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if you remember back to the last caesium video , pete and neil tried to launch a bit of caesium metal into water with the small metallic collider and they had a few problems with surface area and caesium still being stuck in the glass as well . what i have been asked to do today , is take this ampoule of caesium into this piece of machinery here which is one of our glove boxes , try and get it out of the glass so that we can put it in as is . caesium has quite a surprising use , it is used to measure time . i don ’ t know if you have ever thought about it but you could define one second as a fraction of a day , one sixtieth of a minute which is which is a sixtieth of an hour which is then a twenty fourth of a day . but the trouble with that is that you will never be able to tell if the earth was going slower or speeding up because the length of the day would change and you would not notice it so scientists have to have an independent way of defining the second and this is where caesium comes in . and so now the caesium is going in as well . alright , so we will shut the port door so the way in which scientists define the second is in terms of microwaves and the frequency of the microwaves , we need a standard , something that can define a radiowave very very precisely , and this is where caesium comes in . so what i need to do now is open up this door here . the point about caesium is that it is a big atom it can absorb microwaves , the absorption of the microwave causes an electron to move from one energy level to another and the advantage of caesium over all other materials is that this frequency is enormously precise . it is pretty cool it is really good , it is sort of a really pale gold colour . it is still molten at the moment . it is rather like tuning a radio , i don ’ t know if you ’ ve ever tuned a radio but as you turn the knob , sometimes , you don ’ t have to be very precise , you can put it almost anywhere and you get your favourite station , but there are some stations where you have to adjust it very very accurately and there is just one tiny place where you can get the right radio station and caesium is like that , it defines the frequency very very accurately , if you don ’ t hit it right it does not absorb the radiowaves and so you can use it as a standard , so make sure so make sure that everybody has exactly the same frequency of their microwave and then once everybody has got the same , then it is quite easy for everybody to agree that they will count a certain number of waves as being a second . we are going to store the caesium under oil so that it does not react with air when it comes out . so this is ready now for pete to chuck it in some water and we will stand very far back when he does it . so we have got caesium , we have taken it out of the ampoule , neil did that the other day with debbie in their glove box , they have put it into a small plastic weighing boat and immersed it in oil so it can ’ t react with air . now what we need to do is a very technical operation is to punch a hole into the plastic boat so that we can lift it out with a piece of string so we can drop it into some water . i ’ ve got my friend , dr red . it is always good to be very very careful when you are doing chemistry like this , just in case it goes wrong we have the safety procedures in place for us , in case we get surprised . so now neil is going to pass a piece of string through the hole so that we can put it at the end of a pretty long fishing line so that we can drop it into water . so this is neil ’ s new device , it ’ s a very very fancy erection . essentially we have used a laboratory stand , and we have an eyelet so this is just to act as a point where we can raise up our caesium on a piece of string . at the moment , the caesium you can see is a lovely gold colour . would you believe me , it ’ s melting . look at it . oh yeah it ’ s very warm here today and the caesium ’ s melted . so we are just going to try and freeze it again . well we are going to try and refreeze the caesium by cooling it with liquid nitrogen . ok everybody be careful . so we have our caesium under oil . we now need to lift it up using the new device , and then drop it in the water , and let ’ s see what kind of chemical reaction it does today . everybody ready ? neil ? yep ! wow , quite a spectacular reaction . as the caesium reacted with the water , gave away its electron , off she goes , it ’ s caesium plus . awesome , it was pretty good . yeah , it ’ s pretty great you know when , when debbie and neil took the caesium out of the ampoule they were really really good for us because they gave us a really large surface area , so it could react quickly as soon as it went in the water . generating all that lovely hydrogen ready to explode and make a bang . great , good chemistry . well , the reason that caesium reacts so violently is that it is a very large atom , so an electron can be removed very easily , in fact if you dissolve caesium in water , on a very short time scale , a millionth of a second or so , it dissociates into caesium-plus and an electron , and the energy of the electron interacting with the water is enough to separate the two and once the electron is in the water , it then reacts with the water so that h2o dissociates into a hydrogen atom and oh-minus , so in fact what you are making is a caesium salt which is rather like caustic soda , it ’ s a strong alkali and hydrogen , and it is the rapid formation of hydrogen gas that causes part of the shock of the reaction and then the hydrogen will usually catch fire and react with the oxygen in the air to give you a small explosion or a big one depending how much caesium you ’ ve used .
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so this is ready now for pete to chuck it in some water and we will stand very far back when he does it . so we have got caesium , we have taken it out of the ampoule , neil did that the other day with debbie in their glove box , they have put it into a small plastic weighing boat and immersed it in oil so it can ’ t react with air . now what we need to do is a very technical operation is to punch a hole into the plastic boat so that we can lift it out with a piece of string so we can drop it into some water .
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why does debbie open the ampoule of caesium inside a glove box ?
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have you experienced déjà vu ? it 's that shadowy feeling you get when a situation seems familiar . a scene in a restaurant plays out exactly as you remember . the world moves like a ballet you 've choreographed , but the sequence ca n't be based on a past experience because you 've never eaten here before . this is the first time you 've had clams , so what 's going on ? unfortunately , there is n't one single explanation for déjà vu . the experience is brief and occurs without notice , making it nearly impossible for scientists to record and study it . scientists ca n't simply sit around and wait for it to happen to them -- this could take years . it has no physical manifestations and in studies , it 's described by the subject as a sensation or feeling . because of this lack of hard evidence , there 's been a surplus of speculation over the years . since emile boirac introduced déjà vu as a french term meaning `` already seen , '' more than 40 theories attempt to explain this phenomenon . still , recent advancements in neuroimaging and cognitive psychology narrow down the field of prospects . let 's walk through three of today 's more prevalent theories , using the same restaurant setting for each . first up is dual processing . we 'll need an action . let 's go with a waiter dropping a tray of dishes . as the scene unfolds , your brain 's hemispheres process a flurry of information : the waiter 's flailing arms , his cry for help , the smell of pasta . within milliseconds , this information zips through pathways and is processed into a single moment . most of the time , everything is recorded in-sync . however , this theory asserts that déjà vu occurs when there 's a slight delay in information from one of these pathways . the difference in arrival times causes the brain to interpret the late information as a separate event . when it plays over the already-recorded moment , it feels as if it 's happened before because , in a sense , it has . our next theory deals with a confusion of the past rather than a mistake in the present . this is the hologram theory , and we 'll use that tablecloth to examine it . as you scan its squares , a distant memory swims up from deep within your brain . according to the theory , this is because memories are stored in the form of holograms , and in holograms , you only need one fragment to see the whole picture . your brain has identified the tablecloth with one from the past , maybe from your grandmother 's house . however , instead of remembering that you 've seen it at your grandmother 's , your brain has summoned up the old memory without identifying it . this leaves you stuck with familiarity , but no recollection . although you 've never been in this restaurant , you 've seen that tablecloth but are just failing to identify it . now , look at this fork . are you paying attention ? our last theory is divided attention , and it states that déjà vu occurs when our brain subliminally takes in an environment while we 're distracted by one particular object . when our attention returns , we feel as if we 've been here before . for example , just now you focused on the fork and did n't observe the tablecloth or the falling waiter . although your brain has been recording everything in your peripheral vision , it 's been doing so below conscious awareness . when you finally pull yourself away from the fork , you think you 've been here before because you have , you just were n't paying attention . while all three of these theories share the common features of déjà vu , none of them propose to be the conclusive source of the phenomenon . still , while we wait for researchers and inventers to come up with new ways to capture this fleeting moment , we can study the moment ourselves . after all , most studies of déjà vu are based on first-hand accounts , so why ca n't one be yours ? the next time you get déjà vu , take a moment to think about it . have you been distracted ? is there a familiar object somewhere ? is your brain just acting slow ? or is it something else ?
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have you experienced déjà vu ? it 's that shadowy feeling you get when a situation seems familiar .
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why haven ’ t scientists been able to definitively explain the phenomenon of déjà vu ?
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in the 1920 's , the german mathematician david hilbert devised a famous thought experiment to show us just how hard it is to wrap our minds around the concept of infinity . imagine a hotel with an infinite number of rooms and a very hardworking night manager . one night , the infinite hotel is completely full , totally booked up with an infinite number of guests . a man walks into the hotel and asks for a room . rather than turn him down , the night manager decides to make room for him . how ? easy , he asks the guest in room number 1 to move to room 2 , the guest in room 2 to move to room 3 , and so on . every guest moves from room number `` n '' to room number `` n+1 '' . since there are an infinite number of rooms , there is a new room for each existing guest . this leaves room 1 open for the new customer . the process can be repeated for any finite number of new guests . if , say , a tour bus unloads 40 new people looking for rooms , then every existing guest just moves from room number `` n '' to room number `` n+40 '' , thus , opening up the first 40 rooms . but now an infinitely large bus with a countably infinite number of passengers pulls up to rent rooms . countably infinite is the key . now , the infinite bus of infinite passengers perplexes the night manager at first , but he realizes there 's a way to place each new person . he asks the guest in room 1 to move to room 2 . he then asks the guest in room 2 to move to room 4 , the guest in room 3 to move to room 6 , and so on . each current guest moves from room number `` n '' to room number `` 2n '' -- filling up only the infinite even-numbered rooms . by doing this , he has now emptied all of the infinitely many odd-numbered rooms , which are then taken by the people filing off the infinite bus . everyone 's happy and the hotel 's business is booming more than ever . well , actually , it is booming exactly the same amount as ever , banking an infinite number of dollars a night . word spreads about this incredible hotel . people pour in from far and wide . one night , the unthinkable happens . the night manager looks outside and sees an infinite line of infinitely large buses , each with a countably infinite number of passengers . what can he do ? if he can not find rooms for them , the hotel will lose out on an infinite amount of money , and he will surely lose his job . luckily , he remembers that around the year 300 b.c.e. , euclid proved that there is an infinite quantity of prime numbers . so , to accomplish this seemingly impossible task of finding infinite beds for infinite buses of infinite weary travelers , the night manager assigns every current guest to the first prime number , 2 , raised to the power of their current room number . so , the current occupant of room number 7 goes to room number 2^7 , which is room 128 . the night manager then takes the people on the first of the infinite buses and assigns them to the room number of the next prime , 3 , raised to the power of their seat number on the bus . so , the person in seat number 7 on the first bus goes to room number 3^7 or room number 2,187 . this continues for all of the first bus . the passengers on the second bus are assigned powers of the next prime , 5 . the following bus , powers of 7 . each bus follows : powers of 11 , powers of 13 , powers of 17 , etc . since each of these numbers only has 1 and the natural number powers of their prime number base as factors , there are no overlapping room numbers . all the buses ' passengers fan out into rooms using unique room-assignment schemes based on unique prime numbers . in this way , the night manager can accommodate every passenger on every bus . although , there will be many rooms that go unfilled , like room 6 , since 6 is not a power of any prime number . luckily , his bosses were n't very good in math , so his job is safe . the night manager 's strategies are only possible because while the infinite hotel is certainly a logistical nightmare , it only deals with the lowest level of infinity , mainly , the countable infinity of the natural numbers , 1 , 2 , 3 , 4 , and so on . georg cantor called this level of infinity aleph-zero . we use natural numbers for the room numbers as well as the seat numbers on the buses . if we were dealing with higher orders of infinity , such as that of the real numbers , these structured strategies would no longer be possible as we have no way to systematically include every number . the real number infinite hotel has negative number rooms in the basement , fractional rooms , so the guy in room 1/2 always suspects he has less room than the guy in room 1 . square root rooms , like room radical 2 , and room pi , where the guests expect free dessert . what self-respecting night manager would ever want to work there even for an infinite salary ? but over at hilbert 's infinite hotel , where there 's never any vacancy and always room for more , the scenarios faced by the ever-diligent and maybe too hospitable night manager serve to remind us of just how hard it is for our relatively finite minds to grasp a concept as large as infinity . maybe you can help tackle these problems after a good night 's sleep . but honestly , we might need you to change rooms at 2 a.m .
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the process can be repeated for any finite number of new guests . if , say , a tour bus unloads 40 new people looking for rooms , then every existing guest just moves from room number `` n '' to room number `` n+40 '' , thus , opening up the first 40 rooms . but now an infinitely large bus with a countably infinite number of passengers pulls up to rent rooms . countably infinite is the key .
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which set of numbers is used to number the rooms and the bus seats ?
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`` hey , another atom . i 'm hydrogen , nice to meet you . how are you feeling about the jump ? '' `` hi there , i 'm antihydrogen , your antiatom , and to be honest , i 'm feeling kind of neutral . my positron and antiproton balance out , just like your electron and proton , right ? '' `` hey , yeah ! you look just like me , but different somehow . '' `` whoa , be careful ! if we get too close , we 'll disappear in a spark of energy . i 'd like to stay in one piece . '' `` oh wow , sorry . '' `` it 's okay . i was just thinking , it 's kind of weird for us to be chatting like this before our jump above cern . '' `` why 's that ? '' `` well , for starters , how do we know we 'll both fall ? '' `` of course we 'll fall . it 's gravity , you know , the force of attraction between masses . i even know how fast we should fall . galileo showed in that tower experiment that all falling objects accelerate at the same rate , regardless of mass . '' `` that 's for bigger objects . it 's a different story for small particles like us . our mass is so tiny that the gravitational force we experience is miniscule , and if the particles are charged , like my antiproton or your proton , then it becomes impossible to detect compared to the much greater electromagnetic force acting on them . '' `` but that 's only for charged particles . you and i are both neutral . our charges balance out , so the electromagnetic force is small and the gravitational force should be detectable . i know mine 's been measured . '' `` because you 're everywhere , but i 'm kind of hard to find . '' `` why is that , anyway ? should n't there have been an equal amount of matter and antimatter created in the big bang ? '' `` you 'd think so , but then all of those particles would have annihilated each other into energy , remember ? and the universe is obviously full of matter . no one knows why there is more matter than antimatter , which is why scientists are so interested in studying me . '' `` so where do they find you anyway ? '' `` actually , i was made in that lab down there . they needed an accelerator to make my antiproton because it 's so heavy , just as heavy as your proton . getting my positron was easier . it 's much lighter , like your electron , and there are materials that naturally decay by emitting one . then they just had to put the two together and they got me . but it 's only recently that they 've been able to keep me around long enough to study my properties . '' `` and now they 've sent you on this jump with me . hey , wait a minute . '' `` that 's right . we 're reenacting galileo 's experiment , but with matter and antimatter instead of two objects made of matter . '' `` so what 's going to happen ? are you going to fall upwards or something ? '' `` only one way to find out ! ''
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`` hey , another atom . i 'm hydrogen , nice to meet you .
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what is orbiting the antiproton in an antihydrogen atom ?
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( electronic instrumental music ) ( instrumental synthesizer music ) - [ carl ] that 's inevitable that humans would project their hopes and fears upon the cosmos . the standard hollywood attempts are to portray the extraterrestrials as red of claw and fang . pointed heads and nasty dispositions . steven spielberg has made an important step forward , e.t . and close encounters of the third kind , to show the possibility of benign extraterrestrials , but even there , the extraterrestrials are only slight variants on human beings , when the evolutionary record is clear that extraterrestrials would be very different from us and also they 're not awfully smart , his extraterrestrials . - [ studs ] sweet , but not smart . - [ carl ] sweet , but not smart . if you look at timescales , you realize that our civilization is the most backward civilization in the galaxy that could communicate at all , because we 've just invented radio telescopes , just a few decades ago . we had not the ghost of a chance of communicating with anybody else . so if we receive a message , it ca n't be from anybody less capable than we , because anybody less capable ca n't communicate at all . so it has to be somebody much in advance of us and maybe as much in advance of us as we are in advance of the ants , say , or the worms . - [ studs ] you , carl sagan , scientist , astronomer , enlighten me . you think that indeed there may be some sort of intelligence out there ? - [ carl ] may , surely , surely may . there is , we now realize , an enormous number of planets . a range of planetary systems around the nearby stars . so there 's a lot of potential abodes for life . that 's one thing . then there 's the question of organic matter . the carbon-rich complex molecules that are essential for the kind of life we know about , are fantastically abundant . they litter the universe . we see them in asteroids , in comets , in the moons in the outer solar system and even in the cold dark spaces between the stars , so the stuff of life is everywhere , and then there 's time . there are billions of years for biological evolution on all those worlds , there are many worlds that are much older than ours . so you put those together , lots of places , lots of organic matter , lots of time and it seems very hard to believe that our paltry little planet is the only one that 's inhabited . - [ studs ] you know , there 's a phrase you use about the earth people us , we , are so benighted . `` the earth is the ghetto of the universe . '' we 're the ghetto of the universe . - [ carl ] well in an extremely backward and obscure part of the milky way galaxy . we 're 30,000 light years from the center of the galaxy . we 're in the galactic boondocks . this whole galaxy is only one of probably hundreds of billions of other galaxies , a useful calibration of our place in the universe . - [ studs ] there 's also religion and science . - [ carl ] there is a tendency in both schools of thought to think that they have a corner on the truth . i mean , a way to look at it is the following , science and religion on some level are after the same thing . take the question of our origins . both science and religion attempt to approach this question . but the religions all contradict each other , so they ca n't all be right . the judeo-christian islamic religion holds that the world is about 6,000 years old , you just count up the begats in the old testament . it 's very clear , 6,000 years old . the hindus have an infinitely old universe with an infinite number of creations and destructions of the whole universe . now those two major religions ca n't both be right . how do you tell which is right and which is wrong ? well , the only way is to appeal to the natural world around us and the natural world around us shows that the earth , for example , is about four point six billion years old and nothing like 6,000 years old . so a literal reading of the bible simply is a mistake , i mean it 's just wrong , it 's just wrong . as a work of science , it is flawed , it 's the science of the babylonians in the sixth century b.c . we 've learned something since then . - [ voiceover ] this special episode of blank on blank is supported by squarespace . whether your story is out of the ordinary or simply out of this world , you should tell it in an unforgettable way . with user-friendly tools and templates , squarespace helps you capture your story with a captivating website . start your trial today . visit squarespace.com/blankonblank . - [ studs ] well you quote einstein . the cosmic religious feeling , he is religious in that sense , is the strongest , noblest mode of a scientific research , so there 's a religion of sorts that einstein believed in . - [ carl ] right , but it 's very different from most people 's view of religion . einstein talked about god , but for einstein , god was little more than the sum total of the laws of the universe . there was no hint of intervention in daily life , of the efficacy of prayer , of life after death or any of those accouterments of the judeo-christian islamic religion . - [ voiceover ] this episode was also supported by the alfred p. sloan foundation , enhancing public understanding of science , technology and economic performance . more information on sloan at sloan.org . ( peaceful instrumental music ) ( tape reversing )
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take the question of our origins . both science and religion attempt to approach this question . but the religions all contradict each other , so they ca n't all be right .
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according to carl sagan , what question do both science and religion seek to answer ?
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take a look out your window , put on your glasses if you wear them . you might want to grab a pair of binoculars , too , or a magnifying lens . now , what do you see ? well , whatever it is , it 's not the multiple layers of glass right in front of you . but have you ever wondered how something so solid can be so invisible ? to understand that , we have to understand what glass actually is , and where it comes from . it all begins in the earth 's crust , where the two most common elements are silicon and oxygen . these react together to form silicon dioxide , whose molecules arrange themselves into a regular crystalline form known as quartz . quartz is commonly found in sand , where it often makes up most of the grains and is the main ingredient in most type of glass . of course , you probably noticed that glass is n't made of multiple tiny bits of quartz , and for good reason . for one thing , the edges of the rigidly formed grains and smaller defects within the crystal structure reflect and disperse light that hits them . but when the quartz is heated high enough the extra energy makes the molecules vibrate until they break the bonds holding them together and become a flowing liquid , the same way that ice melts into water . unlike water , though , liquid silicon dioxide does not reform into a crystal solid when it cools . instead , as the molecules lose energy , they are less and less able to move into an ordered position , and the result is what is called an amorphous solid . a solid material with the chaotic structure of a liquid , which allows the molecules to freely fill in any gaps . this makes the surface of glass uniform on a microscopic level , allowing light to strike it without being scattered in different directions . but this still does n't explain why light is able to pass through glass rather than being absorbed as with most solids . for that , we need to go all the way down to the subatomic level . you may know that an atom consists of a nucleus with electrons orbiting around it , but you may be surprised to know that it 's mostly empty space . in fact , if an atom were the size of a sports stadium , the nucleus would be like a single pea in the center , while the electrons would be like grains of sand in the outer seats . that should leave plenty of space for light to pass through without hitting any of these particles . so the real question is not why is glass transparent , but why are n't all materials transparent ? the answer has to do with the different energy levels that electrons in an atom can have . think of these as different rows of seats in the stadium stands . an electron is initially assigned to sit in a certain row , but it could jump to a better row , if it only had the energy . as luck would have it , absorbing one of those light photons passing through the atom can provide just the energy the electron needs . but there 's a catch . the energy from the photon has to be the right amount to get an electron to the next row . otherwise , it will just let the photon pass by , and it just so happens that in glass , the rows are so far apart that a photon of visible light ca n't provide enough energy for an electron to jump between them . photons from ultraviolet light , on the other hand , give just the right amount of energy , and are absorbed , which is why you ca n't get a suntan through glass . this amazing property of being both solid and transparent has given glass many uses throughout the centuries . from windows that let in light while keeping out the elements , to lenses that allow us to see both the vast worlds beyond our planet , and the tiny ones right around us . it is hard to imagine modern civilization without glass . and yet for such an important material we rarely think about glass and its impact . it is precisely because the most important and useful quality of glass is being featureless and invisible that we often forget that it 's even there .
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otherwise , it will just let the photon pass by , and it just so happens that in glass , the rows are so far apart that a photon of visible light ca n't provide enough energy for an electron to jump between them . photons from ultraviolet light , on the other hand , give just the right amount of energy , and are absorbed , which is why you ca n't get a suntan through glass . this amazing property of being both solid and transparent has given glass many uses throughout the centuries .
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explain why you ca n't get a suntan through glass .
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a , c , e , d , b , k. no , this is n't some random , out of order alphabet . these are vitamins , and just like letters build words , they 're the building blocks that keep the body running . vitamins are organic compounds we need to ingest in small amounts to keep functioning . they 're the body 's builders , defenders and maintenance workers , helping it to build muscle and bone , make use of nutrients , capture and use energy and heal wounds . if you need convincing about vitamin value , just consider the plight of olden day sailors , who had no access to vitamin-rich fresh produce . they got scurvy . but vitamin c , abundant in fruits and vegetables , was the simple antidote to this disease . while bacteria , fungi and plants produce their own vitamins , our bodies ca n't , so we have to get them from other sources . so how does the body get vitamins from out there into here ? that 's dependent on the form these compounds take . vitamins come in two types : lipid-soluble and water-soluble , and the difference between them determines how the body transports and stores vitamins , and gets rid of the excess . the water-solubles are vitamin c and b complex vitamins that are made up of eight different types that each do something unique . these are dissolved in the watery parts of fruits , vegetables and grains , meaning their passage through the body is relatively straightforward . once inside the system , these foods are digested and the vitamins within them are taken up directly by the bloodstream . because blood plasma is water-based , water-soluble vitamins c and b have their transport cut out for them and can move around freely within the body . for lipid-soluble vitamins , dissolved in fat and found in foods like diary , butter and oils , this trip into the blood is a little more adventurous . these vitamins make it through the stomach and the intestine , where an acidic substance called bile flows in from the liver , breaking up the fat and preparing it for absorption through the intestinal wall . because fat-soluble vitamins ca n't make use of the blood 's watery nature , they need something else to move them around , and that comes from proteins that attach to the vitamins and act like couriers , transporting fat-solubles into the blood and around the body . so , this difference between water- or fat-soluble vitamins determines how they get into the blood , but also how they 're stored or rejected from the body . the system 's ability to circulate water-soluble vitamins in the bloodstream so easily means that most of them can be passed out equally easily via the kidneys . because of that , most water-soluble vitamins need to be replenished on a daily basis through the food we eat . but fat-soluble vitamins have staying power because they can be packed into the liver and in fat cells . the body treats these parts like a pantry , storing the vitamins there and rationing them out when needed , meaning we should n't overload on this type of vitamin because the body is generally well stocked . once we figured the logistics of transport and storage , the vitamins are left to do the work they came here to do in the first place . some , like many of the b complex vitamins , make up coenzymes , whose job it is to help enzymes release the energy from food . other b vitamins then help the body to use that energy . from vitamin c , you get the ability to fight infection and make collagen , a kind of tissue that forms bones and teeth and heals wounds . vitamin a helps make white blood cells , key in the body 's defense , helps shape bones and improves vision by keeping the cells of the eye in check . vitamin d gathers calcium and phosphorus so we can make bones , and vitamin e works as an antioxidant , getting rid of elements in the body that can damage cells . finally , from vitamin k , we score the ability to clot blood , since it helps make the proteins that do this job . without this vitamin variety , humans face deficiencies that cause a range of problems , like fatigue , nerve damage , heart disorders , or diseases like rickets and scurvy . on the other hand , too much of any vitamin can cause toxicity in the body , so there goes the myth that loading yourself with supplements is a great idea . in reality , it 's all about getting the balance right , and hitting that vitamin jackpot .
