only their herd companions but other creatures who have made a strong impression on them . in one case , two circus elephants that had briefly performed together rejoiced when crossing paths 23 years later . this recognition is n't limited to others of their species . elephants have also recognized humans they 've bonded with after decades apart . all of this shows that elephant memory goes beyond responses to stimuli . looking inside their heads , we can see why . the elephant boasts the largest brain of any land mammal , as well as an impressive encephalization quotient . this is the size of the brain relative to what we 'd expect for an animal 's body size , and the elephant 's eq is nearly as high as a chimpanzee 's . and despite the distant relation , convergent evolution has made it remarkably similar to the human brain , with as many neurons and synapses and a highly developed hippocampus and cerebral cortex . it is the hippocampus , strongly associated with emotion , that aids recollection by encoding important experiences into long-term memories . the ability to distinguish this importance makes elephant memory a complex and adaptable faculty beyond rote memorization . it 's what allows elephants who survived a drought in their youth to recognize its warning signs in adulthood , which is why clans with older matriarchs have higher survival rates . unfortunately , it 's also what makes elephants one of the few non-human animals to suffer from post-traumatic stress disorder . the cerebral cortex , on the other hand , enables problem solving , which elephants display in many creative ways . they also tackle problems cooperatively , sometimes even outwitting the researchers and manipulating their partners . and they 've grasped basic arithmetic , keeping track of the relative amounts of fruit in two baskets after multiple changes . the rare combination of memory and problem solving can explain some of elephants ' most clever behaviors , but it does n't explain some of the things we 're just beginning to learn about their mental lives . elephants communicate using everything from body signals and vocalizations , to infrasound rumbles that can be heard kilometers away . and their understanding of syntax suggests that they have their own language and grammar . this sense of language may even go beyond simple communication . elephants create art by carefully choosing and combining different colors and elements . they can also recognize twelve distinct tones of music and recreate melodies . and yes , there is an elephant band . but perhaps the most amazing thing about elephants is a capacity even more important than cleverness : their sense of empathy , altruism , and justice . elephants are the only non-human animals to mourn their dead , performing burial rituals and returning to visit graves . they have shown concern for other species , as well . one working elephant refused to set a log down into a hole where a dog was sleeping , while elephants encountering injured humans have sometimes stood guard and gently comforted them with their trunk . on the other hand , elephant attacks on human villages have usually occurred right after massive poachings or cullings , suggesting deliberate revenge . when we consider all this evidence , along with the fact that elephants are one of the few species who can recognize themselves in a mirror , it 's hard to escape the conclusion that they are conscious , intelligent , and emotional beings . unfortunately , humanity 's treatment of elephants does not reflect this , as they continue to suffer from habitat destruction in asia , ivory poaching in africa , and mistreatment in captivity worldwide . given what we now know about elephants and what they continue to teach us about animal intelligence , it is more important than ever to ensure that what the english poet john donne described as `` nature 's great masterpiece '' does not vanish from the world 's canvas .

and yes , there is an elephant band . but perhaps the most amazing thing about elephants is a capacity even more important than cleverness : their sense of empathy , altruism , and justice . elephants are the only non-human animals to mourn their dead , performing burial rituals and returning to visit graves .

what are some ways in which elephants show empathy and a sense of justice ?

translator : andrea mcdonough reviewer : bedirhan cinar i do n't know about you , but i 'm trying to get this beach body , that p90x , brad pitt , bradley cooper , tyrese , trey songz , matthew mcconaughey beach body ! i 'm trying to sweat in front of everybody . word . and get that shorty with them angelina jolie lips to lick my torso , get me looking like a wet chocolate . look at my biceps . they 're kind of puny . they 're kind of chunky . but i 've been working on them . we can be models . i could take off my shirt mad sexy . i could stare at a camera intensely for 37 seconds straight and not blink . i could bathe in baby oil . i could run on the beach in slow motion . i could cat walk down a runway in zebra panties . i ca n't do that . having a slow metabolism ruins everything . all my friends will be in tank tops , and i 'll be in a hoodie . i 'm good at zipping up my insecurities , thinking i could sweat them out . i 'm trying to get this beach body ! i 'm too skinny . i guzzle junk food like my mouth 's a garbage chute , but my intestines are allergic to trans fat . i want to be a flexing horse leg , galloping beach sand into a red carpet , customized for me to strut the shore side like a centaur on a conveyor belt . i 'm trying to get this beach body , but there is salvation in snack closets , on licked plates of seconds , at the bottom of a pint of ice cream . i use haagen dazs as a morphine cylinder because she said my arms were n't strong enough to carry her . i think i 'm weak . i think i 'm fat . i think i 'm ugly . the beach is no place for a whale like me , for a mini van with its tank on e. i want to be baywatch bareable , broken , bottle-cut , have you seen my muscles and my scars ? you smell that ? that 's macho moisture . my hour-long work out routine consists of 5 minutes of push-ups on my bedroom floor , a denial mirror repelling my lanky limbs ; 5 minutes of keeping my chin high over the bar of self doubt ; 10 minutes placing 100 pounds of failure on my chest so it becomes the elephant in the room ; 10 minutes jogging with ghosts chuckling at my chunky thighs , and i 'll smile , knowing i 'll soon be able to fit in my old butt pants ; 30 minutes thinking sweat is a masculinity cloak . and i 'm weary from trying to work out my irrational fears , drown them in a puddle of perspiration , shove the imperfections i should be proud of under water : my gap-tooth smile , my frizzy hair , my funny shaped head , the extra weight that kept me grounded , the missing pounds that make me a kite flailing free through the wind , not bound by muscle . so , yes , i 'm trying to get this beach body , that channing tatum , david beckham , ll cool j beach body ! but we 're tired and exhausted from trying to be something we 're not .

but i 've been working on them . we can be models . i could take off my shirt mad sexy .

list five people you feel are good role models for people with insecurities or low self esteem . explain why you listed each person .

translator : andrea mcdonough reviewer : bedirhan cinar what do harry potter , katniss everdeen , and frodo all have in common with the heroes of ancient myths ? ( roar ) what if i told you they are all variants of the same hero ? do you believe that ? joseph campbell did . he studied myths from all over the world and published a book called `` the hero with a thousand faces , '' retelling dozens of stories and explaining how each represents the mono-myth , or hero 's journey . so , what is the `` hero 's journey '' ? think of it as a cycle . the journey begins and ends in a hero 's ordinary world , but the quest passes through an unfamiliar , special world . along the way , there are some key events . think about your favorite book or movie . does it follow this pattern ? status quo , that 's where we start . 1:00 : call to adventure . the hero receives a mysterious message . an invitation , a challenge ? 2:00 : assistance the hero needs some help , probably from someone older , wiser . 3:00 : departure the hero crosses the threshold from his normal , safe home , and enters the special world and adventure . we 're not in kansas anymore . 4:00 : trials being a hero is hard work : our hero solves a riddle , slays a monster , escapes from a trap . 5:00 : approach it 's time to face the biggest ordeal , the hero 's worst fear . ( roar ) 6:00 : crisis this is the hero 's darkest hour . he faces death and possibly even dies , only to be reborn . 7:00 : treasure ( roar ) as a result , the hero claims some treasure , special recognition , or power . 8:00 : result this can vary between stories . do the monsters bow down before the hero , or do they chase him as he flees from the special world ? 9:00 : return after all that adventure , the hero returns to his ordinary world . 10:00 : new life this quest has changed the hero ; he has outgrown his old life . 11:00 : resolution all the tangled plot lines get straightened out . 12:00 : status quo , but upgraded to a new level . nothing is quite the same once you are a hero . many popular books and movies follow this ancient formula pretty closely . but let 's see how well `` the hunger games '' fits the hero 's journey template . when does katniss everdeen hear her call to adventure that gets the story moving ? when her sister 's name is called from the lottery . how about assistance ? is anyone going to help her on her adventure ? haymitch . what about departure ? does she leave her ordinary world ? she gets on a train to the capital . ok , so you get the idea . what do you have in common with harry potter , katniss everdeen , and frodo ? well , you 're human , just like them . the hero 's journey myth exists in all human cultures and keeps getting updated , because we humans reflect on our world through symbolic stories of our own lives . you leave your comfort zone , have an experience that transforms you , and then you recover and do it again . you do n't literally slay dragons or fight voldemort , but you face problems just as scary . joseph campbell said , `` in the cave you fear to enter lies the treasure you seek . '' what is the symbolic cave you fear to enter ? auditions for the school play ? baseball tryouts ? love ? watch for this formula in books , movies , and tv shows you come across . you will certainly see it again . but also be sensitive to it in your own life . listen for your call to adventure . accept the challenge . conquer your fear and claim the treasure you seek . and then , do it all over again .

he studied myths from all over the world and published a book called `` the hero with a thousand faces , '' retelling dozens of stories and explaining how each represents the mono-myth , or hero 's journey . so , what is the `` hero 's journey '' ? think of it as a cycle .

what author is most associated with the concept of the hero ’ s journey ?

so this is a sample of ruthenium sponge . so the ruthenium metal has been precipitated to form very fine particles . so here we will just open the box i am rather ashamed that i made a big mistake about the name of ruthenium . i thought it referred to somewhere in middle europe perhaps in czechoslovakia whereas ruthenium actually comes from ruthenia which is the latin translation for the country that is now called russia and , in fact , the element ruthenium was first discovered in russia in the city of kazan . why would that be a particular cause of shame for you ? well , because my father was born in russia and therefore to get something connected to russia wrong is a bit embarrassing . the ruthenium is a very , very reactive metal especially when it is formed in this very fine sponge type material . ruthenium was actually discovered relatively early in the middle of the 19th century . there is some discussion , whether in fact the swedish chemist berzelius analysed something that contained ruthenium and missed it or not , but i am not quite sure about that . but the reason why i am interested in this is because i did my doctorate with a supervisor and if you look at his supervisor and then that ö then go back one supervisor after another you eventually get to the swedish chemist berzelius who was my great , great , great , great , great , great , great supervisor and you will find that most of the chemists now working in the world were related to just a few pioneering chemists in the 18th century . so the ruthenium is very finely divided and if i tip it you can see in the bottom of the vial very fine powders but again because of the particle size this is really dark , very black , very nice sample of ruthenium very useful for catalytic chemistry . it is as a catalyst that ruthenium is particularly famous . ruthenium itself if you look at a lump of the metal is a kind of silvery colour . this is a sample of ruthenium as a catalyst . now because it is an expensive metal the ruthenium is just distributed as a very thin layer on silica . silica is like sand and you can see that this finely divided ruthenium looks black . they are very finely divided so it has a large surface area so the molecules can come in and react it . and my students were using this catalyst to react an organic compound , that is one with carbon and hydrogen and to get it to react with more hydrogen and so they lent me this catalyst so i could show it to you . there are other ruthenium catalysts which dissolve in the solution that you are trying to get the reaction to go . and there is a very famous catalyst named after the american chemist bob grubbs , who won the nobel prize about 4 years ago , and his catalyst does a reaction which most people even some chemists had not heard of called which is called metathesis in which double bonds between two carbon atoms are broken and joined together in a different way . and you can use this for all sorts of things you can make plastics out of oils ; you can make new sorts of wax ; you can make a really great sort of wax that has oxygen atoms in it ; and if you use this for candles then the oxygen atoms make fragrance molecules dissolve much better than in ordinary wax . so you can have a christmas candle which , when you light it , smells of christmas pudding or smells of alcohol or vanilla or whatever spice you want . you canít do that with an ordinary wax but this ruthenium catalyst opens up all sorts of things so that is why he got the nobel prize . he got the nobel prize because he made nice smelling candles ? no , he got the nobel prize because he invented the catalyst that opened up all sorts of reactions that otherwise could not be done . bob grubbs compound has ruthenium and his is the most widely used and it is now used in a whole series of industrial processes . this is another compound of ruthenium which you can see is a rather nice red colour and it has the rather unromantic name of ruthenium bpy three times or chemists who use it call it rubpy . and the point about this compound is that it absorbs light well and it is very stable , you can shine light on it , very intense light for a long time and the compound does not decompose , it does not change . but what it can do when you shine light is that you can move electrons around inside the compound and this compound and ones like it are being used by people to try and capture the light from the sun - capture solar energy

well , because my father was born in russia and therefore to get something connected to russia wrong is a bit embarrassing . the ruthenium is a very , very reactive metal especially when it is formed in this very fine sponge type material . ruthenium was actually discovered relatively early in the middle of the 19th century .

in which type of chemical research lab is ruthenium most useful ?

around 1159 a.d. , a mathematician called bhaskara the learned sketched a design for a wheel containing curved reservoirs of mercury . he reasoned that as the wheels spun , the mercury would flow to the bottom of each reservoir , leaving one side of the wheel perpetually heavier than the other . the imbalance would keep the wheel turning forever . bhaskara 's drawing was one of the earliest designs for a perpetual motion machine , a device that can do work indefinitely without any external energy source . imagine a windmill that produced the breeze it needed to keep rotating . or a lightbulb whose glow provided its own electricity . these devices have captured many inventors ' imaginations because they could transform our relationship with energy . for example , if you could build a perpetual motion machine that included humans as part of its perfectly efficient system , it could sustain life indefinitely . there 's just one problem . they do n't work . ideas for perpetual motion machines all violate one or more fundamental laws of thermodynamics , the branch of physics that describes the relationship between different forms of energy . the first law of thermodynamics says that energy ca n't be created or destroyed . you ca n't get out more energy than you put in . that rules out a useful perpetual motion machine right away because a machine could only ever produce as much energy as it consumed . there would n't be any left over to power a car or charge a phone . but what if you just wanted the machine to keep itself moving ? inventors have proposed plenty of ideas . several of these have been variations on bhaskara 's over-balanced wheel with rolling balls or weights on swinging arms . none of them work . the moving parts that make one side of the wheel heavier also shift its center of mass downward below the axle . with a low center of mass , the wheel just swings back and forth like a pendulum , then stops . what about a different approach ? in the 17th century , robert boyle came up with an idea for a self-watering pot . he theorized that capillary action , the attraction between liquids and surfaces that pulls water through thin tubes , might keep the water cycling around the bowl . but if the capillary action is strong enough to overcome gravity and draw the water up , it would also prevent it from falling back into the bowl . then there are versions with magnets , like this set of ramps . the ball is supposed to be pulled upwards by the magnet at the top , fall back down through the hole , and repeat the cycle . this one fails because like the self-watering pot , the magnet would simply hold the ball at the top . even if it somehow did keep moving , the magnet 's strength would degrade over time and eventually stop working . for each of these machines to keep moving , they 'd have to create some extra energy to nudge the system past its stopping point , breaking the first law of thermodynamics . there are ones that seem to keep going , but in reality , they invariably turn out to be drawing energy from some external source . even if engineers could somehow design a machine that did n't violate the first law of thermodynamics , it still would n't work in the real world because of the second law . the second law of thermodynamics tells us that energy tends to spread out through processes like friction . any real machine would have moving parts or interactions with air or liquid molecules that would generate tiny amounts of friction and heat , even in a vacuum . that heat is energy escaping , and it would keep leeching out , reducing the energy available to move the system itself until the machine inevitably stopped . so far , these two laws of thermodynamics have stymied every idea for perpetual motion and the dreams of perfectly efficient energy generation they imply . yet it 's hard to conclusively say we 'll never discover a perpetual motion machine because there 's still so much we do n't understand about the universe . perhaps we 'll find new exotic forms of matter that 'll force us to revisit the laws of thermodynamics . or maybe there 's perpetual motion on tiny quantum scales . what we can be reasonably sure about is that we 'll never stop looking . for now , the one thing that seems truly perpetual is our search .

there are ones that seem to keep going , but in reality , they invariably turn out to be drawing energy from some external source . even if engineers could somehow design a machine that did n't violate the first law of thermodynamics , it still would n't work in the real world because of the second law . the second law of thermodynamics tells us that energy tends to spread out through processes like friction .

in this video , we focused on the first and second law of thermodynamics to explain the constraints on a perpetual motion machine . if our claim is true , it should be explainable with other frameworks such as newton 's laws . try working it out ! ( hint : start with the self-watering pot . )

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

that 's why i say they 're not really workaholics . they 're workafrolics . jim pattison , chairman of the jim pattison group , is a workafrolic .

which of these people are workafrolics ?

the first standardized tests that we know of were administered in china over 2,000 years ago during the han dynasty . chinese officials used them to determine aptitude for various government posts . the subject matter included philosophy , farming , and even military tactics . standardized tests continued to be used around the world for the next two millennia , and today , they 're used for everything from evaluating stair climbs for firefighters in france to language examinations for diplomats in canada to students in schools . some standardized tests measure scores only in relation to the results of other test takers . others measure performances on how well test takers meet predetermined criteria . so the stair climb for the firefighter could be measured by comparing the time of the climb to that of all other firefighters . this might be expressed in what many call a bell curve . or it could be evaluated with reference to set criteria , such as carrying a certain amount of weight a certain distance up a certain number of stairs . similarly , the diplomat might be measured against other test-taking diplomats , or against a set of fixed criteria , which demonstrate different levels of language proficiency . and all of these results can be expressed using something called a percentile . if a diplomat is in the 70th percentile , 70 % of test takers scored below her . if she scored in the 30th percentile , 70 % of test takers scored above her . although standardized tests are sometimes controversial , they 're simply a tool . as a thought experiment , think of a standardized test as a ruler . a ruler 's usefulness depends on two things . first , the job we ask it to do . our ruler ca n't measure the temperature outside or how loud someone is singing . second , the ruler 's usefulness depends on its design . say you need to measure the circumference of an orange . our ruler measures length , which is the right quantity , but it has n't been designed with the flexibility required for the task at hand . so , if standardized tests are given the wrong job , or are n't designed properly , they may end up measuring the wrong things . in the case of schools , students with test anxiety may have trouble performing their best on a standardized test , not because they do n't know the answers , but because they 're feeling too nervous to share what they 've learned . students with reading challenges may struggle with the wording of a math problem , so their test results may better reflect their literacy rather than numeracy skills . and students who were confused by examples on tests that contain unfamiliar cultural references may do poorly , telling us more about the test taker 's cultural familiarity than their academic learning . in these cases , the tests may need to be designed differently . standardized tests can also have a hard time measuring abstract characteristics or skills , such as creativity , critical thinking , and collaboration . if we design a test poorly , or ask it to do the wrong job , or a job it 's not very good at , the results may not be reliable or valid . reliability and validity are two critical ideas for understanding standardized tests . to understand the difference between them , we can use the metaphor of two broken thermometers . an unreliable thermometer gives you a different reading each time you take your temperature , and the reliable but invalid thermometer is consistently ten degrees too hot . validity also depends on accurate interpretations of results . if people say results of a test mean something they do n't , that test may have a validity problem . just as we would n't expect a ruler to tell us how much an elephant weighs , or what it had for breakfast , we ca n't expect standardized tests alone to reliably tell us how smart someone is , how diplomats will handle a tough situation , or how brave a firefighter might turn out to be . so standardized tests may help us learn a little about a lot of people in a short time , but they usually ca n't tell us a lot about a single person . many social scientists worry about test scores resulting in sweeping and often negative changes for test takers , sometimes with long-term life consequences . we ca n't blame the tests , though . it 's up to us to use the right tests for the right jobs , and to interpret results appropriately .

and all of these results can be expressed using something called a percentile . if a diplomat is in the 70th percentile , 70 % of test takers scored below her . if she scored in the 30th percentile , 70 % of test takers scored above her . although standardized tests are sometimes controversial , they 're simply a tool .

if you score in the 25th percentile on a test , what percentage of test takers scored above you ?