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once inside the system , these foods are digested and the vitamins within them are taken up directly by the bloodstream . because blood plasma is water-based , water-soluble vitamins c and b have their transport cut out for them and can move around freely within the body . for lipid-soluble vitamins , dissolved in fat and found in foods like diary , butter and oils , this trip into the blood is a little more adventurous .
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which vitamins are water-soluble ?
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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 .
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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 .
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use the fraud triangle ( pressure , opportunity and rationalization ) to analyze a recent fraud case you 've seen in the media .
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language is an essential part of our lives that we often take for granted . with it , we can communicate our thoughts and feelings , lose ourselves in novels , send text messages , and greet friends . it 's hard to imagine being unable to turn thoughts into words . but if the delicate web of language networks in your brain became disrupted by stroke , illness , or trauma , you could find yourself truly at a loss for words . this disorder , called aphasia , can impair all aspects of communication . people who have aphasia remain as intelligent as ever . they know what they want to say , but ca n't always get their words to come out correctly . they may unintentionally use substitutions called paraphasias , switching related words , like saying `` dog '' for `` cat , '' or words that sound similar , such as `` house '' for `` horse . '' sometimes , their words may even be unrecognizable . there are several types of aphasia grouped into two categories : fluent , or receptive , aphasia and non-fluent , or expressive , aphasia . people with fluent aphasia may have normal vocal inflection but use words that lack meaning . they have difficulty comprehending the speech of others and are frequently unable to recognize their own speech errors . people with non-fluent aphasia , on the other hand , may have good comprehension but will experience long hesitations between words and make grammatical errors . we all have that tip-of-the-tongue feeling from time to time when we ca n't think of a word , but having aphasia can make it hard to name simple , everyday objects . even reading and writing can be difficult and frustrating . so how does this language loss happen ? the human brain has two hemispheres . in most people , the left hemisphere governs language . we know this because in 1861 , the physician paul broca studied a patient who lost the ability to use all but a single word , `` tan . '' during a postmortem study of that patient 's brain , broca discovered a large lesion in the left hemisphere now known as broca 's area . scientists today believe that broca 's area is responsible in part for naming objects and coordinating the muscles involved in speech . behind broca 's area is wernicke 's area near the auditory cortex . that 's where the brain attaches meaning to speech sounds . damage to wernicke 's area impairs the brain 's ability to comprehend language . aphasia is caused by injury to one or both of these specialized language areas . fortunately , there are other areas of the brain which support these language centers and can assist with communication . even brain areas that control movement are connected to language . fmri studies found that when we hear action words , like `` run '' or `` dance , '' parts of the brain responsible for movement light up as if the body was actually running or dancing . our other hemisphere contributes to language , too , enhancing the rhythm and intonation of our speech . these non-language areas sometimes assist people with aphasia when communication is difficult . so how common is aphasia ? approximately 1 million people in the u.s. alone have it , with an estimated 80,000 new cases per year . about one-third of stroke survivors suffer from aphasia making it more prevalent than parkinson 's disease or multiple sclerosis , yet less widely known . there is one rare form of aphasia called primary progressive aphasia , or ppa , which is not caused by stroke or brain injury , but is actually a form of dementia in which language loss is the first symptom . the goal in treating ppa is to maintain language function for as long as possible before other symptoms of dementia eventually occur . however , when aphasia is acquired from a stroke or brain trauma , language improvement may be achieved through speech therapy . our brain 's ability to repair itself , known as brain plasticity , permits areas surrounding a brain lesion to take over some functions during the recovery process . scientists have been conducting experiments using new forms of technology , which they believe may encourage brain plasticity in people with aphasia . meanwhile , many people with aphasia remain isolated , afraid that others wo n't understand them or give them extra time to speak . by offering them the time and flexibility to communicate in whatever way they can , you can help open the door to language again , moving beyond the limitations of aphasia .
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the goal in treating ppa is to maintain language function for as long as possible before other symptoms of dementia eventually occur . however , when aphasia is acquired from a stroke or brain trauma , language improvement may be achieved through speech therapy . our brain 's ability to repair itself , known as brain plasticity , permits areas surrounding a brain lesion to take over some functions during the recovery process . scientists have been conducting experiments using new forms of technology , which they believe may encourage brain plasticity in people with aphasia . meanwhile , many people with aphasia remain isolated , afraid that others wo n't understand them or give them extra time to speak .
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two things that may encourage brain plasticity are :
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when a team of archaeologists recently came across some 15,000 year-old human remains , they made an interesting discovery . the teeth of those ancient humans were riddled with holes . their cavities were caused by the same thing that still plagues us today , specific tiny microbes that live in our mouths . these microbes are with us soon after birth . we typically pick them up as babies from our mothers ' mouths . and as our teeth erupt , they naturally begin to accumulate communities of bacteria . depending on what we eat , and specifically how much sugar we consume , certain microbes can overpopulate and cause cavities . diets high in sugary foods cause an explosion of bacteria called mutans streptococci in our mouths . like humans , these microorganisms love sugar , using it as a molecular building block and energy source . as they consume it , the bacteria generate byproducts in the form of acids , such as lactic acid . mutans streptococci are resistant to this acid , but unfortunately , our teeth are n't . while each human tooth is coated in a hardy , protective layer of enamel , it 's no match for acid . that degrades the armor over time , leaching away its calcium minerals . gradually , acid wears down a pathway for bacteria into the tooth 's secondary layer called the dentin . since blood vessels and nerves in our teeth are enclosed deep within , at this stage , the expanding cavity does n't hurt . but if the damage extends beyond the dentin , the bacterial invasion progresses causing excruciating pain as the nerves become exposed . without treatment , the whole tooth may become infected and require removal all due to those sugar-loving bacteria . the more sugar our food contains , the more our teeth are put at risk . those cavemen would hardly have indulged in sugary treats , however , so what caused their cavities ? in meat-heavy diets , there would have been a low-risk of cavities developing because lean meat contains very little sugar , but that 's not all our early human ancestors ate . cavemen would also have consumed root vegetables , nuts , and grains , all of which contain carbohydrates . when exposed to enzymes in the saliva , carbohydrates get broken down into simpler sugars , which can become the fodder for those ravenous mouth bacteria . so while ancient humans did eat less sugar compared to us , their teeth were still exposed to sugars . that does n't mean they were unable to treat their cavities , though . archaeological remains show that about 14,000 years ago , humans were already using sharpened flint to remove bits of rotten teeth . ancient humans even made rudimentary drills to smooth out the rough holes left behind and beeswax to plug cavities , like modern-day fillings . today , we have much more sophisticated techniques and tools , which is fortunate because we also need to contend with our more damaging , sugar-guzzling ways . after the industrial revolution , the human incidence of cavities surged because suddenly we had technological advances that made refined sugar cheaper and accessible . today , an incredible 92 % of american adults have had cavities in their teeth . some people are more susceptible to cavities due to genes that may cause certain weaknesses , like softer enamel , but for most , high sugar consumption is to blame . however , we have developed other ways of minimizing cavities besides reducing our intake of sugar and starch . in most toothpastes and many water supplies , we use tiny amounts of fluoride . that strengthens teeth and encourages the growth of enamel crystals that build up a tooth 's defenses against acid . when cavities do develop , we use tooth fillings to fill and close off the infected area , preventing them from getting worse . the best way to avoid a cavity is still cutting down on sugar intake and practicing good oral hygiene to get rid of the bacteria and their food sources . that includes regular tooth brushing , flossing , and avoiding sugary , starchy , and sticky foods that cling to your teeth between meals . gradually , the population of sugar-loving microbes in your mouth will decline . unlike the cavemen of yesteryear , today we have the knowledge required to avert a cavity calamity . we just need to use it .
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when exposed to enzymes in the saliva , carbohydrates get broken down into simpler sugars , which can become the fodder for those ravenous mouth bacteria . so while ancient humans did eat less sugar compared to us , their teeth were still exposed to sugars . that does n't mean they were unable to treat their cavities , though .
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what are some foods that contain hidden sugars that can harm your teeth ?
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( music ) on a typical day at school , endless hours are spent learning the answers to questions . but right now , we 'll do the opposite . we 're going to focus on questions where you ca n't learn the answers , because they 're unknown . i used to puzzle about a lot of things as a boy . for example , what would it feel like to be a dog ? do fish feel pain ? how about insects ? was the big bang just an accident ? and is there a god ? and if so , how are we so sure that it 's a he and not a she ? why do so may innocent people and animals suffer terrible things ? is there really a plan for my life ? is the future yet to be written , or is it already written and we just ca n't see it ? but then , do i have free will ? who am i , anyway ? am i just a biological machine ? but then , why am i conscious ? what is consciousness ? will robots become conscious one day ? i mean , i kind of assumed that some day i would be told the answers to all these questions . i mean , someone must know , right ? huh . guess what ? no one knows . most of those questions puzzle me more now than ever . but diving into them is exciting because it takes you to the edge of knowledge , and you never know what you 'll find there . so , two questions to kick off this series , questions that no one on earth knows the answer to ... text : how many universes are there ? why ca n't we see evidence of alien life ?
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guess what ? no one knows . most of those questions puzzle me more now than ever .
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schools don ’ t devote a lot of time to questions that no one knows the answers to . why ? what effect ( s ) does this have , in your opinion ?
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nicolas steno is rarely heard of outside intro to geology , but anyone hoping to understand life on earth should see how steno expanded and connected those very concepts : earth , life , and understanding . born niels stensen in 1638 denmark , son of a goldsmith , he was a sickly kid whose school chums died of plague . he survived to cut up corpses as an anatomist , studying organs shared across species . he found a duct in animal skulls that sends saliva to the mouth . he refuted descartes ' idea that only humans had a pineal gland , proving it was n't the seat of the soul , arguably , the debut of neuroscience . most remarkable for the time was his method . steno never let ancient texts , aristotelian metaphysics , or cartesian deductions overrule empirical , experimental evidence . his vision , uncluttered by speculation or rationalization , went deep . steno had seen how gallstones form in wet organs by accretion . they obeyed molding principles he knew from the goldsmith trade , rules useful across disciplines for understanding solids by their structural relationships . later , the grand duke of tuscany had him dissect a shark . its teeth resembled tongue stones , odd rocks seen inside other rocks in malta and the mountains near florence . pliny the elder , old roman naturalist , said these fell from the sky . in the dark ages , folks said they were snake tongues , petrified by saint paul . steno saw that tongue stones were shark teeth and vice versa , with the same signs of structural growth . figuring similar things are made in similar ways , he argued the ancient teeth came from ancient sharks in waters that formed rock around the teeth and became mountains . rock layers were once layers of watery sediment , which would lay out horizontally , one atop another , oldest up to newest . if layers were deformed , tilted , cut by a fault or a canyon , that change came after the layer formed . sounds simple today ; back then , revolutionary . he 'd invented stratigraphy and laid geology 's ground work . by finding one origin for shark teeth from two eras by stating natural laws ruling the present also ruled the past , steno planted seeds for uniformitarianism , the idea that the past was shaped by processes observable today . in the 18th and 19th centuries , english uniformitarian geologists , james hutton and charles lyell , studied current , very slow rates of erosion and sedimentation and realized the earth had to be way older than the biblical guestimate , 6000 years . out of their work came the rock cycle , which combined with plate tectonics in the mid-twentieth century to give us the great molten-crusting , quaking , all-encircling theory of the earth , from a gallstone to a 4.5 billion-year-old planet . now think bigger , take it to biology . say you see shark teeth in one layer and a fossil of an organism you 've never seen under that . the deeper fossil 's older , yes ? you now have evidence of the origin and extinction of species over time . get uniformitarian . maybe a process still active today caused changes not just in rocks but in life . it might also explain similarities and differences between species found by anatomists like steno . it 's a lot to ponder , but charles darwin had the time on a long trip to the galapagos , reading a copy of his friend charles lyell 's `` principles of geology , '' which steno sort of founded . sometimes giants stand on the shoulders of curious little people . nicolas steno helped evolve evolution , broke ground for geology , and showed how unbiased , empirical observation can cut across intellectual borders to deepen our perspective . his finest accomplishment , though , may be his maxim , casting the search for truth beyond our senses and our current understanding as the pursuit of the beauty of the as yet unknown . beautiful is what we see , more beautiful is what we know , most beautiful , by far , is what we do n't .
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figuring similar things are made in similar ways , he argued the ancient teeth came from ancient sharks in waters that formed rock around the teeth and became mountains . rock layers were once layers of watery sediment , which would lay out horizontally , one atop another , oldest up to newest . if layers were deformed , tilted , cut by a fault or a canyon , that change came after the layer formed .
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stratigraphy is useful for putting together a timeline of life forms found in rock layers , but what other facts or laws do you need to make that timeline as useful as possible ? what does stratigraphy not provide ?
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what does the french revolution have to do with the time nasa accidentally crashed a $ 200 million orbiter into the surface of mars ? actually , everything . that crash happened due to an error in converting between two measurement systems , u.s. customary units and their s.i , or metric , equivalence . so what 's the connection to the french revolution ? let 's explain . for the majority of recorded human history , units like the weight of a grain or the length of a hand were n't exact and varied from place to place . and different regions did n't just use varying measurements . they had completely different number systems as well . by the late middle ages , the hindu-arabic decimal system mostly replaced roman numerals and fractions in europe , but efforts by scholars like john wilkins to promote standard decimal-based measures were less successful . with a quarter million different units in france alone , any widespread change would require massive disruption . and in 1789 , that disruption came . the leaders of the french revolution did n't just overthrow the monarchy . they sought to completely transform society according to the rational principles of the enlightenment . when the new government took power , the academy of sciences convened to reform the system of measurements . old standards based on arbitrary authority or local traditions were replaced with mathematical and natural relationships . for example , the meter , from the greek word for measure , was defined as 1/10,000,000 between the equator and north pole . and the new metric system was , in the words of the marquis de condorcet , `` for all people , for all time . '' standardizing measurements had political advantages for the revolutionaries as well . nobles could no longer manipulate local units to extract more rent from commoners , while the government could collect taxes more efficiently . and switching to a new republican calendar with ten-day weeks reduced church power by eliminating sundays . adoption of this new system was n't easy . in fact , it was a bit of a mess . at first , people used new units alongside old ones , and the republican calendar was eventually abandoned . when napoléon bonaparte took power , he allowed small businesses to use traditional measurements redefined in metric terms . but the metric system remained standard for formal use , and it spread across the continent , along with france 's borders . while napoléon 's empire lasted eight years , its legacy endured far longer . some european countries reverted to old measurements upon independence . others realized the value of standardization in an age of international trade . after portugal and the netherlands switched to metric voluntarily , other nations followed , with colonial empires spreading the system around the world . as france 's main rival , britain had resisted revolutionary ideas and retained its traditional units . but over the next two centuries , the british empire slowly transitioned , first approving the metric system as an optional alternative before gradually making it offical . however , this switch came too late for thirteen former colonies that had already gained independence . the united states of america stuck with the english units of its colonial past and today remains one of only three countries which have n't fully embraced the metric system . despite constant initiatives for metrication , many americans consider units like feet and pounds more intuitive . and ironically , some regard the once revolutionary metric system as a symbol of global conformity . nevertheless , the metric system is almost universally used in science and medicine , and it continues to evolve according to its original principles . for a long time , standard units were actually defined by carefully maintained physical prototypes . but thanks to improving technology and precision , these objects with limited access and unreliable longevity are now being replaced with standards based on universal constants , like the speed of light . consistent measurements are such an integral part of our daily lives that it 's hard to appreciate what a major accomplishment for humanity they 've been . and just as it arose from a political revolution , the metric system remains crucial for the scientific revolutions to come .
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consistent measurements are such an integral part of our daily lives that it 's hard to appreciate what a major accomplishment for humanity they 've been . and just as it arose from a political revolution , the metric system remains crucial for the scientific revolutions to come .
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what circumstances during the french revolution permitted the metric system to gain a foothold ?
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imagine this : you 're fast asleep when all of a sudden you 're awoken ! and not by your alarm clock . your eyes open , and there 's a demon sitting on your chest , pinning you down . you try to open your mouth and scream , but no sound comes out . you try to get up and run away , but you realize that you are completely immobilized . the demon is trying to suffocate you , but you ca n't fight back . you 've awoken into your dream , and it 's a nightmare . it sounds like a stephen king movie , but it 's actually a medical condition called sleep paralysis , and about half of the population has experienced this strange phenomenon at least once in their life . this panic-inducing episode of coming face-to-face with the creatures from your nightmares can last anywhere from seconds to minutes and may involve visual or auditory hallucinations of an evil spirit or an out-of-body feeling like you 're floating . some have even mistaken sleep paralysis for an encounter with a ghost or an alien abduction . in 1867 , dr. silas weir mitchell was the first medical professional to study sleep paralysis . `` the subject awakes to consciousness of his environment but is incapable of moving a muscle . lying to all appearance , still asleep . he 's really engaged for a struggle for movement , fraught with acute mental distress . could he but manage to stir , the spell would vanish instantly . '' even though dr. mitchell was the first to observe patients in a state of sleep paralysis , it 's so common that nearly every culture throughout time has had some kind of paranormal explanation for it . in medieval europe , you might think that an incubus , a sex-hungry demon in male form , visited you in the night . in scandinavia , the mare , a damned woman , is responsible for visiting sleepers and sitting on their rib cages . in turkey , a jinn holds you down and tries to strangle you . in thailand , phi am bruises you while you sleep . in the southern united states , the hag comes for you . in mexico , you could blame subirse el muerto , the dead person , on you . in greece , mora sits upon your chest and tries to asphyxiate you . in nepal , khyaak the ghost resides under the staircase . it may be easier to blame sleep paralysis on evil spirits because what 's actually happening in your brain is much harder to explain . modern scientists believe that sleep paralysis is caused by an abnormal overlap of the rem , rapid eye movement , and waking stages of sleep . during a normal rem cycle , you 're experiencing a number of sensory stimuli in the form of a dream , and your brain is unconscious and fully asleep . during your dream , special neurotransmitters are released , which paralyze almost all of your muscles . that 's called rem atonia . it 's what keeps you from running in your bed when you 're being chased in your dreams . during an episode of sleep paralysis , you 're experiencing normal components of rem . you 're dreaming and your muscles are paralyzed , only your brain is conscious and wide awake . this is what causes you to imagine that you 're having an encounter with a menacing presence . so this explains the hallucinations , but what about the feelings of panic , strangling , choking , chest pressure that so many people describe ? well during rem , the function that keeps you from acting out your dreams , rem atonia , also removes voluntary control of your breathing . your breath becomes more shallow and rapid . you take in more carbon dioxide and experience a small blockage of your airway . during a sleep paralysis episode , a combination of your body 's fear response to a perceived attack by an evil creature and your brain being wide awake while your body is in an rem sleep state triggers a response for you to take in more oxygen . that makes you gasp for air , but you ca n't because rem atonia has removed control of your breath . this struggle for air while your body sleeps creates a perceived sensation of pressure on the chest or suffocation . while a few people experience sleep paralysis regularly and it may be linked to sleep disorders such as narcolepsy , many who experience an episode of sleep paralysis do so infrequently , perhaps only once in a lifetime . so you can rest easy , knowing that an evil entity is not trying to haunt , possess , strangle , or suffocate you . save that for the horror films !
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could he but manage to stir , the spell would vanish instantly . '' even though dr. mitchell was the first to observe patients in a state of sleep paralysis , it 's so common that nearly every culture throughout time has had some kind of paranormal explanation for it . in medieval europe , you might think that an incubus , a sex-hungry demon in male form , visited you in the night .
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even though there is a scientific explanation for the phenomenon of sleep paralysis , people all over the worlds still have paranormal explanations for it . why do you think that is ?
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what would you do if you thought your country was on the path to tyranny ? if you saw one man gaining too much power , would you try to stop him ? even if that man was one of your closest friends and allies ? these were the questions haunting roman senator marcus junius brutus in 44 bce , the year julius caesar would be assassinated . opposing unchecked power was n't just a political matter for brutus ; it was a personal one . he claimed descent from lucius junius brutus , who had helped overthrow the tyrannical king known as tarquin the proud . instead of seizing power himself , the elder brutus led the people in a rousing oath to never again allow a king to rule . rome became a republic based on the principle that no one man should hold too much power . now , four and a half centuries later , this principle was threatened . julius ceasar 's rise to the powerful position of consul had been dramatic . years of military triumphs had made him the wealthiest man in rome . and after defeating his rival pompey the great in a bitter civil war , his power was at its peak . his victories and initiatives , such as distributing lands to the poor , had made him popular with the public , and many senators vied for his favor by showering him with honors . statues were built , temples were dedicated , and a whole month was renamed , still called july today . more importantly , the title of dictator , meant to grant temporary emergency powers in wartime , had been bestowed upon caesar several times in succession . and in 44 bce , he was made dictator perpetuo , dictator for a potentially unlimited term . all of this was too much for the senators who feared a return to the monarchy their ancestors had fought to abolish , as well as those whose own power and ambition were impeded by caesar 's rule . a group of conspirators calling themselves the liberators began to secretly discuss plans for assassination . leading them were the senator gaius cassius longinus and his friend and brother-in-law , brutus . joining the conspiracy was not an easy choice for brutus . even though brutus had sided with pompey in the ill-fated civil war , caesar had personally intervened to save his life , not only pardoning him but even accepting him as a close advisor and elevating him to important posts . brutus was hesitant to conspire against the man who had treated him like a son , but in the end , cassius 's insistence and brutus 's own fear of caesar 's ambitions won out . the moment they had been waiting for came on march 15 . at a senate meeting held shortly before caesar was to depart on his next military campaign , as many as 60 conspirators surrounded him , unsheathing daggers from their togas and stabbing at him from all sides . as the story goes , caesar struggled fiercely until he saw brutus . despite the famous line , `` et tu , brute ? '' written by shakespeare , we do n't know caesar 's actual dying words . some ancient sources claim he said nothing , while others record the phrase , `` and you , child ? `` , fueling speculation that brutus may have actually been caesar 's illegitimate son . but all agree that when caesar saw brutus among his attackers , he covered his face and gave up the fight , falling to the ground after being stabbed 23 times . unfortunately for brutus , he and the other conspirators had underestimated caesar 's popularity among the roman public , many of whom saw him as an effective leader , and the senate as a corrupt aristocracy . within moments of caesar 's assassination , rome was in a state of panic . most of the other senators had fled , while the assassins barricaded themselves on the capitoline hill . mark antony , caesar 's friend and co-consul , was swift to seize the upper hand , delivering a passionate speech at caesar 's funeral days later that whipped the crowd into a frenzy of grief and anger . as a result , the liberators were forced out of rome . the ensuing power vacuum led to a series of civil wars , during which brutus , facing certain defeat , took his own life . ironically , the ultimate result would be the opposite of what the conspirators had hoped to accomplish : the end of the republic and the concentration of power under the office of emperor . opinions over the assassination of caesar were divided from the start and have remained so . as for brutus himself , few historical figures have inspired such a conflicting legacy . in dante 's `` inferno , '' he was placed in the very center of hell and eternally chewed by satan himself for his crime of betrayal . but swift 's `` gulliver 's travels '' described him as one of the most virtuous and benevolent people to have lived . the interpretation of brutus as either a selfless fighter against dictatorship or an opportunistic traitor has shifted with the tides of history and politics . but even today , over 2000 years later , questions about the price of liberty , the conflict between personal loyalties and universal ideals , and unintended consequences remain more relevant than ever .
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even if that man was one of your closest friends and allies ? these were the questions haunting roman senator marcus junius brutus in 44 bce , the year julius caesar would be assassinated . opposing unchecked power was n't just a political matter for brutus ; it was a personal one .
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which position was permanently granted to julius caesar in 44 bce ?
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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 .
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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 .
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force is the product of
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this might seem hard to believe , but right now , 300 million women across the planet are experiencing the same thing : a period . the monthly menstrual cycle that leads to the period is a reality most women on earth will go through in their lives . but why is this cycle so universal ? and what makes it a cycle in the first place ? periods last anywhere between two and seven days , arising once within in a 28-day rotation . that whole system occurs on repeat , happening approximately 450 times during a woman 's life . behind the scenes are a series of hormonal controls that fine tune the body 's internal workings to make menstruation start or stop during those 28 days . this inner machinery includes two ovaries stocked with thousands of tiny sacks called follicles that each contain one oocyte , an unfertilized egg cell . at puberty , ovaries hold over 400 thousand egg cells , but release only one each month , which results in pregnancy or a period . here 's how this cycle unfolds . each month beginning around puberty , the hormone-producing pituitary gland in the brain starts releasing two substances into the blood : follicle stimulating hormone and luteinizing hormone . when they reach the ovaries , they encourage the internal egg cells to grow and mature . the follicles respond by pumping out estrogen . the egg cells grow and estrogen levels peak , inhibiting the production of fsh , and telling the pituitary to pump out more lh . that causes only the most mature egg cell from one of the ovaries to burst out of the follicle and through the ovary wall . this is called ovulation , and it usually happens ten to sixteen days before the start of a period . the tiny oocyte moves along the fallopian tube . a pregnancy can only occur if the egg is fertilized by a sperm cell within the next 24 hours . otherwise , the egg 's escapade ends , and the window for pregnancy closes for that month . meanwhile , the now empty follicle begins to release progesterone , another hormone that tells the womb 's lining to plump up with blood and nutrients in preparation for a fertilized egg that may embed there and grow . if it does n't embed , a few days later , the body 's progesterone and estrogen levels plummet , meaning the womb stops padding out and starts to degenerate , eventually falling away . blood and tissue leave the body , forming the period . the womb can take up to a week to clear out its unused contents , after which , the cycle begins anew . soon afterwards , the ovaries begin to secrete estrogen again , and the womb lining thickens , getting ready to accommodate a fertilized egg or be shed . hormones continually control these activities by circulating in ideal amounts delivered at just the right time . the cycle keeps on turning , transforming each day and each week into a milestone along its course towards pregnancy or a period . although this cycle appears to move by clockwork , there 's room for variation . women and their bodies are unique , after all . menstrual cycles occur at diffferent times in the month , ovulation comes at various points in the cycle , and some periods last longer than others . menstruation even begins and ends at different times in life for different women , too . in other words , variations between periods are normal . appreciating these differences and learning about this monthly process can empower women , giving them the tools to understand and take charge of their own bodies . that way , they 're able to factor this small cycle into a much larger cycle of life .
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although this cycle appears to move by clockwork , there 's room for variation . women and their bodies are unique , after all . menstrual cycles occur at diffferent times in the month , ovulation comes at various points in the cycle , and some periods last longer than others .
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why do you think women 's periods vary so much ?
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translator : andrea mcdonough reviewer : bedirhan cinar you know what the greatest secret of history is ? it 's that history can be changed . and , yeah , yeah , i know , everyone says history ca n't be changed , but it can . and today we 're going to talk about how history is n't just something that goes backwards , history goes forward too . and all those great things that have n't happened yet , that 's history that 's just waiting to be written . so how do you change history ? i 'm going to tell you by sharing with you the three things that i tell my kids every night when i tuck them into bed . it 's true . i stole the idea from a friend of mine who told me what his father used to share with him . every single night , when i tuck my kids into bed , i tell them these three things : dream big , work hard , and stay humble . so let 's look at them all . first , dream big . you know who has the biggest , best dreams of all ? you , young people . you know how old martin luther king , jr. was when he became the leader of the most famous bus boycott in history ? he was 26 . you know how old amelia earhart was when she broke her first world record ? 25 you know how old steve jobs was when he co-founded apple computer ? 21 and you know how old jerry siegel and joe shuster were when they came up with their idea for the greatest superhero of all time , the first one , that they named `` superman '' ? these guys were 17 years old ! two 17-year-old kids created superman . they were n't good looking . ( look at the picture , right ? ) they were n't popular . they had no money , but they were two best friends with one dream . and with just their imaginations , they gave the world superman . and i know , creating superman is a once-in-a-lifetime big dream , so i want to tell you about alexandra scott . she goes by alex . alex was diagnosed with cancer before she was even a year old , and that was the only life she knew : sickness , chemotherapy , and surgery . when she was four , alex asked her parents could she put a lemonade stand in the front yard ? she did n't want to buy anything for herself , she wanted to use the money to give it to doctors to help other kids with cancer . ok , in a single day , alex 's lemonade stand raised $ 2,000 ! but , here 's what i love : soon after that , other lemonade stands started popping up , all with alex 's name on it . eventually , they raised $ 200,000 . and then alex had a new goal . she said let 's raise $ 1,000,000 . on june 12 , 2004 , hundreds of lemonade stands started opening up in every state in the country . ordinary people selling water and sugar and lemons to help kids with cancer . nearly two months later , alex died while her parents were holding her hands . she was 8 years old . but before she died , alex said that next year 's goal should be $ 5,000,000 . today , her dream has raised over $ 45,000,000 and it is still going strong ! one idea , one girl , one big dream . and you know what she said ? this is a direct quote before she died . she said , `` oh , we can do it ! if other people will help me , i think we can do it . i know we can do it ! '' you dream big , i do n't care how old you are , and do n't let anyone tell you otherwise , you will change history . and that leads me to the second thing i tell my kids : work hard . such a simple one , everyone knows this one . work hard . i saw this one for my father and my father died a few months ago . when i was growing up in brooklyn , ok , my father , he worked hard . he had no money , we had , no money growing up . he worked every saturday , every sunday . i watched first-hand every weekend what hard work was . and i saw that the hardest work of all is being resilient when you 're facing failure . when i started writing my first book , my first book got me 24 rejection letters . to be clear , there are only 20 publishers , i got 24 rejection letters , ok ? that means that some people were writing me twice to make sure i got the point . but it was n't until i was writing my ninth book , a book of heroes for my son , that i found my favorite story of working hard through failure . it was a story that a friend told me about the wright brothers . that every time the wright brothers went out to fly their plane , they would bring enough extra materials for multiple crashes . that means for every time they went out , they knew they would fail . and they would crash and rebuild , and crash and rebuild , and that 's why they took off . i love that story . i wanted my son to hear that story , i wanted my daughter to hear that story , i wanted everyone to know that if you dream big and you work hard and you fight failure , you will change history and do what no one on this planet has ever done before . and that leads me to the final thing i tell them : stay humble . here 's the thing : if you invent the world 's first airplane , or superman , or a multi-million dollar lemonade stand , you do n't need to be humble . you can get a tattoo on your face that says , `` i 'm the best ! '' right ? but pay attention here : no one likes a jerk . in fact , the world needs fewer loudmouths , so stay humble ! when thomas jefferson wrote the declaration of independence , you know he never took credit for writing it while he was alive ? it was n't until he died and it was in his obituary that the average american found out that he was the author . that 's humble . so there 's the big secret : dream big , work hard , stay humble . `` wait , '' you 're saying , `` that 's it ? '' `` what , you tell me a bunch of stories and what ? how do i change history ? '' here 's the answer : all history ever is is a bunch of stories , conflicting stories , big stories , little stories , our stories . so how do you change history ? all you got to do is write your story . ok ? no , i 'm serious , this is it . if people think history is a bunch of facts and dates you got to memorize , that 's not what history is at all . history is a selection process , and it chooses every single one of us every single day . the only question is , do you hear the call ? and that leads me to the most important thing i 'm going to tell you here : you will change history . some of you will change it in big ways , affecting millions of people . others of you will do it in more personal ways , helping a family member or someone who needs it . but let me tell you right now , one is not more important than the other . if you help people in mass or one-by-one , that 's how history gets changed , when you take action . but when you start writing your story and you get scared , as we all inevitably do , i want you to know one thing : no one is born a hero . every single person that we talked about today , whether they were a 26 year old preacher , or two 17 year old nerds , or little girl who had cancer , every single one of them had moments where they doubted themselves , like you , like me . they had moments where they worried about school and friendships and would they be accepted by others , like you , like me . they had moments where they worried about loneliness and failure and would they ever succeed , like you , like me . but the best part is , you do n't have to start a multi-million dollar lemonade stand to change the world , all you got to do is help one person , be kind to one person , that 's the answer . it 's my core belief , it is in every story i just told you . i believe ordinary people change the world . i do n't care how much money you have , i do n't care where you go to school , that is all nonsense to me . i believe in regular people and their ability to affect change in this world . i believe in my father , and a 25 year old daredevil named amelia , and a little girl who sells lemonade like nobody 's business . and it 's why i believe in that very first hero we were talking about today , superman . to me , the most important part of the story is n't superman . the most important part of the story is clark kent . and you want to know why ? because we 're all clark kent . we all know what it 's like to be boring and ordinary and wish we could do something incredibly beyond ourselves . but here 's the real news : we all can do something incredibly beyond ourselves . i got 24 rejection letters on my first book , 24 people who told me to give it up , and i do n't look back on the experience and say , `` i was right , and they were wrong , and haha on them . '' what i look back and realize is that every single one of those rejection letters told me to work harder , to dream bigger , and you better believe it , made me more humble , but it also made me want it more than anything . so whatever it is you dream big about , whatever it is you work hard for , do n't let anyone tell you , you 're too young and do n't let anyone tell you no . every life makes history . and every life is a story . thank you .
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i believe in my father , and a 25 year old daredevil named amelia , and a little girl who sells lemonade like nobody 's business . and it 's why i believe in that very first hero we were talking about today , superman . to me , the most important part of the story is n't superman . the most important part of the story is clark kent . and you want to know why ?
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tell a short story about what makes your hero so important to you .
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some superheroes can grow to the size of a building at will . that 's very intimidating ! but a scientist must ask where the extra material is coming from . the law of conservation of mass implies that mass can neither be created nor destroyed , which means that our hero 's mass will not change just because his size changes . for instance , when we bake a fluffy sponge cake , even though the resulting delicious treat is much bigger in size than the cake batter that went into the oven , the weight of the cake batter should still equal the weight of the cake plus the moisture that has evaporated . in a chemical equation , molecules rearrange to make new compounds , but all the components should still be accounted for . when our hero expands from 6 feet tall to 18 feet tall , his height triples . galileo 's square cube law says his weight will be 27 - 3 times 3 times 3 equals 27 - times his regular weight since he has to expand in all three dimensions . so , when our superhero transforms into a giant , we are dealing with two possibilities . our hero towering at 18 feet still only weighs 200 pounds , the original weight in this human form . now , option two , our hero weighs 5,400 pounds - 200 pounds times 27 equals 5,400 pounds - when he is 18 feet tall , which means he also weighs 5,400 pounds when he is 6 feet tall . nobody can get in the same elevator with him without the alarm going off . now , option two seems a little more scientifically plausible , but it begs the question , how does he ever walk through the park without sinking into the ground since the pressure he is exerting on the soil is calculated by his mass divided by the area of the bottom of his feet ? and what kind of super socks and super shoes is he putting on his feet to withstand all the friction that results from dragging his 5,400 pound body against the road when he runs ? and can he even run ? and i wo n't even ask how he finds pants flexible enough to withstand the expansion . now , let 's explore the density of the two options mentioned above . density is defined as mass divided by volume . the human body is made out of bones and flesh , which has a relatively set density . in option one , if the hero weighs 200 pounds all the time , then he would be bones and flesh at normal size . when he expands to a bigger size while still weighing 200 pounds , he essentially turns himself into a giant , fluffy teddy bear . in option two , if the hero weighs 5,400 pounds all the time , then he would be bones and flesh at 18 feet with 5,400 pounds of weight supported by two legs . the weight would be exerted on the leg bones at different angles as he moves . bones , while hard , are not malleable , meaning they do not bend , so they break easily . the tendons would also be at risk of tearing . tall buildings stay standing because they have steel frames and do not run and jump around in the jungle . our hero , on the other hand , one landing at a bad angle and he 's down . assuming his bodily function is the same as any mammal 's , his heart would need to pump a large amount of blood throughout his body to provide enough oxygen for him to move 5,400 pounds of body weight around . this would take tremendous energy , which he would need to provide by consuming 27 times 3,000 calories of food every day . now , that is roughly 150 big macs . 27 times 3,000 calculated equals 81,000 calculated slash 550 calories equals 147 . he would n't have time to fight crime because he would be eating all the time and working a 9-to-5 job in order to afford all the food he eats . and what about superheroes who can turn their bodies into rocks or sand ? well , everything on earth is made out of elements . and what defines each element is the number of protons in the nucleus . that is how our periodic table is organized . hydrogen has one proton , helium , two protons , lithium , three protons , and so on . the primary component of the most common form of sand is silicon dioxide . meanwhile , the human body consists of 65 % oxygen , 18 % carbon , 10 % hydrogen , and 7 % of various other elements including 0.002 % of silicon . in a chemical reaction , the elements recombine to make new compounds . so , where is he getting all this silicon necessary to make the sand ? sure , we can alter elements by nuclear fusion or nuclear fission . however , nuclear fusion requires so much heat , the only natural occurrence of this process is in stars . in order to utilize fusion in a short amount of time , the temperature of the area needs to be hotter than the sun . every innocent bystander will be burned to a crisp . rapid nuclear fission is not any better since it often results in many radioactive particles . our hero would become a walking , talking nuclear power plant , ultimately harming every person he tries to save . and do you really want the heat of the sun or a radioactive nuclear plant inside of your body ? now , which superpower physics lesson will you explore next ? shifting body size and content , super speed , flight , super strength , immortality , and invisibility .
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but a scientist must ask where the extra material is coming from . the law of conservation of mass implies that mass can neither be created nor destroyed , which means that our hero 's mass will not change just because his size changes . for instance , when we bake a fluffy sponge cake , even though the resulting delicious treat is much bigger in size than the cake batter that went into the oven , the weight of the cake batter should still equal the weight of the cake plus the moisture that has evaporated .
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please use three examples to explain galileo ’ s law of conservation of mass .
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ah , romantic love - beautiful and intoxicating , heartbreaking and soul-crushing , often all at the same time . why do we choose to put ourselves through its emotional wringer ? does love make our lives meaningful , or is it an escape from our loneliness and suffering ? is love a disguise for our sexual desire , or a trick of biology to make us procreate ? is it all we need ? do we need it at all ? if romantic love has a purpose , neither science nor psychology has discovered it yet . but over the course of history , some of our most respected philosophers have put forward some intriguing theories . love makes us whole , again . the ancient greek philosopher plato explored the idea that we love in order to become complete . in his `` symposium '' , he wrote about a dinner party , at which aristophanes , a comic playwright , regales the guests with the following story : humans were once creatures with four arms , four legs , and two faces . one day , they angered the gods , and zeus sliced them all in two . since then , every person has been missing half of him or herself . love is the longing to find a soulmate who 'll make us feel whole again , or , at least , that 's what plato believed a drunken comedian would say at a party . love tricks us into having babies . much , much later , german philosopher arthur schopenhauer maintained that love based in sexual desire was a voluptuous illusion . he suggested that we love because our desires lead us to believe that another person will make us happy , but we are sorely mistaken . nature is tricking us into procreating , and the loving fusion we seek is consummated in our children . when our sexual desires are satisfied , we are thrown back into our tormented existences , and we succeed only in maintaining the species and perpetuating the cycle of human drudgery . sounds like somebody needs a hug . love is escape from our loneliness . according to the nobel prize-winning british philosopher bertrand russell , we love in order to quench our physical and psychological desires . humans are designed to procreate , but without the ecstasy of passionate love , sex is unsatisfying . our fear of the cold , cruel world tempts us to build hard shells to protect and isolate ourselves . love 's delight , intimacy , and warmth helps us overcome our fear of the world , escape our lonely shells , and engage more abundantly in life . love enriches our whole being , making it the best thing in life . love is a misleading affliction . siddhārtha gautama , who became known as the buddha , or the enlightened one , probably would have had some interesting arguments with russell . buddha proposed that we love because we are trying to satisfy our base desires . yet , our passionate cravings are defects , and attachments , even romantic love , are a great source of suffering . luckily , buddha discovered the eight-fold path , a sort of program for extinguishing the fires of desire so that we can reach nirvana , an enlightened state of peace , clarity , wisdom , and compassion . the novelist cao xueqin illustrated this buddhist sentiment that romantic love is folly in one of china 's greatest classical novels , `` dream of the red chamber . '' in a subplot , jia rui falls in love with xi-feng who tricks and humiliates him . conflicting emotions of love and hate tear him apart , so a taoist gives him a magic mirror that can cure him as long as he does n't look at the front of it . but of course , he looks at the front of it . he sees xi-feng . his soul enters the mirror and he is dragged away in iron chains to die . not all buddhists think this way about romantic and erotic love , but the moral of this story is that such attachments spell tragedy , and should , along with magic mirrors , be avoided . love lets us reach beyond ourselves . let 's end on a slightly more positive note . the french philosopher simone de beauvoir proposed that love is the desire to integrate with another and that it infuses our lives with meaning . however , she was less concerned with why we love and more interested in how we can love better . she saw that the problem with traditional romantic love is it can be so captivating , that we are tempted to make it our only reason for being . yet , dependence on another to justify our existence easily leads to boredom and power games . to avoid this trap , beauvoir advised loving authentically , which is more like a great friendship . lovers support each other in discovering themselves , reaching beyond themselves , and enriching their lives and the world together . though we might never know why we fall in love , we can be certain that it will be an emotional rollercoaster ride . it 's scary and exhilarating . it makes us suffer and makes us soar . maybe we lose ourselves . maybe we find ourselves . it might be heartbreaking , or it might just be the best thing in life . will you dare to find out ?
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since then , every person has been missing half of him or herself . love is the longing to find a soulmate who 'll make us feel whole again , or , at least , that 's what plato believed a drunken comedian would say at a party . love tricks us into having babies .
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plato 's character aristophanes in symposium suggests that love is the longing to find :
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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 .
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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 .
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which president did banneker write to regarding the poor treatment of black slaves in the country ?
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we check the time every day , all day long . but did you ever wonder - where did telling time come from ? why does it matter what time it is ? who determined the clock and why in the world are there so many different time zones ? the first form of telling time was the sundial and the earliest sundials known from the archaeological record are obelisks from nearly 5,000 years ago . sundials indicate the time by casting a shadow onto a surface . the object that casts the shadow is a stick in the center known as a gnomon . a well-constructed sundial can measure time with remarkable accuracy , and sundials were used to monitor the performance of clocks until the modern era . but sundials have their limitations too . obviously they require the sun to shine , so they do n't work at all during the night when it 's dark . many different devices have been used over the years to estimate the passage of time : candles and sticks of incense that burn down at fairly predictable speeds have been used , along with the hourglass . hourglasses are devices in which fine sand pours through a tiny hole at a constant rate and indicates a predetermined passage of an arbitrary period of time . the origin of the hourglass is uncertain , although beginning in the 14th century , the hourglass was used commonly , especially on board ships . the motion of the boat on the water did not affect the hourglass , unlike other time-measuring devices . the mechanical clock was invented in the 13th century which sparked a big change in traditional timekeeping methods . this modern clock relied on the swing of a pendulum or the vibration of a quartz crystal , which was far more accurate than sand or candles . today , the basis for scientific time is a continuous count of seconds based on atomic clocks all around the world , known as the international atomic time . why does it matter that we keep track of time ? well , time regulates our daily lives and makes it possible to accurately communicate with people all over the world . without a time system , we would have many challenges in farming , social structures , communication , and business . take the american railroad system , for example . in the mid-19th century , each railroad used its own standard time generally based on the local time of its headquarters , and the railroad 's train schedules were published using its own time . some major railroad junctions served by several different railroads had a separate clock for each railroad , each showing a different time . the distance between new york and boston is about 2 degrees , or 8 minutes , which can be the difference between making or missing your train connection . if the difference between new york and boston is 8 minutes , imagine the difference between boston and australia . the use of time zones irons out these differences and makes communication significantly smoother . a time zone is a region on earth that has a uniform standard time . there are 40 time zones on land because the earliest and latest time zones are 26 hours apart . any given calendar date exists at some point on the globe for 50 hours . so the next time someone asks you `` what time is it ? '' your answer may be a whole lot more complicated than it used to be .
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why does it matter what time it is ? who determined the clock and why in the world are there so many different time zones ? the first form of telling time was the sundial and the earliest sundials known from the archaeological record are obelisks from nearly 5,000 years ago .
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the basis of the world clock is :
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how much would you pay for a bouquet of tulips ? a few dollars ? a hundred dollars ? how about a million dollars ? probably not . well , how much would you pay for this house , or partial ownership of a website that sells pet supplies ? at different points in time , tulips , real estate and stock in pets.com have all sold for much more than they were worth . in each instance , the price rose and rose and then abruptly plummeted . economists call this a bubble . so what is exactly is going on with a bubble ? well , let 's start with the tulips to get a better idea . the 17th century saw the netherlands enter the dutch golden age . by the 1630s , amsterdam was an important port and commercial center . dutch ships imported spices from asia in huge quantities to earn profits in europe . so amsterdam was brimming with wealthy , skilled merchants and traders who displayed their prosperity by living in mansions surrounded by flower gardens . and there was one flower in particularly high demand : the tulip . the tulip was brought to europe on trading vessels that sailed from the east . because of this , it was considered an exotic flower that was also difficult to grow , since it could take years for a single tulip to bloom . during the 1630s , an outbreak of tulip breaking virus made select flowers even more beautiful by lining petals with multicolor , flame-like streaks . a tulip like this was scarcer than a normal tulip and as a result , prices for these flowers started to rise , and with them , the tulip 's popularity . it was n't long before the tulip became a nationwide sensation and tulip mania was born . a mania occurs when there is an upward movement of price combined with a willingness to pay large sums of money for something valued much lower in intrinsic value . a recent example of this is the dot-com mania of the 1990s . stocks in new , exciting websites were like the tulips of the 17th century . everybody wanted some . the more people who wanted the tulip , the higher the price could go . at one point , a single tulip bulb sold for more than ten times the annual salary of a skilled craftsman . in the stock market , the price of stock is based on the supply and demand of investors . stock prices tend to rise when it seems like a company will earn more in the future . investors might then buy more of the stock , raising the prices even further due to an increased demand . this can result in a feedback loop where investors get caught up in the hype and ultimately drive prices far above intrinsic value , creating a bubble . all that is needed for a mania to end and for a bubble to burst is the collective realization that the price of the stock , or a tulip , far exceeds its worth . that 's what happened with both manias . suddenly the demand ended . prices were pushed to staggering lows , and pop ! the bubbles burst , and the market crashed . today , scholars work long and hard trying to predict what causes a bubble and how to avoid them . tulip mania is an effective illustration of the underlying principles at work in a bubble and can help us understand more recent examples like the real estate bubble of the late 2000s . the economy will continue to go through phases of booms and busts . so while we wait for the next mania to start , and the next bubble to burst , treat yourself to a bouquet of tulips and enjoy the fact that you did n't have to pay an arm and a leg for them .
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in each instance , the price rose and rose and then abruptly plummeted . economists call this a bubble . so what is exactly is going on with a bubble ?
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how does an economic bubble burst ?
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what 's that sound ? depending on whom you ask , the crackle of popping joints is either the sound of sweet relief or the noxious tones of a stomach-turning habit . really , though . what 's that sound ? i mean , why does bending your joints in a certain way make them pop like that ? scientists have offered several explanations , including rapidly stretching ligaments , and in severe cases , actual bones grinding against each other . but the most common explanation for why your stretched-out joints sound like bubbles popping is that , well , there are bubbles in there . the joints in your fingers are the easiest ones to crack , but many people also crack the joints between vertebrae in their neck and back , and even their hips , wrists , shoulders and so on . all these joints are synovial joints , and they 're the most flexible ones in your body . the space between the two bones is filled with a viscous liquid , synovial fluid , which contains long , lubricating molecules , like hyaluronic acid and lubricin . synovial fluid is more or less the texture of egg yolk and its primary purpose is to cushion the bones and help them glide past each other . it also contains phagocytic cells that help clean up any bone or cartilage debris that ends up in the joint . but the reason it 's important for knuckle cracking is that , like other fluids in your body , it contains lots of dissolved gas molecules . knuckle-crackers know that to get that satisfying pop , you stretch the joint farther than it normally goes by bending your fingers backwards , for example . when you do that , the bones move away from each other . the space between bones gets bigger , but the amount of synovial fluid stays constant . that creates a low-pressure zone that pulls dissolved gases out of the synovial fluid , just like the carbon dioxide that fizzes out of soda when you twist open the cap . inside the joint , the escaping gases form a bubble with a pop . but the bubble does n't last long . the surrounding fluid presses on it until it finally collapses . the bubble 's gases scatter throughout the synovial cavity and slowly dissolve back into the fluid over the course of about twenty minutes , which is why it can take a while before you can pop the same joint again . some scientists think there may actually be two pops . one when the bubble forms , and another when it bursts . popping a joint temporarily enlarges it , which may be why dedicated knuckle- , neck- and back-crackers say the habit makes their joints feel looser and more flexible . but you may have heard from a concerned relative or annoyed officemate that cracking your joints will give you arthritis . a doctor named donald unger heard this , too . so , determined to disprove his mother 's warnings , he cracked the knuckles of his left hand repeatedly for 50 years , while the right-hand knuckles went unpopped . 36,500 cracks later , both hands were arthritis-free . for this selfless act of devotion to science , dr. unger received an ig nobel prize , a parody of the nobel prize that recognizes wacky , but weirdly fascinating , scientific accomplishments . unger wrote that his results should prompt investigation into other parental beliefs , like the importance of eating spinach . the jury 's still out on that one . as for knuckle-cracking , one study suggests that all that joint stretching and bubble bursting can cause your hands to swell and weaken your grip . but the biggest proven danger seems to be annoying those around you .