for most of us , two degrees celsius is a tiny difference in temperature , not even enough to make you crack a window . but scientists have warned that as co2 levels in the atmosphere rise , an increase in the earth 's temperature by even this amount can lead to catastrophic effects all over the world . how can such a small measurable change in one factor lead to massive and unpredictable changes in other factors ? the answer lies in the concept of a mathematical tipping point , which we can understand through the familiar game of billiards . the basic rule of billiard motion is that a ball will go straight until it hits a wall , then bounce off at an angle equal to its incoming angle . for simplicity 's sake , we 'll assume that there is no friction , so balls can keep moving indefinitely . and to simplify the situation further , let 's look at what happens with only one ball on a perfectly circular table . as the ball is struck and begins to move according to the rules , it follows a neat star-shaped pattern . if we start the ball at different locations , or strike it at different angles , some details of the pattern change , but its overall form remains the same . with a few test runs , and some basic mathematical modeling , we can even predict a ball 's path before it starts moving , simply based on its starting conditions . but what would happen if we made a minor change in the table 's shape by pulling it apart a bit , and inserting two small straight edges along the top and bottom ? we can see that as the ball bounces off the flat sides , it begins to move all over the table . the ball is still obeying the same rules of billiard motion , but the resulting movement no longer follows any recognizable pattern . with only a small change to the constraints under which the system operates , we have shifted the billiard motion from behaving in a stable and predictable fashion , to fluctuating wildly , thus creating what mathematicians call chaotic motion . inserting the straight edges into the table acts as a tipping point , switching the systems behavior from one type of behavior ( regular ) , to another type of behavior ( chaotic ) . so what implications does this simple example have for the much more complicated reality of the earth 's climate ? we can think of the shape of the table as being analogous to the co2 level and earth 's average temperature : constraints that impact the system 's performance in the form of the ball 's motion or the climate 's behavior . during the past 10,000 years , the fairly constant co2 atmospheric concentration of 270 parts per million kept the climate within a self-stabilizing pattern , fairly regular and hospitable to human life . but with co2 levels now at 400 parts per million , and predicted to rise to between 500 and 800 parts per million over the coming century , we may reach a tipping point where even a small additional change in the global average temperature would have the same effect as changing the shape of the table , leading to a dangerous shift in the climate 's behavior , with more extreme and intense weather events , less predictability , and most importantly , less hospitably to human life . the hypothetical models that mathematicians study in detail may not always look like actual situations , but they can provide a framework and a way of thinking that can be applied to help understand the more complex problems of the real world . in this case , understanding how slight changes in the constraints impacting a system can have massive impacts gives us a greater appreciation for predicting the dangers that we can not immediately percieve with our own senses . because once the results do become visible , it may already be too late .

with only a small change to the constraints under which the system operates , we have shifted the billiard motion from behaving in a stable and predictable fashion , to fluctuating wildly , thus creating what mathematicians call chaotic motion . inserting the straight edges into the table acts as a tipping point , switching the systems behavior from one type of behavior ( regular ) , to another type of behavior ( chaotic ) . so what implications does this simple example have for the much more complicated reality of the earth 's climate ?

when the behavior of a system switches from being regular to chaotic after a change is added , this is called :

nothing stuck to mafia boss john gotti who evaded justice for years by bribing and threatening jurors and witnesses . that earned him the name the teflon don after one of the slipperiest materials on earth . teflon was in the spacesuits the apollo crew wore for the moon landing , in pipes and valves used in the manhattan project , and maybe in your kitchen as the nonstick coating on frying pans and cookie sheets . so what is this slippery solid , and why does n't anything stick to it ? teflon is a brand name for polytetrafluoroethylene , or ptfe . it was stumbled upon accidentally in 1938 by a 27-year-old american chemist named roy plunkett while he was trying to develop a non-toxic refrigerant fluid for dupont , a chemicals company . the strange , white substance that formed inside his lab canister was chemically inert , meaning it would n't react with other substances . it also had an extremely low coefficient of friction , making other materials slide right off it . teflon 's properties make it perfect when you need something slippery , chemical resistant , or waterproof , which means it has a lot of applications . it can be found all over the place , as a coating on raincoats , industrial ball bearings , artificial joints , circuit boards , and even the rocky mountains-themed roof of the denver international airport . the incredible properties of ptfe come from its molecular structure . it 's a polymer , meaning it 's made of long chains of repeating units of atoms strung together . a ptfe chain has a backbone of carbon atoms , each of which is attached to two fluorines . the fluorine atoms surround the carbon like armor , spiraling around the chain , and the bond between carbon and fluorine is incredibly tight . like a couple that ignores everyone except each other , carbon and fluorine interact so strongly that the normal , intermolecular forces that help substances stick to each other do n't stand a chance . even the famously adhesive feet of geckos usually ca n't get a grip . but wait ! if ptfe does n't stick to anything , how can it be so firmly attached to something like a pan ? one method involves sandblasting the pan or etching it with chemicals to make it rough . then , a special primer is applied , which acts like glue . its exact composition is a trade secret guarded by each manufacturer . the pan is sprayed with liquid ptfe and heated to around 800 degrees fahrenheit . the layers then solidify into a smooth , slick coating . when you later cook eggs in this ptfe-coated pan , the extra tight carbon-fluorine bonds just ignore the water and fat and protein molecules in the eggs . without those interactions , the food just slides around without sticking . you might wonder if it 's safe to cook in a ptfe-coated pan . the answer is yes , if you 're careful . ptfe is stable at moderate temperatures , like you 'd use to cook eggs or fish , but above 500 degrees fahrenheit , it starts to degrade , and heating it further releases fumes that can make you feel sick . an empty pan can reach 500 degrees fast over high heat , but most kitchens are ventilated well enough to dissipate the fumes . people used to also think that accidentally consuming ptfe that flaked off a scratched pan was bad for you , but the current consensus is that it 's harmless . because ptfe does n't interact with other chemicals very well , it is n't thought to break down inside your body . whether it 's safe to manufacture teflon is another story . dupont and its spin-off company chemours now face lawsuits worth millions of dollars . they 've been accused of polluting the environment for decades and exposing employees and local communities to health risks associated with a toxic chemical called pfoa . that chemical was involved in manufacturing teflon . as for john gotti , in 1992 , the mob boss was finally convicted of five counts of murder , among other charges . that prompted the head of the fbi office in new york city to announce , `` the teflon is gone . the don is covered in velcro , and all the charges stuck . ''

the layers then solidify into a smooth , slick coating . when you later cook eggs in this ptfe-coated pan , the extra tight carbon-fluorine bonds just ignore the water and fat and protein molecules in the eggs . without those interactions , the food just slides around without sticking .

why is it so hard for ptfe to form chemical bonds with outside molecules ?

sugar is playing hide and seek with you . you 'd think it would be pretty easy for you to win , considering all the sugar in sodas , ice cream , candy , and big white bags labeled sugar . people get about half of their added sugars from those drinks and treats , so it might seem like sugar is hiding in plain sight , but like someone in the witness protection program , the other half is hidden in places you 'd least suspect . check the ingredients on ketchup , bologna , spaghetti sauce , soy milk , sports drinks , fish sticks , and peanut butter . you 'll find sugar hiding in most of those products . in fact , you 'll find added sugars in three-quarters of the more than 600,000 items available in grocery stores . but how is sugar hiding ? ca n't you just look on food labels ? it 's not that easy . just like your friend robert might go by bob , robby , rob , bobby , or roberto , added sugar has a lot of aliases . and by a lot , we do n't mean five or six , try fifty-six . there 's brown rice syrup , barley malt , demerara , florida crystals , muscovado , and , of course , high fructose corn syrup , sometimes called hfcs , or corn sugar . even sugar 's tricky nicknames have nicknames . grape or apple concentrate has the same effects on your body as its 55 sugary twins . and even though organic evaporated cane juice sounds healthy , when you evaporate it , you get sugar ! chemically speaking , it 's all the same . and even trickier , when multiple added types of sugars are used in one type of product , they get buried down in a long list of ingredients , so the sugar content might appear to be okay , but when you add them all together , sugar can be the single biggest ingredient . currently , the fda does n't suggest a recommended daily limit for sugar , so it 's hard to tell if this 65 grams in a bottle of soda is a little or a lot . but the world health organization recommends limiting sugar to just 5 % of your total calories , or about 25 grams per day . so , 65 grams is well over twice that amount . but just what is sugar ? what 's the difference between glucose and fructose ? well , both are carbohydrates with the same chemical composition of carbon , hydrogen , and oxygen . but they have very different structures and behave quite differently in our bodies . glucose is the best source of energy for nearly all organisms on earth . it can be metabolized by all organs in the body . fructose , on the other hand , is metabolized primarily in the liver , and when your liver gets overloaded with sweet , sweet fructose , the excess is metabolized to fat . fresh fruits actually contain fructose , but it 's naturally occurring and does n't cause an overload because the fiber in fruit slows its absorption . this gives your liver the time it needs to do its job . it 's sugar that makes cookies chewy and candy crunchy . it even turns bread crust a beautiful , golden brown . it 's also a great preservative ; it does n't spoil or evaporate , so the foods it 's added to are easier to store and ship long distances and tend to be cheaper . that 's why sugar is hiding everywhere . actually , it might be easier to list the foods that added sugar is n't hiding in , things like : vegetables , eggs , meats , fish , fruit , raw nuts , even your kitchen sink . simply choosing water over soda , juices , and sports drinks is a great way to avoid hidden added sugar . at the very least , try to pay attention to food labels , so you can keep your sugar intake at a healthy level . because in this game of hide and seek , every time you do n't find added sugar , you win !

glucose is the best source of energy for nearly all organisms on earth . it can be metabolized by all organs in the body . fructose , on the other hand , is metabolized primarily in the liver , and when your liver gets overloaded with sweet , sweet fructose , the excess is metabolized to fat . fresh fruits actually contain fructose , but it 's naturally occurring and does n't cause an overload because the fiber in fruit slows its absorption .

fructose is metabolized ( burned for energy ) in the :

water is the liquid of life . we drink it , we bathe in it , we farm , cook , and clean with it . it 's the most abundant molecule in our bodies . in fact , every life form we know of would die without it . but most importantly , without water , we would n't have iced tea . mmmm , iced tea . why do these ice cubes float ? if these were cubes of solid argon in a cup of liquid argon , they would sink . and the same goes for most other substances . but solid water , a.k.a . ice , is somehow less dense than liquid water . how 's that possible ? you already know that every water molecule is made up of two hydrogen atoms bonded to one oxygen atom . let 's look at a few of the molecules in a drop of water , and let 's say the temperature is 25 degrees celcius . the molecules are bending , stretching , spinning , and moving through space . now , let 's lower the temperature , which will reduce the amount of kinetic energy each of these molecules has so they 'll bend , stretch , spin , and move less . and that means that on average , they 'll take up less space . now , you 'd think that as the liquid water starts to freeze , the molecules would just pack together more and more closely , but that 's not what happens . water has a special kind of interaction between molecules that most other substances do n't have , and it 's called a hydrogen bond . now , remember that in a covalent bond two electrons are shared , usually unequally , between atoms . in a hydrogen bond , a hydrogen atom is shared , also unequally , between atoms . one hydrogen bond looks like this . two look like this . here 's three and four and five , six , seven , eight , nine , ten , eleven , twelve , i could go on . in a single drop of water , hydrogen bonds form extended networks between hundreds , thousands , millions , billions , trillions of molecules , and these bonds are constantly breaking and reforming . now , back to our water as it cools down . above 4 degrees celcius , the kinetic energy of the water molecules keeps their interactions with each other short . hydrogen bonds form and break like high school relationships , that is to say , quickly . but below 4 degrees , the kinetic energy of the water molecules starts to fall below the energy of the hydrogen bonds . so , hydrogen bonds form much more frequently than they break and beautiful structures start to emerge from the chaos . this is what solid water , ice , looks like on the molecular level . notice that the ordered , hexagonal structure is less dense than the disordered structure of liquid water . and you know that if an object is less dense than the fluid it 's in , it will float . so , ice floats on water , so what ? well , let 's consider a world without floating ice . the coldest part of the ocean would be the pitch-black ocean floor , once frozen , always frozen . forget lobster rolls since crustaceans would lose their habitats , or sushi since kelp forests would n't grow . what would canadian kids do in winter without pond hockey or ice fishing ? and forget james cameron 's oscar because the titanic totally would have made it . say goodbye to the white polar ice caps reflecting sunlight that would otherwise bake the planet . in fact , forget the oceans as we know them , which at over 70 % of the earth 's surface area , regulate the atmosphere of the whole planet . but worst of all , there would be no iced tea . mmmmm , iced tea .

above 4 degrees celcius , the kinetic energy of the water molecules keeps their interactions with each other short . hydrogen bonds form and break like high school relationships , that is to say , quickly . but below 4 degrees , the kinetic energy of the water molecules starts to fall below the energy of the hydrogen bonds .

at room temperature , hydrogen bonds ________ .

can you grow a human bone outside the human body ? the answer may soon be yes , but before we can understand how that 's possible , we need to look at how bones grow naturally inside the body . most bones start in a growing fetus as a soft , flexible cartilage . bone-forming cells replace the cartilage with a spongy mineral lattice made of elements like calcium and phosphate . this lattice gets harder , as osteoblasts , which are specialized bone-forming cells , deposit more mineral , giving bones their strength . while the lattice itself is not made of living cells , networks of blood vessels , nerves and other living tissues grow through special channels and passages . and over the course of development , a legion of osteoblasts reinforce the skeleton that protects our organs , allows us to move , produces blood cells and more . but this initial building process alone is not enough to make bones strong and functional . if you took a bone built this way , attached muscles to it , and tried to use it to lift a heavy weight , the bone would probably snap under the strain . this does n't usually happen to us because our cells are constantly reinforcing and building bone wherever they 're used , a principle we refer to as wolff 's law . however , bone materials are a limited resource and this new , reinforcing bone can be formed only if there is enough material present . fortunately , osteoblasts , the builders , have a counterpart called osteoclasts , the recyclers . osteoclasts break down the unneeded mineral lattice using acids and enzymes so that osteoblasts can then add more material . one of the main reasons astronauts must exercise constantly in orbit is due to the lack of skeletal strain in free fall . as projected by wolff 's law , that makes osteoclasts more active than osteoblasts , resulting in a loss of bone mass and strength . when bones do break , your body has an amazing ability to reconstruct the injured bone as if the break had never happened . certain situations , like cancer removal , traumatic accidents , and genetic defects exceed the body 's natural ability for repair . historical solutions have included filling in the resulting holes with metal , animal bones , or pieces of bone from human donors , but none of these are optimal as they can cause infections or be rejected by the immune system , and they ca n't carry out most of the functions of healthy bones . an ideal solution would be to grow a bone made from the patient 's own cells that 's customized to the exact shape of the hole , and that 's exactly what scientists are currently trying to do . here 's how it works . first , doctors extract stem cells from a patient 's fat tissue and take ct scans to determine the exact dimensions of the missing bone . they then model the exact shape of the hole , either with 3d printers , or by carving decellularized cow bones . those are the bones where all of the cells have been stripped away , leaving only the sponge-like mineral lattice . they then add the patient 's stem cells to this lattice and place it in a bioreactor , a device that will simulate all of the conditions found inside the body . temperature , humidity , acidity and nutrient composition all need to be just right for the stem cells to differentiate into osteoblasts and other cells , colonize the mineral lattice , and remodel it with living tissue . but there 's one thing missing . remember wolff 's law ? an artificial bone needs to experience real stress , or else it will come out weak and brittle , so the bioreactor constantly pumps fluids around the bone , and the pressure tells the osteoblasts to add bone density . put all of this together , and within three weeks , the now living bone is ready to come out of the bioreactor and to be implanted into the patient 's body . while it is n't yet certain that this method will work for humans , lab grown bones have already been successfully implanted in pigs and other animals , and human trials may begin as early as 2016 .

one of the main reasons astronauts must exercise constantly in orbit is due to the lack of skeletal strain in free fall . as projected by wolff 's law , that makes osteoclasts more active than osteoblasts , resulting in a loss of bone mass and strength . when bones do break , your body has an amazing ability to reconstruct the injured bone as if the break had never happened . certain situations , like cancer removal , traumatic accidents , and genetic defects exceed the body 's natural ability for repair .

how do osteoclasts break down the bone ?

so , we ’ re braving the elements brady , to repeat the experiment that we did quite some time ago , so you will remember that we had a very small balloon of hydrogen match on a stick to hydrogen , big bang coming ! are you ready ? yep ! here we go ! and the fact that we ’ ve come outside , might actually give you an idea of what we are going to do , cause we are going to make it a little bit bigger , so let ’ s go and fill a balloon . alright , cool . well , hydrogen , i think is very important because , it is the simplest atom , it ’ s the atom , consists of a positively charged proton which is relatively large and a negatively charged electron , that goes round it . electric match ? i think an electric match will go well on that . yep . oh , look at the tension on the balloon ! hold it , i ’ ve really gone for it and blown that one up . the tension ! what happens is that hydrogen is reacting with oxygen and h2 plus o2 reacts to form h2o and an oxygen atom and then that oxygen atom goes on to react with another hydrogen molecule to make more water and the reaction generates a lot of heat and that heat , heats up more gas to make it react faster , so you generate more and more heat , so the reaction that begins quite slowly with the first few molecules , runs away and that is why you get the explosion . so here we have a rather large balloon of hydrogen , neil is just preparing our electric match which we are going to attach to the side of this balloon . and some of the biggest explosions in the 20th century , the chernobyl reactor , the space shuttle that blew up when it was taking off , were in fact explosions caused by hydrogen and oxygen . so we ’ ve filled up a balloon of hydrogen , and i think if you look at the hydrogen balloon you will see that it is slightly larger than those we have attempted before . now we are going to try to detonate it or burn the hydrogen , in the air by giving it a match and the match we are going to use is again an electric match , which is connected to our detonator box . if you stick a pin in the balloon , the balloon will burst because the rubber will break , but the hydrogen will come out and it won ’ t react with the oxygen because the hydrogen is cool , it ’ s at the same temperature as the air , but the reaction of hydrogen and oxygen like many reactions involves so called activation energy , you have to put in a certain amount of energy to get it going . but once you get it going , you get more heat coming out , than you put in to start it off . so , let ’ s arm the circuit , 5-4-3-2-1 . that was more like it . lovely ! when pete puts the match to the balloon , first of all the match burns a hole in the balloon , and then the heat gets the hydrogen and oxygen near the outside of the balloon and they start reacting and the heat then spreads through the volume of the hydrogen and oxygen , faster probably than the balloon is bursting and as it spreads through the temperature builds up and up and up because you are generating so much heat . the reason that you hear a noise , is because , it causes a rise in pressure which sends a pressure wave out through the air and it hits your ears or the microphone on your camera . i honestly don ’ t know why you see any colour . i suspect that the colour may actually be caused by the burning balloon which contains carbon and is really like the flame on a candle . because normally when you have a hydrogen/oxygen flame you don ’ t see any colour at all . alternatively , it may be some impurities in the gas , but i suspect that what you are seeing in the fire ball is just the burning of the balloon . the other thing which is really quite exciting about hydrogen is that in principle if you heat hydrogen to really high temperatures , you can get two hydrogen atoms to fuse together , or rather , it will not work with hydrogen , but it will work with a heavier form of hydrogen which is know as deuterium where instead of a proton and an electron , you have a proton and a neutron , which is a neutral particle , and an electron , and two molecules of deuterium can fuse together to make one atom of helium which has two protons , two neutrons , and two electrons and this produces a lot of energy . it is the basis of the so-called hydrogen bombs , which are like super atomic bombs , but which require an enormously high temperature to get the reaction to go . you can probably hear it hitting and fizzing into the bottle there . there is great hope that in the end much of the world ’ s energy crisis can be solved by doing this so called nuclear fusion of deuterium to make helium which would produce energy extremely cleanly . so here , we ’ ll just tie it off , if my welsh hands can actually tie a knot on a balloon , ‘ cause , you know we are all a little bit bizarre . deuterium gas , in all its properties , will be very similar to that of hydrogen , of course it is denser , because it has a neutron as well as a proton but it is still much lighter than air so a deuterium balloon will still float up to the ceiling and make pete look just as stupid as the hydrogen one . you ’ ve got to keep hold of it . or you lose it or you lose it , you know ! i was thinking more of fusing it , that sounds like a really big explosion we could do out the back . no ! fusing reactors are way beyond what pete can do unless he is a lot cleverer than i think . i got a balloon ! i had a balloon of hydrogen ! that is the second time you have done that ! now it ’ s going to go up there eventually anyway !

you can probably hear it hitting and fizzing into the bottle there . there is great hope that in the end much of the world ’ s energy crisis can be solved by doing this so called nuclear fusion of deuterium to make helium which would produce energy extremely cleanly . so here , we ’ ll just tie it off , if my welsh hands can actually tie a knot on a balloon , ‘ cause , you know we are all a little bit bizarre .

according to the professor , which clean source of energy could potentially solve the energy challenge ?