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it also contains phagocytic cells that help clean up any bone or cartilage debris that ends up in the joint . but the reason it 's important for knuckle cracking is that , like other fluids in your body , it contains lots of dissolved gas molecules . knuckle-crackers know that to get that satisfying pop , you stretch the joint farther than it normally goes by bending your fingers backwards , for example .
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describe what happens to a molecule of dissolved gas from the time just before the joint is popped to about twenty minutes afterwards .
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there is a curse that has plagued humanity since ancient times . the greeks fought it by chewing aromatic resins , while the chinese resorted to egg shells . in the ancient jewish talmud , it 's even considered legal grounds for divorce . this horrible scourge is halitosis , otherwise known as bad breath . but what causes it , and why is it so universally terrifying ? well , think of some of the worst odors you can imagine , like garbage , feces or rotting meat . all of these smells come from the activity of microorganisms , particularly bacteria , and , as disgusting as it may sound , similar bacteria live in the moisture-rich environment of your mouth . do n't panic . the presence of bacteria in your body is not only normal , it 's actually vital for all sorts of things , like digestion and disease prevention . but like all living things , bacteria need to eat . the bacteria in your mouth feed off of mucus , food remnants , and dead tissue cells . in order to absorb nutrients through their cell membranes , they must break down the organic matter into much smaller molecules . for example , they 'll break proteins into their component amino acids and then break those down even further into various compounds . some of the foul-smelling byproducts of these reactions , such as hydrogen sulfide and cadaverine , escape into the air and waft their way towards unsuspecting noses . our sensitivity to these odors and interpretation of them as bad smells may be an evolutionary mechanism warning us of rotten food and the presence of disease . smell is one of our most intimate and primal senses , playing a huge role in our attraction to potential mates . in one poll , 59 % of men and 70 % of women said they would n't go on a date with someone who has bad breath , which may be why americans alone spend $ 1 billion a year on various breath products . fortunately , most bad breath is easily treated . the worst smelling byproducts come from gram-negative bacteria that live in the spaces between gums and teeth and on the back of the tongue . by brushing and flossing our teeth , using antibacterial mouthwash at bedtime , gently cleaning the back of the tongue with a plastic scraper and even just eating a healthy breakfast , we can remove many of these bacteria and their food sources . in some cases , these measures may not be enough due to dental problems , nasal conditions , or rarer ailments , such as liver disease and uncontrolled diabetes . behaviors like smoking and excessive alcohol consumption also have a very recognizable odor . regardless of cause , the bad smell almost always originates in the mouth and not the stomach or elsewhere in the body . but one of the biggest challenges lies in actually determining how our breath smells in the first place , and it 's unclear why . it may be that we 're too acclimatized to the smell inside our own mouths to judge it . and methods like cupping your hands over your mouth , or licking and smelling your wrist do n't work perfectly either . one study showed that even when people do this , they tend to rate the smell subjectively according to how bad they thought it was going to be . but there 's one simple , if socially difficult , way of finding out how your breath smells : just take a deep breath and ask a friend .
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in one poll , 59 % of men and 70 % of women said they would n't go on a date with someone who has bad breath , which may be why americans alone spend $ 1 billion a year on various breath products . fortunately , most bad breath is easily treated . the worst smelling byproducts come from gram-negative bacteria that live in the spaces between gums and teeth and on the back of the tongue .
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do you think that some people are more offended by bad breath than others ?
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they say , 'time is money , ' but what does one really have to do with the other ? meet sheila ! she just got her first big bonus . sheila knows exactly what she wants to do with that money . she 's had her eye on a nice convertible for a while now . yes , sheila , that 's a nice car ! oh , looks like sheila is a little short . but wait ! she has an idea . sheila is a smart cookie . she knows that if she deposits the money for a year instead of buying the car today , she will earn interest . then she 'll be able to afford the car . sheila knows that the value of her deposit one year from now will equal the money deposited today plus the interest earned . we call sheila 's money deposited today the present value of money . and the value of sheila 's deposit next year is the future value of money . what connects one to the other ? the interest rate , also known as the time value of money . now , with a little bit of rearranging , we can figure out the future value of sheila 's money with this equation . so in a year , the future value will be $ 11,000 . well , it 's been a year ! and there 's sheila , with enough money to buy the car . sheila really understands the future value of money . now , i just hope she understands the speed limit ! now , meet timmy . he 's also gotten his bonus . the money seems to be burning a hole in his pocket . yes , timmy , that 's a nice car that will surely impress people . oh ! looks like you 're a little short . maybe you can follow sheila 's example . you see , timmy , just like sheila , after the first year , you 'll have $ 11,000 . but timmy , that is still not enough to buy that fancy car . why do n't you leave the money deposited for another year ? let 's see how your deposit will be doing in two years . with a little bit of rearranging , it becomes the value of your money next year , times one plus the interest rate . we can then convert the future value one year from now to the present value times one plus the interest rate . we can even simplify this further by just squaring the value of one plus the interest rate . sorry , timmy , you 'll have more money after two years , but you still ca n't afford the car ! i do n't know how many more years you 'll have to wait , but i can tell you one way we can figure it out . do you see that little number two in the equation ? any number that you put in there is the number of years that you are waiting , also known as the period . sure , timmy , we can see how much you 'll have in five years . let 's connect future value and present value across five years . let 's watch the period increase from two to five . after 5 years , you 'll have $ 16,105.10 . sorry , timmy , you have to wait a little longer . 10 years ? yeah ! let 's see if you 'll be able to buy the car then . not quite . well , timmy , it looks like you 'll need 26 years to afford this car . you should ask sheila for a ride to the beach . maybe a bicycle will suit you better ? i hear the bus is pretty cheap !
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sure , timmy , we can see how much you 'll have in five years . let 's connect future value and present value across five years . let 's watch the period increase from two to five .
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could you extrapolate the concepts of investments , present value , future value and interest rates into other financial concepts like expected sales given present sales numbers , growth rate and number of years ?
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nicolas steno is rarely heard of outside intro to geology , but anyone hoping to understand life on earth should see how steno expanded and connected those very concepts : earth , life , and understanding . born niels stensen in 1638 denmark , son of a goldsmith , he was a sickly kid whose school chums died of plague . he survived to cut up corpses as an anatomist , studying organs shared across species . he found a duct in animal skulls that sends saliva to the mouth . he refuted descartes ' idea that only humans had a pineal gland , proving it was n't the seat of the soul , arguably , the debut of neuroscience . most remarkable for the time was his method . steno never let ancient texts , aristotelian metaphysics , or cartesian deductions overrule empirical , experimental evidence . his vision , uncluttered by speculation or rationalization , went deep . steno had seen how gallstones form in wet organs by accretion . they obeyed molding principles he knew from the goldsmith trade , rules useful across disciplines for understanding solids by their structural relationships . later , the grand duke of tuscany had him dissect a shark . its teeth resembled tongue stones , odd rocks seen inside other rocks in malta and the mountains near florence . pliny the elder , old roman naturalist , said these fell from the sky . in the dark ages , folks said they were snake tongues , petrified by saint paul . steno saw that tongue stones were shark teeth and vice versa , with the same signs of structural growth . figuring similar things are made in similar ways , he argued the ancient teeth came from ancient sharks in waters that formed rock around the teeth and became mountains . rock layers were once layers of watery sediment , which would lay out horizontally , one atop another , oldest up to newest . if layers were deformed , tilted , cut by a fault or a canyon , that change came after the layer formed . sounds simple today ; back then , revolutionary . he 'd invented stratigraphy and laid geology 's ground work . by finding one origin for shark teeth from two eras by stating natural laws ruling the present also ruled the past , steno planted seeds for uniformitarianism , the idea that the past was shaped by processes observable today . in the 18th and 19th centuries , english uniformitarian geologists , james hutton and charles lyell , studied current , very slow rates of erosion and sedimentation and realized the earth had to be way older than the biblical guestimate , 6000 years . out of their work came the rock cycle , which combined with plate tectonics in the mid-twentieth century to give us the great molten-crusting , quaking , all-encircling theory of the earth , from a gallstone to a 4.5 billion-year-old planet . now think bigger , take it to biology . say you see shark teeth in one layer and a fossil of an organism you 've never seen under that . the deeper fossil 's older , yes ? you now have evidence of the origin and extinction of species over time . get uniformitarian . maybe a process still active today caused changes not just in rocks but in life . it might also explain similarities and differences between species found by anatomists like steno . it 's a lot to ponder , but charles darwin had the time on a long trip to the galapagos , reading a copy of his friend charles lyell 's `` principles of geology , '' which steno sort of founded . sometimes giants stand on the shoulders of curious little people . nicolas steno helped evolve evolution , broke ground for geology , and showed how unbiased , empirical observation can cut across intellectual borders to deepen our perspective . his finest accomplishment , though , may be his maxim , casting the search for truth beyond our senses and our current understanding as the pursuit of the beauty of the as yet unknown . beautiful is what we see , more beautiful is what we know , most beautiful , by far , is what we do n't .
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nicolas steno is rarely heard of outside intro to geology , but anyone hoping to understand life on earth should see how steno expanded and connected those very concepts : earth , life , and understanding . born niels stensen in 1638 denmark , son of a goldsmith , he was a sickly kid whose school chums died of plague .
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what might a uniformitarianist meteorologist say about the prospect of a super-blizzard covering the northern hemisphere of the earth over the course of a day ?
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translator : andrea mcdonough reviewer : bedirhan cinar at birth , our bodies are roughly 75 % water . we remain mostly water for the rest of our lives . we can not survive even a week without fresh water . there 's no life without it for ecosystems , societies , and individuals . so , how much usable water is there on earth ? most of the water on earth is ocean , a salty 97.5 % , to be precise , and the remaining 2.5 % is fresh water . that little sliver of liquid sustains human life on earth , it literally holds up civilizations . 2.5 % is a small proportion to be sure , and even that is broken down into smaller parts : surface water , water in ice caps and polar regions , and ground water . first , surface water . all the liquid water above ground is surface water and it is a tiny blip of an amount . 0.3 % of all fresh water is surface water . it may seem counterintuitive , but it accounts for little streams all over the planet . all rivers , including the nile , the jordan , and the mississippi , and lakes , large to small , like victoria , the great lakes , and baikal . second , ice caps and polar regions freeze up to 70 % of the planet 's fresh water . this water is significant , but it is n't available for human use in a regular way . finally , nearly 30 % of all water on earth is ground water . as the name suggests , that 's water in the ground . it can rest still and deep in huge caverns , or it can snuggle in the little crevices of rock and pebble . the upshot - thank goodness for ground water ! it 's invisible to us , but it is much more plentiful than surface water . it is much more reliable and easier to obtain than frozen water . without ground water , our societies would be parched . so , how are we using that water ? as a result of industrialization and population growth , demand for fresh water skyrocketed in the last century . where is all that water going ? first , we have to remember that fresh water is a global concern , but it is always local . context matters . the sahara is not seattle . still , some general information can help us get a handle on major trends . who consumes the most fresh water ? and , what sectors consume the most fresh water ? first , who . well , the united states consumes the most water per capita of any country in the entire world , followed by parts of europe and large industrializing nations like china . but , this does n't tell us what water is being used for . so let 's look at it another way . if we ask what kinds of uses water is going towards , we see a different picture . agriculture accounts for roughly 70 % of global fresh water consumption . again , remember the numbers vary by region , but still , it 's a staggering amount . and , this makes a certain kind of sense : we need to eat , we need water to grow food ; the bigger the population , the more food we need ; and , the wealthier we get , the more meat we eat , and the more water is required to produce our food . furthermore , 22 % of all fresh water worldwide goes to industrial uses . this includes the production of electricity , the extraction of fossil fuels , and the manufacturing of all manner of goods , from microchips , to paper , to blimps . 70 % to agriculture , 22 % to industrial uses , what 's left ? 8 % all those domestic uses - cooking , cleaning , bathing , drinking - it 's a drop in the bucket of overall water use .
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if we ask what kinds of uses water is going towards , we see a different picture . agriculture accounts for roughly 70 % of global fresh water consumption . again , remember the numbers vary by region , but still , it 's a staggering amount .
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what accounts for nearly 70 % of global fresh water consumption ?
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since the dawn of humanity , an estimated 100.8 billion people have lived and died , a number that increases by about .8 % of the world 's population each year . what happens to all of those people 's bodies after they die and will the planet eventually run out of burial space ? when a person 's heart stops beating , the body passes through several stages before it begins decomposing . within minutes after death , the blood begins settling in the lower-most parts of the body . usually eight to twelve hours later , the skin in those areas is discolored by livor mortis , or post-mortem stain . and while at the moment of death the body 's muscles relax completely in a condition called primary flaccidity , they stiffen about two to six hours later in what 's known as rigor mortis . this stiffening spreads through the muscles , and its speed can be affected by age , gender , and the surrounding environment . the body also changes temperature , usually cooling off to match its environment . next comes decomposition , the process by which bacteria and insects break apart the body . many factors affect the rate of decomposition . there is , however , a basic guide of the effect of the environment on decompositon called casper 's law . it says that if all other factors are equal , a body exposed to air decomposes twice as fast as one immersed in water and eight times as fast as one buried in earth . soil acidity also greatly affects bone preservation . high-acidity soils with a ph of less than 5.3 will rapidly decompose bone , whereas in a neutral or basic soil with a ph of 7 or more , a skeleton can remain in relatively good condition for centuries . different cultures throughout history have developed unique approaches to burials . as far back as the first neanderthal burials , death was accompanied by rituals , like the positioning , coloring , or decorating of corpses . traditional christian burials decorate the body in dress , while in traditional islam , a body is wrapped in a piece of ritual fabric with the face oriented toward mecca . traditional hindus ceremonially burn the body , and zoroastrians , followers of one of the oldest monotheistic religions , traditionally place bodies atop a tower to expose them to the sun and scavenging birds.` before the industrial revolution , burials were simple and accessible . these days , with suitable burial land running out in high-population areas , purchasing private gravesites can be costly , and many people ca n't afford simple burials . even cremation , the second most common burial practice in the world , comes with a high cost . as for the question of running out of space , the issue is n't so much about total land in the world as it is that large populations cluster together within cities . most of the big cities in the world may run out of suitable burial grounds within a century . for london , it 's even sooner . that may happen by 2035 . so are there alternatives to traditional burials that might help with the space issue ? in some countries , skyscraper cemeteries enable vertical burials . some options focus on the body 's relationship with the environment . promession , for example , freeze-dries and pulverizes the body , creating a powder that can turn into compost when mixed with oxygen and water . there are also green burials that use special materials , such as biodegradable caskets , urns that sprout trees , and burial suits that grow mushrooms . eternal reefs take that concept to the depths of the ocean using a mixture of ashes and cement to create marine habitats for sea life . death is an inevitable part of the human condition , but how we treat bodies and burials continues to evolve . we may each have different spiritual , religious , or practical approaches to dying , but the ever-increasing demand for burial space might give us a push to be creative about where our bodies go after the final stages of life .
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many factors affect the rate of decomposition . there is , however , a basic guide of the effect of the environment on decompositon called casper 's law . it says that if all other factors are equal , a body exposed to air decomposes twice as fast as one immersed in water and eight times as fast as one buried in earth . soil acidity also greatly affects bone preservation .
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based on the casper 's law , a body decomposes in_____8 times as fast as in____ .
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consider throwing a ball straight into the air . can you predict the motion of the ball after it leaves your hand ? sure , that 's easy . the ball will move upward until it gets to some highest point , then it will come back down and land in your hand again . of course , that 's what happens , and you know this because you have witnessed events like this countless times . you 've been observing the physics of everyday phenomena your entire life . but suppose we explore a question about the physics of atoms , like what does the motion of an electron around the nucleus of a hydrogen atom look like ? could we answer that question based on our experience with everyday physics ? definietly not . why ? because the physics that governs the behavior of systems at such small scales is much different than the physics of the macroscopic objects you see around you all the time . the everyday world you know and love behaves according to the laws of classical mechanics . but systems on the scale of atoms behave according to the laws of quantum mechanics . this quantum world turns out to be a very strange place . an illustration of quantum strangeness is given by a famous thought experiment : schrödinger 's cat . a physicist , who does n't particularly like cats , puts a cat in a box , along with a bomb that has a 50 % chance of blowing up after the lid is closed . until we reopen the lid , there is no way of knowing whether the bomb exploded or not , and thus , no way of knowing if the cat is alive or dead . in quantum physics , we could say that before our observation the cat was in a superposition state . it was neither alive nor dead but rather in a mixture of both possibilities , with a 50 % chance for each . the same sort of thing happens to physical systems at quantum scales , like an electron orbiting in a hydrogen atom . the electron is n't really orbiting at all . it 's sort of everywhere in space , all at once , with more of a probability of being at some places than others , and it 's only after we measure its position that we can pinpoint where it is at that moment . a lot like how we did n't know whether the cat was alive or dead until we opened the box . this brings us to the strange and beautiful phenomenon of quantum entanglement . suppose that instead of one cat in a box , we have two cats in two different boxes . if we repeat the schrödinger 's cat experiment with this pair of cats , the outcome of the experiment can be one of four possibilities . either both cats will be alive , or both will be dead , or one will be alive and the other dead , or vice versa . the system of both cats is again in a superposition state , with each outcome having a 25 % chance rather than 50 % . but here 's the cool thing : quantum mechanics tells us it 's possible to erase the both cats alive and both cats dead outcomes from the superposition state . in other words , there can be a two cat system , such that the outcome will always be one cat alive and the other cat dead . the technical term for this is that the states of the cats are entangled . but there 's something truly mindblowing about quantum entanglement . if you prepare the system of two cats in boxes in this entangled state , then move the boxes to opposite ends of the universe , the outcome of the experiment will still always be the same . one cat will always come out alive , and the other cat will always end up dead , even though which particular cat lives or dies is completely undetermined before we measure the outcome . how is this possible ? how is it that the states of cats on opposite sides of the universe can be entangled in this way ? they 're too far away to communicate with each other in time , so how do the two bombs always conspire such that one blows up and the other does n't ? you might be thinking , `` this is just some theoretical mumbo jumbo . this sort of thing ca n't happen in the real world . '' but it turns out that quantum entanglement has been confirmed in real world lab experiments . two subatomic particles entangled in a superposition state , where if one spins one way then the other must spin the other way , will do just that , even when there 's no way for information to pass from one particle to the other indicating which way to spin to obey the rules of entanglement . it 's not surprising then that entanglement is at the core of quantum information science , a growing field studying how to use the laws of the strange quantum world in our macroscopic world , like in quantum cryptography , so spies can send secure messages to each other , or quantum computing , for cracking secret codes . everyday physics may start to look a bit more like the strange quantum world . quantum teleportation may even progress so far , that one day your cat will escape to a safer galaxy , where there are no physicists and no boxes .
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two subatomic particles entangled in a superposition state , where if one spins one way then the other must spin the other way , will do just that , even when there 's no way for information to pass from one particle to the other indicating which way to spin to obey the rules of entanglement . it 's not surprising then that entanglement is at the core of quantum information science , a growing field studying how to use the laws of the strange quantum world in our macroscopic world , like in quantum cryptography , so spies can send secure messages to each other , or quantum computing , for cracking secret codes . everyday physics may start to look a bit more like the strange quantum world .
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quantum entanglement is central to studying :
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so nickel is a metal which can produce allergies in some people , people get allergic to nickel . and it ’ s a metal which is found in canada and sir ludwig mond founder of the company that later becomes ici discovered a process for extracting nickel from the ore using carbon monoxide and started a huge factory on the south coast of wales . and the so-called nickel carbonyl was really quite an important industrial compound even though it was fantastically toxic . and it ’ s unusual as a metal compound because it boils at room temperature and usually one thinks of metal compounds as salts . nickel is now used quite a lot in the plating industry for plating materials , iron and steel in particular , and then often you would put chromium or something on top . used to be used for plating the inside of tins for peas and things like that . and sometimes the sulphur from inside the peas would be released by bacteria and would react to find strange black spots across the insides of the tin .
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so nickel is a metal which can produce allergies in some people , people get allergic to nickel . and it ’ s a metal which is found in canada and sir ludwig mond founder of the company that later becomes ici discovered a process for extracting nickel from the ore using carbon monoxide and started a huge factory on the south coast of wales .
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where is nickel principally found ?
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translator : andrea mcdonough reviewer : bedirhan cinar i would like to introduce you to my favorite parasite . there are millions that i could choose from and this is it : it 's called the jewel wasp . you can find it in parts of africa and asia . it 's a little under an inch long , and it is a beautiful looking parasite . now , you may be saying to yourself , `` this is not a parasite . it 's not a tapeworm , it 's not a virus , how could a wasp be a parasite ? '' you are probably thinking about regular wasps , you know , the ones that build paper nests as their house . well , the thing is that the jewel wasp makes its house inside a living cockroach . here 's how it happens . a jewel wasp is flying around , looking for a cockroach . when it sees one , it lands and bites on its wing . so , i 'll be the cockroach . be-wha ! bewha ! and the cockroach starts shaking it off , `` get away from me ! '' the wasp very quickly starts stinging the cockroach . all of a sudden , the cockroach ca n't move , for about a minute . and then it recovers and stands up . it could run away now , but it does n't . it just does n't want to . it just stays there . it 's become a zombie slave . again , i 'm not making this up . the wasp goes off , it walks away and finds a hole and digs it out , makes it into a burrow . it walks back . this can take up to half an hour . the cockroach is still there . what do we do now ? the wasps grabs onto one of the antenna , bites down on it , of the cockroach , and pulls the cockroach . and the cockroach says , `` alright , '' and walks like a dog on a leash . the wasp takes it all the way down into the burrow . the cockroach says , `` nice place . '' the wasp takes care of some business and then goes and leaves the burrow and seals it shut , leaving the cockroach entombed in darkness , still alive . the cockroach says , `` alright , i 'll stay here if you want . '' now , i mentioned that the cockroach took care , ah , the wasp took care of a little business before it left the burrow . the business was laying an egg on the underside of the cockroach . the egg hatches . out comes a wasp larva . it looks kind of like a maggot with big , nasty jaws . it chews a hole into the cockroach and starts to feed from the outside . it gets bigger , like you can see over here . and then when it gets big enough , it decides to crawl into the hole , into the cockroach . so now it 's inside the still-living cockroach and the cockroach does n't mind much . this goes on for about a month . the larva grows and grows and grows , then makes a pupa , kind of like a cocoon . inside there it grows eyes , it grows wings , it grows legs , the cockroach is still alive , still waiting . finally the wasp is ready to leave , and that 's when the cockroach finally dies because the fullly-formed adult wasp crawls out of the cockroach 's dying body . the wasp shakes itself off , climbs out of the burrow , goes and finds another wasp to mate with to start this whole , crazy cycle again . so , this is not science fiction , this happens every day , all over the world . and scientists are totally fascinated by this . they 're just starting to figure out how all this happens . and , when you really start to look at the science of it , you start to kind of respect this very creepy wasp . you see , the thing is that when it attacks the cockroach , it 's not just stinging wildly , it delivers two precise stings . it knows this cockroach 's nervous system like you know the back of your hand . the first sting goes to that spot there , called the `` walking rhythm generators , '' and , as you can guess , those are the neurons that send signals to the legs to move . it blocks the channels that the neurons use to send these signals . so the cockroach wants to go , it wants to run away , but it ca n't because it ca n't move its legs . and that lasted for about a minute . this is really sophisticated pharmacology . we actually use the same method , a drug called ivermectin , to cure river blindness , which is caused by a parasitic worm that gets into your eye . if you take ivermectin , you paralyze the worm using the same strategy . now , we discovered this in the 1970s , the wasp has been doing this for millions of years . then comes the second sting . now the second sting actually hits two places along the way . and to try to imagine how this can happen , i want you to picture yourself with a friend who 's got a very long , very , very scary looking needle . and your friend , or at least you thought he was your friend , sticks it in your neck , goes into your skull , stops off at one part of your brain and injects some drugs , then keeps going in your brain and injects some more . these are two particular spots , marked here , `` seg '' , and you can see the tip of it in the brain , marked `` br '' . now , we can do this , but it 's really hard for us . it 's called stereotactic drug delivery . you have to put a patient in a big metal frame to hold them still , you need cat scans to know where you 're going , so you look at the picture and say , `` are we going the right way ? '' the jewel wasp has sensors on its stinger and scientists think that it can actually feel its way through the cockroach 's brain until it gets to the exact , right place , and then penetrates an individual neuron and then delivers the goods . so , this is quite amazing stuff , and what seems to happen then is that the wasp is taking away the control that the cockroach has over its own body . it 's taking away the cockroach 's free will . we did n't really appreciate that cockroaches have free will until this wasp showed us . and , we have no idea how it 's doing this , we do n't know yet what the venom has in it and we do n't know which circuits it 's hitting in the cockroach 's brain , and i think that 's why this is , most of all , my favorite parasite because we have so much left to learn from it . thank you very much .
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now , we can do this , but it 's really hard for us . it 's called stereotactic drug delivery . you have to put a patient in a big metal frame to hold them still , you need cat scans to know where you 're going , so you look at the picture and say , `` are we going the right way ? ''
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what is it called when doctors , using a long needle , deliver medicines directly into the human brain ?
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take a look at the water in this glass . refreshing , hydrating , and invaluable to your survival . before you take a sip , though , how do you know that the water inside is free from disease-causing organisms and pollutants ? one out of ten people in the world ca n't actually be sure that their water is clean and safe to drink . why is that ? inadequate sanitation , poor protection of drinking water sources , and improper hygiene often lead to sewage and feces-contaminated water . that 's the ideal breeding ground for dangerous bacteria , viruses , and parasites . and the effects of these pathogens are staggering . diarrheal disease from unsafe water is one of the leading causes of death around the world for children under five . and according to a u.n. report from 2010 , microbial water-borne illnesses killed more people per year than war . proper treatment processes , though , can address these threats . they usually have three parts : sedimentation , filtration , and disinfection . once water has been collected in a treatment facility , it 's ready for cleaning . the first step , sedimentation , just takes time . the water sits undisturbed , allowing heavier particles to sink to the bottom . often , though , particles are just too small to be removed by sedimentation alone and need to be filtered . gravity pulls the water downward through layers of sand that catch leftover particles in their pores , prepping the water for its final treatment , a dose of disinfectant . chemicals , primarily forms of chlorine and ozone , are mixed in to kill off any pathogens and to disinfect pipes and storage systems . chlorine is highly effective in destroying water 's living organisms , but its use remains government-regulated because it has potentially harmful chemical byproducts . and if an imbalance of chlorine occurs during the disinfection process , it can trigger other chemical reactions . for example , levels of chlorine byproducts , like trihalomethanes , could skyrocket , leading to pipe corrosion and the release of iron , copper , and lead into drinking water . water contamination from these and other sources including leaching , chemical spills , and runoffs , has been linked to long-term health effects , like cancer , cardiovascular and neurological diseases , and miscarriage . unfortunately , analyzing the exact risks of chemically contaminated water is difficult . so while it 's clear that disinfectants make us safer by removing disease-causing pathogens , experts have yet to determine the full scope of how the chemical cocktail in our drinking water really impacts human health . so how can you tell whether the water you have access to , whether from a tap or otherwise , is drinkable ? firstly , too much turbidity , trace organic compounds , or high-density heavy metals like arsenic , chromium , or lead , mean that the water is unsuitable for consumption . a lot of contaminants , like lead or arsenic , wo n't be obvious without tests , but some clues , like cloudiness , brown or yellow coloration , a foul odor , or an excessive chlorine smell can indicate the need to investigate further . water testing kits can go a step further and confirm the presence of many different contaminants and chemicals . with many types of contamination , there are ways of treating water where it 's used instead of close to its source . point-of-use treatment has actually been around for thousands of years . ancient egyptians boiled away many organic contaminants with the sun 's heat . and in ancient greece , hippocrates designed a bag that trapped bad tasting sediments from water . today , point-of-use processes usually involve ionization to lower mineral content . they also use adsorption filtration , where a porous material called activated carbon strains the water to remove contaminants and chemical byproducts . while it 's not always an effective long-term solution , point-of-use treatment is portable , easy to install , and adaptable . and in regions where large-scale systems are unavailable , or where water has been contaminated further along its journey , these systems can mean the difference between life and death . clean water remains a precious and often scarce commodity . there are nearly 800 million of us who still do n't have regular access to it . the good news is that continued developments in water treatment , both on a large and small scale , can alleviate a lot of unsafe conditions . implementing proper systems where they 're needed and paying careful attention to the ones already in place will fulfill one of the most basic of our human needs .
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and the effects of these pathogens are staggering . diarrheal disease from unsafe water is one of the leading causes of death around the world for children under five . and according to a u.n. report from 2010 , microbial water-borne illnesses killed more people per year than war .
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when exposed to unsafe water , children under five often :
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in a time-lapse video , it looks like a monster coming alive . for a moment , it sits there innocuously . then , ripples move across its surface . it bulges outwards , bursting with weird boils . it triples in volume . its color darkens ominously , and its surface hardens into an alien topography of peaks and craters . then , the kitchen timer dings . your cookie is ready . what happened inside that oven ? do n't let the apron deceive you ! bakers are mad scientists . when you slide the pan into the oven , you 're setting off a series of chemical reactions that transform one substance , dough , into another , cookies . when the dough reaches 92 degrees fahrenheit , the butter inside melts , causing the dough to start spreading out . butter is an emulsion , or mixture of two substances that do n't want to stay together , in this case , water and fat , along with some dairy solids that help hold them together . as the butter melts , its trapped water is released . and as the cookie gets hotter , the water expands into steam . it pushes against the dough from the inside , trying to escape through the cookie walls like ridley scott 's chest-bursting alien . your eggs may have been home to squirming salmonella bacteria . an estimated 142,000 americans are infected this way each year . though salmonella can live for weeks outside a living body and even survive freezing , 136 degrees is too hot for them . when your dough reaches that temperature , they die off . you 'll live to test your fate with a bite of raw dough you sneak from your next batch . at 144 degrees , changes begin in the proteins , which come mostly from the eggs in your dough . eggs are composed of dozens of different kinds of proteins , each sensitive to a different temperature . in an egg fresh from the hen , these proteins look like coiled up balls of string . when they 're exposed to heat energy , the protein strings unfold and get tangled up with their neighbors . this linked structure makes the runny egg nearly solid , giving substance to squishy dough . water boils away at 212 degrees , so like mud baking in the sun , your cookie gets dried out and it stiffens . cracks spread across its surface . the steam that was bubbling inside evaporates , leaving behind airy pockets that make the cookie light and flaky . helping this along is your leavening agent , sodium bicarbonate , or baking soda . the sodium bicarbonate reacts with acids in the dough to create carbon dioxide gas , which makes airy pockets in your cookie . now , it 's nearly ready for a refreshing dunk in a cool glass of milk . one of science 's tastiest reactions occurs at 310 degrees . this is the temperature for maillard reactions . maillard reactions result when proteins and sugars break down and rearrange themselves , forming ring-like structures , which reflect light in a way that gives foods like thanksgiving turkey and hamburgers their distinctive , rich brown color . as this reaction occurs , it produces a range of flavor and aroma compounds , which also react with each other , forming even more complex tastes and smells . caramelization is the last reaction to take place inside your cookie . caramelization is what happens when sugar molecules break down under high heat , forming the sweet , nutty , and slightly bitter flavor compounds that define , well , caramel . and , in fact , if your recipe calls for a 350 degree oven , it 'll never happen , since caramelization starts at 356 degrees . if your ideal cookie is barely browned , like a northeasterner on a beach vacation , you could have set your oven to 310 degrees . if you like your cookies to have a nice tan , crank up the heat . caramelization continues up to 390 degrees . and here 's another trick : you do n't need that kitchen timer ; your nose is a sensitive scientific instrument . when you smell the nutty , toasty aromas of the maillard reaction and caramelization , your cookies are ready . grab your glass of milk , put your feet up , and reflect that science can be pretty sweet .
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cracks spread across its surface . the steam that was bubbling inside evaporates , leaving behind airy pockets that make the cookie light and flaky . helping this along is your leavening agent , sodium bicarbonate , or baking soda .
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what makes cookies light and airy ?
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language is an essential part of our lives that we often take for granted . with it , we can communicate our thoughts and feelings , lose ourselves in novels , send text messages , and greet friends . it 's hard to imagine being unable to turn thoughts into words . but if the delicate web of language networks in your brain became disrupted by stroke , illness , or trauma , you could find yourself truly at a loss for words . this disorder , called aphasia , can impair all aspects of communication . people who have aphasia remain as intelligent as ever . they know what they want to say , but ca n't always get their words to come out correctly . they may unintentionally use substitutions called paraphasias , switching related words , like saying `` dog '' for `` cat , '' or words that sound similar , such as `` house '' for `` horse . '' sometimes , their words may even be unrecognizable . there are several types of aphasia grouped into two categories : fluent , or receptive , aphasia and non-fluent , or expressive , aphasia . people with fluent aphasia may have normal vocal inflection but use words that lack meaning . they have difficulty comprehending the speech of others and are frequently unable to recognize their own speech errors . people with non-fluent aphasia , on the other hand , may have good comprehension but will experience long hesitations between words and make grammatical errors . we all have that tip-of-the-tongue feeling from time to time when we ca n't think of a word , but having aphasia can make it hard to name simple , everyday objects . even reading and writing can be difficult and frustrating . so how does this language loss happen ? the human brain has two hemispheres . in most people , the left hemisphere governs language . we know this because in 1861 , the physician paul broca studied a patient who lost the ability to use all but a single word , `` tan . '' during a postmortem study of that patient 's brain , broca discovered a large lesion in the left hemisphere now known as broca 's area . scientists today believe that broca 's area is responsible in part for naming objects and coordinating the muscles involved in speech . behind broca 's area is wernicke 's area near the auditory cortex . that 's where the brain attaches meaning to speech sounds . damage to wernicke 's area impairs the brain 's ability to comprehend language . aphasia is caused by injury to one or both of these specialized language areas . fortunately , there are other areas of the brain which support these language centers and can assist with communication . even brain areas that control movement are connected to language . fmri studies found that when we hear action words , like `` run '' or `` dance , '' parts of the brain responsible for movement light up as if the body was actually running or dancing . our other hemisphere contributes to language , too , enhancing the rhythm and intonation of our speech . these non-language areas sometimes assist people with aphasia when communication is difficult . so how common is aphasia ? approximately 1 million people in the u.s. alone have it , with an estimated 80,000 new cases per year . about one-third of stroke survivors suffer from aphasia making it more prevalent than parkinson 's disease or multiple sclerosis , yet less widely known . there is one rare form of aphasia called primary progressive aphasia , or ppa , which is not caused by stroke or brain injury , but is actually a form of dementia in which language loss is the first symptom . the goal in treating ppa is to maintain language function for as long as possible before other symptoms of dementia eventually occur . however , when aphasia is acquired from a stroke or brain trauma , language improvement may be achieved through speech therapy . our brain 's ability to repair itself , known as brain plasticity , permits areas surrounding a brain lesion to take over some functions during the recovery process . scientists have been conducting experiments using new forms of technology , which they believe may encourage brain plasticity in people with aphasia . meanwhile , many people with aphasia remain isolated , afraid that others wo n't understand them or give them extra time to speak . by offering them the time and flexibility to communicate in whatever way they can , you can help open the door to language again , moving beyond the limitations of aphasia .
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sometimes , their words may even be unrecognizable . there are several types of aphasia grouped into two categories : fluent , or receptive , aphasia and non-fluent , or expressive , aphasia . people with fluent aphasia may have normal vocal inflection but use words that lack meaning .
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aphasia affects :
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so you 're going to the museum and it 's great . the guards check your bag so you , i do n't know , shoot a painting ; you go up some fancy escalators , you see naked statues . and then it happens . you see a super ugly medieval baby . why do medieval babies look like ugly middle aged men ? this baby looks like he wants to tell you to that 'a boat is just a money pit ' . it might seem like medieval artists were just bad at drawing . but it turns out that babies in medieval art are actually ugly for a reason . while there were breakthroughs in anatomy and perspective that happened later in the renaissance , ugly medieval babies were an intentional choice before that time . if somebody told you to paint like pablo picasso and you gave them norman rockwell , you would have screwed up . and it 's the same way for artists working in churches in italy . it 's because most of these babies were depictions of jesus and mary . they were influenced by the idea of the homunculus , which is latin for little man . these babies looked like benjamin button because philosophers believed jesus was born perfectly formed and unchanged . the adult jesus was represented in the baby jesus . until the renaissance , when everything changed . generally , we think of the middle ages lasting from around the 5th to 15th century , and it kind of overlapped the beginning of the renaissance in the 14th century . the renaissance probably began in florence italy , but it 's important to note that it unfolded over centuries and countries in a time when everything moved slowly . so , it was n't instant beautiful babies everywhere . still , the change in style did happen , and it happened for a couple of reasons . places like florence were getting richer and churches were n't the only places that could afford paintings . people could get their own babies painted , and they wanted them to look like cute chubby babies , not homunculi . and because the renaissance was all about classics , they looked at greek and roman art , which was all about idealized forms that ditched the medieval abstraction for beauty . anyway , the point is that after the renaissance cherubs did n't seem out of place , and neither did cuter pictures of baby jesus as the renaissance spread through europe . and it 's kinda stayed that way since . we want babies who look like they need their cheeks pinched , not their prostates checked . we want them chubby and cute , and we want babies that fit our ideals . because those medieval babies ? they have a face that only a mother can love .
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we want them chubby and cute , and we want babies that fit our ideals . because those medieval babies ? they have a face that only a mother can love .
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what changes in culture allowed for babies to become cuter in paintings ?
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so nickel is a metal which can produce allergies in some people , people get allergic to nickel . and it ’ s a metal which is found in canada and sir ludwig mond founder of the company that later becomes ici discovered a process for extracting nickel from the ore using carbon monoxide and started a huge factory on the south coast of wales . and the so-called nickel carbonyl was really quite an important industrial compound even though it was fantastically toxic . and it ’ s unusual as a metal compound because it boils at room temperature and usually one thinks of metal compounds as salts . nickel is now used quite a lot in the plating industry for plating materials , iron and steel in particular , and then often you would put chromium or something on top . used to be used for plating the inside of tins for peas and things like that . and sometimes the sulphur from inside the peas would be released by bacteria and would react to find strange black spots across the insides of the tin .
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so nickel is a metal which can produce allergies in some people , people get allergic to nickel . and it ’ s a metal which is found in canada and sir ludwig mond founder of the company that later becomes ici discovered a process for extracting nickel from the ore using carbon monoxide and started a huge factory on the south coast of wales . and the so-called nickel carbonyl was really quite an important industrial compound even though it was fantastically toxic . and it ’ s unusual as a metal compound because it boils at room temperature and usually one thinks of metal compounds as salts .
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what is the compound used to extract nickel from the ore in the process developed by ludwig mond ?
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we live in an age of protest . on campuses and public squares , on streets and social media , protesters around the world are challenging the status quo . protest can thrust issues onto the national or global agenda , it can force out tyrants , it can activate people who have long been on the sidelines of civic life . while protest is often necessary , is it sufficient ? consider the arab spring . all across the middle east , citizen protesters were able to topple dictators . afterwards , though , the vacuum was too often filled by the most militant and violent . protest can generate lasting positive change when it 's followed by an equally passionate effort to mobilize voters , to cast ballots , to understand government , and to make it more inclusive . so here are three core strategies for peacefully turning awareness into action and protest into durable political power . first , expand the frame of the possible , second , choose a defining fight , and third , find an early win . let 's start with expanding the frame of the possible . how often have you heard in response to a policy idea , `` that 's just never going to happen '' ? when you hear someone say that , they 're trying to define the boundaries of your civic imagination . the powerful citizen works to push those boundaries outward , to ask what if - what if it were possible ? what if enough forms of power - people power , ideas , money , social norms - were aligned to make it happen ? simply asking that question and not taken as given all the givens of conventional politics is the first step in converting protest to power . but this requires concreteness about what it would look like to have , say , a radically smaller national government , or , by contrast , a big single-payer healthcare system , a way to hold corporations accountable for their misdeeds , or , instead , a way to free them from onerous regulations . this brings us to the second strategy , choosing a defining fight . all politics is about contrasts . few of us think about civic life in the abstract . we think about things in relief compared to something else . powerful citizens set the terms of that contrast . this does n't mean being uncivil . it simply means thinking about a debate you want to have on your terms over an issue that captures the essence of the change you want . this is what the activists pushing for a $ 15 minimum wage in the u.s. have done . they do n't pretend that $ 15 by itself can fix inequality , but with this ambitious and contentious goal , which they achieved first in seattle and then beyond , they have forced a bigger debate about economic justice and prosperity . they 've expanded the frame of the possible , strategy one , and created a sharp emblematic contrast , strategy two . the third key strategy , then , is to seek and achieve an early win . an early win , even if it 's not as ambitious as the ultimate goal , creates momentum , which changes what people think is possible . the solidarity movement , which organized workers in cold war poland emerged just this way , first , with local shipyard strikes in 1980 that forced concessions , then , over the next decade , a nationwide effort that ultimately helped topple poland 's communist government . getting early wins sets in motion a positive feedback loop , a contagion , a belief , a motivation . it requires pressuring policymakers , using the media to change narrative , making arguments in public , persuading skeptical neighbors one by one by one . none of this is as sexy as a protest , but this is the history of the u.s. civil rights movement , of indian independence , of czech self-determination . not the single sudden triumph , but the long , slow slog . you do n't have to be anyone special to be part of this grind , to expand the frame of the possible , to pick a defining fight , or to secure an early win . you just have to be a participant and to live like a citizen . the spirit of protest is powerful . so is showing up after the protest . you can be the co-creator of what comes next .
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you just have to be a participant and to live like a citizen . the spirit of protest is powerful . so is showing up after the protest .
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which of the following is not something that protest alone can achieve ?
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emily dickinson said over a century ago that `` there is no frigate like a book to take us lands away ... '' and it 's true . when we pick up a book , turn on the tv , or watch a movie , we 're carried away down the currents of story into a world of imagination . and when we land , on a shore that is both new and familiar , something strange happens . stepping onto the shore , we 're changed . we do n't retrace the footsteps of the authors or characters we followed here . no ; instead , we walk a mile in their shoes . researchers in psychology , neuroscience , child development and biology are finally starting to gain quantifiable scientific evidence , showing what writers and readers have always known : that stories have a unique ability to change a person 's point of view . scholars are discovering evidence that stories shape culture , and that much of what we believe about life comes not from fact , but from fiction - that our ideas of class , marriage and even gender are relatively new , and that many ideologies which held fast for centuries were revised within the 18th century , and redrafted in the pages of the early novel . imagine a world where class , and not hard work , decides a person 's worth ; a world where women are simply men 's more untamed copy ; a world where marriage for love is a novel notion . well , that was the world in which samuel richardson 's `` pamela '' first appeared . richardson 's love story starred a poor , serving-class heroine , who is both more superior and smarter than her upper-class suitor . the book , challenging a slew of traditions , caused quite a ruckus . there was more press for `` pamela '' than for parliament . it spawned intense debate and several counter-novels . still , for all those who could n't accept `` pamela , '' others were eager for this new fictional world . this best seller and all its literary heirs - `` pride and prejudice , '' `` jane eyre , '' and yes , even `` twilight '' - have continuously shared the same tale and taught similar lessons , which are now conventional and commonplace . similarly , novels have helped shape the minds of thought leaders across history . some scholars say that darwin 's theory of evolution is highly indebted to the plots he read and loved . his theory privileges intelligence , swiftness , and adaptability to change - all core characteristics in a hero . whether you 're reading `` harry potter '' or `` great expectations , '' you 're reading the kind of plot that inspired darwin . yet , recent studies show that his theory might not be the whole story . our sense of being a hero - one man or one woman or even one species taking on the challenges of the world - might be wrong . instead of being hardwired for competition for being the solitary heroes in our own story , we might instead be members of a shared quest . more hobbit than harry . sometimes , of course , the shoes we 've been walking in can get plain worn out . after all , we have n't walked just one mile in jane austen 's or mark twain 's shoes - we 've walked about 100 trillion miles in them . this is n't to say that we ca n't read and enjoy the classics ; we should travel with dickens , let pip teach us what to expect from ourselves , have a talk with austen and elizabeth about our prides and prejudices . we should float with twain down the mississippi , and have jim show us what it means to be good . but on our journey , we should also keep in mind that the terrain has changed . we 'll start shopping around for boots that were made for walking into a new era . take , for instance , katniss everdeen and her battle with the capitol . can `` hunger games '' lead us into thinking about capitalism in a new way ? can it teach us a lesson about why the individual should not put herself before the group ? will `` uglies '' reflect the dangers of pursuing a perfect body and letting the media define what is beautiful ? will `` seekers '' trod a path beyond global warming ? will the life-and-death struggles of toklo , kallik , lusa and the other bears chart a course for understanding animals and our place in their world ? only the future will tell which stories will engage our imagination , which tales of make-believe we 'll make tomorrow . but the good news is this : there are new stories to venture in every day , new tales that promise to influence , to create and to spark change - stories that you might even write yourself . so i guess the final question is this : what story will you try on next ?
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emily dickinson said over a century ago that `` there is no frigate like a book to take us lands away ... '' and it 's true . when we pick up a book , turn on the tv , or watch a movie , we 're carried away down the currents of story into a world of imagination .
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who said , `` there is no frigate like a book to take us lands away '' ?
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here are some images of clusters of galaxies . they 're exactly what they sound like . they are these huge collections of galaxies , bound together by their mutual gravity . so most of the points that you see on the screen are not individual stars , but collections of stars , or galaxies . now , by showing you some of these images , i hope that you will quickly see that galaxy clusters are these beautiful objects , but more than that , i think galaxy clusters are mysterious , they are surprising , and they 're useful . useful as the universe 's most massive laboratories . and as laboratories , to describe galaxy clusters is to describe the experiments that you can do with them . and i think there are four major types , and the first type that i want to describe is probing the very big . so , how big ? well , here is an image of a particular galaxy cluster . it is so massive that the light passing through it is being bent , it 's being distorted by the extreme gravity of this cluster . and , in fact , if you look very carefully you 'll be able to see rings around this cluster . now , to give you a number , this particular galaxy cluster has a mass of over one million billion suns . it 's just mind-boggling how massive these systems can get . but more than their mass , they have this additional feature . they are essentially isolated systems , so if we like , we can think of them as a scaled-down version of the entire universe . and many of the questions that we might have about the universe at large scales , such as , how does gravity work ? might be answered by studying these systems . so that was very big . the second things is very hot . okay , if i take an image of a galaxy cluster , and i subtract away all of the starlight , what i 'm left with is this big , blue blob . this is in false color . it 's actually x-ray light that we 're seeing . and the question is , if it 's not galaxies , what is emitting this light ? the answer is hot gas , million-degree gas -- in fact , it 's plasma . and the reason why it 's so hot goes back to the previous slide . the extreme gravity of these systems is accelerating particles of gas to great speeds , and great speeds means great temperatures . so this is the main idea , but science is a rough draft . there are many basic properties about this plasma that still confuse us , still puzzle us , and still push our understanding of the physics of the very hot . third thing : probing the very small . now , to explain this , i need to tell you a very disturbing fact . most of the universe 's matter is not made up of atoms . you were lied to . most of it is made up of something very , very mysterious , which we call dark matter . dark matter is something that does n't like to interact very much , except through gravity , and of course we would like to learn more about it . if you 're a particle physicist , you want to know what happens when we smash things together . and dark matter is no exception . well , how do we do this ? to answer that question , i 'm going to have to ask another one , which is , what happens when galaxy clusters collide ? here is an image . since galaxy clusters are representative slices of the universe , scaled-down versions . they are mostly made up of dark matter , and that 's what you see in this bluish purple . the red represents the hot gas , and , of course , you can see many galaxies . what 's happened is a particle accelerator at a huge , huge scale . and this is very important , because what it means is that very , very small effects that might be difficult to detect in the lab , might be compounded and compounded into something that we could possibly observe in nature . so , it 's very funny . the reason why galaxy clusters can teach us about dark matter , the reason why galaxy clusters can teach us about the physics of the very small , is precisely because they are so very big . fourth thing : the physics of the very strange . certainly what i 've said so far is crazy . okay , if there 's anything stranger i think it has to be dark energy . if i throw a ball into the air , i expect it to go up . what i do n't expect is that it go up at an ever-increasing rate . similarly , cosmologists understand why the universe is expanding . they do n't understand why it 's expanding at an ever-increasing rate . they give the cause of this accelerated expansion a name , and they call it dark energy . and , again , we want to learn more about it . so , one particular question that we have is , how does dark energy affect the universe at the largest scales ? depending on how strong it is , maybe structure forms faster or slower . well , the problem with the large-scale structure of the universe is that it 's horribly complicated . here is a computer simulation . and we need a way to simplify it . well , i like to think about this using an analogy . if i want to understand the sinking of the titanic , the most important thing to do is not to model the little positions of every single little piece of the boat that broke off . the most important thing to do is to track the two biggest parts . similarly , i can learn a lot about the universe at the largest scales by tracking its biggest pieces and those biggest pieces are clusters of galaxies . so , as i come to a close , you might feel slightly cheated . i mean , i began by talking about how galaxy clusters are useful , and i 've given some reasons , but what is their use really ? well , to answer this , i want to give you a quote by henry ford when he was asked about cars . he had this to say : `` if i had asked people what they wanted , they would have said faster horses . '' today , we as a society are faced with many , many difficult problems . and the solutions to these problems are not obvious . they are not faster horses . they will require an enormous amount of scientific ingenuity . so , yes , we need to focus , yes , we need to concentrate , but we also need to remember that innovation , ingenuity , inspiration -- these things come when we broaden our field of vision when we step back when we zoom out . and i ca n't think of a better way to do this than by studying the universe around us . thanks . ( applause )
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so , it 's very funny . the reason why galaxy clusters can teach us about dark matter , the reason why galaxy clusters can teach us about the physics of the very small , is precisely because they are so very big . fourth thing : the physics of the very strange .