you may think you know the words that sit plainly in black on your page , but do n't be fooled . some words are capable of taking on different guises , masquerading as nouns , verbs and adjectives that alter their meanings entirely . this seeming superpower is called lexical ambiguity . it can turn words and sentences into mazes that mess with our minds . for example , consider the following : buffalo buffalo buffalo buffalo buffalo buffalo buffalo buffalo . that may sound like nonsense , but it 's actually a grammatically correct sentence . how ? well , buffalo is proper noun , a noun , and a verb . it refers to an animal also known as a bison , an american city , and it can also mean to bully . these different interpretations create a sequence of words that is grammatically correct as it stands , though it helps to add in a few implied phrases and punctuation marks to reveal what 's really going on . buffalo buffalo are bison from the city of buffalo , and this sentence has three groups of them . group a , which is bullied by group b , bullies group c. in other words , bison from buffalo that other bison from buffalo bully also bully bison from buffalo . if you let each buffalo perform its role , the meaning becomes apparent . what if the bunch of bullying buffalo decides to cross the ocean ? not just on any ship , but a ship-shipping ship shipping shipping-ships ? that sentence sounds just as outrageous , but there 's logic to the babble . ship can mean a vessel and to transport . when we sub in those meanings , a clearer picture emerges . here we have a huge ship-carrying vessel transporting ships that themselves are designed to carry goods across the sea . a ship-shipping ship , shipping shipping-ships . how about some entertainment on board this unusual vessel to offset the scuffling buffalo ? consider the can-can . can-can can-can can can can can can-can . here , the word can comes in many guises . there 's can-can , the flamboyant dance , can , that means able to , and can , figuratively meaning to outperform . by sticking in a comma and including the implied meanings , this sentence becomes clearer . can-can dances that can-can dances are able to outperform , can also outperform other can-can dances . you would n't necessarily use any of these sentences in a conversation . they 're just too ridiculous . yet they serve as an extreme example on just how tangled everyday language can be . lexical ambiguities sail into our speech and writing all the time , spreading confusion and misunderstanding wherever they can-can .

some words are capable of taking on different guises , masquerading as nouns , verbs and adjectives that alter their meanings entirely . this seeming superpower is called lexical ambiguity . it can turn words and sentences into mazes that mess with our minds .

here 's an example of lexical ambiguity . see if you can figure out what this sentence is saying : `` will , will will will 's will to will ? ''

what if electricity could travel forever without being diminished ? what if a computer could run exponentially faster with perfect accuracy ? what technology could those abilities build ? we may be able to find out thanks to the work of the three scientists who won the nobel prize in physics in 2016 . david thouless , duncan haldane , and michael kosterlitz won the award for discovering that even microscopic matter at the smallest scale can exhibit macroscopic properties and phases that are topological . but what does that mean ? first of all , topology is a branch of mathematics that focuses on fundamental properties of objects . topological properties do n't change when an object is gradually stretched or bent . the object has to be torn or attached in new places . a donut and a coffee cup look the same to a topologist because they both have one hole . you could reshape a donut into a coffee cup and it would still have just one . that topological property is stable . on the other hand , a pretzel has three holes . there are no smooth incremental changes that will turn a donut into a pretzel . you 'd have to tear two new holes . for a long time , it was n't clear whether topology was useful for describing the behaviors of subatomic particles . that 's because particles , like electrons and photons , are subject to the strange laws of quantum physics , which involve a great deal of uncertainty that we do n't see at the scale of coffee cups . but the nobel laureates discovered that topological properties do exist at the quantum level . and that discovery may revolutionize materials science , electronic engineering , and computer science . that 's because these properties lend surprising stability and remarkable characteristics to some exotic phases of matter in the delicate quantum world . one example is called a topological insulator . imagine a film of electrons . if a strong enough magnetic field passes through them , each electron will start traveling in a circle , which is called a closed orbit . because the electrons are stuck in these loops , they 're not conducting electricity . but at the edge of the material , the orbits become open , connected , and they all point in the same direction . so electrons can jump from one orbit to the next and travel all the way around the edge . this means that the material conducts electricity around the edge but not in the middle . here 's where topology comes in . this conductivity is n't affected by small changes in the material , like impurities or imperfections . that 's just like how the hole in the coffee cup is n't changed by stretching it out . the edge of such a topological insulator has perfect electron transport : no electrons travel backward , no energy is lost as heat , and the number of conducting pathways can even be controlled . the electronics of the future could be built to use this perfectly efficient electron highway . the topological properties of subatomic particles could also transform quantum computing . quantum computers take advantage of the fact that subatomic particles can be in different states at the same time to store information in something called qubits . these qubits can solve problems exponentially faster than classical digital computers . the problem is that this data is so delicate that interaction with the environment can destroy it . but in some exotic topological phases , the subatomic particles can become protected . in other words , the qubits formed by them ca n't be changed by small or local disturbances . these topological qubits would be more stable , leading to more accurate computation and a better quantum computer . topology was originally studied as a branch of purely abstract mathematics . thanks to the pioneering work of thouless , haldane , and kosterlitz , we now know it can be used to understand the riddles of nature and to revolutionize the future of technologies .

the electronics of the future could be built to use this perfectly efficient electron highway . the topological properties of subatomic particles could also transform quantum computing . quantum computers take advantage of the fact that subatomic particles can be in different states at the same time to store information in something called qubits .

topological qubit is superb for quantum computing , not because it is ____ .

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 .

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 .

how does the `` girl with the pearl earring '' differ from much of vermeer ’ s other work ?

watch the center of this disk . you are getting sleepy . no , just kidding . i 'm not going to hypnotize you . but are you starting to see colors in the rings ? if so , your eyes are playing tricks on you . the disk was only ever black and white . you see , your eyes do n't always capture the world as a video camera would . in fact , there are quite a few differences , owing to the anatomy of your eye and the processing that takes place in your brain and its outgrowth , the retina . let 's start with some similarities . both have lenses to focus light and sensors to capture it , but even those things behave differently . the lens in a camera moves to stay focused on an object hurtling towards it , while the one in your eye responds by changing shape . most camera lenses are also achromatic , meaning they focus both red and blue light to the same point . your eye is different . when red light from an object is in focus , the blue light is out of focus . so why do n't things look partially out of focus all the time ? to answer that question , we first need to look at how your eye and the camera capture light : photoreceptors . the light-sensitive surface in a camera only has one kind of photoreceptor that is evenly distributed throughout the focusing surface . an array of red , green and blue filters on top of these photoreceptors causes them to respond selectively to long , medium and short wavelength light . your eye 's retinas , on the other hand , have several types of photoreceptors , usually three for normal light conditions , and only one type for lowlight , which is why we 're color blind in the dark . in normal light , unlike the camera , we have no need for a color filter because our photoreceptors already respond selectively to different wavelengths of light . also in contrast to a camera , your photoreceptors are unevenly distributed , with no receptors for dim light in the very center . this is why faint stars seem to disappear when you look directly at them . the center also has very few receptors that can detect blue light , which is why you do n't notice the blurred blue image from earlier . however , you still perceive blue there because your brain fills it in from context . also , the edges of our retinas have relatively few receptors for any wavelength light . so our visual acuity and ability to see color falls off rapidly from the center of our vision . there is also an area in our eyes called the blind spot where there are no photoreceptors of any kind . we do n't notice a lack of vision there because once again , our brain fills in the gaps . in a very real sense , we see with our brains , not our eyes . and because our brains , including the retinas , are so involved in the process , we are susceptible to visual illusions . here 's another illusion caused by the eye itself . does the center of this image look like it 's jittering around ? that 's because your eye actually jiggles most of the time . if it did n't , your vision would eventually shut down because the nerves on the retina stop responding to a stationary image of constant intensity . and unlike a camera , you briefly stop seeing whenever you make a larger movement with your eyes . that 's why you ca n't see your own eyes shift as you look from one to the other in a mirror . video cameras can capture details our eyes miss , magnify distant objects and accurately record what they see . but our eyes are remarkably efficient adaptations , the result of hundreds of millions of years of coevolution with our brains . and so what if we do n't always see the world exactly as it is . there 's a certain joy to be found watching stationary leaves waving on an illusive breeze , and maybe even an evolutionary advantage . but that 's a lesson for another day .

both have lenses to focus light and sensors to capture it , but even those things behave differently . the lens in a camera moves to stay focused on an object hurtling towards it , while the one in your eye responds by changing shape . most camera lenses are also achromatic , meaning they focus both red and blue light to the same point .

all good quality cameras use an achromatic lens to project a clear image on the photoreceptors , whereas the lens in the human eye _____ .

aristotle famously said , `` nature fears of empty space '' when he claimed that a true vacuum , a space devoid of matter , could not exist because the surrounding matter would immediately fill it . fortunately , he turned out to be wrong . a vacuum is a key component of the barometer , an instrument for measuring air pressure . and because air pressure correlates to temperature and rapid shifts in it can contribute to hurricanes , tornadoes and other extreme weather events , a barometer is one of the most essential tools for weather forecasters and scientists alike . how does a barometer work , and how was it invented ? well , it took awhile . because the theory of aristotle and other ancient philosophers regarding the impossibility of a vacuum seemed to hold true in everyday life , few seriously thought to question it for nearly 2,000 years -- until necessity raised the issue . in the early 17th century , italian miners faced a serious problem when they found that their pumps could not raise water more than 10.3 meters high . some scientists at the time , including one galileo galilei , proposed that sucking air out of the pipe was what made water rise to replace the void . but that its force was limited and could lift no more than 10.3 meters of water . however , the idea of a vacuum existing at all was still considered controversial . and the excitement over galileo 's unorthodox theory , led gasparo berti to conduct a simple but brilliant experiment to demonstrate that it was possible . a long tube was filled with water and placed standing in a shallow pool with both ends plugged . the bottom end of the tube was then opened and water poured out into the basin until the level of the water remaining in the tube was 10.3 meters . with a gap remaining at the top , and no air having entered the tube , berti had succeeded in directly creating a stable vacuum . but even though the possibility of a vacuum had been demonstrated , not everyone was satisfied with galileo 's idea that this empty void was exerting some mysterious yet finite force on the water . evangelista torricelli , galileo 's young pupil and friend , decided to look at the problem from a different angle . instead of focusing on the empty space inside the tube , he asked himself , `` what else could be influencing the water ? '' because the only thing in contact with the water was the air surrounding the pool , he believed the pressure from this air could be the only thing preventing the water level in the tube from dropping further . he realized that the experiment was not only a tool to create a vacuum , but operated as a balance between the atmospheric pressure on the water outside the tube and the pressure from the water column inside the tube . the water level in the tube decreases until the two pressures are equal , which just happens to be when the water is at 10.3 meters . this idea was not easily accepted , as galileo and others had traditionally thought that atmospheric air has no weight and exerts no pressure . torricelli decided to repeat berti 's experiment with mercury instead of water . because mercury was denser , it fell farther than the water and the mercury column stood only about 76 centimeters tall . not only did this allow torricelli to make the instrument much more compact , it supported his idea that weight was the deciding factor . a variation on the experiment used two tubes with one having a large bubble at the top . if galileo 's interpretation had been correct , the bigger vacuum in the second tube should have exerted more suction and lifted the mercury higher . but the level in both tubes was the same . the ultimate support for torricelli 's theory came via blaise pascal who had such a mercury tube taken up a mountain and showed that the mercury level dropped as the atmospheric pressure decreased with altitude . mercury barometers based on torricelli 's original model remained one of the most common ways to measure atmospheric pressure until 2007 when restrictions on the use of mercury due to its toxicity led to them no longer being produced in europe . nevertheless , torricelli 's invention , born of the willingness to question long accepted dogmas about vacuums and the weight of air , is an outstanding example of how thinking outside of the box -- or the tube -- can have a heavy impact .

the ultimate support for torricelli 's theory came via blaise pascal who had such a mercury tube taken up a mountain and showed that the mercury level dropped as the atmospheric pressure decreased with altitude . mercury barometers based on torricelli 's original model remained one of the most common ways to measure atmospheric pressure until 2007 when restrictions on the use of mercury due to its toxicity led to them no longer being produced in europe . nevertheless , torricelli 's invention , born of the willingness to question long accepted dogmas about vacuums and the weight of air , is an outstanding example of how thinking outside of the box -- or the tube -- can have a heavy impact .

what happened to mercury barometers in 2007 ?

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 .

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 .

describe the anatomical path of memory-making , beginning with the input of new material and ending with consolidation as a long-term memory .

sunken relics , ghostly shipwrecks , and lost cities . these are n't just wonders found in fictional adventures . beneath the ocean 's surface , there are ruins where people once roamed and shipwrecks loaded with artifacts from another time . this is the domain of underwater archaeology , where researchers discover and study human artifacts that slipped into the sea . they 're not on a treasure hunt . underwater archaeology reveals important information about ancient climates and coastlines , it tells us how humans sailed the seas , and what life was like millennia ago . so what exactly can we find ? at shallow depths mingled in with modern-day items , we 've discovered all sorts of ancient artifacts . this zone contains evidence of how our ancestors fished , how they repaired their ships , disposed of their trash , and even their convicted pirates , who were buried below the tide line . and it 's not just our recent history . 800,000-year old footprints were found along the shore in norfolk , britain . in these shallow depths , the remains of sunken cities also loom up from the sea floor , deposited there by earthquakes , tsunamis , and earth 's sinking plates . almost every sunken city can be found at these shallow depths because the sea level has changed little in the several thousand years that city-building civilizations have existed . for instance , in shallow waters off the coast of italy lies baia , a roman seaside town over 2,000 years old . there , it 's possible to swim among the ruins of structures built by rome 's great families , senators , and emperors . and then there are shipwrecks . as ships grow too old for use , they 're usually abandoned near shore in out-of-the-way places like estuaries , rivers , and shallow bays . archaeologists use these like a timeline to map a harbor 's peaks and declines , and to get clues about the historic art of shipbuiding . at roskilde in denmark , for example , five purposefully sunken vessels reveal how vikings crafted their fearsome long ships 1,000 years ago . when we descend a bit further , we reach the zone where the deepest human structures lie , like ancient harbor walls and quays . we also see more shipwrecks sunk by storms , war , and collisions . we 're still excavating many of these wrecks today , like blackbeard 's ship , which is revealing secrets about life as an 18th century pirate . but past 50 feet , there are even deeper , better preserved shipwrecks , like the wreck at antikythera , which sank during the 1st century bc . when it was discovered , it contained statues , trade cargo , and also the earliest known computer , a mysterious device called the antikythera mechanism that kept track of astronomical changes and eclipses . today , it gives archaeologists vital information about the knowledge possessed by the ancient greeks . it is in this zone that we also begin to find aircraft and submarines , such as those from the world wars . plunging as deep as 200 feet , we can find some of the earliest and rarest signs of human history . prior to 5,000 years ago , there was a lot more dry land because glaciers trapped much of the water that now forms the sea . our ancestors spread across these lands , and so on the sea floor , we find their camps , stone tools , and the bones of animals they hunted . these sites give us invaluable knowledge about our ancestor 's migration patterns , hunting methods , and technologies . in the deepest zone , no human has ever walked . this area has been submerged since well before mankind evolved . the only artifacts we find are those that have drifted down from above , like nasa 's saturn v rocket engines at 14,000 feet , and the deepest shipwrecks . the ocean is like a huge underwater museum that constantly adds to our knowledge about humanity . with only a fraction of it explored , discoveries are sure to continue long into the future .

sunken relics , ghostly shipwrecks , and lost cities . these are n't just wonders found in fictional adventures . beneath the ocean 's surface , there are ruins where people once roamed and shipwrecks loaded with artifacts from another time .

shipwrecks are found at every depth , but sites like sunken cities are only found within specific zones . what processes play a role in the location of different types of archaeological sites in different zone ?

sometime in the early 1750s , a 22-year-old man named benjamin banneker sat industriously carving cogs and gears out of wood . he pieced the parts together to create the complex inner working of a striking clock that would , hopefully , chime every hour . all he had to help him was a pocket watch for inspiration and his own calculations . and yet , his careful engineering worked . striking clocks had already been around for hundreds of years , but banneker 's may have been the first created in america , and it drew fascinated visitors from across the country . in a show of his brilliance , the clock continued to chime for the rest of banneker 's life . born in 1731 to freed slaves on a farm in baltimore , maryland , from his earliest days , the young banneker was obsessed with math and science . and his appetite for knowledge only grew as he taught himself astronomy , mathematics , engineering , and the study of the natural world . as an adult , he used astronomy to accurately predict lunar and solar events , like the solar eclipse of 1789 , and even applied his mathematical skills to land use planning . these talents caught the eye of a local baltimore businessman , andrew ellicott , who was also the surveyor general of the united states . recognizing banneker 's skills in 1791 , ellicott appointed him as an assistant to work on a prestigious new project , planning the layout of the nation 's capitol . meanwhile , banneker turned his brilliant mind to farming . he used his scientific expertise to pioneer new agricultural methods on his family 's tobacco farm . his fascination with the natural world also led to a study on the plague life cycle of locusts . then in 1792 , banneker began publishing almanacs . these provided detailed annual information on moon and sun cycles , weather forecasts , and planting and tidal time tables . banneker sent a handwritten copy of his first almanac to virginia 's secretary of state thomas jefferson . this was a decade before jefferson became president . banneker included a letter imploring jefferson to `` embrace every opportunity to eradicate that train of absurd and false ideas and opinions '' that caused prejudice against black people . jefferson read the almanac and wrote back in praise of banneker 's work . banneker 's correspondence with the future president is now considered to be one of the first documented examples of a civil rights protest letter in america . for the rest of his life , he fought for this cause , sharing his opposition to slavery through his writing . in 1806 at the age of 75 , banneker died after a lifetime of study and activism . on the day of his funeral , his house mysteriously burned down , and the majority of his life 's work , including his striking clock , was destroyed . but still , his legacy lives on .

sometime in the early 1750s , a 22-year-old man named benjamin banneker sat industriously carving cogs and gears out of wood . he pieced the parts together to create the complex inner working of a striking clock that would , hopefully , chime every hour .

benjamin banneker is said to be the first african-american man of science . what sort of limitations would he have faced in his time and how did overcome them ?

we hear about calories all the time . how many calories are in this cookie ? how many are burned by 100 jumping jacks , or long distance running , or fidgeting ? but what is a calorie , really , and how many of them do we actually need ? calories are a way of keeping track of the body 's energy budget . a healthy balance occurs when we put in about as much energy as we lose . if we consistently put more energy into our bodies than we burn , the excess will gradually be stored as fat in our cells , and we 'll gain weight . if we burn off more energy than we replenish , we 'll lose weight . so we have to be able to measure the energy we consume and use , and we do so with a unit called the calorie . one calorie , the kind we measure in food , also called a large calorie , is defined as the amount of energy it would take to raise the temperature of one kilogram of water by one degree celsius . everything we consume has a calorie count , a measure of how much energy the item stores in its chemical bonds . the average pizza slice has 272 calories , there are about 78 in a piece of bread , and an apple has about 52 . that energy is released during digestion , and stored in other molecules that can be broken down to provide energy when the body needs it . it 's used in three ways : about 10 % enables digestion , about 20 % fuels physical activity , and the biggest chunk , around 70 % , supports the basic functions of our organs and tissues . that third usage corresponds to your basal metabolic rate , a number of calories you would need to survive if you were n't eating or moving around . add in some physical activity and digestion , and you arrive at the official guidelines for how many calories the average person requires each day : 2000 for women and 2500 for men . those estimates are based on factors like average weight , physical activity and muscle mass . so does that mean everyone should shoot for around 2000 calories ? not necessarily . if you 're doing an energy guzzling activity , like cycling the tour de france , your body could use up to 9000 calories per day . pregnancy requires slightly more calories than usual , and elderly people typically have a slower metabolic rate , energy is burned more gradually , so less is needed . here 's something else you should know before you start counting calories . the calorie counts on nutrition labels measure how much energy the food contains , not how much energy you can actually get out of it . fibrous foods like celery and whole wheat take more energy to digest , so you 'd actually wind up with less energy from a 100 calorie serving of celery than a 100 calorie serving of potato chips . not to mention the fact that some foods offer nutrients like protein and vitamins , while others provide far less nutritional value . eating too many of those foods could leave you overweight and malnourished . and even with the exact same food , different people might not get the same number of calories . variations in things like enzyme levels , gut bacteria , and even intestine length , means that every individual 's ability to extract energy from food is a little different . so a calorie is a useful energy measure , but to work out exactly how many of them each of us requires we need to factor in things like exercise , food type , and our body 's ability to process energy . good luck finding all of that on a nutrition label .