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challenge question : conservation of energy and the fact that galaxy clusters are radiating x-rays tells us that ________ .
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just for a moment , focus on your breath . in slowly . out slowly . in slowly . out . the same pattern repeats within every one of us and consider your pulse . the beat is built into the very fabric of our being . simply put , we 're creatures of rhythm and repetition . it 's central to our experience , rhythm and repetition , rhythm and repetition . on , and in , and on , and out . and we delight in those aspects everyday , in the rhythm of a song , the beat of the drum , the nod of your head , or in the repetition of soup cans , the rows of an orchard , the artistry of petals . pattern can be pleasure . in language , rhythm and repetition are often used as the building blocks for poetry . there 's the rhythm of language , created by syllables and their emphasis , such as , `` so long as men can breathe or eyes can see . '' and there 's the repetition of language at multiple levels : the repetition of letters , `` so long lives this and this gives life to thee , '' of sounds , `` breathe , '' `` see , '' `` thee , '' and of words . with so many uses , repetition is one of the poet 's most malleable and reliable tools . it can lift or lull the listener , amplify or diminish the line , unify or diversify ideas . in fact , even rhythm itself , a repeated pattern of stressed syllables , is a form of repetition . yet for all its varied uses , too much repetition can backfire . imagine writing the same sentence on the blackboard twenty times , again , and again , and again , and again , or imagine a young child clamoring for her mother 's attention , `` mom , mom , mommy , mom , mom . '' not exactly what we might call poetry . so what is poetic repetition , and why does it work ? possibly most familiar is rhyme , the repetition of like sounds in word endings . as with shakespeare 's example , we often encounter rhyme at the ends of lines . repetition in this way creates an expectation . we begin to listen for the repetition of those similar sounds . when we hear them , the found pattern is pleasurable . like finding waldo in the visual chaos , we hear the echo in the oral chatter . yet , rhyme need not surface solely at a line 's end . notice the strong `` i '' sound in , `` so long lives this and this gives life to thee . '' this repetition of vowel sounds is called assonance and can also be heard in eminem 's `` lose yourself . '' notice how the `` e '' and `` o '' sounds repeat both within in and at the end of each line : `` oh , there goes gravity , oh , there goes rabbit , he choked , he so mad but he wo n't give up that easy , no , he wo n't have it , he knows his whole back 's to these ropes . '' the alternating assonance creates its own rhythm , and invites us to try our own voices in echoing it . similarly , consonance is the repetition of like consonant sounds , such as the `` l '' and `` th '' in , `` so long lives this and this gives life to thee . '' in fact , this type of specific consonance , which occurs at the beginning of words may be familiar to you already . it 's called alliteration , or front rhyme . great examples include tongue twisters . betty bought some butter but the butter was bitter so betty bought some better butter to make the bitter butter better . here , the pleasure in pattern is apparent as we trip over the consonance both within words and at their start . yet tongue twisters also reflect the need for variation in poetic repetition . while challenging to say , they 're seen by some as lesser imitations of poetry , or gimmicky because they hammer so heavily on the same sounds , closer to that blackboard-style of repetition . ultimately , this is the poet 's balancing act , learning when to repeat and when to riff , when to satisfy expectations , and when to thwart them , and in that balance , it may be enough to remember we all live in a world of wild variation and carry with us our own breath and beat , our own repetition wherever we go .
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pattern can be pleasure . in language , rhythm and repetition are often used as the building blocks for poetry . there 's the rhythm of language , created by syllables and their emphasis , such as , `` so long as men can breathe or eyes can see . ''
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which of the following is an example of repetition in language ?
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- so the other group of ants [ dr. corrie moreau , curator/ants ] that we have today are bullet ants . [ dr. corrie moreau , curator/ants ] - why are they called bullet ants ? [ bullet ant , paraponera clavata ] - well , they 're called bullet ants [ bullet ant , paraponera clavata ] because their sting is so painful [ * causing excruciating pain , numbness & amp ; amp ; trembling ] it feels like you were shot by a gun . [ * causing excruciating pain , numbness & amp ; amp ; trembling ] - and you 've experienced this firsthand ? - i have , just once , i 'd like to keep it that way . and so you can see they 're actually quite tremendous ants , i mean , they 're really foreboding , [ * worker bullet ants are 18–30 mm long ] they 're crazy big and they 're cool . [ * worker bullet ants are 18–30 mm long ] - are they the largest ant ? - they 're one of the largest ants . there 's another genus called dinoponera . [ dinoponera , dinoponera australis ] in some ways larger . [ * females may surpass 30–40 mm in length ] not as painful of a sting , though . [ * females may surpass 30–40 mm in length ] this is paraponera . [ bullet ant , paraponera clavata ] we 're studying the gut bacteria actually in this group of ants . but we 're also interested in the venom . and so what i was telling you is part of the reason i brought them back alive is that at one point i had tried to milk them , because my colleague was like , `` it 's because we were n't sure if we 'd have permits to bring back alive . '' - yeah . - you can just milk them . so i can show you how i attempted to do it and i will tell you that it did n't work in the end . when i got the venom back it was actually not usable . but let me grab my equipment . - it 's not every day you get to milk a venomous ant . at work . - so this is our fancy equipment . so if you think about , like , how they milk the venom from spiders , right ? usually they just have them bite something and squirt the venom inside and it 's the same principle . so again , we just have our empty tubes , and we have a little bit of parafilm , right , which is essentially just like a waxy kind of paper-y thing that we can stretch across the top of this . and we 're going to get them to try to sting through the tube and deposit their venom on the side of the tube . - wow . - yeah . one thing i have noticed is , what 's really interesting actually , is with these bullet ants , when you collect them in the wild they 're incredibly aggressive . you disturb them at all , and they just go into immediate attack mode . in fact in the field , if you even like blow on them , you can physically hear them stridulate , which is a way of communicating between individuals . and now that they 've been in the lab for just a few days , they 're actually almost docile . and so i 'm curious to see whether they 'll even sting through this . but we 'll try . yeah , see , this one stridulates . so now let 's see if we put her abdomen up , yeah , she is depositing her sting through . - oh ! - see that ? - sting it ! sting it ! - so you see , she 's got her sting out , this is where i do n't want to lose control of her . she 'll try to sting through , oh , there , you saw that sting go ? that 's huge . - yeah . wow . focus your anger . - we will try to get another one to sting - come on , ladies . - you look like a new victim , raaah , let 's get her all mad . - yeaaaah ! oh , she 's stridulating . - she 's actually kinda not mad as much anymore . - they're—they 're just like , they 're like , `` corrie , we wan na hang out , i thought we were cool . '' - i know , that 's probably exactly what they think . - like , `` come on , corrie , '' `` i read your latest paper about climactic regional distribution '' `` of my sister species . '' i do n't even know if that 's what you 've written about , i do n't even know if that— those words even make sense . - you do n't read all my scientific publications ? - um , i probably could n't get through the abstract . not—not just yours , but most . - i wo n't take it personally . oh , yeah , she 's got a very big sting , so let 's see if i can get her to— - yeah . sting it . - so that 's how you milk a bullet ant for their venom . so essentially , just getting them to sting through this material , they have now deposited their venom all over the top of this and inside of that tube , so i can just shove that in there and then take it back to an analytical lab to look at what are the—what 's the chemistry within the venom . now , i 've already told you that that did n't work so successfully , so in a sense , what we need to do is dissect out the venom glad , and that 's where it gets a little more tricky , because in this case , you can see they 're big and— - cranky . - cranky . and they do n't like to hold still . do this under the microscope . okay , so now , again , we 're gon na just pull off her abdomen , oh god , these are some tough ants . [ * abdomen ] even tougher than the bullet ants . - wow . - so now we 've got— - you did it . - —her body separated from her abdomen . i wan na just tease apart some of the parts of the abdomen and then we can usually pull the venom gland out through the sting . so i 'm just gon na start pulling apart the body , and since i do n't want to rupture the venom gland , i wan na try not to stab too much . - yeah , this is meticulous work , dissecting ants . - yeah . - what is the smallest ant that you 'll work on under a microscope ? - oh , i 'll work on anyone . - even the ones that are so small that you ca n't even see them on the labels ? - yep , even those . i 've had to dissect out their guts , too . - how do you even get forceps that small ? - suspense , right ? - yeah , the pressure . - yeah , nothing like having to dissect on camera , too . as if it 's not hard enough , right ? - yeah , all the viewers are at home , quietly judging you . they 're like , `` well , when i dissected ants last— '' - i was thinking they were biting their fingernails in suspense . - yeah , that too . - so at the one end , let 's see if i can put it in a good orientation— you can actually see the left side , if you look through the microscope , you can actually see the sting hanging all the way out . [ * sting ] - oh yeah ! - it 's like a giant hypodermic needle . - yeah . - and then starting at the other end on the right side , we can actually start to see those parts of the digestive system . so first you have the crop , right ? [ * crop ] so it 's that social food sharing organ , which then transitions into the mid gut and then into what 's called the ileum [ * mid gut , * ileum ] and then finally into the rectum , [ * rectum ] and then alongside that is where the venom gland sits . [ * venom gland ] - that 's amazing . - yeah , it 's really awesome . one of the things that 's cool when you first open them up is that the contents within the gut , you can see fat and you can see the trachea and all those other things , and even within the gut , it 's either clear like it almost looks like water , or sometimes you can see things that look like waste , but within the venom sac , it 's actually almost like oil . and so when you burst it , it 's literally like oil coming out , not like liquid , like , you know , in the same sense . - cool . - yeah . - nice . - so now the question is , are you gon na hold a bullet ant for 10 seconds ? the brain scoop is brought to you by the field museum in chicago it still has brains on it .
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and so you can see they 're actually quite tremendous ants , i mean , they 're really foreboding , [ * worker bullet ants are 18–30 mm long ] they 're crazy big and they 're cool . [ * worker bullet ants are 18–30 mm long ] - are they the largest ant ? - they 're one of the largest ants .
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how long are worker bullet ants ?
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translator : tom carter reviewer : bedirhan cinar why are gas stations always built right next to other gas stations ? why can i drive for a mile without finding a coffee shop and then stumble across three on the same corner ? why do grocery stores , auto repair shops and restaurants always seem to exist in groups instead of being spread evenly throughout a community ? while there are several factors that might go into deciding where to place your business , clusters of similar companies can be explained by a very simple story called hotelling 's model of spatial competition . imagine that you sell ice cream at the beach . your beach is one mile long and you have no competition . where would you place your cart in order to sell the most product ? in the middle . the one-half-mile walk may be too far for some people at each end of the beach , but your cart serves as many people as possible . one day you show up at work just as your cousin teddy is arriving at the beach with his own ice cream cart . in fact , he 's selling exactly the same type of ice cream as you are . you agree that you will split the beach in half . in order to ensure that customers do n't have to walk too far you set up your cart a quarter mile south of the beach center , right in the middle of your territory . teddy sets up a quarter mile north of the center , in the middle of teddy territory . with this agreement , everyone south of you buys ice cream from you . everyone north of teddy buys from him , and the 50 % of beachgoers in between walk to the closest cart . no one walks more than a quarter of a mile , and both vendors sell to half of the beachgoers . game theorists consider this a socially optimal solution . it minimizes the maximum number of steps any visitor must take in order to reach an ice cream cart . the next day , when you arrive at work , teddy has set up his cart in the middle of the beach . you return to your location a quarter mile south of center and get the 25 % of customers to the south of you . teddy still gets all of the customers north in teddy territory , but now you split the 25 % of people in between the two carts . day three of the ice cream wars , you get to the beach early , and set up right in the center of teddy territory , assuming you 'll serve the 75 % of beachgoers to your south , leaving your cousin to sell to the 25 % of customers to the north . when teddy arrives , he sets up just south of you stealing all of the southerly customers , and leaving you with a small group of people to the north . not to be outdone , you move 10 paces south of teddy to regain your customers . when you take a mid-day break , teddy shuffles 10 paces south of you , and again , steals back all the customers to the far end of the beach . throughout the course of the day , both of you continue to periodically move south towards the bulk of the ice cream buyers , until both of you eventually end up at the center of the beach , back to back , each serving 50 % of the ice-cream-hungry beachgoers . at this point , you and your competitive cousin have reached what game theorists call a nash equilibrium - the point where neither of you can improve your position by deviating from your current strategy . your original strategy , where you were each a quarter mile from the middle of the beach , did n't last , because it was n't a nash equilibrium . either of you could move your cart towards the other to sell more ice cream . with both of you now in the center of the beach , you ca n't reposition your cart closer to your furthest customers without making your current customers worse off . however , you no longer have a socially optimal solution , since customers at either end of the beach have to walk further than necessary to get a sweet treat . think about all the fast food chains , clothing boutiques , or mobile phone kiosks at the mall . customers may be better served by distributing services throughout a community , but this leaves businesses vulnerable to aggressive competition . in the real world , customers come from more than one direction , and businesses are free to compete with marketing strategies , by differentiating their product line , and with price cuts , but at the heart of their strategy , companies like to keep their competition as close as possible .
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throughout the course of the day , both of you continue to periodically move south towards the bulk of the ice cream buyers , until both of you eventually end up at the center of the beach , back to back , each serving 50 % of the ice-cream-hungry beachgoers . at this point , you and your competitive cousin have reached what game theorists call a nash equilibrium - the point where neither of you can improve your position by deviating from your current strategy . your original strategy , where you were each a quarter mile from the middle of the beach , did n't last , because it was n't a nash equilibrium . either of you could move your cart towards the other to sell more ice cream .
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how does a nash equilibrium affect consumers ?
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imagine as a thought experiment that you live in a small village and depend on the local fish pond for food . you share the pond with three other villagers . the pond starts off with a dozen fish , and the fish reproduce . for every two fish , there will be one baby added each night . so , in order to maximize your supply of food , how many fish should you catch each day ? take a moment to think about it . assume baby fish grow to full size immediately and that the pond begins at full capacity , and ignore factors like the sex of the fish you catch . the answer ? one , and it 's not just you . the best way to maximize every villager 's food supply is for each fisherman to take just one fish each day . here 's how the math works . if each villager takes one fish , there will be eight fish left over night . each pair of fish produces one baby , and the next day , the pond will be fully restocked with twelve fish . if anyone takes more than one , the number of reproductive pairs drops , and the population wo n't be able to bounce back . eventually , the fish in the lake will be gone , leaving all four villagers to starve . this fish pond is just one example of a classic problem called the tragedy of the commons . the phenomenon was first described in a pamphlet by economist william forster lloyd in 1833 in a discussion of the overgrazing of cattle on village common areas . more than 100 years later , ecologist garrett hardin revived the concept to describe what happens when many individuals all share a limited resource , like grazing land , fishing areas , living space , even clean air . hardin argued that these situations pit short-term self-interest against the common good , and they end badly for everyone , resulting in overgrazing , overfishing , overpopulation , pollution , and other social and environmental problems . the key feature of a tragedy of the commons is that it provides an opportunity for an individual to benefit him or herself while spreading out any negative effects across the larger population . to see what that means , let 's revisit our fish pond . each individual fisherman is motivated to take as many fish as he can for himself . meanwhile , any decline in fish reproduction is shared by the entire village . anxious to avoid losing out to his neighbors , a fisherman will conclude that it 's in his best interest to take an extra fish , or two , or three . unfortunately , this is the same conclusion reached by the other fisherman , and that 's the tragedy . optimizing for the self in the short term is n't optimal for anyone in the long term . that 's a simplified example , but the tragedy of the commons plays out in the more complex systems of real life , too . the overuse of antibiotics has led to short-term gains in livestock production and in treating common illnesses , but it 's also resulted in the evolution of antibiotic-resistant bacteria , which threaten the entire population . a coal-fired power plant produces cheap electricity for its customers and profits for its owners . these local benefits are helpful in the short term , but pollution from mining and burning coal is spread across the entire atmosphere and sticks around for thousands of years . there are other examples , too . littering , water shortages , deforestation , traffic jams , even the purchase of bottled water . but human civilization has proven it 's capable of doing something remarkable . we form social contracts , we make communal agreements , we elect governments , and we pass laws . all this to save our collective selves from our own individual impulses . it is n't easy , and we certainly do n't get it right nearly all of the time . but humans at our best have shown that we can solve these problems and we can continue to do so if we remember hardin 's lesson . when the tragedy of the commons applies , what 's good for all of us is good for each of us .
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these local benefits are helpful in the short term , but pollution from mining and burning coal is spread across the entire atmosphere and sticks around for thousands of years . there are other examples , too . littering , water shortages , deforestation , traffic jams , even the purchase of bottled water .
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of all the examples in the video , which do you think is the most important ? why ?
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this is the bop . the bop is a type of social dance . dance is a language , and social dance is an expression that emerges from a community . a social dance is n't choreographed by any one person . it ca n't be traced to any one moment . each dance has steps that everyone can agree on , but it 's about the individual and their creative identity . because of that , social dances bubble up , they change , and they spread like wildfire . they are as old as our remembered history . in african-american social dances , we see over 200 years of how african and african-american traditions influenced our history . the present always contains the past . and the past shapes who we are and who we will be . ( clapping ) the juba dance was born from enslaved africans ' experience on the plantation . brought to the americas , stripped of a common spoken language , this dance was a way for enslaved africans to remember where they 're from . it may have looked something like this . slapping thighs , shuffling feet and patting hands : this was how they got around the slave owners ' ban on drumming , improvising complex rhythms just like ancestors did with drums in haiti or in the yoruba communities of west africa . it was about keeping cultural traditions alive and retaining a sense of inner freedom under captivity . it was the same subversive spirit that created this dance : the cakewalk , a dance that parodied the mannerisms of southern high society -- a way for the enslaved to throw shade at the masters . the crazy thing about this dance is that the cakewalk was performed for the masters , who never suspected they were being made fun of . now you might recognize this one . 1920s -- the charleston . the charleston was all about improvisation and musicality , making its way into lindy hop , swing dancing and even the kid n play , originally called the funky charleston . started by a tight-knit black community near charleston , south carolina , the charleston permeated dance halls where young women suddenly had the freedom to kick their heels and move their legs . now , social dance is about community and connection ; if you knew the steps , it meant you belonged to a group . but what if it becomes a worldwide craze ? enter the twist . it 's no surprise that the twist can be traced back to the 19th century , brought to america from the congo during slavery . but in the late '50s , right before the civil rights movement , the twist is popularized by chubby checker and dick clark . suddenly , everybody 's doing the twist : white teenagers , kids in latin america , making its way into songs and movies . through social dance , the boundaries between groups become blurred . the story continues in the 1980s and '90s . along with the emergence of hip-hop , african-american social dance took on even more visibility , borrowing from its long past , shaping culture and being shaped by it . today , these dances continue to evolve , grow and spread . why do we dance ? to move , to let loose , to express . why do we dance together ? to heal , to remember , to say : `` we speak a common language . we exist and we are free . ''
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the charleston was all about improvisation and musicality , making its way into lindy hop , swing dancing and even the kid n play , originally called the funky charleston . started by a tight-knit black community near charleston , south carolina , the charleston permeated dance halls where young women suddenly had the freedom to kick their heels and move their legs . now , social dance is about community and connection ; if you knew the steps , it meant you belonged to a group .
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the charleston started in a tight knit community in south carolina in the 1920 ’ s . but by the 1930 ’ s it had an impact on women everywhere . why ?
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it was a night like any other night , except here i was climbing the platonic peaks like romeo on a second date . ( ugh ) i was there for the dame . she had eyes like imaginary numbers and curves that went on forever . said she wanted to go home . said i could help . said the pay was good . did n't say anything about climbing a ... voice : `` who 's there ? '' manny brot : `` manny brot , private eye . '' voice : `` what are you doing here ? '' `` a pretty number sent me to find a stolen dingus . '' voice : `` well , to enter the cave , you must answer my riddles three . '' what was it with riddles , and why do they always come in threes ? `` is it an egg ? '' `` no . why would it be an egg ? '' `` it 's usually an egg . '' `` what can i hold in my hand , but has zero area ? '' `` is it a dodo egg ? '' `` it 's not an egg ! '' i took out the rock that had nearly brained me before and gave it a hard ponder . the size of the rising bump on my conk said to me that this thing had area , and a lot of it . but what if i carved out a triangle from this side here ? as any mook could see , this triangle had a quarter of the area of the full triangle . i did the same thing again with each of the smaller triangles . again , a quarter of the remaining area -- gone . and i just kept going . after an infinite number of cuts , i was satisfied that my triangle had zero area . a bounded shape with zero area . now , it 's not often that i surprise myself , but my own two mitts had created something crazy , and new . `` very good . ( ahem ) now , show me a shape with finite area , but an infinitely long perimeter . '' `` let me get this straight . if i want to make a snip in the border of this shape , smooth it out , and lay it on the ground ... `` `` it would go on for ... `` `` wait 'til i 'm through , and then you can talk . it would go on forever . '' `` are you through ? '' `` yeah . '' `` so show me that shape then . '' mmm ... i had n't been this stuck since the rubik 's cube fiasco of '58 . all the shapes i knew had perimeters . circles : 2πr . triangles : sum of their sides . what 's this ? an angle . an angle from heaven . what if i were to pinch each side , like so . a third of the way through , just so . and do it again , and again , and again . after each pinch , the perimeter got a third longer because where there had been three line segments , now there were four . as for the area , every pinch made more triangles , that 's true . but those triangles were getting smaller and smaller . you could say that the area was converging , approaching a fixed number , while the perimeter was just getting bigger and bigger , uncontrollably ballooning like an overindulgent birthday clown . after infinity pinches , flimflam , there it was : finite area , but infinite perimeter . now that is a piece of work . `` oh , you 're good . ( ahem ) riddle three : show me a picture that if i magnify it under my microscope , i 'll keep seeing the original picture , no matter how much i zoom in . '' `` you 're a strange little man . '' `` thank you . '' i was out of ideas , so i looked at my muse , my complex dora . voice : `` who 's the dame ? '' and then it hit me . `` she 's a heart breaker , my fractal femme fatale . will she do ? '' `` yes , she 'll do just fine . '' ( lightning ) it was dark , and at first i thought the cave was empty , but then i noticed : the box . the dame had played me like a triangle . she had told me she wanted to go home . ( lightning ) what she really wanted was to bring her home here . the fractals spread everywhere . most of them the same no matter how deep you looked at them , like dora 's mugshot . some had infinitely long perimeters , others were objects with no area or volume , all of them created through infinite repetition . so , you wanted to know what fractals are ? well , kid , they 're the stuff that dreams are made of . ( music )
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did n't say anything about climbing a ... voice : `` who 's there ? '' manny brot : `` manny brot , private eye . '' voice : `` what are you doing here ? ''
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how many times did manny have to pinch the snowflake ( the answer to the second riddle ) ?
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what could octopuses possibly have in common with us ? after all , they do n't have lungs , spines , or even a plural noun we can all agree on . but what they do have is the ability to solve puzzles , learn through observation , and even use tools , just like some other animals we know . and what makes octopus intelligence so amazing is that it comes from a biological structure completely different from ours . the 200 or so species of octopuses are mollusks belonging to the order cephalopoda , greek for head-feet . those heads contain impressively large brains , with a brain to body ratio similar to that of other intelligent animals , and a complex nervous system with about as many neurons as that of a dog . but instead of being centralized in the brain , these 500 million neurons are spread out in a network of interconnected ganglia organized into three basic structures . the central brain only contains about 10 % of the neurons , while the two huge optic lobes contain about 30 % . the other 60 % are in the tentacles , which for humans would be like our arms having minds of their own . this is where things get even more interesting . vertebrates like us have a rigid skeleton to support our bodies , with joints that allow us to move . but not all types of movement are allowed . you ca n't bend your knee backwards , or bend your forearm in the middle , for example . cephalopods , on the other hand , have no bones at all , allowing them to bend their limbs at any point and in any direction . so shaping their tentacles into any one of the virtually limitless number of possible arrangements is unlike anything we are used to . consider a simple task , like grabbing and eating an apple . the human brain contains a neurological map of our body . when you see the apple , your brain 's motor center activates the appropriate muscles , allowing you to reach out with your arm , grab it with your hand , bend your elbow joint , and bring it to your mouth . for an octopus , the process is quite different . rather than a body map , the cephalopod brain has a behavior library . so when an octopus sees food , its brain does n't activate a specific body part , but rather a behavioral response to grab . as the signal travels through the network , the arm neurons pick up the message and jump into action to command the movement . as soon as the arm touches the food , a muscle activation wave travels all the way through the arm to its base , while the arm sends back another wave from the base to the tip . the signals meet halfway between the food and the base of the arm , letting it know to bend at that spot . what all this means is that each of an octopus 's eight arms can essentially think for itself . this gives it amazing flexibility and creativity when facing a new situation or problem , whether its opening a bottle to reach food , escaping through a maze , moving around in a new environment , changing the texture and the color of its skin to blend into the scenery , or even mimicking other creatures to scare away enemies . cephalopods may have evolved complex brains long before our vertebrate relatives . and octopus intelligence is n't just useful for octopuses . their radically different nervous system and autonomously thinking appendages have inspired new research in developing flexible robots made of soft materials . and studying how intelligence can arise along such a divergent evolutionary path can help us understand more about intelligence and consciousness in general . who knows what other forms of intelligent life are possible , or how they process the world around them .
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what could octopuses possibly have in common with us ? after all , they do n't have lungs , spines , or even a plural noun we can all agree on .
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which of the following sentences is correct ?
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physicists , air traffic controllers , and video game creators all have at least one thing in common : vectors . what exactly are they , and why do they matter ? to answer , we first need to understand scalars . a scalar is a quantity with magnitude . it tells us how much of something there is . the distance between you and a bench , and the volume and temperature of the beverage in your cup are all described by scalars . vector quantities also have a magnitude plus an extra piece of information , direction . to navigate to your bench , you need to know how far away it is and in what direction , not just the distance , but the displacement . what makes vectors special and useful in all sorts of fields is that they do n't change based on perspective but remain invariant to the coordinate system . what does that mean ? let 's say you and a friend are moving your tent . you stand on opposite sides so you 're facing in opposite directions . your friend moves two steps to the right and three steps forward while you move two steps to the left and three steps back . but even though it seems like you 're moving differently , you both end up moving the same distance in the same direction following the same vector . no matter which way you face , or what coordinate system you place over the camp ground , the vector does n't change . let 's use the familiar cartesian coordinate system with its x and y axes . we call these two directions our coordinate basis because they 're used to describe everything we graph . let 's say the tent starts at the origin and ends up over here at point b . the straight arrow connecting the two points is the vector from the origin to b . when your friend thinks about where he has to move , it can be written mathematically as 2x + 3y , or , like this , which is called an array . since you 're facing the other way , your coordinate basis points in opposite directions , which we can call x prime and y prime , and your movement can be written like this , or with this array . if we look at the two arrays , they 're clearly not the same , but an array alone does n't completely describe a vector . each needs a basis to give it context , and when we properly assign them , we see that they are in fact describing the same vector . you can think of elements in the array as individual letters . just as a sequence of letters only becomes a word in the context of a particular language , an array acquires meaning as a vector when assigned a coordinate basis . and just as different words in two languages can convey the same idea , different representations from two bases can describe the same vector . the vector is the essence of what 's being communicated , regardless of the language used to describe it . it turns out that scalars also share this coordinate invariance property . in fact , all quantities with this property are members of a group called tensors . various types of tensors contain different amounts of information . does that mean there 's something that can convey more information than vectors ? absolutely . say you 're designing a video game , and you want to realistically model how water behaves . even if you have forces acting in the same direction with the same magnitude , depending on how they 're oriented , you might see waves or whirls . when force , a vector , is combined with another vector that provides orientation , we have the physical quantity called stress , which is an example of a second order tensor . these tensors are also used outside of video games for all sorts of purposes , including scientific simulations , car designs , and brain imaging . scalars , vectors , and the tensor family present us with a relatively simple way of making sense of complex ideas and interactions , and as such , they 're a prime example of the elegance , beauty , and fundamental usefulness of mathematics .
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to answer , we first need to understand scalars . a scalar is a quantity with magnitude . it tells us how much of something there is .
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give an example of a scalar that you have used in your everyday life . describe what makes it a scalar .
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astronomers have discovered thousands of planets orbiting stars other than the sun . they come in all sizes , at different orbital distances from their stars . the closest of them are trillions of miles away , and even the largest are just fuzzy patches in the fields of high-powered telescopes . but if one of these planets is close in size to the earth and orbits not too close and too far away from its parent star , it could be rocky and warm enough to have oceans and perhaps life . astronomers discover these potentially habitable planets , and their eyes get big and wide . could one of these distant worlds carry the building blocks of life ? or even a living , breathing , civilization ? is the question , `` are we alone in the universe ? '' about to be answered ? but wait . maybe we should ask a different question first . should we try to find out if we 're alone in the universe ? if we do find the atmospheric fingerprints of life on one of these small , distant worlds , should we try to contact any beings who may live there ? is that wise ? three decades ago , nasa decided the answer was yes . voyager 1 and 2 were launched in 1977 to explore the giant planets in the solar system . each spacecraft carried a golden phonograph record , a time capsule of sorts that included clues and messages meant to convey the story of human civilization . the contents of these gold-plated copper disks were chosen by a committee chaired by american astronomer and author carl sagan . they included over 100 images , and a range of sounds from the natural world : ocean waves , thunder , the sounds of birds and whales . the records also included music from many different time periods and cultures , greetings in 55 languages , and messages from the president of the united states , and the un secretary general . they also included a map . each golden record displays the location of our solar system with respect to fourteen pulsars . their precise , unique frequencies were indicated so that intelligent , extraterrestrial lifeforms could use them to find the earth . many years later , renowned physicist stephen hawking said that it was a mistake to give an alien species a roadmap to our planet . hawking suspected that any extraterrestrial life probably was n't any more complex than microbes , but he warned that if an advanced alien species did visit earth , it could be as catastrophic as christopher columbus 's arrival was for the native americans . meanwhile , the golden records continue their journeys . in 1990 , both voyager spacecraft passed beyond the orbit of pluto . voyager 1 entered interstellar space in 2012 , and will reach the nearest stellar system in 40,000 years . if either spacecraft is discovered by extraterrestrial life , there 's a possibility that they could decipher the clues from the golden record and one day reach our planet . that 's particularly true if theirs is a much more technologically advanced civilization . that life could be benevolent , as we would hope to be if humans are one day able to achieve interstellar travel . or it could be hostile . searching for planets that might have life means staring into a great abyss . we 'll likely have no clear knowledge of the evolutionary stage , sentience , character , or intentions of the first form of life we discover . so it 's a risk to turn our eyes outwards . we risk our very way of life . but it may be a greater risk not to look , to deny the very pioneering spirits that help shape our own species . we are all born curious about the world and the universe . pursuing that curiosity is one of humankind 's greatest achievements . perhaps there is room to push the frontiers of science , provided that we cradle alongside our fervor another of humankind 's greatest assets : hope .
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that life could be benevolent , as we would hope to be if humans are one day able to achieve interstellar travel . or it could be hostile . searching for planets that might have life means staring into a great abyss . we 'll likely have no clear knowledge of the evolutionary stage , sentience , character , or intentions of the first form of life we discover .
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in this particular area of study , one of the ways astronomers look for planets where life might exist is to look for planets that could be warm enough for surface :
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if you tried to pay for something with a piece of paper , you might run into some trouble . unless , of course , the piece of paper was a hundred dollar bill . but what is it that makes that bill so much more interesting and valuable than other pieces of paper ? after all , there 's not much you can do with it . you ca n't eat it . you ca n't build things with it . and burning it is actually illegal . so what 's the big deal ? of course , you probably know the answer . a hundred dollar bill is printed by the government and designated as official currency , while other pieces of paper are not . but that 's just what makes them legal . what makes a hundred dollar bill valuable , on the other hand , is how many or few of them are around . throughout history , most currency , including the us dollar , was linked to valuable commodities and the amount of it in circulation depended on a government 's gold or silver reserves . but after the us abolished this system in 1971 , the dollar became what is known as fiat money , meaning not linked to any external resource but relying instead solely on government policy to decide how much currency to print . which branch of our government sets this policy ? the executive , the legislative , or the judicial ? the surprising answer is : none of the above ! in fact , monetary policy is set by an independent federal reserve system , or the fed , made up of 12 regional banks in major cities around the country . its board of governors , which is appointed by the president and confirmed by the senate , reports to congress , and all the fed 's profit goes into the us treasury . but to keep the fed from being influenced by the day-to-day vicissitudes of politics , it is not under the direct control of any branch of government . why does n't the fed just decide to print infinite hundred dollar bills to make everyone happy and rich ? well , because then the bills would n't be worth anything . think about the purpose of currency , which is to be exchanged for goods and services . if the total amount of currency in circulation increases faster than the total value of goods and services in the economy , then each individual piece will be able to buy a smaller portion of those things than before . this is called inflation . on the other hand , if the money supply remains the same , while more goods and services are produced , each dollar 's value would increase in a process known as deflation . so which is worse ? too much inflation means that the money in your wallet today will be worth less tomorrow , making you want to spend it right away . while this would stimulate business , it would also encourage overconsumption , or hoarding commodities , like food and fuel , raising their prices and leading to consumer shortages and even more inflation . but deflation would make people want to hold onto their money , and a decrease in consumer spending would reduce business profits , leading to more unemployment and a further decrease in spending , causing the economy to keep shrinking . so most economists believe that while too much of either is dangerous , a small , consistent amount of inflation is necessary to encourage economic growth . the fed uses vast amounts of economic data to determine how much currency should be in circulation , including previous rates of inflation , international trends , and the unemployment rate . like in the story of goldilocks , they need to get the numbers just right in order to stimulate growth and keep people employed , without letting inflation reach disruptive levels . the fed not only determines how much that paper in your wallet is worth but also your chances of getting or keeping the job where you earn it .
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what makes a hundred dollar bill valuable , on the other hand , is how many or few of them are around . throughout history , most currency , including the us dollar , was linked to valuable commodities and the amount of it in circulation depended on a government 's gold or silver reserves . but after the us abolished this system in 1971 , the dollar became what is known as fiat money , meaning not linked to any external resource but relying instead solely on government policy to decide how much currency to print .
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what is united states currency linked to ?
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the victory of the underdog over the favored team . the last minute penalty shot that wins the tournament . the high-energy training montages . many people love to glorify victory on the playing field , cheer for favorite teams , and play sports . but here 's a question : should we be so obsessed with sports ? is playing sports actually as good for us as we make it out to be , or just a fun and entertaining pastime ? what does science have to say ? first of all , it 's well accepted that exercise is good for our bodies and minds , and that 's definitely true . exercising , especially when we 're young , has all sorts of health benefits , like strengthening our bones , clearing out bad cholesterol from our arteries , and decreasing the risk of stroke , high blood pressure , and diabetes . our brains also release a number of chemicals when we workout , including endorphins . these natural hormones , which control pain and pleasure responses in the cental nervous system , can lead to feelings of euphoria , or , what 's often called , a runner 's high . increased endorphins and consistent physical activity in general can sharpen your focus and improve your mood and memory . so does that mean we get just as much benefit going to the gym five days a week as we would joining a team and competing ? well , here 's where it gets interesting : because it turns out that if you can find a sport and a team you like , studies show that there are all sorts of benefits that go beyond the physical and mental benefits of exercise alone . some of the most significant are psychological benefits , both in the short and long term . some of those come from the communal experience of being on a team , for instance , learning to trust and depend on others , to accept help , to give help , and to work together towards a common goal . in addition , commitment to a team and doing something fun can also make it easier to establish a regular habit of exercise . school sport participation has also been shown to reduce the risk of suffering from depression for up to four years . meanwhile , your self-esteem and confidence can get a big boost . there are a few reasons for that . one is found in training . just by working and working at skills , especially with a good coach , you reinforce a growth mindset within yourself . that 's when you say , `` even if i ca n't do something today , i can improve myself through practice and achieve it eventually . '' that mindset is useful in all walks of life . and then there 's learning through failure , one of the most transformative , long-term benefits of playing sports . the experience of coming to terms with defeat can build the resilience and self-awareness necessary to manage academic , social , and physical hurdles . so even if your team is n't winning all the time , or at all , there 's a real benefit to your experience . now , not everyone will enjoy every sport . perhaps one team is too competitive , or not competitive enough . it can also take time to find a sport that plays to your strengths . that 's completely okay . but if you spend some time looking , you 'll be able to find a sport that fits your individual needs , and if you do , there are so many benefits . you 'll be a part of a supportive community , you 'll be building your confidence , you 'll be exercising your body , and you 'll be nurturing your mind , not to mention having fun .
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some of those come from the communal experience of being on a team , for instance , learning to trust and depend on others , to accept help , to give help , and to work together towards a common goal . in addition , commitment to a team and doing something fun can also make it easier to establish a regular habit of exercise . school sport participation has also been shown to reduce the risk of suffering from depression for up to four years .
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which of the following is an effect of cardiovascular exercise ?
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with social media sites being used by ⅓ of the entire world , they ’ ve clearly had an major influence on society . but what about our bodies ? here are 5 crazy ways that social media and the internet are affecting your brain right now ! can ’ t log off ? surprisingly , 5-10 % of internet users are actually unable to control how much time they spend online . though it ’ s a psychological addiction as opposed to a substance addiction , brain scans of these people actually show a similar impairment of regions that those with drug dependence have . specifically , there is a clear degradation of white matter in the regions that control emotional processing , attention and decision making . because social media provides immediate rewards with very little effort required , your brain begin to rewire itself , making you desire these stimulations . and you begin to crave more of this neurological excitement after each interaction . sounds a little like a drug , right ? we also see a shift when looking at multi-tasking . you might think that those who use social media or constantly switch between work and websites are better at multitasking , but studies have found that when comparing heavy media users to others , they perform much worse during task switching tests . increased multi-tasking online reduces your brains ability to filter out interferences , and can even make it harder for your brain to commit information to memory . like when your phone buzzes in the middle of productive work . or wait ... did it even buzz ? phantom vibration syndrome is a relatively new psychological phenomenon where you think you felt your phone go off , but it didn ’ t . in one study , 89 % of test subjects said they experienced this at least once every two weeks . it would seem that our brains now perceive an itch as an actual vibration from our phone . as crazy as it seems , technology has begun to rewire our nervous systems - and our brains are being triggered in a way they never have been before in history . social media also triggers a release of dopamine - the feel good chemical . using mri scans , scientist found that the reward centres in people ’ s brains are much more active when they are talking about their own views , as opposed to listening to others . not so surprising - we all love talking about ourselves right ? but it turns out that while 30-40 % of face-to-face conversations involve communicating our own experiences , around 80 % of social media communication is self involved . the same part of your brain related to orgasms , motivation and love are stimulated by your social media use - and even more so when you know you have an audience . our body is physiologically rewarding us for talking about ourselves online ! but it ’ s not all so self involved . in fact , studies on relationships have found that partners tend to like each other more if they meet for the first time online rather than with a face to face interaction . whether it ’ s because people are more anonymous or perhaps more clear about their future goals , there is a statistical increase in successful partnerships that started online . so while the internet has changed our verbal communication with increased physical separation , perhaps the ones that matter most end up even closer . speaking of social media , we had you ask us questions on twitter , instagram , facebook , tumblr , google+ and every other social platform we could find and did a q & amp ; amp ; a video over on asapthought ! so if you feel getting some insider info on asapscience and behind the scenes , check it out with the link in the description ! got a burning question you want answered ? ask it in the comments or on facebook and twitter . we also finally got a po box , for all of you amazing science lovers who have requested to send us mail or other stuff over the years . and we ’ d love to hear from all of you ! so feel free use the address on the screen or in the description box . and subscribe for more weekly science videos !
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not so surprising - we all love talking about ourselves right ? but it turns out that while 30-40 % of face-to-face conversations involve communicating our own experiences , around 80 % of social media communication is self involved . the same part of your brain related to orgasms , motivation and love are stimulated by your social media use - and even more so when you know you have an audience .
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describe the main differences between face to face conversations and social media postings .
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( music ) i want everyone to put their hands on top of their head . yeah , yeah , yeah . put your hands on top of your head . just relax . just stay calm . everything will be nice and smooth if you just participate and just relax , okay ? yeah . all right , now put your hands down . do n't be no hero . put your hands down . okay ? all right . now . cool . good . i want you to run all that financial aid . yeah , sucka , put the scholarships in the bag , yeah , yeah . put the scholarships in the bag . yeah , you too , yeah , yeah , yeah . yeah , you . yeah , yeah . you over there , go put the pell grants in the bag . put the pell grants in there too . yeah , you . go . yeah , yeah , yeah . you , go over to that booth and get me some of them subsidized , some of them subsidized loans . it ai n't a game no more . i know you 're hiding the money somewhere here . with all this tuition you got me and my homies payin ' -- woo ! -- i 'm about to get gangster-scholar up in here . up in here . i 'm about to go n.w.a . meets beastie boys if i do n't see the cash , man . cause we 're not gon na take it . ♪ oh ... oh , you thought i was playing . oh , you thought this was a game . back up , back up . mind your business , that 's all . what do you , think this is a game ? what ? huh ? you do n't even know me . i 'll say something else . do n't call me crazy . do not call me -- rives , tell 'em do n't call me crazy before i go crazy . i 'm telling you , now i 'm about to go crazy . i 'm about to go tupac thug life in here . like , `` i ai n't a killer but do n't push me . revenge is like the sweetest joy -- '' woo ! i 'm about to go biggie smalls brooklyn type , like , `` super nintendo , sega genesis . when i was dead broke -- '' woo ! i 'm about to go krs-one cuckoo for cocoa puffs-type wild . like , `` wa da da dang , wa da da da dang , listen to my nine millimeter go bang . '' you know what ? you are dumb . you are really dumb . hide your kids , hide your wife , 'cause we gettin ' financial aid all up and in and around here . you think this is a game ? you think i want to be out here doing this ? do you know how hard it was to find these guns ? all right , i 'm sorry . you understand ? i 'm just trying to get my education . you know what i mean ? i 'm just trying to fight for the opportunity that my great-great-great-grandfather died for , you know what i 'm saying ? you know how my ancestors did sit-ins , just so i can sit in a classroom . and all these years , all y'all been doing is strangling the life out of my bank statement , leaving my pockets as vacant as parking lots . professor willie lynch taught you well , huh ? keep the body , take the money . force feed my people deception and failure . condition our brains to malfunction at the sight of success . just keep the cycle going . make us pay for an education that will end up failing us . put us in debt so we 're giving back the money we earned from our back-breaking work . this seems all too familiar . sounds like the rust of shackles locking their way onto my degree . sounds like the thirteenth amendment in reverse . lecture halls should n't feel like cotton fields , should n't sound like muffled freedom songs trapped in the jaws of a generation 's dreams . oho ! oh , it all makes sense . give us enough to get by but not enough to provide for ourselves . keep us psychologically feeble so we lose our purpose in the process . stop thieving our aspirations out of our sleep . do n't call it financial aid if you 're not helping anyone with it . we have fought . we have fought way too hard to let green paper build a barricade in front of our futures . i will not let you potentially rob food out of my children 's stomach . best believe i 'm going out blasting . i ai n't no killer , but do n't push me . i wish it did n't come to this , but i have to for my cousins in haiti who do n't even know what a college looks like , for my best friend raymond sitting in cell block nine instead of a university , for the nooses hanging my gpa by its neck . there is no other option . there is no other way . just , please , put the money in the bag . put the money in the bag . i just want to go to school , man . i just want to get my education . i just want to learn . i just want to grow . put the money in the bag , please . just put the money in the bag .
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oho ! oh , it all makes sense . give us enough to get by but not enough to provide for ourselves .
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lissaint makes eloquent use of simile , as in
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if i were to distill the 20 years of elephant research that i 've done into one sentence , what would it be ? what could i tell you ? i would say that elephants are just like us ! and what do i mean by that ? it takes a lot of patience to be out there in the field and trying to figure out patterns of these very slow and intelligent animals . but over time , it is true they are very similar to us . and you think , `` well , how can i say that ? look , they have huge ears , they have really long noses . what do you mean they 're like us ? '' well , in fact , their families are very similar to ours . and family is extremely important to elephants . they grow up in very tight-knit families and they have extended families . and it 's just like our family reunions where you have all the aunts gathering around with all the food they 're going to bring and plan , and all the boys are thinking , `` are we going to play our video games together ? are we going to spar ? '' it 's very , very similar , and it 's jubilant , and screaming , yelling , it 's really amazing to see . but , as soon as you get that family gathering , it 's just like a wedding or anything else , all of the sudden the family politics come out , and the lower-ranking individuals in this scene , you see the arrow off to the back , the lower-ranking individuals already know their station , they 're going to drink at the muddiest part of the pan because the whole family 's here and we ca n't drink at the best water because that 's reserved for the top-ranking family . what 's also very similar is that you have elders in the group that everyone reveres . this is the matriarch , and the other female is reaching over and doing what 's called a trunk to mouth placing her trunk in the mouth , and it 's a sign of respect , it 's kind of like a handshake , but it 's also like a salute . and this salute is learned at a very young age . now , ritual and bonding within the family also facilitates coordinated activities . so , here 's a young female whose calf has fallen into the trough and she does n't know what to do and she panics . well , the older female , that 's the matriarch , she says , `` no problem here , '' she just scoops the baby out . now , that 's not true for a lot of different families , they ca n't coordinate very well , the younger females do n't really know what to do , but the older ones will just get down , kneel down together and pick the baby out . another thing that 's very similar is the coming of age of teenage boys . male elephants at the age of about 12 to 15 . the biggest elephant in this photograph here is an elephant who 's about the leave the family . he gets too big , he gets a little fresh , the adult females had enough of him , but he also is independent , he wants to go out and play with the guys . so what happens then is that you have this all male society , very ritual male society . greg is our main dominant bull here , you can see him in the middle . he 's got a huge posse , his following reveres him . and it 's very interesting how very good leaders , very good dominant individuals know how to titrate the carrot and the stick . this guy 's a master at it , and there 's other bullies out there that want to kind of want to create their own little following , but they ca n't do it because they 're too agressive . and so when he 's not around they try and sweet talk the underlings to come into their fold , and they actually become less agressive . so it 's very interesting to see how politics play out in these male and female societies . now back to the ladies here . in a core family group you 'll have a mother , maybe even a grandmother , her daughters and all of their offspring , the male and female calves . and what 's very interesting here is that how character makes a difference . so each matriarch has a very different character . these two characters are kind of curious , they 're uncertain , whereas these other two characters are really agressive . `` we 're going to charge first , ask questions later . '' but then there are also matriarchs that say , `` forget it ! i 'm going to run first and then figure it out when we 're in the bush and it 's safe . '' but the wisest matriarch , the matriarchs that succeed best in all of the studies that have been done , is the one that assesses the danger and decides is this worth running away from or is this not a big deal at all . now being social is super important for elephants and of course right at the beginning , just like early childhood development , socialization is very important . bathing together , eating together , playing together , rough housing , this is all very important for social development . and who has n't tried to beat their sibling to the head of the line coming into the water hole ? and these relationships from the beginning is just like best friends forever for real . these females are going to live together for life . now if it 's a male , female they might know each other for life , but it 's really important to develop those bonds early on . those are the relationships that are going to save you later . i 'll show you a little schoolyard scenario here . where , i think if you just focus on what 's happening here you can see that we have the bully , he 's pulling on the trunk of this baby calf , and then we have the diplomat who 's reaching over and saying , `` no , do n't do that ! stop doing that ! '' and then , of course , we have the bystander . and how do you get these three different characters within the family ? it 's kind of fascinating to think that elephants really are just like us . and so i got curious about this and i thought , `` well , what if you measure the difference in character of a dominant female 's calf versus a lower-ranking female 's calf , and see what happens in their growing up . '' and so we started doing this . and you can see this little guy with his ears out , really charging at you . the difference between that character and the character who holds back , wants to touch mom , is n't so certain about what 's going on here . but the other one 's charging ahead all confident . well , we started measuring how far away a calf will stray from mom , how often do they touch others , how often do they initiate play , and then look at the dominance of the females , of their mothers . and what we found is that socializing with the dominant calves actually socialize more significantly more than the lower-ranking calves . and what it looks like is it 's not that the lower-ranking calves do n't want to play , they 're actually not allowed to interact with the higher-ranking calves . they get swatted away from the dominant females . and so this is kind of the downside of , okay we are very much like elephants , elephants are as much like us , but it 's kind of for better or for worse because i can also see this happening in humans and maybe we should take a lesson from that . one last thing that we found is that the males will be the risk-takers , they 're more independent and they 're more likely to spend more time away from mom . and that 's very true in human societies and with other social animals . so i hope i 've convinced you that we have very similar lives to elephants and that elephants have very individual , durable characters that we 've measured across years . the bully always tends to be the bully unless there 's some kind of social upset , and he decides he better be a softy or else he 's not going to gain favor at all . and then you have the gentle giants that are always going to be gentle . the young males really need mentoring from the elders , and those gentle giants are very good at doing that , soliciting them . leaving family is a really hard things for the males , but they survive and they figure out who to hang out with . so , just to end here , i just wanted to say that since they are so similar to us , and have these characters , i hope when you see them on tv or you go out and you 're lucky enough to see them in the wild , that maybe you 'll think of them as individual characters deserving of our attention , and also deserving of our protection . thank you .