the average pizza slice has 272 calories , there are about 78 in a piece of bread , and an apple has about 52 . that energy is released during digestion , and stored in other molecules that can be broken down to provide energy when the body needs it . it 's used in three ways : about 10 % enables digestion , about 20 % fuels physical activity , and the biggest chunk , around 70 % , supports the basic functions of our organs and tissues .

where is the energy stored in our food ?

let 's say there 's a disaster that sends humanity back to the stone age . can our knowledge and history survive ? the printed page will decompose . hard drive storage will deteriorate . even stones will eventually crumble . but we might have something inside us that can outlast these physical limitations : deoxyribonucleic acid . dna already stores our biological information . from eye color to skin tone , it programs our entire bodies . dna is made of four organic bases : adenine , guanine , cytosine , and thymine , or a , g , c , and t. the specific sequence of these bases into groups of three , known as codons , gives our cells instructions to make each of the proteins in our bodies . but this code can be used for other things , too , like secret messages . in 1999 , scientists in new york created an alphabet in which each of the 64 possible dna codons substituted for a specific letter , number , or grammar symbol . they spliced a 22-character message into a long strand of dna and surrounded it with specific genetic markers . they then hid the dna over a period in a type-written letter with only a small smudge to give the location away . they mailed the letter back to themselves . then they examined the letter looking for the dna strand . once the dna strand was located , they found the genetic markers . then , they sequenced the dna and successfully decoded the message . it soon became obvious that dna cryptography could code for much more than simple text . by translating the 1 's and 0 's of binary code into dna codons , digital data could be programmed into synthetic dna , then decoded back into its original form . in 2012 , uk scientists encoded 739 kilobytes of computer files into dna strands , including all 154 shakespeare sonnets and an excerpt from martin luther king 's `` i have a dream '' speech . and four years later , researchers at microsoft and the university of washington broke that record . they used binary coding to capture a whopping 200 megabytes of data , including the universal declaration of human rights and a high-def ok go music video , all in strings of dna . as far as storage capacity goes , dna stands out because of the surprising amount of information it can hold in so little space . the current theoretical limit of dna 's storage capacity is so high that you could fit 100 million hd movies on a pencil eraser . it 's even conceivable that one day we could fit all of the information currently on the internet into the space of a shoe box . also , computers and the magnetic tape and discs that their information is stored on only last for a few decades , at most , before degrading and becoming unreliable . meanwhile , dna has a half-life of 500 years , meaning that 's how long it takes for half of its bonds to break . and if left in a cold and dark environment , dna could potentially last for hundreds of thousands of years . and if that is n't long enough , scientists experimented with having synthetic dna auto-reproduce . after creating their own strands of dna that spelled out the lyrics to the children 's song `` it 's a small world , '' they placed them into the genome of a microbe nicknamed conan the bacterium . conan belongs to a species which can survive in a vacuum , or without water , for six years , or come out unscathed after being exposed to a dose of radiation 1,000 times that which would kill a human . according to the experiment , the bacterium was able to reproduce at least 100 generations without data loss . theoretically , if the organism had redundant copies of the information that could be used to automatically correct mistakes , the information could stay preserved even longer . so one day , you might be able to create a living , growing , knowledge archive in your own backyard , and its seeds might carry your family 's history , a detailed breakdown of the world 's political upheavals , or the sum of humanity 's knowledge into forests and across continents . perhaps even into the far reaches of space . though we might one day disappear , perhaps our legacy can still live on , if anyone would think to find it .

in 1999 , scientists in new york created an alphabet in which each of the 64 possible dna codons substituted for a specific letter , number , or grammar symbol . they spliced a 22-character message into a long strand of dna and surrounded it with specific genetic markers . they then hid the dna over a period in a type-written letter with only a small smudge to give the location away .

the first message sent via dna was ___________ characters long .

it should be alright ! there it goes ! aww , actually that ’ s quite spectacular at the end . and in my second-year , i think i love boron far too much i think , ‘ cause i talk about it too much . you love boron ? i love boron ! no , i used to do lots of chemistry with boron , i kind of moved away a little bit from boron now but i really like it . boron is an interesting element . it is one of the few that i have actually made myself when i was at school . boron sits on top of the group 13 . its atomic number is 5 , so it is a metalloid , so elemental boron is a metalloid which basically means that it has some of the properties of a non metal and some of the properties of a metal . i mixed an oxide of boron with magnesium , heated it up and then , it is a really dramatic reaction when you add water at the end to try and destroy the magnesium boride that has formed because you get puffs of gas coming off which burst into flames rather like little anti-aircraft guns . but boron itself was rather disappointing ; it ’ s a sort of brown powder . i mean there is a more of a powdery brown boron , there are several crystalline sort of types of alatropes of boron . there is one actually that is really , really hard , so the black crystalline boron is actually very , very hard . it ’ s just below diamond on mohs scale of hardness , so i believe . and actually in america , there is a town called boron . it ’ s in california , it ’ s got a population of around 2000 which actually was set up around the world ’ s biggest borax mine which is in california . well it used to be transported on trains of mules and the company that produced it used to have as their trademark a train of 20 mules sort of going along . of great interest to us chemists , well over the last sort of 50 , maybe sort of 60-70 years , have been the boron hydrides or borades . so boron hydrides are basically clusters of borons with hydrogens around them . and one of particular use and interest in the 50s was one called pentaborane , which basically : penta , five , it ’ s got five borons in it . and pentaborate was investigated during the cold war or in the early part of the cold war as being a rocket fuel . it actually burns with a green flame . they actually called it the ‘ green dragon ’ because it burns with a very , very hot green flame and also because it is pretty toxic , which i can actually show you if i … it is probably not going to be spectacular . and boron complexes or borax compounds are used in a variety of things . it is not a particularly expensive material . it is used in washing powder , particularly perborate which when you heat it up in the washing machine when the water gets to 60 degrees centigrade it turns into hydrogen peroxide which can then bleach the clothes and this is why the famous washing powder is called persil , because the ‘ per ’ stands for perborate and the ‘ sil ’ stands for silicate so it is really a mixture of perborate and silicate . ok so this isn ’ t pentaborane because pentaborane spontaneously combusts in the air . this is just benzene boronic acid . it ’ s an organic compound with some boron in it . so hopefully we can see , we should be able to see , if i can get some at the end of my spatula , that it should be able to burn with some sort of green flame . hey , there it is . you can also see a bit of yellow which is the organic bit going as well . it should be alright ! there it goes ! aww , actually that was quite spectacular at the end . ok .

no , i used to do lots of chemistry with boron , i kind of moved away a little bit from boron now but i really like it . boron is an interesting element . it is one of the few that i have actually made myself when i was at school .

there are several allotropes of boron ; debbie , who loves this element , presents two of them . the amorphous form of boron is a brown powder , and the crystalline form of boron , the black form , has an important property . what is this property ?

bean bags are awesome . but i see a few people out there who are standing , we 've got some over here , and standing takes more work than lounging . using the live strong organization 's online database of weight loss resources , you can calculate that by the time i 'm done with this speech , those of you who are standing will have burned 7.5 more calories than those of you who are bean-bagging it . ( laughter ) okay , here 's a question , speaking of weight loss , specifically weight , this speech is live . i 'm actually here in front of you guys , we 're all here together . but this speech is being recorded and it will become a video that people can access all over the world on computers , mobile devices , televisions . i weight about 190 pounds . how much will the video weigh ? asking questions like that is what i do every week on my channel vsauce . for the last two years , i have been asking really fun questions , mind-boggling questions , and approaching them as sincerely as i can , celebrating scientific concepts and scientists . and i research and write and produce and host and edit and upload and run the social media all by myself , but it 's not lonely , because vsauce has more than 2 million subscribers , and every month , my videos are seen by more than 20 million people . yeah . ( applause ) it 's very exciting . i 've found that asking a strange question is a great way to get people in , not just people , but fans . and fans are different than just viewers or an audience , because fans want to come back . they subscribe to you on youtube and they want to watch everything you 've made and everything you plan to make in the future because we are curious people and sparking curiosity is great bait . it 's a great way to catch a human . and once you 've caught them , you have this captive audience that you can , with the goal in mind of answering the question , accidentally teach a lot of things to . so , let 's take a look at some of my videos . here are eight of them . but down here in the lower-right corner , `` what color is a mirror ? '' when people see that , it 's very difficult not to click , because you think , `` come on , are you serious ? how could you possibly answer that question ? '' well , so far , 7.6 million people have watched this five-minute video about what color a mirror is . and in that episode , i answer the question and i get a chance to explain what would normally be kind of dry topics : optics , diffuse versus specular reflection , how light works , how light works on the retina , and even the etymology of color terms like white and black . okay , spoiler alert : mirrors are not clear , they are not silvery , like they 're often illustrated . mirrors , technically speaking , are just a tiny , tiny , little bit ... green . you can demonstrate this by putting two mirrors next to each other , facing so they reflect back and forth forever . look down that infinite reflection , and it will get dimmer , because some light is lost or absorbed every time , but it will also become greener , because green light , that is light of a wavelength that we perceive as green , is best reflected by most mirrors . okay , so , how much does a video weigh ? well , when you stream a video onto your computer , that information is temporarily stored using electrons . and the number of electrons on your device wo n't actually increase or decrease . but it takes energy to store them in one place , and , thanks to our friend albert einstein , we know that energy and mass are related . okay , so here 's the thing : let 's say you 're watching a youtube video at a really nice resolution , 720p . assuming a typical bit rate , we can figure that a minute of youtube video is going to need to involve about 10 million electrons on your device . plugging all those electrons and the energy it takes to hold them in the correct place for you to see the video , into that formula , we can figure out that one minute of youtube video increases the mass of your computer by about 10 to the negative 19th grams . written out , it looks like this . ( whistle ) that 's like nothing . you could call that nothing , and you would n't really get in trouble , because the best scales we 've ever invented that we could try to use to actually to detect that change are only accurate to 10 to the negative 9th grams . so , we ca n't measure it , but we can , like we just did , calculate it . and that 's really cool because when i was a kid , my school had two shelves of science books . that was really cool , but i read all of them within , like , two grades , and it was hard to get more books because books are heavy , you need space for them and moving books around is tougher than what we can do today . with numbers that small , i can fit thousands of books on my own little personal electronic reader . i can stream hours and hours and days and days of youtube video without my computer ever getting measurably heavier . and as information becomes that light , it becomes a lot more democratic , meaning that more teachers and presenters and creators and viewers than ever before can be involved . right now , on youtube , there is an explosion of content like this happening . the three vsauce channels are down there in the corner . but everyone else , all together , collectively , their views dwarf what i can do alone or with the people that i work with , and that is really , really exciting . it turns out that tapping into people 's curiosity and responsibly answering their questions is a brilliant way to build fans and an audience and get in viewers . it 's even a great way for brands and companies to build trust . so , calculating the weight of a video is kind of a funny question , but i can not wait to see what we ask and answer next . as always , thanks for watching . ( applause )

but it takes energy to store them in one place , and , thanks to our friend albert einstein , we know that energy and mass are related . okay , so here 's the thing : let 's say you 're watching a youtube video at a really nice resolution , 720p . assuming a typical bit rate , we can figure that a minute of youtube video is going to need to involve about 10 million electrons on your device . plugging all those electrons and the energy it takes to hold them in the correct place for you to see the video , into that formula , we can figure out that one minute of youtube video increases the mass of your computer by about 10 to the negative 19th grams .

how many electrons are involved in a minute of youtube video ?

there are many stories that can be told about world war ii , from the tragic to the inspring . but perhaps one of the most heartrending experiences was that of the akune family , divided by the war against each other and against their own identities . ichiro akune and his wife yukiye immigrated to america from japan in 1918 in search of opportunity , opening a small grocery store in central california and raising nine children . but when mrs. akune died in 1933 , the children were sent to live with relatives in japan , their father following soon after . though the move was a difficult adjustment after having been born and raised in america , the oldest son , harry , formed a close bond with his grand uncle , who taught him the japanese language , culture and values . nevertheless , as soon as harry and his brother ken were old enough to work , they returned to the country they considered home , settling near los angeles . but then , december 7 , 1941 , the attack on pearl harbor . now at war with japan , the united states government did not trust the loyalty of those citizens who had family or ancestral ties to the enemy country . in 1942 , about 120,000 japanese americans living on the west coast were stripped of their civil rights and forcibly relocated to internment camps , even though most of them , like harry and ken , were nisei , american or dual citizens who had been born in the us to japanese immigrant parents . the brothers not only had very limited contact with their family in japan , but found themselves confined to a camp in a remote part of colorado . but their story took another twist when recruiters from the us army 's military intelligence service arrived at the camp looking for japanese-speaking volunteers . despite their treatment by the government , harry and ken jumped at the chance to leave the camp and prove their loyalty as american citizens . having been schooled in japan , they soon began their service , translating captured documents , interrogating japanese soldiers , and producing japanese language propaganda aimed at persuading enemy forces to surrender . the brothers ' work was invaluable to the war effort , providing vital strategic information about the size and location of japanese forces . but they still faced discrimination and mistrust from their fellow soldiers . harry recalled an instance where his combat gear was mysteriously misplaced just prior to parachuting into enemy territory , with the white officer reluctant to give him a weapon . nevertheless , both brothers continued to serve loyally through the end of the war . but harry and ken were not the only akune brothers fighting in the pacific . unbeknownst to them , two younger brothers , the third and fourth of the five akune boys , were serving dutifully in the imperial japanese navy , saburo in the naval airforce , and 15-year-old shiro as an orientation trainer for new recruits . when the war ended , harry and ken served in the allied occupational forces and were seen as traitors by the locals . when all the akune brothers gathered at a family reunion in kagoshima for the first time in a decade , it was revealed that the two pairs had fought on opposing sides . tempers flared and a fight almost broke out until their father stepped in . the brothers managed to make peace and saburo and shiro joined harry and ken in california , and later fought for the us army in korea . it took until 1988 for the us government to acknowledge the injustice of its internment camps and approve reparations payments to survivors . for harry , though , his greatest regret was not having the courage to thank his japanese grand uncle who had taught him so much . the story of the akune brothers is many things : a family divided by circumstance , the unjust treatment of japanese americans , and the personal struggle of reconciling two national identities . but it also reveals a larger story about american history : the oppression faced by immigrant groups and their perseverance in overcoming it .

but they still faced discrimination and mistrust from their fellow soldiers . harry recalled an instance where his combat gear was mysteriously misplaced just prior to parachuting into enemy territory , with the white officer reluctant to give him a weapon . nevertheless , both brothers continued to serve loyally through the end of the war .

like other ethnic groups , many japanese-americans suffered discrimination by other americans . this was also true in the u.s. military . describe what happened to harry akune just before he boarded the paratrooper plane that was to drop them over enemy territory . why do you think harry had good reason to suspect the white officer of discriminating against him ?

this is a thought experiment . let 's say at some point in the not so distant future , you 're barreling down the highway in your self-driving car , and you find yourself boxed in on all sides by other cars . suddenly , a large , heavy object falls off the truck in front of you . your car ca n't stop in time to avoid the collision , so it needs to make a decision : go straight and hit the object , swerve left into an suv , or swerve right into a motorcycle . should it prioritize your safety by hitting the motorcycle , minimize danger to others by not swerving , even if it means hitting the large object and sacrificing your life , or take the middle ground by hitting the suv , which has a high passenger safety rating ? so what should the self-driving car do ? if we were driving that boxed in car in manual mode , whichever way we 'd react would be understood as just that , a reaction , not a deliberate decision . it would be an instinctual panicked move with no forethought or malice . but if a programmer were to instruct the car to make the same move , given conditions it may sense in the future , well , that looks more like premeditated homicide . now , to be fair , self-driving cars are are predicted to dramatically reduce traffic accidents and fatalities by removing human error from the driving equation . plus , there may be all sorts of other benefits : eased road congestion , decreased harmful emissions , and minimized unproductive and stressful driving time . but accidents can and will still happen , and when they do , their outcomes may be determined months or years in advance by programmers or policy makers . and they 'll have some difficult decisions to make . it 's tempting to offer up general decision-making principles , like minimize harm , but even that quickly leads to morally murky decisions . for example , let 's say we have the same initial set up , but now there 's a motorcyclist wearing a helmet to your left and another one without a helmet to your right . which one should your robot car crash into ? if you say the biker with the helmet because she 's more likely to survive , then are n't you penalizing the responsible motorist ? if , instead , you save the biker without the helmet because he 's acting irresponsibly , then you 've gone way beyond the initial design principle about minimizing harm , and the robot car is now meting out street justice . the ethical considerations get more complicated here . in both of our scenarios , the underlying design is functioning as a targeting algorithm of sorts . in other words , it 's systematically favoring or discriminating against a certain type of object to crash into . and the owners of the target vehicles will suffer the negative consequences of this algorithm through no fault of their own . our new technologies are opening up many other novel ethical dilemmas . for instance , if you had to choose between a car that would always save as many lives as possible in an accident , or one that would save you at any cost , which would you buy ? what happens if the cars start analyzing and factoring in the passengers of the cars and the particulars of their lives ? could it be the case that a random decision is still better than a predetermined one designed to minimize harm ? and who should be making all of these decisions anyhow ? programmers ? companies ? governments ? reality may not play out exactly like our thought experiments , but that 's not the point . they 're designed to isolate and stress test our intuitions on ethics , just like science experiments do for the physical world . spotting these moral hairpin turns now will help us maneuver the unfamiliar road of technology ethics , and allow us to cruise confidently and conscientiously into our brave new future .

our new technologies are opening up many other novel ethical dilemmas . for instance , if you had to choose between a car that would always save as many lives as possible in an accident , or one that would save you at any cost , which would you buy ? what happens if the cars start analyzing and factoring in the passengers of the cars and the particulars of their lives ?

in the first scenario , which option would best protect the autonomous car and its occupants ?

imagine setting sail from hawaii in a canoe . your target is a small island thousands of kilometers away in the middle of the pacific ocean . that 's a body of water that covers more than 160 million square kilometers , greater than all the landmasses on earth combined . for thousands of years , polynesian navigators managed voyages like this without the help of modern navigational aids . ancient polynesians used the sun , moon , stars , planets , ocean currents , and clouds as guides that allowed them to see the ocean as a series of pathways rather than an obstacle . their voyages began around 1500 b.c . when the people who would settle polynesia first set sail from southeast asia . early polynesians eventually settled a vast area of islands spread over 40 million square kilometers of the pacific ocean . some historians believe the voyagers moved from place to place to avoid overpopulation . others , that they were driven by war . voyages became less frequent by around 1300 a.d. as polynesian societies became more rooted in specific locations . during the voyaging period , successful journeys depended on a number of factors : well-built canoes , the skill of navigators , and weather being some of the biggest . voyages relied on sturdy wa'a kaulua , or double-hulled canoes , which were powered by sails and steered with a single large oar . canoe building involved the whole community , bringing together the navigators , canoe builders , priests , chanters , and hula dancers . navigators were keen observers of the natural world . they were abundantly familiar with trade wind-generated ocean swells , which typically flow northeast or southeast . by day , navigators could identify direction by the rocking motion of their canoes caused by these swells . but sunrise and sunset were even more useful . the sun 's position indicated east and west and created low light on the ocean that made it possible to see swells directly . at night , navigators used something called a star compass , which was n't a physical object , but rather a sort of mental map . they memorized the rising and setting points of stars and constellations at different times of the year . they used those to divide the sky into four quadrants , subdivided into 32 houses , with the canoe in the middle . so , for example , when they saw the star pira ‘ atea rising from the ocean , they knew that to be northeast . they had some other tricks , too . the earth 's axis points towards hokupa'a , or the north star , so called because it 's the one fixed point in the sky as the earth rotates and always indicates north . however , it 's not visible south of the equator , so navigators there could use a constellation called newe , or the southern cross , and some mental tricks to estimate where south is . for instance , draw a line through these two stars , extend it 4.5 times , and draw another line from there to the horizon . that 's south . but the sky also contains navigational aids much closer to earth , the clouds . besides being useful weather cues , under the right conditions , they can indicate landmasses . for instance , the lagoons of pacific atolls can actually be seen reflected on the underside of clouds , if you know what to look for . and high masses of clouds can indicate mountainous islands . once navigators neared their destination , other clues , such as the flight patterns of birds , floating debris or vegetation , and types of fish in the area helped determine the proximity of land . for example , the manu-o-ku had a known flight range of 190 kilometers , and could be followed back to shore . so how do we know all of this ? partially through evidence in petroglyphs , written observations of european explorers , and polynesian oral traditions . but also by trying them out for ourselves . in 2017 , a voyaging canoe called hokulea completed a worldwide voyage using only these techniques . if that seems remarkable , remember the ancient polynesians , who through close study and kinship with nature , were able to forge these paths across an unfathomably vast , vibrant living ocean .

voyages relied on sturdy wa'a kaulua , or double-hulled canoes , which were powered by sails and steered with a single large oar . canoe building involved the whole community , bringing together the navigators , canoe builders , priests , chanters , and hula dancers . navigators were keen observers of the natural world .

what was the most valued aspect in canoe building ?

- when you get to space , because you 're in a zero g environment , some really funky things happen to your body . ( upbeat music ) i grew an inch . right now , i 'm 5'11 '' but in space i was six-feet tall . on the ground , gravity compresses your spine , it pulls you down , the force factor going down . in space , without gravity pulling your spine down , every vertebrae has a chance to move up , which gives you your extra inch of height . after my spine elongated , when i went to bed on the first night , i felt some back pain , some lower back pain , and so i actually curled up to kind of alleviate that pain , to kind of stretch it out even more . a few other ways the body can change in space are the heart gets smaller and changes shape because it 's not having to pump as hard to pull the blood up from your feet , 'cause now things are just floating and working inside your body so it 's pumping easier , therefore the muscle walls actually changes the shape and they get smaller . without gravity , your bones , they change shape and they lose calcium , and they become more brittle . so , we run on a treadmill that you strap yourself down to and you run on the treadmill to actually give loads into your bones to keep them from atrophying and losing bone density or calcium . for some people in space , your intracranial pressure changes with pushes on your eyeball and that changes its shape , therefore requiring you to wear glasses in space , so it effects your vision . so , we keep different prescriptions of glasses on board just in case someone 's vision changes . any changes in our bodies and anything that happens in space , it 's worth it for the spirit of exploration .

- when you get to space , because you 're in a zero g environment , some really funky things happen to your body . ( upbeat music ) i grew an inch .

1. you grow taller in space . how can this happen ?

it 's not hard to imagine a world where at any given moment , you and everyone you know could be wiped out without warning at the push of a button . this was the reality for millions of people during the 45-year period after world war ii , now known as the cold war . as the united states and soviet union faced off across the globe , each knew that the other had nuclear weapons capable of destroying it . and destruction never loomed closer than during the 13 days of the cuban missile crisis . in 1961 , the u.s. unsuccessfully tried to overthrow cuba 's new communist government . that failed attempt was known as the bay of pigs , and it convinced cuba to seek help from the u.s.s.r. soviet premier nikita khrushchev was happy to comply by secretly deploying nuclear missiles to cuba , not only to protect the island , but to counteract the threat from u.s. missiles in italy and turkey . by the time u.s. intelligence discovered the plan , the materials to create the missiles were already in place . at an emergency meeting on october 16 , 1962 , military advisors urged an airstrike on missile sites and invasion of the island . but president john f. kennedy chose a more careful approach . on october 22 , he announced that the the u.s. navy would intercept all shipments to cuba . there was just one problem : a naval blockade was considered an act of war . although the president called it a quarantine that did not block basic necessities , the soviets did n't appreciate the distinction . in an outraged letter to kennedy , khrushchev wrote , `` the violation of freedom to use international waters and international airspace is an act of aggression which pushes mankind toward the abyss of world nuclear missile war . '' thus ensued the most intense six days of the cold war . while the u.s. demanded the removal of the missiles , cuba and the u.s.s.r insisted they were only defensive . and as the weapons continued to be armed , the u.s. prepared for a possible invasion . on october 27 , a spy plane piloted by major rudolph anderson was shot down by a soviet missile . the same day , a nuclear-armed soviet submarine was hit by a small-depth charge from a u.s. navy vessel trying to signal it to come up . the commanders on the sub , too deep to communicate with the surface , thought war had begun and prepared to launch a nuclear torpedo . that decision had to be made unanimously by three officers . the captain and political officer both authorized the launch , but vasili arkhipov , second in command , refused . his decision saved the day and perhaps the world . but the crisis was n't over . for the first time in history , the u.s. military set itself to defcon 2 , the defense readiness one step away from nuclear war . with hundreds of nuclear missiles ready to launch , the metaphorical doomsday clock stood at one minute to midnight . but diplomacy carried on . in washington , d.c. , attorney general robert kennedy secretly met with soviet ambassador anatoly dobrynin . after intense negotiation , they reached the following proposal . the u.s. would remove their missiles from turkey and italy and promise to never invade cuba in exchange for the soviet withdrawal from cuba under u.n. inspection . once the meeting had concluded , dobrynin cabled moscow saying time is of the essence and we should n't miss the chance . and at 9 a.m. the next day , a message arrived from khrushchev announcing the soviet missiles would be removed from cuba . the crisis was now over . while criticized at the time by their respective governments for bargaining with the enemy , contemporary historical analysis shows great admiration for kennedy 's and khrushchev 's ability to diplomatically solve the crisis . but the disturbing lesson was that a slight communication error , or split-second decision by a commander , could have thwarted all their efforts , as it nearly did if not for vasili arkhipov 's courageous choice . the cuban missile crisis revealed just how fragile human politics are compared to the terrifying power they can unleash .

in washington , d.c. , attorney general robert kennedy secretly met with soviet ambassador anatoly dobrynin . after intense negotiation , they reached the following proposal . the u.s. would remove their missiles from turkey and italy and promise to never invade cuba in exchange for the soviet withdrawal from cuba under u.n. inspection .

which of the following is not part of the agreement between the us and the ussr ?

translator : tom carter reviewer : bedirhan cinar ( zombie sounds ) doctor 1 : so , how did it get to be this way ? doctor 2 : well , it 's my professional opinion that the large gaping bite mark on its shoulder might have something to do with it . d1 : thanks . i mean , what causes its behavioral abnormalities ? d2 : well , we know all behaviors are rooted in the brain , so i 'd expect that something 's gone terribly wrong probably in there . d1 : thanks again , doctor obvious . let me be more specific . what changes in the brain would have to occur in order to cause this kind of behavior ? d2 : hmm . well , let 's see . the first thing i notice is how it moves . stiff legged , with long , lumbering steps , very slow and awkward . almost like what you 'd see in parkinson 's disease . maybe something 's wrong with his basal ganglia ? those are a collection of deep brain regions that regulate movement , through a neurochemical called dopamine . although most people think of dopamine as the `` happy '' chemical of the brain , the dopamine-containing neurons in the basal ganglia die off in parkinson 's disease , that 's what causes it . makes it more and more difficult to initiate actions . d1 : what ? look again at how it moves . stiff legs , long stance , these are n't parkinsonian movements , parkinson 's patients take short , shuffling steps , and the posture 's all wrong . this looks to me like what happens when the cerebellum is damaged . the cerebellum 's a little cauliflower-shaped area in the back of your head , but do n't let its size fool you . that little guy contains almost half of the neurons in the entire brain . patients who suffer degeneration from this region , something called spino-cerebellar ataxia , show a lack of coordination that results in stiff legs , wide stance , and a lumbering walk . my money 's on the cerebellum . d2 : touché . ok . so we 've nailed its motor problems . now what about that whole groaning , lack of talking thing ? d1 : hmm . you know , it sounds kind of like expressive aphasia , or broca 's aphasia , which makes producing words difficult . this is caused by damage to the inferior frontal gyrus , or possibly the anterior insula , both regions behind your temple on the left side of your head . d2 : i think you 're only half right . zombies definitely ca n't communicate , that 's for sure . but they do n't seem to do a good job of understanding things either . watch this . hey , walker ! your father smelt of elderberries ! ( laughs ) see ? no reaction . either it 's not a monty python fan , or it ca n't understand me . i 'd say this is like spot-on fluent wernicke 's aphasia , damage to an area at the junction of two of the brain 's lobes , temporal and parietal , typically on the left side of the brain , is the culprit . this area is physically connected to broca 's area , that you mentioned , by a massive bundle of neurofibers called the arcuate fasciculus . i hypothesize that this massive bundle of connections is completely wiped out in a zombie . it would be like taking out the superhighway between two cities . one city that manufactures a product , and the other that ships it out to the rest of the world . without that highway , the product distribution just shuts down . d1 : so , basically it 's a moot point to reason with a zombie , since they ca n't understand you , let alone talk back . d2 : ( laughs ) i mean , you could try , man , but i 'm going to stay on this side of the glass .

ok . so we 've nailed its motor problems . now what about that whole groaning , lack of talking thing ?

why is it not enough to make global statements like “ they have movement problems ” or “ they have language problems ” when trying to diagnose the nature of an injury in a neurological patient ? how do the specific details of their symptoms provide insights as to the nature of the brain damage ?

have you ever noticed something swimming in your field of vision ? it may look like a tiny worm or a transparent blob , and whenever you try to get a closer look , it disappears , only to reappear as soon as you shift your glance . but do n't go rinsing out your eyes ! what you are seeing is a common phenomenon known as a floater . the scientific name for these objects is muscae volitantes , latin for `` flying flies , '' and true to their name , they can be somewhat annoying . but they 're not actually bugs or any kind of external objects at all . rather , they exist inside your eyeball . floaters may seem to be alive , since they move and change shape , but they are not alive . floaters are tiny objects that cast shadows on the retina , the light-sensitive tissue at the back of your eye . they might be bits of tissue , red blood cells , or clumps of protein . and because they 're suspended within the vitreous humor , the gel-like liquid that fills the inside of your eye , floaters drift along with your eye movements , and seem to bounce a little when your eye stops . floaters may be only barely distinguishable most of the time . they become more visible the closer they are to the retina , just as holding your hand closer to a table with an overhead light will result in a more sharply defined shadow . and floaters are particularly noticeable when you are looking at a uniform bright surface , like a blank computer screen , snow , or a clear sky , where the consistency of the background makes them easier to distinguish . the brighter the light is , the more your pupil contracts . this has an effect similar to replacing a large diffuse light fixture with a single overhead light bulb , which also makes the shadow appear clearer . there is another visual phenomenon that looks similar to floaters but is in fact unrelated . if you 've seen tiny dots of light darting about when looking at a bright blue sky , you 've experienced what is known as the blue field entoptic phenomenon . in some ways , this is the opposite of seeing floaters . here , you are not seeing shadows but little moving windows letting light through to your retina . the windows are actually caused by white blood cells moving through the capillaries along your retina 's surface . these leukocytes can be so large that they nearly fill a capillary causing a plasma space to open up in front of them . because the space and the white blood cells are both more transparent to blue light than the red blood cells normally present in capillaries , we see a moving dot of light wherever this happens , following the paths of your capillaries and moving in time with your pulse . under ideal viewing conditions , you might even see what looks like a dark tail following the dot . this is the red blood cells that have bunched up behind the leukocyte . some science museums have an exhibit which consists of a screen of blue light , allowing you to see these blue sky sprites much more clearly than you normally would . while everybody 's eyes experience these sort of effects , the number and type vary greatly . in the case of floaters , they often go unnoticed , as our brain learns to ignore them . however , abnormally numerous or large floaters that interfere with vision may be a sign of a more serious condition , requiring immediate medical treatment . but the majority of the time entoptic phenomena , such as floaters and blue sky sprites , are just a gentle reminder that what we think we see depends just as much on our biology and minds as it does on the external world .

and floaters are particularly noticeable when you are looking at a uniform bright surface , like a blank computer screen , snow , or a clear sky , where the consistency of the background makes them easier to distinguish . the brighter the light is , the more your pupil contracts . this has an effect similar to replacing a large diffuse light fixture with a single overhead light bulb , which also makes the shadow appear clearer .

why can you see floaters more easily when your pupil contracts ?

some of the world 's most recognizable symbols exist to sell products , others to steer traffic or advance political causes . but there 's one whose main purpose is to help people . you may know it as the wheelchair symbol , or a sign for people with disabilities , but its formal title as maintained by the iso is the international symbol of access . but despite its familiarity , many people are unclear as to what the symbol actually means , which has a lot to do with the symbol itself and the way it came about . in 1968 , the international commission on technology and accessibility held a design contest . they were looking for a symbol that would be readily identifiable from a reasonable distance , self-descriptive , simple , practical , and could n't be confused with existing signage . the winning design , which did n't have a head , was created by a danish designer named susanne koefed . the addition of a head a year later gave it a more human form , and within ten years , it was endorsed by both the united nations and the iso . with minimal cost and minimal fuss , a global icon was born . there have been a few tweaks over the decades . the graphic artists guild added more rounded , human-like features , and in 2012 , the accessible icon project produced a more dynamic version . but what does it really represent ? what 's its purpose ? put simply , it 's a sign to identify where there are accessible facilities . the strength of such an internationally recognized image is that wherever you travel , you do n't need to speak the language or have in-depth cultural knowledge . if you require an accessible toilet , the sign shows the way . but the confusion comes from the term accessibility and what that actually means . many people assume that because the symbol depicts a wheelchair , that accessible facilities are meant only for people who use wheelchairs , or those , at the very least , who have a visible physical condition . but accessibility is a broad concept that applies to many , many different conditions . that includes people with autism , visual impairments , and autoimmune diseases , like lupus , which can cause pain and fatigue , along with many other conditions . in fact , the world health organization estimates that there are approximately 1 billion people who experience some form of disability , which means that this group is very likely to include yourself , or a family member , a classmate , a friend , or a work colleague . and people who use wheelchairs only make up about 65 million , or 15 % of the total . the vast majority have non-visible disabilities . accessible parking spaces , facilities , and entrances are designed with that entire group in mind . so it 's easy to see why in recent years people have begun to raise questions about whether the symbol is really appropriate for what it 's meant to do . and it 's not just about accuracy . it 's common for people to become indignant , sometimes abusive , when they see people without visible disabilities using accessible facilities . the symbol is unfortunately creating widespread issues for the very people and families it 's meant to help . the recent redesigns have attempted with some success to acknowledge concerns over the current symbol . but some think that a complete redesign is in order . it 's a difficult task , though . how do you replace a symbol that 's familiar the world over ? and what do you replace it with ?

but there 's one whose main purpose is to help people . you may know it as the wheelchair symbol , or a sign for people with disabilities , but its formal title as maintained by the iso is the international symbol of access . but despite its familiarity , many people are unclear as to what the symbol actually means , which has a lot to do with the symbol itself and the way it came about .

what was missing from the original design of the international symbol of access ?

so we 're gon na go find some liquid nitrogen . we keep it in a really large dewar tank at the back of the shop , so we 're gon na go find that now . so this is a dewar that we used to keep the liquid nitrogen in within the building so it 's much more convenient for us and our students to get it . so what we 're gon na do now is we 're gon na fill up our small dewar to carry the nitrogen back to the lab . so you can probably hear it hissing and fizzing going into the bottle , and you can see all the nitrogen evaporating off . nitrogen exists as a gas . molecules of n2 . and it is interesting , because the bond between the two nitrogen atoms is the strongest bond that you can get between any two atoms in the periodic table . any two atoms that are the same . sometimes , if you have two atoms that are different , the bond can be slightly stronger , but the nn triple bond is one of the strongest that you can have . so what we 're doing is we 're filling up the dewar with liquid nitrogen so that we can take that back to our lab to do our next experiment . so many explosive compounds , things that you 've heard of , like tnt and other explosives , all contain nitrogen , which are isolated atoms , and when the explosion goes off the atoms come together and release energy . nitrogen is used widely in laboratories , partly because it 's not as reactive as oxygen , so if you do an experiment in an atmosphere of nitrogen you can avoid reactions that might occur with air . you can also use nitrogen when it 's liquified as a coolant . liquid nitrogen boils at -196 degrees centigrade , 77 degrees absolute , and you can just hold it in a normal thermous flask . so this is a dewar of liquid nitrogen , and you can see that the nitrogen is evaporating from the top , coming out and frosting , coming down over the sides because it 's a little bit more dense than the air . you can see it 's heavily laden with ice , and you can see that the ice crystals are starting to grow on the top of the dewar here . it 's very cold though , so we must n't touch it for too long . so if we just tip some out on the floor , we can see that the nitrogen itself will come out like a liquid , like pouring water , but the interesting thing is , water , when i pour it on the floor it forms a puddle . it does nothing useful . in fact , it sort of gets in the way . but liquid nitrogen , when i pour it on the floor , it forms these really quite nice bubbles , and they fly across to the side of the room and take all the dust with them . pretty cool . but if you put materials like rubber or flowers into liquid nitrogen , instead of being soft and bendy they become really rigid , and you can smash them with a hammer . so you can see all of the bubbles forming on this steel tray now , and they 're sweeping away all the dust quite nicely as they evaporate and move further afield . so neil 's got a piece of tubing , and it 's really quite flexible tubing , you can see it 's really floppy , and now he 's gon na put it into the cryogenic liquid nitrogen and freeze it , and see what happens to the rubber . but you see another interesting thing there is that the liquid nitrogen is siphoning out through the tube , and that 's a really good joke , because you can direct that siphon at someones trousers and freeze their legs . so i think that 's enough , neil , let 's see if it 's a bit harder . wow , that shattered . and there 's quite a nice little operation that i 've heard about , in which you can take the lens out of somebody 's eye when they 're suitably anaesthetized , and this lens can be frozen and then put on the lathe and you can change its shape so you get the right shape , and then you let it unfreeze , it goes soft again , and you pop it back into their eye . . . . . . . . . . . . . captions by www.subply.com

so you can see all of the bubbles forming on this steel tray now , and they 're sweeping away all the dust quite nicely as they evaporate and move further afield . so neil 's got a piece of tubing , and it 's really quite flexible tubing , you can see it 's really floppy , and now he 's gon na put it into the cryogenic liquid nitrogen and freeze it , and see what happens to the rubber . but you see another interesting thing there is that the liquid nitrogen is siphoning out through the tube , and that 's a really good joke , because you can direct that siphon at someones trousers and freeze their legs .

in the school of chemistry at the university of nottingham , there is a lift ( elevator ) with a sign that states , “ danger ! risk of asphyxiation . do not ride in the lift with dewars containing cryogenic liquids ” . why ?

every year , about 1,000 new words are added to the oxford english dictionary . where do they come from , and how do they make it into our everyday lives ? with over 170,000 words currently in use in the english language , it might seem we already have plenty . yet , as our world changes , new ideas and inventions spring forth , and science progresses , our existing words leave gaps in what we want to express and we fill those gaps in several ingenious , practical , and occasionally peculiar ways . one way is to absorb a word from another language . english has borrowed so many words over its history that nearly half of its vocabulary comes directly from other languages . sometimes , this is simply because the thing the word describes was borrowed itself . rome and france brought legal and religious concepts , like altar and jury , to medieval england , while trade brought crops and cuisine , like arabic coffee , italian spaghetti , and indian curry . but sometimes , another language has just the right word for a complex idea or emotion , like naïveté machismo , or schadenfreude . scientists also use classical languages to name new concepts . clone , for example , was derived from the ancient greek word for twig to describe creating a new plant from a piece of the old . and today , the process works both ways , with english lending words like software to languages all over the world . another popular way to fill a vocabulary gap is by combining existing words that each convey part of the new concept . this can be done by combining two whole words into a compound word , like airport or starfish , or by clipping and blending parts of words together , like spork , brunch , or internet . and unlike borrowings from other languages , these can often be understood the first time you hear them . and sometimes a new word is n't new at all . obsolete words gain new life by adopting new meanings . villain originally meant a peasant farmer , but in a twist of aristocratic snobbery came to mean someone not bound by the knightly code of chivalry and , therefore , a bad person . a geek went from being a carnival performer to any strange person to a specific type of awkward genius . and other times , words come to mean their opposite through irony , metaphor , or misuse , like when sick or wicked are used to describe something literally amazing . but if words can be formed in all these ways , why do some become mainstream while others fall out of use or never catch on in the first place ? sometimes , the answer is simple , as when scientists or companies give an official name to a new discovery or technology . and some countries have language academies to make the decisions . but for the most part , official sources like dictionaries only document current usage . new words do n't originate from above , but from ordinary people spreading words that hit the right combination of useful and catchy . take the word meme , coined in the 1970s by sociobiologist richard dawkins from the ancient greek for imitation . he used it to describe how ideas and symbols propagate through a culture like genes through a population . with the advent of the internet , the process became directly observable in how jokes and images were popularized at lightning speed . and soon , the word came to refer to a certain kind of image . so meme not only describes how words become part of language , the word is a meme itself . and there 's a word for this phenomenon of words that describe themselves : autological . not all new words are created equal . some stick around for millennia , some adapt to changing times , and others die off . some relay information , some interpret it , but the way these words are created and the journey they take to become part of our speech tells us a lot about our world and how we communicate within it .

and sometimes a new word is n't new at all . obsolete words gain new life by adopting new meanings . villain originally meant a peasant farmer , but in a twist of aristocratic snobbery came to mean someone not bound by the knightly code of chivalry and , therefore , a bad person .

new words tell us a lot about ourselves ? why do you think this is so ?

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 .

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 .

parmalat falsified financial statements to hide losses from their subsidiaries .

what happens after death ? is there a restful paradise ? an eternal torment ? a rebirth ? or maybe just nothingness ? well , one chinese emperor thought that whatever the hereafter was , he better bring an army . we know that because in 1974 , farmers digging a well near their small village stumbled upon one of the most important finds in archeological history : vast underground chambers surrounding that emperor 's tomb , and containing more than 8,000 life-size clay soldiers ready for battle . the story of the subterranean army begins with ying zheng , who came to power as the king of the qin state at the age of 13 in 246 bce . ambitious and ruthless , he would go on to become qin shi huangdi , the first emperor of china after uniting its seven warring kingdoms . his 36 year reign saw many historic accomplishments , including a universal system of weights and measures , a single standardized writing script for all of china , and a defensive barrier that would later come to be known as the great wall . but perhaps qin shi huangdi dedicated so much effort to securing his historical legacy because he was obsessed with his mortality . he spent his last years desperately employing alchemists and deploying expeditions in search of elixirs of life that would help him achieve immortality . and as early as the first year of his reign , he began the construction of a massive underground necropolis filled with monuments , artifacts , and an army to accompany him into the next world and continue his rule . this magnificent army is still standing in precise battle formation and is split across several pits . one contains a main force of 6,000 soldiers , each weighing several hundred pounds , a second has more than 130 war chariots and over 600 horses , and a third houses the high command . an empty fourth pit suggests that the grand project could not be finished before the emperor 's death . in addition , nearby chambers contain figures of musicians and acrobats , workers and government officials , and various exotic animals , indicating that emperor qin had more plans for the afterlife than simply waging war . all the figurines are sculpted from terracotta , or baked earth , a type of reddish brown clay . to construct them , multiple workshops and reportedly over 720,000 laborers were commandeered by the emperor , including groups of artisans who molded each body part separately to construct statues as individual as the real warriors in the emperor 's army . they stand according to rank and feature different weapons and uniforms , distinct hairstyles and expressions , and even unique ears . originally , each warrior was painted in bright colors , but their exposure to air caused the paint to dry and flake , leaving only the terracotta base . it is for this very reason that another chamber less than a mile away has not been excavated . this is the actual tomb of qin shi huangdi , reported to contain palaces , precious stones and artifacts , and even rivers of mercury flowing through mountains of bronze . but until a way can be found to expose it without damaging the treasures inside , the tomb remains sealed . emperor qin was not alone in wanting company for his final destination . ancient egyptian tombs contain clay models representing the ideal afterlife , the dead of japan 's kofun period were buried with sculptures of horses and houses , and the graves of the jaina island off the mexican coast are full of ceramic figurines . fortunately , as ruthless as he was , emperor qin chose to have servants and soldiers built for this purpose , rather than sacrificing living ones to accompany him , as had been practiced in egypt , west africa , anatolia , parts of north america and even china during the previous shang and zhou dynasties . and today , people travel from all over the world to see these stoic soldiers silently awaiting their battle orders for centuries to come .

in addition , nearby chambers contain figures of musicians and acrobats , workers and government officials , and various exotic animals , indicating that emperor qin had more plans for the afterlife than simply waging war . all the figurines are sculpted from terracotta , or baked earth , a type of reddish brown clay . to construct them , multiple workshops and reportedly over 720,000 laborers were commandeered by the emperor , including groups of artisans who molded each body part separately to construct statues as individual as the real warriors in the emperor 's army .

terracotta , or also known as “ _______ ” is a type of ______ clay .

if someone called you scum , you 'd probably be offended , but scientifically , they might not be far off . have you ever thought about where your food comes from ? you might say it comes from plants , animals , or even fungi , but you 'd probably rather not think about the rotting organisms and poop that feed those plants , animals , and fungi . so really , you and most of the matter in your body are just two or three degrees of separation from things like pond scum . all species in an ecosystem , from the creatures in a coral reef to the fish in a lake to the lions on the savannah , are directly or indirectly nourished by dead stuff . most of the organic matter in our bodies , if we trace it back far enough , comes from co2 and water through photosynthesis . plants use the energy from sunlight to transform carbon dioxide and water from the environment into glucose and oxygen . that glucose is then transformed into more complex organic molecules to form leaves , stems , roots , fruit , and so on . the energy stored in these organic molecules supports the food chains with which we 're familiar . you 've probably seen illustrations like this or this . these green food chains start with living plants at their base . but in real-life terrestrial ecosystems , less than 10 % of plant matter is eaten while it 's still alive . what about the other 90 ? well , just look at the ground on an autumn day . living plants shed dead body parts : fallen leaves , broken branches , and even underground roots . many plants are lucky enough to go their whole lives without being eaten , eventually dying and leaving remains . all of these uneaten , undigested , and dead plant parts , that 90 % of terrestrial plant matter ? that becomes detritus , the base of what we call the brown food chain , which looks more like this . what happens to plants also happens to all other organisms up the food chain : some are eaten alive , but most are eaten only when they 're dead and rotting . and all along this food chain , living things shed organic matter and expel digestive waste before dying and leaving their remains to decay . all that death sounds grim , right ? but it 's not . all detritus is ultimately consumed by microbes and other scavengers , so it actually forms the base of the brown food chain that supports many other organisms , including us . scientists are learning that this detritus is an unexpectedly huge energy source , fueling most natural ecosystems . but the interactions within an ecosystem are even more complex than that . what a food chain really represents is a single pathway of energy flow . and within any ecosystem , many of these flows are linked together to form a rich network of interactions , or food web , with dead matter supporting that network at every step . the resulting food web is so connected that almost every species is no more than two degrees from detritus , even us humans . you probably do n't eat rotting things , poop , or pond scum directly , but your food sources probably do . many animals we eat either feed directly on detritus themselves , like pork , poultry , mushrooms , shellfish , or catfish and other bottom feeders , or they are fed animal by-products . so , if you 're thinking nature is full of waste , you 're right . but one organism 's garbage is another 's gold , and all that rotting dead stuff ultimately provides the energy that nourishes us and most of life on earth , as it passes through the food web . now that 's some food for thought .

many plants are lucky enough to go their whole lives without being eaten , eventually dying and leaving remains . all of these uneaten , undigested , and dead plant parts , that 90 % of terrestrial plant matter ? that becomes detritus , the base of what we call the brown food chain , which looks more like this .

what molecule from the atmosphere is captured during photosynthesis to generate plant food and biomass ?

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 .

in the mid-1970 ’ s , erno rubik invented the rubik ’ s cube . but that doesn ’ t mean knew how to solve it .

when was the rubik 's cube invented and who invented it ?

translator : andrea mcdonough reviewer : bedirhan cinar so as an astronomer , when i look at the sky with other people , they always ask me , `` what is your favorite place in the universe ? what is your favorite galaxy ? what is your favorite planet ? '' my answer is earth . that 's right . this is a very special place , even for an astronomer . we look at a lot of places , but there 's only one that we know of in the whole universe that we can live on . it 's an amazing planet , there is an amazing number of things happening , some of them , you are hearing about it today . that 's the only place in the universe where we know that there is life , so that makes it extremely special . what i 'm going to talk to you about is this great adventure in astronomy that is happening where we are actually actively looking for other places like this . it 's impossible to imagine the number of possibilities , what happens on those other planets that can be habitable . so that 's what i 'm going to tell you about . so , the first thing we have to think of is , well , what makes a planet habitable ? and , the easiest thing to do is to look at our own solar system . we have multiple examples . the first thing we learn is that size matters . we ca n't have a planet that 's too small or too big . if we look at a planet that is too small , it does n't have an atmosphere . the moon , technically not a planet , but a good example for this , is too small , it does n't hold an atmosphere . jupiter - very , very big - and it actually is mostly composed of gas , it has no surface you can stand on . the earth is just right . the second thing that we learned is that the planet has to be at the right distance from its star . if the planet is too close to its star , it 's too hot . that 's the case for venus . here i have a picture that was taken by a spacecraft that landed on venus , and the surface , although it 's rocky and quite familiar to us compared to earth , it 's really too hot . at the opposite end , if a planet is too far from the star , it is too cold . that 's the case for mars . so , we need to look for planets that are at the right distance from their star and also of the right size . so , one other thing , you know , you might think , `` oh , this is really hard because the planet has to be just right . it only happened once in our solar system . '' but when you look at the sky at night , and here 's a video that i took actually from hawaii , a dark place where you can see a lot of stars , the first thing you notice is that there are a lot of stars . so , the odds are in our favor , even if a small fraction of the stars have habitable planets . there are a lot of stars . on a moonless night , in a dark site , if you count the stars in the sky and you count five stars per second , it would take you 15 minutes to count all of the stars in the sky . that is a tiny fraction of the stars in our galaxy . if you count all the stars in our galaxy , and you also count at five stars per second , it would take you more than 1,000 years to count all the stars in our galaxy . and then , if you manage to count the galaxies in the universe , if you count five galaxies per second , it would take you also more than 1,000 years to count all of the galaxies in the universe . so the numbers are just astronomical , there 's a lot of opportunities for exoplanets . there has to be a large number of exoplanets along which there are , on which there could be life . so this is very exciting . so let 's imagine that maybe only 1 in 100 stars has the right kind of planet , and i think this is pessimistic . if you could visit one of those planets per second , it 'll take you sixty years to actually visit all of them in our galaxy alone . that 's , i think , one second is not enough to study them . so , there 's a few hundred of us in this room . if we divided the task and each of us basically took a couple of minutes to study each planet , it would take us a life time to do this . meet back again and tell those amazing stories of what we would have seen in maybe some ted senior event . so , why is it hard ? why do n't we have pictures of exoplanets with aliens on them ? well , here 's an example . this is a picture that was taken by the cassinni spacecraft as it was orbiting saturn . it 's actually behind saturn , so what you see is the sun that is blocked by saturn . and if you look very , in detail , if you have very sharp eyesight , you will see all of us . we 're all on that picture . here is where we are . um , so that 's what earth starts to look like when we look at it from far away . now , we have to do the same thing around other stars , and the planet is very close to the star . so this is zooming in to us . all of us are on that little dot at the time the picture was taken . so , what i work on is inventing optics , tricks to actually do this , to take images of planets around those other stars . this is my easiest coronagraph . we call this optic tricks , `` coronagraph '' . this is the easiest one i ever built . i just put my thumb in front of the sun and then you can see things around it . that 's what we 're trying to do , but we need to do it much better than what i did in this picture . and , there are two things we need to do : we need a much better eye , call them telescopes , and we need more fancy , clever ways to do it than putting a thumb . so as an example , one of the projects i work on is for the subaru telescope , which you can see here in this picture . it 's a very large telescope , so i replace my eye by a large telescope . and , the other thing that we do is the coronagraph is not just a stupid thumb , it 's this very complicated thing that 's shown in that picture that i would love to have time to tell you about . just to give you a sense for size , this arrow points to a door on the side of the telescope , and if you have very sharp eyes , you can see that there is a railing going around the telescope , so it 's a really big eye . so , i think the most exciting thing for me is actually to look at the night sky , to see all these stars and wonder , `` well , are there people on planets around those stars ? '' because there must be amazing things happening around those stars that we do n't know yet . during your life time , we will start to actually figure out those things . and the most exciting thing for me is to think about , maybe , beings on those stars looking back at our star and wondering the same thing . so i think the future will be extremely exciting because we are starting to figure out those things and amazing range of possibilities is , i think , even wider than our imagination . thank you .

that 's what we 're trying to do , but we need to do it much better than what i did in this picture . and , there are two things we need to do : we need a much better eye , call them telescopes , and we need more fancy , clever ways to do it than putting a thumb . so as an example , one of the projects i work on is for the subaru telescope , which you can see here in this picture .

guyon says we need a better eye . what does he mean ?

translator : andrea mcdonough reviewer : jessica ruby there are still lots of things about space that we may never be able to answer , like is time travel possible ? or are aliens living somewhere else in the milky way ? but there is one thing i believe about space : space is trying to kill me . space is n't out to get me personally . it 's also trying to kill you and everybody else . think about it . space does n't naturally have what we need to survive when we travel there : no air , it 's too hot or too cold , no ozone to protect us from those nasty uv rays , either . this all sounds bad , but what can space really do to me if i stay on earth ? what we need to understand is that objects in space can cause people to think their days are numbered , even when there are events on earth that can hurt or kill us before something from space does . so , what are the odds that one of these objects will really affect earth and you and me in our lifetime ? well , we can take what we know about the universe to try and figure that out . you might have heard stories about asteroids hitting the earth . that would be pretty bad . scientists think asteroids might have killed off most of the dinosaurs . sounds like something we should worry about , right ? well , astronomers can now watch asteroids in space and see them coming using complex computer models to predict the deadly rock 's path . for a while , the reported odds that asteroid apophis would strike earth in 2036 were once 1 in 625 . but , after updating their data , astronomers now say the chances are extremely low . okay , what about the sun ? hollywood movies like to pick on our sun by showing earth destroyed by solar flares or the sun dying out , which would cause earth to freeze . astronomers predict our sun contains enough gas to make energy for another 3 to 5 billion years . so , in 3 to 5 billion years , if people still exist on earth , they 'll have to deal with that . but today , well , we 're safe . sometimes the sun does shoot flares at earth , but the magnetic fields surrounding our planet blocks most of that radiation . the radiation that does get through creates things like the aurora borealis . gigantic solar flares can mess with our satellites and electrical equipment , but the chances of it killing you are pretty slim . okay , what about that supermassive black hole in the middle of our galaxy ? what happens to earth , and us , when it pulls us in ? after all , it is supermassive . nope , not going to happen . that 's one big object that ca n't bother us . how can we be so sure ? our solar system is on the edge of the milky way while the nearest supermassive black hole is about 26,000 light years from earth . that means we are n't on that black hole 's menu . so , you still think space objects are trying to kill you even after what i 've told you so far ? i think i 've even convinced myself that odds are really good that space and the objects up there wo n't kill me after all . but i 'll probably keep looking up just to make sure nothing is headed my way .

gigantic solar flares can mess with our satellites and electrical equipment , but the chances of it killing you are pretty slim . okay , what about that supermassive black hole in the middle of our galaxy ? what happens to earth , and us , when it pulls us in ?

why wo n't a supermassive black hole pull earth into it ?

welcome to the i grad fafsa tutorial this step-by-step instruction will walk you through an answer any questions , feel free to complete the fafsa alongside this video and press pause or rewind if you need it instant replay before you begin filling out the fafsa you may want to make sure you 're equipped with the following ... your driver 's license number , your social security number , a list to the schools you plan on applying to , or have already applied to , your tax return for the prior-year and your parents if you 're considered a dependent student here is how to determine whether you are dependent or independent student . to be considered an independent student you must meet at least one of the following criteria : be 24 years of age or older when you file a fafsa , be an orphan or a ward of court , be a us military veteran be a graduate or professional student , be married , have legal dependence of your own , have a financial aid administrator who is documented your independence because of unusual circumstances . even if you do n't live with your parents , they do n't claim you on their taxes or support you financially , you may still be considered a dependent student . if you are filling out the fafsa for the first time , you and one of your parents , if you 're a dependent will be asked at the end of the online form to apply for pin before signing electronically . make sure the pin and security question you choose are ones that you will remember , also , make sure that you have a printer nearby so that you can print up all the important documentation you 'll need this information every year you attend school the website for the fafsa is www.fafsa.ed.gov please note that filling out the fafsa is free and does not cost any money if you are being asked to pay for the form you are on the wrong site champ . okay let 's get started ... once you 're on the site you want to click the start here button , whether you 're filling out the fafsa for the first time or you 've done this before you 'll be asked 4 very important questions . your first and last name , your social security number , and your date of birth . just make sure to use your full legal name , as written on your social security card . click next and continue on to the next page . award years run from july 1st to june 30th , not january 1st to december 31st , so just make sure to pick the correct award year for your attendance , for example ... if you filling out the fafsa in february you 're not going to attend school until september , just make sure to select the correct award year that september falls within . you 'll then be asked to choose a password . this is different than your pin , but you should keep track of it just the same , once you 've filled out both entries for your password , go ahead and click next to continue . use the links on this page to answer any questions about the fafsa before getting started , otherwise just go ahead to the next section . as you can see the top portion of this form is already filled out for you , fill out all the information below that correctly , and then you have the option to enter in your driver 's license information , once you finished just click next . now , ... to confirm your eligibility just choose the option that best describes your citizenship status . if you 're neither a citizen nor an eligible non-citizen contact the financial aid department at the school to which you 're applying , they 'll assist you with determining your eligibility . the next question will ask you about your high school completion status for the upcoming award year , be sure to choose the best answer for your situation and degree or certificate if you 're unsure you can contact the financial aid department if you qualify , work-study programs at your school can be a great way for you to pay off your tuition costs but that sounds like a good option for you and your school offers it , click yes on the drop down option , if you 're unsure do a little research and if work-study just is n't for you choose the not interested option and continue on . make sure to choose the correct option for whether or not you have a bachelor 's degree , double check it too , because it could really cause trouble should you choose incorrectly . when the fafsa asked about your parents educational status these questions are designed to determine if you or a first-generation college student or not finish with this page in just click next . on the next page you 'll be asked the name city and state of the high school you attend okay ... in this section just enter all the schools that you 're applying to or which you 've been accepted . to choose schools for what you 're applying , click on the school 's state and city . at the bottom type in the school name or click on search for a list of all schools in the area choose your school from the box and add it to the selected school portion of the form . to choose more than one school , click add another school and just start the process over . make sure to apply to any school you may want to attend once you 're done double check to make sure they 're all correct . you will have the option of choosing whether you want to live on campus , off-campus , or with a parent . make your choice and click the next button . there are two types of students in the world ; dependent and independent . you 'll need to answer the following questions in order to determine your status , with each question there will be an explanation just to the right of the dependency section if you are under the age of 24 , but answered yes to one or more of these questions then you 're declared as an independent . if you answered yes to one or more the questions you may also be required to show documented proof . that 's why it 's important that you answer all the questions correctly and honestly . if you 're confused by a question or not sure if the situations applicable to you , you 'll want to contact your financial aid department at the schools to which you 've applied . if you choose emancipated minor-in foster care both parents are deceased a dependent or ward of the court or homeless , make sure you have the right documentation to follow up with these claims . if you answered no to all these questions but believe you have special circumstances that might declare you an independent contact the financial aid department and they 'll request the proper documentation from you in order to request the dependency change . however , supplying documentation does n't guarantee your dependency change request will be approved . if you 're dependent make sure you have your and your parents tax returns from the previous year . before we get started on entering in all that information it 's important to know that there is an irs data retrieval tool . that allows fafsa on the web applicants to a request and retrieve their tax information data right from the irs . in order to use the irs data retrieval tool applicants must ; have a valid social security number , have filed a federal tax return to the previous year , and have an unchanged marital status since december 31st of the previous year if you 've just filed your taxes you may not be able to use the tool . do n't worry though , if you have the proper documentation you can enter it manually on the fafsa form . if you 're eligible to use the irs data retrieval tool you 'll be led to the following pages , please note that if you 're dependent student your parents information will be required first , and then you 'll be redirected back to the beginning to enter your own information . first , choose from the drop down tab already filed if you answered no to the questions below you 'll be asked for your pin , then click the irs button to proceed . then you leave the fafsa website be led to the irs website click ok to continue . once on the irs website enter all of your information correctly , all information must match your tax return , once you 're done , click submit . if the irs is able to retrieve your information will then be asked if you like your information transferred to the fafsa , check the box and click transfer now then you 'll sign and submit your fafsa if you 're ineligible to use the irs data retrieval tool will need to enter everything in the old fashion way , ... so get to typing ! now this is the part where those tax returns will come in handy , if you just filed your tax return or have n't done so yet you may estimate the information from the prior year 's tax return , once you 've filed you can return to the fafsa and make corrections . you can also use the irs data retrieval tool to make those updates corrections if you have any questions or are n't sure what to enter you can always refer to the side of the page in the help and hints box . this will give you instructions to each question and assist you in filling everything out correctly and completely . continue filling out all your information and click next to continue . congratulations ! ... you have completed the fafsa on your way to be receiving financial aid to help pay for school the next page gives you when efc number efc stands for estimated family contribution , you later receive an award letter from the school or schools to which you applied . the award letter will tell you how much money you will be awarded ! thanks for watching our little igrad fafsa tutorial we wish you the best of luck this school season .

welcome to the i grad fafsa tutorial this step-by-step instruction will walk you through an answer any questions , feel free to complete the fafsa alongside this video and press pause or rewind if you need it instant replay before you begin filling out the fafsa you may want to make sure you 're equipped with the following ... your driver 's license number , your social security number , a list to the schools you plan on applying to , or have already applied to , your tax return for the prior-year and your parents if you 're considered a dependent student here is how to determine whether you are dependent or independent student .

who should you contact if your situation has special circumstances which the fafsa may not take into account ?

translator : andrea mcdonough reviewer : bedirhan cinar let 's talk about the facts of life . you remember that conversation you had when you were a kid about sex or drugs with your parents or some trusted adult ? probably not because it 's a myth . you do n't talk to kids about that stuff . it 's just so embarrassing . and , hey , maybe that 's ok. we 've been outsourcing the facts of life for decades . we spend billions of dollars on it . so , why talk to kids when you can just turn on the tv ? i learned about drugs from an egg and a frying pan : `` this is drugs , and this is your brain on drugs . pssssssss . any questions ? '' yeah , actually , i did . but it 's not about questions . it 's about data . in the 1980 's when i was growing up , those data were terrifying parents : 1 % of high school seniors had try heroin , 12 % hallucinogens , 12 % tranquilizers , 17 % cocaine , 26 % stimulants , and over 50 % of us had tried marijuana . it was an epidemic ! at least , that 's what they told us . and marijuana was the gateway drug , leading to all the harder stuff . of course , 92 % of us were drinking alcohol , and that was killing more of us than all drugs combined . but , nevermind , it 's legal . so we declared war on drugs ! nancy reagan was our general . all drugs will kill you , so just say , `` no ! '' just say , `` no ! '' to pot . just say , `` no ! '' to cocaine . just say , `` no ! '' to everything . so simple ! if you want to save kids , you have to scare the hell out of them ! and we spent ridiculous amounts of money doing that . soon that war on drugs spread to become a war on sex . we were pushing abstinence on kids to fight aids . and when all the data finally came home , guess what : completely ineffective . we love big solutions to big problems , do n't we ? what if the facts of life do n't work that way ? what if the experience of having that conversation ca n't be mass-produced ? what if it ca n't be scaled up ? well , that would be very frustrating for everyone in this industry , would n't it ? and , many of them are really trying to help . who , then ? us . we have to talk to kids . openly and honestly . but are we ready to be honest ? i do n't think so . we mythologize childhood . mine was in stone mountain , georgia , a completely typical 1980 's american suburb . for the parents , a wholesome paradise of bridge parties and tennis games . for us kids , we were all working on a secret research project , and our laboratory was in the woods after school , under the covers during sleep-overs , really , any opportunity we could take to peel off our clothes and investigate . what were these things , bodies ? what do they do ? we had to figure them out and that 's childhood . it 's not just fun and games , it 's actually a manhattan project of nakedness . and then you walk into your first class in middle school , and the bomb goes off . you are not just a body any more . oh no , now you are grotesque . that 's when the suffering really starts . so , yeah , talk to kids . but if you are not honest about your own experiences first , everything you say smells like bullshit . do n't worry , you can practice and you should start by talking to the one kid you definitely know : you . what kind of kid were you ? what troubled you ? for me , it was age 13 . that was the worst year . i was obsessively curious about sex and also deeply ashamed by it . it was n't my only problem , of course , not by a long shot , but it was the beginning of a downward spiral . and my bad luck was to hit bottom while watching `` the wall '' by pink floyd , which is a bad idea for a miserable 13-year old high on weed . so , that night , for whatever reason , it seemed like good idea to shave off my eyebrows , and then try to kill myself by swallowing all the pills in the bathroom , which was not at all fatal , but everyone noticed the eyebrows . and that made middle school extra fun . so , what was your low point ? and if you could build a time machine to travel back and talk to that kid , what would you say to yourself ? for me , it was easy . all i really needed was someone to reassure me that somehow i was a normal part of the universe . but i did n't feel like i could talk to anyone . and yet weirdly , i fully expected a time traveler to materialize at any time because i was a geek . i did n't know if it would be my unborn son or a t-101 cyborg . but either one would be awesome ! hey , it 's me , yourself from the future , in the year 2012 . i have crucial information for you , but not about the future , about the past , a billion years in the past , when this planet was covered with nothing but cells and all they did was fight , eat , and divide ; fight , eat , and divide . except for one . and that 's your ancestor . this cell enslaved other ones , but master and slave became one . and then those cells invented sex , and then they invented the first bodies with each cell doing a different job , some smelling , some moving , some eating . and the job of sex went to a special cell called the gamete . and those bodies became giant . the distance to the next body was vast so they had to swim . most would be lost and die so they were mass-produced . soon the oceans were a non-stop riot of sex and death until 500 million years ago , when the first beast crawled onto land . land is hard because bodies are heavy . and the sun kills gametes . to keep them safe , so deep inside of a body , the mother builds a tiny ocean . outside are events of unimaginable violence . whole new forms of life are being created only to be wiped away . millions of years are flashing by . but in here , it 's always the same . peace . just peace . maybe we will never know why , but of all the possible bodies that have appeared on this planet , it was this one , bilaterally symmetric , warm-blooded , bigger than a mouse , smaller than a horse , 2 legs , 10 toes , no tail , big brain , language , technology , and civilization rising and falling for thousands of years . and here you are , a 13-year old human perplexed and embarrassed about sex . that 's what i came here to tell you : we do n't know why sex evolved nor why it persists . why do n't we just clone ourselves like all life did a billion years ago ? it 's so much more efficient . we would all have babies , no mates . it could be that children who are genetically different from each other are protected from disease . and that is still our best guess . so be comforted to know that even in the distant future , in the year 2012 , we still do n't know what sex is for . it is perplexing . you should n't be embarrassed by it . sex is a beautiful puzzle . and without it , you simply would not be here . by the way , be nice to your little sister . she 's your best friend . you 'll see .

it could be that children who are genetically different from each other are protected from disease . and that is still our best guess . so be comforted to know that even in the distant future , in the year 2012 , we still do n't know what sex is for .

what is our best guess for why sex exists ?

translator : elena montrasio reviewer : ted translators admin [ his holiness pope francis filmed in vatican city first shown at ted2017 ] good evening – or , good morning , i am not sure what time it is there . regardless of the hour , i am thrilled to be participating in your conference . i very much like its title – `` the future you '' – because , while looking at tomorrow , it invites us to open a dialogue today , to look at the future through a `` you . '' `` the future you : '' the future is made of yous , it is made of encounters , because life flows through our relations with others . quite a few years of life have strengthened my conviction that each and everyone 's existence is deeply tied to that of others : life is not time merely passing by , life is about interactions . as i meet , or lend an ear to those who are sick , to the migrants who face terrible hardships in search of a brighter future , to prison inmates who carry a hell of pain inside their hearts , and to those , many of them young , who can not find a job , i often find myself wondering : `` why them and not me ? '' i , myself , was born in a family of migrants ; my father , my grandparents , like many other italians , left for argentina and met the fate of those who are left with nothing . i could have very well ended up among today 's `` discarded '' people . and that 's why i always ask myself , deep in my heart : `` why them and not me ? '' first and foremost , i would love it if this meeting could help to remind us that we all need each other , none of us is an island , an autonomous and independent `` i , '' separated from the other , and we can only build the future by standing together , including everyone . we don ’ t think about it often , but everything is connected , and we need to restore our connections to a healthy state . even the harsh judgment i hold in my heart against my brother or my sister , the open wound that was never cured , the offense that was never forgiven , the rancor that is only going to hurt me , are all instances of a fight that i carry within me , a flare deep in my heart that needs to be extinguished before it goes up in flames , leaving only ashes behind . many of us , nowadays , seem to believe that a happy future is something impossible to achieve . while such concerns must be taken very seriously , they are not invincible . they can be overcome when we do n't lock our door to the outside world . happiness can only be discovered as a gift of harmony between the whole and each single component . even science – and you know it better than i do – points to an understanding of reality as a place where every element connects and interacts with everything else . and this brings me to my second message . how wonderful would it be if the growth of scientific and technological innovation would come along with more equality and social inclusion . how wonderful would it be , while we discover faraway planets , to rediscover the needs of the brothers and sisters orbiting around us . how wonderful would it be if solidarity , this beautiful and , at times , inconvenient word , were not simply reduced to social work , and became , instead , the default attitude in political , economic and scientific choices , as well as in the relationships among individuals , peoples and countries . only by educating people to a true solidarity will we be able to overcome the `` culture of waste , '' which does n't concern only food and goods but , first and foremost , the people who are cast aside by our techno-economic systems which , without even realizing it , are now putting products at their core , instead of people . solidarity is a term that many wish to erase from the dictionary . solidarity , however , is not an automatic mechanism . it can not be programmed or controlled . it is a free response born from the heart of each and everyone . yes , a free response ! when one realizes that life , even in the middle of so many contradictions , is a gift , that love is the source and the meaning of life , how can they withhold their urge to do good to another fellow being ? in order to do good , we need memory , we need courage and we need creativity . and i know that ted gathers many creative minds . yes , love does require a creative , concrete and ingenious attitude . good intentions and conventional formulas , so often used to appease our conscience , are not enough . let us help each other , all together , to remember that the other is not a statistic or a number . the other has a face . the `` you '' is always a real presence , a person to take care of . there is a parable jesus told to help us understand the difference between those who 'd rather not be bothered and those who take care of the other . i am sure you have heard it before . it is the parable of the good samaritan . when jesus was asked : `` who is my neighbor ? '' - namely , `` who should i take care of ? '' - he told this story , the story of a man who had been assaulted , robbed , beaten and abandoned along a dirt road . upon seeing him , a priest and a levite , two very influential people of the time , walked past him without stopping to help . after a while , a samaritan , a very much despised ethnicity at the time , walked by . seeing the injured man lying on the ground , he did not ignore him as if he were n't even there . instead , he felt compassion for this man , which compelled him to act in a very concrete manner . he poured oil and wine on the wounds of the helpless man , brought him to a hostel and paid out of his pocket for him to be assisted . the story of the good samaritan is the story of today ’ s humanity . people 's paths are riddled with suffering , as everything is centered around money , and things , instead of people . and often there is this habit , by people who call themselves `` respectable , '' of not taking care of the others , thus leaving behind thousands of human beings , or entire populations , on the side of the road . fortunately , there are also those who are creating a new world by taking care of the other , even out of their own pockets . mother teresa actually said : `` one can not love , unless it is at their own expense . '' we have so much to do , and we must do it together . but how can we do that with all the evil we breathe every day ? thank god , no system can nullify our desire to open up to the good , to compassion and to our capacity to react against evil , all of which stem from deep within our hearts . now you might tell me , `` sure , these are beautiful words , but i am not the good samaritan , nor mother teresa of calcutta . '' on the contrary : we are precious , each and every one of us . each and every one of us is irreplaceable in the eyes of god . through the darkness of today 's conflicts , each and every one of us can become a bright candle , a reminder that light will overcome darkness , and never the other way around . to christians , the future does have a name , and its name is hope . feeling hopeful does not mean to be optimistically naïve and ignore the tragedy humanity is facing . hope is the virtue of a heart that does n't lock itself into darkness , that does n't dwell on the past , does not simply get by in the present , but is able to see a tomorrow . hope is the door that opens onto the future . hope is a humble , hidden seed of life that , with time , will develop into a large tree . it is like some invisible yeast that allows the whole dough to grow , that brings flavor to all aspects of life . and it can do so much , because a tiny flicker of light that feeds on hope is enough to shatter the shield of darkness . a single individual is enough for hope to exist , and that individual can be you . and then there will be another `` you , '' and another `` you , '' and it turns into an `` us . '' and so , does hope begin when we have an `` us ? '' no . hope began with one `` you . '' when there is an `` us , '' there begins a revolution . the third message i would like to share today is , indeed , about revolution : the revolution of tenderness . and what is tenderness ? it is the love that comes close and becomes real . it is a movement that starts from our heart and reaches the eyes , the ears and the hands . tenderness means to use our eyes to see the other , our ears to hear the other , to listen to the children , the poor , those who are afraid of the future . to listen also to the silent cry of our common home , of our sick and polluted earth . tenderness means to use our hands and our heart to comfort the other , to take care of those in need . tenderness is the language of the young children , of those who need the other . a child ’ s love for mom and dad grows through their touch , their gaze , their voice , their tenderness . i like when i hear parents talk to their babies , adapting to the little child , sharing the same level of communication . this is tenderness : being on the same level as the other . god himself descended into jesus to be on our level . this is the same path the good samaritan took . this is the path that jesus himself took . he lowered himself , he lived his entire human existence practicing the real , concrete language of love . yes , tenderness is the path of choice for the strongest , most courageous men and women . tenderness is not weakness ; it is fortitude . it is the path of solidarity , the path of humility . please , allow me to say it loud and clear : the more powerful you are , the more your actions will have an impact on people , the more responsible you are to act humbly . if you don ’ t , your power will ruin you , and you will ruin the other . there is a saying in argentina : `` power is like drinking gin on an empty stomach . '' you feel dizzy , you get drunk , you lose your balance , and you will end up hurting yourself and those around you , if you don ’ t connect your power with humility and tenderness . through humility and concrete love , on the other hand , power – the highest , the strongest one – becomes a service , a force for good . the future of humankind is n't exclusively in the hands of politicians , of great leaders , of big companies . yes , they do hold an enormous responsibility . but the future is , most of all , in the hands of those people who recognize the other as a `` you '' and themselves as part of an `` us . '' we all need each other . and so , please , think of me as well with tenderness , so that i can fulfill the task i have been given for the good of the other , of each and every one , of all of you , of all of us . thank you .

only by educating people to a true solidarity will we be able to overcome the `` culture of waste , '' which does n't concern only food and goods but , first and foremost , the people who are cast aside by our techno-economic systems which , without even realizing it , are now putting products at their core , instead of people . solidarity is a term that many wish to erase from the dictionary . solidarity , however , is not an automatic mechanism .

how does pope francis describe the term ‘ solidarity ’ ?

[ 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 .

[ 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 .

a fish narrates this video . how do plankton figure into the fish ’ s story ?

muscles . we have over 600 of them . they make up between 1/3 and 1/2 of our body weight , and along with connective tissue , they bind us together , hold us up , and help us move . and whether or not body building is your hobby , muscles need your constant attention because the way you treat them on a daily basis determines whether they will wither or grow . say you 're standing in front of a door , ready to pull it open . your brain and muscles are perfectly poised to help you achieve this goal . first , your brain sends a signal to motor neurons inside your arm . when they receive this message , they fire , causing muscles to contract and relax , which pull on the bones in your arm and generate the needed movement . the bigger the challenge becomes , the bigger the brain 's signal grows , and the more motor units it rallies to help you achieve your task . but what if the door is made of solid iron ? at this point , your arm muscles alone wo n't be able to generate enough tension to pull it open , so your brain appeals to other muscles for help . you plant your feet , tighten your belly , and tense your back , generating enough force to yank it open . your nervous system has just leveraged the resources you already have , other muscles , to meet the demand . while all this is happening , your muscle fibers undergo another kind of cellular change . as you expose them to stress , they experience microscopic damage , which , in this context , is a good thing . in response , the injured cells release inflammatory molecules called cytokines that activate the immune system to repair the injury . this is when the muscle-building magic happens . the greater the damage to the muscle tissue , the more your body will need to repair itself . the resulting cycle of damage and repair eventually makes muscles bigger and stronger as they adapt to progressively greater demands . since our bodies have already adapted to most everyday activities , those generally do n't produce enough stress to stimulate new muscle growth . so , to build new muscle , a process called hypertrophy , our cells need to be exposed to higher workloads than they are used to . in fact , if you do n't continuously expose your muscles to some resistance , they will shrink , a process known as muscular atrophy . in contrast , exposing the muscle to a high-degree of tension , especially while the muscle is lengthening , also called an eccentric contraction , generates effective conditions for new growth . however , muscles rely on more than just activity to grow . without proper nutrition , hormones , and rest , your body would never be able to repair damaged muscle fibers . protein in our diet preserves muscle mass by providing the building blocks for new tissue in the form of amino acids . adequate protein intake , along with naturally occurring hormones , like insulin-like growth factor and testosterone , help shift the body into a state where tissue is repaired and grown . this vital repair process mainly occurs when we 're resting , especially at night while sleeping . gender and age affect this repair mechanism , which is why young men with more testosterone have a leg up in the muscle building game . genetic factors also play a role in one 's ability to grow muscle . some people have more robust immune reactions to muscle damage , and are better able to repair and replace damaged muscle fibers , increasing their muscle-building potential . the body responds to the demands you place on it . if you tear your muscles up , eat right , rest and repeat , you 'll create the conditions to make your muscles as big and strong as possible . it is with muscles as it is with life : meaningful growth requires challenge and stress .

muscles . we have over 600 of them .

on earth , the pull of gravity creates a constant force that muscles must overcome to generate movement . considering how muscle size relates to resistance , and how the body adapts to demands placed upon it , what would happen to our muscles if the force of gravity suddenly doubled ? ( hint : consider astronauts in space )

mysteries of vernacular : lady , woman . lady is tied to a number of words that seem at first glance etymologically unrelated . she traces her roots back to the old english words hlaf , which referred to a loaf of bread and is the direct ancestor of our modern word loaf , and daege , which meant maid and is the root of our word dairy , the place where the dairymaid works . together , hlaf and daege became hlafdige , literally loaf maid , or , more figuratively , kneader of bread . as early as the ninth century , hlafdige was the name for a mistress of servants , or the female head of the household . the old english word for a male head of household was hlafweard , a compound of hlaf , loaf , and weard , which meant keeper and is the word of modern words like ward and warden . both hlafweard , the breadwinner , and hlafdige , the bread kneader , came to be titles of respect , referring to citizens of higher social standing . through a process known as syncopation , both words lost their internal sounds to become lord and lady , respectively . though still an expression of courtesy , lady has since moved down the ladder of social standing and is now often used to mean simply a woman .

mysteries of vernacular : lady , woman . lady is tied to a number of words that seem at first glance etymologically unrelated .

what are some surnames or titles that , like lady , reference the lives and livelihoods of our ancestors ?

among the great poets of literary history , certain names like homer , shakespeare , milton , and whitman are instantly recognizable . however , there 's an early 20th century great french poet whose name you may not know : guillaume apollinaire . he was a close friend and collaborator of artists like picasso , rousseau , and chagall . he coined the term surrealism , and he was even suspected of stealing the mona lisa in 1911 . during his short lifetime , he created poetry that combined text and image in a way that seemingly predicted an artistic revolution to come . in the late 19th and early 20th century paris , the low-rent districts of montmartre and montparnasse were home to every kind of starving artist . it was all they could afford . these painters , writers , and intellectuals , united in their artistic passion and counterculture beliefs , made up france 's bohemian subculture . and their works of art , literature , and intellect would shake up the world . at the turn of the 20th century , within this dynamic scene , art critic , poet , and champion of the avant-garde , guillaume apollinaire was a well-known fixture . as an art critic , apollinaire explained the cubist and surrealist movements to the world , and rose to the defense of many young artists in the face of what was often a xenophobic and narrow-minded public . as a poet , apollinaire was passionate about all forms of art and a connoisseur of medieval literature , especially calligraphy and illuminated initials . as a visionary , apollinaire saw a gap between two artistic institutions . on one side was the popular , highly lauded traditional art forms of the time . on the other , the forms of artistic expression made possible through surrealism , cubism , and new inventions , like the cinema and the phonograph . within that divide , through the creation of his most important contribution to poetry , the calligram , guillaume apollinaire built a bridge . apollinaire created the calligram as a poem picture , a written portrait , a thoughts drawing , and he used it to express his modernism and his desire to push poetry beyond the normal bounds of text and verse and into the 20th century . some of his calligrams are funny , like the `` lettre-océan . '' some of them are dedicated to his young dead friends , like `` la colombe poignardée et le jet d'eau . '' some of them are the expression of an emotional moment , as is `` il pleut '' : `` it 's raining women 's voices as if they had died even in memory , and it 's raining you as well , marvellous encounters of my life , o little drops . those rearing clouds begin to neigh a whole universe of auricular cities . listen if it rains while regret and disdain weep to an ancient music . listen to the bonds fall off which hold you above and below . '' each calligram is intended to allow readers to unchain themselves from the regular experience of poetry , and feel and see something new . `` lettre-océan '' is first an image to be seen before even the words are read . text-only elements combine with words in shapes and forms . two circular forms , one locked in a square , the other , morph beyond the page in the shape of a spiral . together they create a picture that hints towards cubism . then on closer reading of the text , the descriptive words within suggest the image of an aerial view of the eiffel tower . they give tribute to electromagnetic waves of the telegraph , a new form of communication at the time . undoubtedly , the deeply layered artistic expressions in apollinaire 's calligrams are not just a brilliant display of poetic prowess from a master of the form . each calligram itself is also a snapshot in time , encapsulating the passion , the excitement , and the anticipation of all the bohemian artists of paris , including apollinaire , most of whom are well ahead of their time , and with their innovative work , eagerly grasping for the future .

among the great poets of literary history , certain names like homer , shakespeare , milton , and whitman are instantly recognizable . however , there 's an early 20th century great french poet whose name you may not know : guillaume apollinaire . he was a close friend and collaborator of artists like picasso , rousseau , and chagall .

how could you explain “ avant-garde ” in france during the early 20th century ?

meet the nurdles . they may be tiny , look harmless , and sound like a bunch of cartoon characters , but do n't be fooled . these little guys are plotting ocean domination . nurdles are some of the planet 's most pervasive pollutants , found in lakes , rivers , and oceans across the globe . the tiny factory-made pellets form the raw material for every plastic product we use . and each year , billions of pounds of nurdles are produced , melted , and molded into toys , bottles , buttons , bags , pens , shoes , toothbrushes , and beads . they are everywhere . and they come in many guises , multi-colored and many-shaped , they range in size from just a few millimeters to mere specks that are only visible through a microscope . but their real advantage in the quest for ocean domination is their incredible endurance , which allows them to persist in an environment for generations because their artificial makeup makes them unable to biodegrade . so , just as long as they do n't get into the environment , we have nothing to worry about , right ? the problem is nurdles have a crafty way of doing exactly this . produced in several countries and shipped to plastic manufacturing plants the world over , nurdles often escape during the production process , carried by runoff to the coast or during shipping when they 're mistakenly tipped into the waves . once in the water , nurdles are swiftly carried by currents , ultimately winding up in huge circulating ocean systems called gyres , where they convene to plan their tactics . the earth has five gyres that act as gathering points , but the headquarters of nurdle ocean domination are in the pacific ocean , where the comparative enormity of the gyre and the resulting concentration of pollution is so huge that it 's known as the great pacific garbage patch . here , nurdles have good company . this gyre draws in all kinds of pollution , but because they do n't biodegrade , plastics dominate , and they come from other sources besides nurdles , too . you know those tiny beads you see in your face wash or your toothpaste ? they 're often made of plastic , and after you flush them down the drain , some also end up in this giant garbage patch , much to the delight of the nurdles , building up their plastic army there . and then there are the large pieces of unrecycled plastic litter , like bottles and carrier bags , transported by runoff from land to sea . over time , these plastic chunks turn into a kind of nurdle , too , but one that 's been worn down by the elements , not made in a factory . and as if they were n't threatening enough , the rough , pitted surfaces of these microplastics , the name we give to all those collective plastic bits , water-born chemicals stick , or adhere , to them , making them toxic . this gathering has grown so immense that the oceanic garbage patch can shift from around the size of texas to something the size of the united states . but while this toxic tornado is circulating , the birds , fish , filter feeders , whales , and crustaceans around it are just going about their daily business , which means they 're looking for food . unfortunately for them , tiny bits of floating plastic look a lot like fish eggs and other enticing bits of food . but once ingested , microplastics have a very different and terrible habit of sticking around . inside an animal 's stomach , they not only damage its health with a cocktail of toxins they carry but can also lead to starvation because although nurdles may be ingested , they 're never digested , tricking an animal into feeling like it 's continually full and leading to its eventual death . when one organism consumes another , microplastics and their toxins are then passed up through the food chain . and that 's how , bit by bit , nurdles accomplish their goal , growing ever more pervasive as they wipe out marine life and reshape the ocean 's ecosystems . so , how to break this cycle ? the best solution would be to take plastics out of the equation altogether . that 'll take a lot of time but requires only small collective changes , like more recycling , replacing plastics with paper and glass , and ditching that toothpaste with the microbeads . if we accomplish these things , perhaps over time fewer and fewer nurdles will turn up at that giant garbage patch , their army of plastics will grow weaker , and they 'll surrender the ocean to its true keepers once more .

meet the nurdles . they may be tiny , look harmless , and sound like a bunch of cartoon characters , but do n't be fooled .

nurdles can :

at about six o'clock in the morning on september 14 , 2015 , scientists witnessed something no human had ever seen : two black holes colliding . both about 30 times as massive as our sun , they had been orbiting each other for millions of years . as they got closer together , they circled each other faster and faster . finally , they collided and merged into a single , even bigger , black hole . a fraction of a second before their crash , they sent a vibration across the universe at the speed of light . and on earth , billions of years later , a detector called the laser interferometer gravitational wave observatory , or ligo for short , picked it up . the signal only lasted a fifth of a second and was the detector 's first observation of gravitational waves . what are these ripples in space ? the answer starts with gravity , the force that pulls any two objects together . that 's the case for everything in the observable universe . you 're pulling on the earth , the moon , the sun , and every single star , and they 're pulling on you . the more mass something has , the stronger its gravitational pull . the farther away the object , the lower its pull . if every mass has an effect on every other mass in the universe , no matter how small , then changes in gravity can tell us about what those objects are doing . fluctuations in the gravity coming from the universe are called gravitational waves . gravitational waves move out from what caused them , like ripples on a pond , getting smaller as they travel farther from their center . but what are they ripples on ? when einstein devised his theory of relativity , he imagined gravity as a curve in a surface called space-time . a mass in space creates a depression in space-time , and a ball rolling across a depression will curve like it 's being attracted to the other mass . the bigger the mass , the deeper the depression and the stronger the gravity . when the mass making the depression moves , that sends out ripples in space-time . these are gravitationl waves . what would a gravitational wave feel like ? if our bodies were sensitive enough to detect them , we 'd feel like we were being stretched sideways while being compressed vertically . and in the next instant , stretched up and down while being compressed horizontally , sideways , then up and down . this back and forth would happen over and over as the gravitational wave passed right through you . but this happens on such a minute scale that we ca n't feel any of it . so we 've built detectors that can feel it for us . that 's what the ligo detectors do . and they 're not the only ones . there are gravitational wave detectors spread across the world . these l-shaped instruments have long arms , whose exact length is measured with lasers . if the length changes , it could be because gravitational waves are stretching and compressing the arms . once the detectors feel a gravitational wave , scientists can extract information about the wave 's source . in a way , detectors like ligo are big gravitational wave radios . radio waves are traveling all around you , but you ca n't feel them or hear the music they carry . it takes the right kind of detector to extract the music . ligo detects a gravitational wave signal , which scientists then study for data about the object that generated it . they can derive information , like its mass and the shape of its orbit . we can also hear gravitational waves by playing their signals through speakers , just like the music a radio extracts from radio waves . so those two black holes colliding sounds like this . scientists call this slide whistle-like noise a chirp , and it 's the signature of any two objects orbiting into each other . the black hole collision was just one example of what gravitational waves can tell us . other high-energy astronomical events will leave gravitational echoes , too . the collapse of a star before it explodes in a supernova , or a very dense neutron stars colliding . every time we create a new tool to look at space , we discover something we did n't expect , something that might revolutionize our understanding of the universe . ligo 's no different . in the short time it 's been on , ligo 's already revealed surprises , like that black holes collide more often than we ever expected . it 's impossible to say , but exciting to imagine , what revelations may now be propagating across space towards our tiny blue planet and its new way of perceiving the universe .

these are gravitationl waves . what would a gravitational wave feel like ? if our bodies were sensitive enough to detect them , we 'd feel like we were being stretched sideways while being compressed vertically .

if a gravitational wave was strong enough for you to feel , what would it feel like ?

think of all the food made in the world each year . hard to picture ? then , imagine that you are all of humanity , and on a plate in front of you is the one lovely annual meal you make for yourself . you did all sorts of work putting that meal on your table . you must be eager to consume the fruits of your labor . and the vegetables and meats and waffles of your labor , too , right ? well , oddly enough , a third of that meal ends up in the trash . a third of the food we eat globally , an estimated 1.3 billion tons ends up as waste . all the work we put into producing that food is wasted . and what 's worse , it costs us . america alone spends an estimated 165 billion dollars a year managing food waste . we 're wasting food , energy , and money . perhaps worst of all , we 're wasting the chance to change , to make the system of food consumption more efficient . if you want to bring on that change , you should know about a humble yet diligent and ever-so-crucial ally : the worm . worms convert organic waste and other compostable products into natural fertilizers . up to 75 % of what we put in the waste stream can become food and bedding material for vermicomposting . you can create a worm bin in your own home to see the composting process in action . first off , you need worms and not your typical earthworms . you need redworms , eisenia foetida , the species responsible for most vermicomposting in north america . these red wigglers are surface dwellers who do n't burrow too deep , they 're optimal feeders around room temperature , and they 're well-suited to converting organic waste into usable fertilizer . now , your worms might be vermin , but they need a comfortable space to live and work : some bedding materials , either shredded paper or cardboard , some moisture , and , of course , food , mainly , your leftovers , slightly decomposed table scraps . the worms break down food waste and other organic matter into castings , a fancy synonym for worm poop . their excrement is absolutely teeming with microbes , which continue the decomposition process , making all those once-wasted nutrients available again as fertilizer . the timeline for the whole process varies depending on the quantity of worms , the temperature , and how much waste is added to the bin . and there 's another timeline to consider . in a healthy worm-bin habitat , worm reproduction will occur when the wigglers become sexually mature , indicated by an elongation of the segments into a bulbous structure . three-month old wigglers can produce two to three semi-translucent yellow worm cocoons a week . you thought only moths and butterflies come out of cocoons ? well , we ca n't all be majestic . it takes around 11 weeks for new babies to hatch . when your bin seems to be full of living vermicelli noodles , it 's time to share the bounty with your friends and start a vermicompost club . or keep those worms to yourself and start a business . vermicomposting is n't confined only to small worm bins , it 's an emerging entrepreneurial enterprise . large-scale facilities convert bulk organic waste and even manure into rich , black castings called black gold . its value as a soil additive is unparalleled , and it can help plants resist harmful pathogens . the lack of available land in urban environments , coupled with growing interest in smaller-scale farming means there is a market for vermicomposting . many communities use composting as part of zero-waste strategies , and they can sell their worm-eaten table scraps to local farms , hungry for rich fertilizer . so , instead of wasting money , dumping wasted food in landfills , we can remake waste into an asset , putting it back into our food system to make it more sustainable , all with the help of the humble worm , the tiny organism that can help us change the way we look at food 's place in our lives and our place in the world , as long as we give the little guy a place at our table . well , not an actual seat at the table . a bin in the shed is fine .

and there 's another timeline to consider . in a healthy worm-bin habitat , worm reproduction will occur when the wigglers become sexually mature , indicated by an elongation of the segments into a bulbous structure . three-month old wigglers can produce two to three semi-translucent yellow worm cocoons a week .

worm reproduction can occur relatively rapidly . how long does it take for a worm to become sexually mature ?

the largest organ in your body is n't your liver or your brain . it 's your skin , with a surface area of about 20 square feet in adults . though different areas of the skin have different characteristics , much of this surface performs similar functions , such as sweating , feeling heat and cold , and growing hair . but after a deep cut or wound , the newly healed skin will look different from the surrounding area , and may not fully regain all its abilities for a while , or at all . to understand why this happens , we need to look at the structure of the human skin . the top layer , called the epidermis , consists mostly of hardened cells , called keratinocytes , and provides protection . since its outer layer is constantly being shed and renewed , it 's pretty easy to repair . but sometimes a wound penetrates into the dermis , which contains blood vessels and the various glands and nerve endings that enable the skin 's many functions . and when that happens , it triggers the four overlapping stages of the regenerative process . the first stage , hemostasis , is the skin 's response to two immediate threats : that you 're now losing blood and that the physical barrier of the epidermis has been compromised . as the blood vessels tighten to minimize the bleeding , in a process known as vasoconstriction , both threats are averted by forming a blood clot . a special protein known as fibrin forms cross-links on the top of the skin , preventing blood from flowing out and bacteria or pathogens from getting in . after about three hours of this , the skin begins to turn red , signaling the next stage , inflammation . with bleeding under control and the barrier secured , the body sends special cells to fight any pathogens that may have gotten through . among the most important of these are white blood cells , known as macrophages , which devour bacteria and damage tissue through a process known as phagocytosis , in addition to producing growth factors to spur healing . and because these tiny soldiers need to travel through the blood to get to the wound site , the previously constricted blood vessels now expand in a process called vasodilation . about two to three days after the wound , the proliferative stage occurs , when fibroblast cells begin to enter the wound . in the process of collagen deposition , they produce a fibrous protein called collagen in the wound site , forming connective skin tissue to replace the fibrin from before . as epidermal cells divide to reform the outer layer of skin , the dermis contracts to close the wound . finally , in the fourth stage of remodeling , the wound matures as the newly deposited collagen is rearranged and converted into specific types . through this process , which can take over a year , the tensile strength of the new skin is improved , and blood vessels and other connections are strengthened . with time , the new tissue can reach from 50-80 % of some of its original healthy function , depending on the severity of the initial wound and on the function itself . but because the skin does not fully recover , scarring continues to be a major clinical issue for doctors around the world . and even though researchers have made significant strides in understanding the healing process , many fundamental mysteries remain unresolved . for instance , do fibroblast cells arrive from the blood vessels or from skin tissue adjacent to the wound ? and why do some other mammals , such as deer , heal their wounds much more efficiently and completely than humans ? by finding the answers to these questions and others , we may one day be able to heal ourselves so well that scars will be just a memory .

the largest organ in your body is n't your liver or your brain . it 's your skin , with a surface area of about 20 square feet in adults . though different areas of the skin have different characteristics , much of this surface performs similar functions , such as sweating , feeling heat and cold , and growing hair . but after a deep cut or wound , the newly healed skin will look different from the surrounding area , and may not fully regain all its abilities for a while , or at all .

identify three features of the newly formed skin that are different from a healthy patch of skin . suggest a reason for each of these differences .

so here i ’ ve got a really nice sample of silicon , alright ? ok. i ’ m going to take it out of the bottle… of the… i ’ m going to have to wash my hands after this . so silicon is a very common element , it ’ s particularly found in sand which is the oxide of silica ; that ’ s the compound of oxygen and silicon . it is also found in a variety of minerals which contain silicon , oxygen and another metal which are known as silicates . and silicates occur in an enormous number of different minerals . it ’ s sort of the part of science that unless you are a specialist you find quite boring but if you really go into it like everything else it becomes really quite interesting . so this is a piece of polycrystalline silicon . it ’ s a really quite fantastic element and it ’ s very often used , or in fact it ’ s used very regularly to make electronic components . all of the computers that we use and actually the camera that you are recording me on now are based upon silicon technology . silicon is also extremely important and the basis of most of the electronic devices we use : my watch , your video camera , and also in computers . and if we look over here , i have got here this is an example of a silicon wafer ; you can see at the back this is silicon . so the silicon is grown as a single crystal from which we can make very highly-refined architectures on silicon chips , but you see here we have a polycrystalline sample so it is very pretty the way that it interacts with the light and you can see the different grain sizes . so let me take it out . did martyn show you the single crystal , the wafer ? yeah , he ’ s got a single chip , yeah , yeah . cause if you can get the light coming off it , you can get all sorts of different coloured affects . here you can see , this is pure silicon on the back and on the front , people have grown chips these are the pentium 4 chips for the computer , i think , i am not absolutely sure but i think these are the chips and these are the connectors on either side . so there are a whole lot of these chips and they grow a large number of them at once . these are chopped up and tested and the ones that worked are put into computers and the ones that are no good are just chucked and so this is a fantastically delicate piece of engineering making these . this is so-called 20cm wafer . they now make silicon chips on a 30cm wafer which is about this size and you can get a large number more on them . if you get a single crystal of this silicon structure , it can diffract the light and change the light so that it diffracts and bends off at different angles so that you get like a rainbow effect off it . it ’ s really quite beautiful . a compound of silicon , silicon nitride is extremely tough and very light so it ’ s very difficult to break and silicon nitride for example is used in the impellers in turbo chargers in cars . so when you put your foot down on the accelerator it will spin up very fast because it is very light but it is very strong so it won ’ t very suddenly fall to bits as it is revving up inside your engine . right i must put that there because i want to put that back in a bag .

it ’ s really quite beautiful . a compound of silicon , silicon nitride is extremely tough and very light so it ’ s very difficult to break and silicon nitride for example is used in the impellers in turbo chargers in cars . so when you put your foot down on the accelerator it will spin up very fast because it is very light but it is very strong so it won ’ t very suddenly fall to bits as it is revving up inside your engine .

which of these daily objects contains silicon atoms ?

somewhere right now , people are lining up to scare themselves , maybe with a thrill ride or horror movie . in fact , in october of 2015 alone , about 28 million people visited a haunted house in the u.s . but many consider this behavior perplexing , asking the question , `` what could possibly be fun about being scared ? '' fear has a bad rap , but it 's not all bad . for starters , fear can actually feel pretty good . when a threat triggers our fight or flight response , our bodies prepare for danger by releasing chemicals that change how our brains and bodies function . this automatic response jumpstarts systems that can aid in survival . they do this by making sure we have enough energy and are protected from feeling pain , while shutting down nonessential systems , like critical thought . feeling pain-free and energized , while not getting caught up in worrisome thoughts that normally occupy our brains , that all sounds great , and it can be because this response is similar , though not exactly the same to what we experience in positive , high-arousal states , like excitement , happiness , and even during sex . the difference lays in the context . if we 're in real danger , we 're focused on survival , not fun . but when we trigger this high arousal response in a safe place , we can switch over to enjoying the natural high of being scared . it 's why people on roller coasters can go from screaming to laughing within moments . your body is already in a euphoric state . you 're just relabeling the experience . and though the threat response is universal , research shows differences between individuals in how the chemicals associated with the threat response work . this explains why some are more prone to thrill-seeking than others . other normal physical differences explain why some may love the dizziness associated with a loop-de-loop , while loathing the stomach-drop sensation of a steep roller coaster , or why some squeal with delight inside a haunted house , but retreat in terror if taken to an actual cemetery . fear brings more than just a fun , natural high . doing things that we 're afraid of can give us a nice boost of self-esteem . like any personal challenge , whether it 's running a race or finishing a long book , when we make it through to the end , we feel a sense of accomplishment . this is true even if we know we 're not really in any danger . our thinking brains may know the zombies are n't real , but our bodies tell us otherwise . the fear feels real , so when we make it through alive , the satisfaction and sense of accomplishment also feel real . this is a great evolutionary adaptation . those who had the right balance of bravery and wit to know when to push through the fear and when to retreat were rewarded with survival , new food , and new lands . finally , fear can bring people together . emotions can be contagious , and when you see your friend scream and laugh , you feel compelled to do the same . this is because we make sense of what our friends are experiencing by recreating the experience ourselves . in fact , the parts of the brain that are active when our friend screams are active in us when we watch them . this not only intensifies our own emotional experience , but makes us feel closer to those we 're with . the feeling of closeness during times of fear is aided by the hormone oxytocin released during fight or flight . fear is a powerful emotional experience , and anything that triggers a strong reaction is going to be stored in our memory really well . you do n't want to forget what can hurt you . so if your memory of watching a horror film with your friends is positive and left you with a sense of satisfaction , then you 'll want to do it over and over again .

your body is already in a euphoric state . you 're just relabeling the experience . and though the threat response is universal , research shows differences between individuals in how the chemicals associated with the threat response work .

why have humans evolved to experience fear in the manner that we do ? what have been , and are , the benefits to our survival ?