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well , in fact , their families are very similar to ours . and family is extremely important to elephants . they grow up in very tight-knit families and they have extended families .
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when male elephants grow up and leave their family as adults , they ________ .
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one , two , three , four , five , six , seven , eight , nine , and zero . with just these ten symbols , we can write any rational number imaginable . but why these particular symbols ? why ten of them ? and why do we arrange them the way we do ? numbers have been a fact of life throughout recorded history . early humans likely counted animals in a flock or members in a tribe using body parts or tally marks . but as the complexity of life increased , along with the number of things to count , these methods were no longer sufficient . so as they developed , different civilizations came up with ways of recording higher numbers . many of these systems , like greek , hebrew , and egyptian numerals , were just extensions of tally marks with new symbols added to represent larger magnitudes of value . each symbol was repeated as many times as necessary and all were added together . roman numerals added another twist . if a numeral appeared before one with a higher value , it would be subtracted rather than added . but even with this innovation , it was still a cumbersome method for writing large numbers . the way to a more useful and elegant system lay in something called positional notation . previous number systems needed to draw many symbols repeatedly and invent a new symbol for each larger magnitude . but a positional system could reuse the same symbols , assigning them different values based on their position in the sequence . several civilizations developed positional notation independently , including the babylonians , the ancient chinese , and the aztecs . by the 8th century , indian mathematicians had perfected such a system and over the next several centuries , arab merchants , scholars , and conquerors began to spread it into europe . this was a decimal , or base ten , system , which could represent any number using only ten unique glyphs . the positions of these symbols indicate different powers of ten , starting on the right and increasing as we move left . for example , the number 316 reads as 6x10^0 plus 1x10^1 plus 3x10^2 . a key breakthrough of this system , which was also independently developed by the mayans , was the number zero . older positional notation systems that lacked this symbol would leave a blank in its place , making it hard to distinguish between 63 and 603 , or 12 and 120 . the understanding of zero as both a value and a placeholder made for reliable and consistent notation . of course , it 's possible to use any ten symbols to represent the numerals zero through nine . for a long time , the glyphs varied regionally . most scholars agree that our current digits evolved from those used in the north african maghreb region of the arab empire . and by the 15th century , what we now know as the hindu-arabic numeral system had replaced roman numerals in everyday life to become the most commonly used number system in the world . so why did the hindu-arabic system , along with so many others , use base ten ? the most likely answer is the simplest . that also explains why the aztecs used a base 20 , or vigesimal system . but other bases are possible , too . babylonian numerals were sexigesimal , or base 60 . any many people think that a base 12 , or duodecimal system , would be a good idea . like 60 , 12 is a highly composite number that can be divided by two , three , four , and six , making it much better for representing common fractions . in fact , both systems appear in our everyday lives , from how we measure degrees and time , to common measurements , like a dozen or a gross . and , of course , the base two , or binary system , is used in all of our digital devices , though programmers also use base eight and base 16 for more compact notation . so the next time you use a large number , think of the massive quantity captured in just these few symbols , and see if you can come up with a different way to represent it .
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numbers have been a fact of life throughout recorded history . early humans likely counted animals in a flock or members in a tribe using body parts or tally marks . but as the complexity of life increased , along with the number of things to count , these methods were no longer sufficient .
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what is the difference between additive and positional numerical systems and what are the benefits and disadvantages of using one system rather than the other ? can you think of some instances in which we still use tally marks or similar tools ?
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so you just strained a muscle and the inflammation is unbearable . you wish you had something ice-cold to dull the pain , but to use an ice pack , you would have had to put it in the freezer hours ago . fortunately , there 's another option . a cold pack can be left at room temperature until the moment you need it , then just snap it as instructed and within seconds you 'll feel the chill . but how can something go from room temperature to near freezing in such a short time ? the answer lies in chemistry . your cold pack contains water and a solid compound , usually ammonium nitrate , in different compartments separated by a barrier . when the barrier is broken , the solid dissolves causing what 's known as an endothermic reaction , one that absorbs heat from its surroundings . to understand how this works , we need to look at the two driving forces behind chemical processes : energetics and entropy . these determine whether a change occurs in a system and how energy flows if it does . in chemistry , energetics deals with the attractive and repulsive forces between particles at the molecular level . this scale is so small that there are more water molecules in a single glass than there are known stars in the universe . and all of these trillions of molecules are constantly moving , vibrating and rotating at different rates . we can think of temperature as a measurement of the average motion , or kinetic energy , of all these particles , with an increase in movement meaning an increase in temperature , and vice versa . the flow of heat in any chemical transformation depends on the relative strength of particle interactions in each of a substance 's chemical states . when particles have a strong mutual attractive force , they move rapidly towards one another , until they get so close , that repulsive forces push them away . if the initial attraction was strong enough , the particles will keep vibrating back and forth in this way . the stronger the attraction , the faster their movement , and since heat is essentially motion , when a substance changes to a state in which these interactions are stronger , the system heats up . but our cold packs do the opposite , which means that when the solid dissolves in the water , the new interactions of solid particles and water molecules with each other are weaker than the separate interactions that existed before . this makes both types of particles slow down on average , cooling the whole solution . but why would a substance change to a state where the interactions were weaker ? would n't the stronger preexisting interactions keep the solid from dissolving ? this is where entropy comes in . entropy basically describes how objects and energy are distributed based on random motion . if you think of the air in a room , there are many different possible arrangements for the trillions of particles that compose it . some of these will have all the oxygen molecules in one area , and all the nitrogen molecules in another . but far more will have them mixed together , which is why air is always found in this state . now , if there are strong attractive forces between particles , the probability of some configurations can change even to the point where the odds do n't favor certain substances mixing . oil and water not mixing is an example . but in the case of the ammonium nitrate , or other substance in your cold pack , the attractive forces are not strong enough to change the odds , and random motion makes the particles composing the solid separate by dissolving into the water and never returning to their solid state . to put it simply , your cold pack gets cold because random motion creates more configurations where the solid and water mix together and all of these have even weaker particle interaction , less overall particle movement , and less heat than there was inside the unused pack . so while the disorder that can result from entropy may have caused your injury in the first place , its also responsible for that comforting cold that soothes your pain .
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your cold pack contains water and a solid compound , usually ammonium nitrate , in different compartments separated by a barrier . when the barrier is broken , the solid dissolves causing what 's known as an endothermic reaction , one that absorbs heat from its surroundings . to understand how this works , we need to look at the two driving forces behind chemical processes : energetics and entropy .
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when a reaction is endothermic :
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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 . ''
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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 .
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why do fluorine atoms in ptfe line up in a spiral fashion around the carbon backbone ?
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english , like all languages , is a messy business . you can be uncouth but not couth . you can be ruthless , but good luck trying to show somebody that you have ruth unless you happen to be married to someone named ruth . it 's bad to be unkempt but impossible to be kempt , or sheveled as opposed to disheveled . there are other things that make no more sense than those but that seem normal now because the sands of time have buried where they came from . for example , did you ever wonder why a nickname for edward is ned ? where 'd the n come from ? it 's the same with nellie for ellen . afterall , if someone 's name is ethan , we do n't nickname him nethan , nor do we call our favorite maria , nmaria . in fact , if anyone did , our primary urge would be to either scold them or gently hide them away until the company had departed . all these nicknames trace back to a mistake , although , a perfectly understandable one . in fact , even the word nickname is weird . what 's so `` nick '' about a nickname ? is it that it 's a name that has a nick in it ? let 's face it , not likely . actually , in old english , the word was ekename , and eke meant also or other . you can see eke still used in chaucer 's < em > canterbury tales < /em > in a sentence like , `` whan zephyrus eek with his sweete breeth , '' which meant , `` when zephyr also with his sweet breath . '' ekename meant `` also name . '' what happened was that when people said , `` an ekename , '' it could sound like they were saying , `` a nekename , '' and after a while , so many people were hearing it that way that they started saying , `` that 's my nickname , '' instead of , `` that 's my ekename . '' now , the word had a stray n at the front that started as a mistake , but from now on was what the word really was . it was rather as if you had gum on the bottom of your shoe and stepped on a leaf , dragged that leaf along for the rest of your life , were buried wearing that shoe and went to heaven in it to spend eternity wedded to that stray , worn-out leaf . ekename picked up an n and never let it go . the same thing happened with other words . old english speakers cut otches into wood . but after centuries of being asked to cut an otch into something , it was easy to think you were cutting a notch instead , and pretty soon you were . in a world where almost no one could read , it was easier for what people heard to become , after awhile , what it started to actually be . here 's where the ned-style nicknames come in . old english was more like german than our english is now , and just as in german , my is mein , in old english , my was meen . you would say meen book , actually boke in old english , or meen cat . and just as today , we might refer to our child as my dahlia or my laura , in old english , they would say , `` meen ed '' . that is mein ed , mein ellie . you see where this is going . as time passed , meen morphed into the my we know today . that meant that when people said , `` mein ed , '' it sounded like they were saying my ned . that is , it sounded like whenever someone referred to edward affectionately , they said ned instead of ed . behold , the birth of a nickname ! or an ekename . hence , also nellie for ellen and nan for ann , and even in the old days , nabby for abigal . president john adam 's wife abigail 's nickname was nabby . all sorts of words are like this . old english speakers wore naprons , but a napron sounds like an apron , and that gave birth to a word apron that no one in beowulf would have recognized . umpire started as numpires , too . if all of this sounds like something sloppy that we modern people would never do , then think about something you hear all the time and probably say , `` a whole nother . '' what 's nother ? we have the word another , of course , but it 's composed of an and other , or so we thought . yet , when we slide whole into the middle , we do n't say , `` a whole other , '' we clip that n off of the an and stick it to other and create a new word , nother . for a long time , nobody was writing these sort of things down or putting them in a dictionary , but that 's only because writing is more codified now than it was 1,000 years ago . so , when you see a weird word , remember that there might be a whole nother side to the story .
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it was rather as if you had gum on the bottom of your shoe and stepped on a leaf , dragged that leaf along for the rest of your life , were buried wearing that shoe and went to heaven in it to spend eternity wedded to that stray , worn-out leaf . ekename picked up an n and never let it go . the same thing happened with other words .
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words picked up an extra n from :
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if you 've watched the news or followed politics chances are you 've heard the term orwellian thrown around in one context or another . but have you ever stopped to think about what it really means , or why it 's used so often ? the term was named after british author eric blair known by his pen name george orwell . because his most famous work , the novel `` 1984 , '' depicts an oppressive society under a totalitarian government , `` orwellian '' is often used simply to mean authoritarian . but using the term in this way not only fails to fully convey orwell 's message , it actually risks doing precisely what he tried to warn against . orwell was indeed opposed to all forms of tyranny , spending much of his life fighting against anti-democratic forces of both the left-wing and the right . but he was also deeply concerned with how such ideologies proliferate . and one of his most profound insights was the importance that language plays in shaping our thoughts and opinions . the government of `` 1984 '' 's oceania controls its people 's actions and speech in some ways that are obvious . their every move and word is watched and heard , and the threat of what happens to those who step out of line is always looming overhead . other forms of control are not so obvious . the population is inundated with a constant barrage of propaganda made up of historical facts and statistics manufactured in the ministry of truth . the ministry of peace is the military . labor camps are called `` joycamps . '' political prisoners are detained and tortured in the ministry of love . this deliberate irony is an example of doublespeak , when words are used not to convey meaning but to undermine it , corrupting the very ideas they refer to . the regime 's control of language goes even further , eliminating words from the english language to create the official dialect of newspeak , a crudely limited collection of acronyms and simple concrete nouns lacking any words complex enough to encourage nuanced or critical thought . this has an effect on the psyche orwell calls , `` doublethink , '' a hypnotic state of cognitive dissonance in which one is compelled to disregard their own perception in place of the officially dictated version of events , leaving the individual completely dependent on the state 's definition of reality itself . the result is a world in which even the privacy of one 's own thought process is violated , where one may be found guilty of thoughtcrime by talking in their sleep , and keeping a diary or having a love affair equals a subversive act of rebellion . this might sound like something that can only happen in totalitarian regimes , but orwell was warning us about the potential for this occurring even in democratic societies . and this is why `` authoritarian '' alone does not `` orwellian '' make . in his essay , `` politics and the english language , '' he described techniques like using pretentious words to project authority , or making atrocities sound acceptable by burying them in euphemisms and convoluted sentence structures . but even more mundane abuses of language can affect the way we think about things . the words you see and hear in everyday advertising have been crafted to appeal to you and affect your behavior , as have the soundbites and talking points of political campaigns which rarely present the most nuanced perspective on the issues . and the way that we use ready-made phrases and responses gleaned from media reports or copied from the internet makes it easy to get away with not thinking too deeply or questioning your assumptions . so the next time you hear someone use the word orwellian , pay close attention . if they 're talking about the deceptive and manipulative use of language , they 're on the right track . if they 're talking about mass surveillance and intrusive government , they 're describing something authoritarian but not necessarily orwellian . and if they use it as an all-purpose word for any ideas they dislike , it 's possible their statements are more orwellian than whatever it is they 're criticizing . words have the power to shape thought . language is the currency of politics , forming the basis of society from the most common , everyday interactions to the highest ideals . orwell urged us to protect our language because ultimately our ability to think and communicate clearly is what stands between us and a world where war is peace and freedom is slavery .
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but have you ever stopped to think about what it really means , or why it 's used so often ? the term was named after british author eric blair known by his pen name george orwell . because his most famous work , the novel `` 1984 , '' depicts an oppressive society under a totalitarian government , `` orwellian '' is often used simply to mean authoritarian .
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true or false : george orwell gave his unconditional endorsement to all left-leaning political parties .
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what is at the center of the universe ? it 's an essential question that humans have been wondering about for centuries . but the journey toward an answer has been a strange one . if you wanted to know the answer to this question in third century b.c.e . greece , you might look up at the night sky and trust what you see . that 's what aristotle , the guy to ask back then , did . he thought that since we 're on earth , looking up , it must be the center , right ? for him , the sphere of the world was made up of four elements : earth , water , air , and fire . these elements shifted around a nested set of solid crystalline spheres . each of the wandering stars , the planets , had their own crystal sphere . the rest of the universe and all of its stars were on the last crystal sphere . if you watch the sky change over time , you could see that this idea worked fine at explaining the motion you saw . for centuries , this was central to how europe and the islamic world saw the universe . but in 1543 , a guy named copernicus proposed a different model . he believed that the sun was at the center of the universe . this radically new idea was hard for a lot of people to accept . after all , aristotle 's ideas made sense with what they could see , and they were pretty flattering to humans . but a series of subsequent discoveries made the sun-centric model hard to ignore . first , johannes kepler pointed out that orbits are n't perfect circles or spheres . then , galileo 's telescope caught jupiter 's moons orbiting around jupiter , totally ignoring earth . and then , newton proposed the theory of universal gravitation , demonstrating that all objects are pulling on each other . eventually , we had to let go of the idea that we were at the center of the universe . shortly after copernicus , in the 1580s , an italian friar , giordano bruno , suggested the stars were suns that likely had their own planets and that the universe was infinite . this idea did n't go over well . bruno was burned at the stake for his radical suggestion . centuries later , the philosopher rene descartes proposed that the universe was a series of whirlpools , which he called vortices , and that each star was at the center of a whirlpool . in time , we realized there were far more stars than aristotle ever dreamed . as astronomers like william herschel got more and more advanced telescopes , it became clear that our sun is actually one of many stars inside the milky way . and those smudges we see in the night sky ? they 're other galaxies , just as vast as our milky way home . maybe we 're farther from the center than we ever realized . in the 1920s , astronomers studying the nebuli wanted to figure out how they were moving . based on the doppler effect , they expected to see blue shift for objects moving toward us , and red shift for ones moving away . but all they saw was a red shift . everything was moving away from us , fast . this observation is one of the pieces of evidence for what we now call the big bang theory . according to this theory , all matter in the universe was once a singular , infinitely dense particle . in a sense , our piece of the universe was once at the center . but this theory eliminates the whole idea of a center since there ca n't be a center to an infinite universe . the big bang was n't just an explosion in space ; it was an explosion of space . what each new discovery proves is that while our observations are limited , our ability to speculate and dream of what 's out there is n't . what we think we know today can change tomorrow . as with many of the thinkers we just met , sometimes our wildest guesses lead to wonderful and humbling answers and propel us toward even more perplexing questions .
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what is at the center of the universe ? it 's an essential question that humans have been wondering about for centuries .
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what did aristotle and most of the ancient greeks think was at the center of the universe ?
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food does n't last . in days , sometimes hours , bread goes moldy , apple slices turn brown , and bacteria multiply in mayonnaise . but you can find all of these foods out on the shelf at the grocery store , hopefully unspoiled , thanks to preservatives . but what exactly are preservatives ? how do they help keep food edible and are they safe ? there are two major factors that cause food to go bad : microbes and oxidation . microbes like bacteria and fungi invade food and feed off its nutrients . some of these can cause diseases , like listeria and botulism . others just turn edibles into a smelly , slimy , moldy mess . meanwhile , oxidation is a chemical change in the food 's molecules caused by enzymes or free radicals which turn fats rancid and brown produce , like apples and potatoes . preservatives can prevent both types of deterioration . before the invention of artificial refrigeration , fungi and bacteria could run rampant in food . so we found ways to create an inhospitable environment for microbes . for example , making the food more acidic unravels enzymes that microbes need to survive . and some types of bacteria can actually help . for thousands of years , people preserved food using bacteria that produce lactic acid . the acid turns perishable vegetables and milk into longer lasting foods , like sauerkraut in europe , kimchi in korea , and yogurt in the middle east . these cultured foods also populate your digestive track with beneficial microbes . many synthetic preservatives are also acids . benzoic acid in salad dressing , sorbic acid in cheese , and propionic acid in baked goods . are they safe ? some studies suggest that benzoates , related to benzoic acid , contribute to hyperactive behavior . but the results are n't conclusive . otherwise , these acids seem to be perfectly safe . another antimicrobial strategy is to add a lot of sugar , like in jam , or salt , like in salted meats . sugar and salt hold on to water that microbes need to grow and actually suck moisture out of any cells that may be hanging around , thus destroying them . of course , too much sugar and salt can increase your risk of heart disease , diabetes , and high blood pressure , so these preservatives are best in moderation . antimicrobial nitrates and nitrites , often found in cured meats , ward off the bacteria that cause botulism , but they may cause other health problems . some studies linking cured meats to cancer have suggested that these preservatives may be the culprit . meanwhile , antioxidant preservatives prevent the chemical changes that can give food an off-flavor or color . smoke has been used to preserve food for millennia because some of the aromatic compounds in wood smoke are antioxidants . combining smoking with salting was an effective way of preserving meat before refrigeration . for antioxidant activity without a smoky flavor , there are compounds like bht and tocopherol , better known as vitamin e. like the compounds in smoke , these sop up free radicals and stave off rancid flavors that can develop in foods like oils , cheese , and cereal . other antioxidants like citric acid and ascorbic acid help cut produce keep its color by thwarting the enzyme that causes browning . some compounds like sulfites can multitask . they 're both antimicrobials and antioxidants . sulfites may cause allergy symptoms in some people , but most antioxidant preservatives are generally recognized as safe . so should you be worried about preservatives ? well , they 're usually near the end of the ingredients list because they 're used in very small amounts determined by the fda to be safe . nevertheless , some consumers and companies are trying to find alternatives . packaging tricks , like reducing the oxygen around the food can help , but without some kind of chemical assistance , there are very few foods that can stay shelf stable for long .
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for antioxidant activity without a smoky flavor , there are compounds like bht and tocopherol , better known as vitamin e. like the compounds in smoke , these sop up free radicals and stave off rancid flavors that can develop in foods like oils , cheese , and cereal . other antioxidants like citric acid and ascorbic acid help cut produce keep its color by thwarting the enzyme that causes browning . some compounds like sulfites can multitask .
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which of these can prevent cut produce from browning ?
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it starts with a cough , or a wheeze . soon , your chest feels tight . your breathing speeds up and gets shallower , making you feel short of breath . these are common symptoms of an asthma attack . around the world , more than 300 million people suffer from asthma , and around 250,000 people die from it each year . but why do people get asthma and how can this disease be deadly ? asthma affects the respiratory system , particularly the smaller airways , such as the bronchi and bronchioles . these airways have an inner lining called the mucosa that 's surrounded by a layer of smooth muscle . in people with asthma , the airways are chronically inflamed , which can make them hyper-responsive to certain triggers . some of the many asthma triggers include tobacco smoke , pollen , dust , fragrances , exercise , cold weather , stress , and even the common cold . when people with asthma are exposed to these triggers , an asthma attack , or exacerbation , can occur . but how exactly do such everyday factors lead to an asthma attack ? if an asthmatic is exposed to a trigger , the smooth rings of muscle that circle the small airways in their lungs contract and become narrow . simultaneously , the trigger worsens inflammation , causing the mucosal lining to become more swollen and secrete more mucus . under normal conditions , the body uses this mucus to trap and clear particles , like pollen or dust , but during an asthma attack , it blocks the narrowed airways , making it even harder to breathe . these effects lead to this symptoms of asthma . smooth muscle constriction results in the feeling of chest tightness . excess mucus and increased inflammation can cause coughing . and the wheezing noise ? that happens because as the airways constrict , air whistles as it passes through the narrowed space . these symptoms may make a person feel like they 're running out of air . yet counterintuitively , during an asthma attack , the inflammation can make it harder to exhale than inhale . over time , this leads to an excess of air in the lungs , a phenomenon known as hyperinflation . the trapping of air inside the lungs forces the body to work harder to move air in and out of them . over time , this can lead to reduced oxygen delivery to the body 's organs and tissues . sometimes , in untreated severe asthma attacks , the body ca n't keep up , which can lead to death from lack of oxygen . so how do we prevent these uncomfortable and potentially fatal attacks in people who have asthma ? one way is to reduce the presence of triggers . unfortunately , the world is an unpredictable place and exposure to triggers ca n't always be controlled . this is where inhalers , the primary treatment for asthma , come in . these medications help asthmatics both control and prevent their asthma symptoms . inhalers transport medication along the affected airways using a liquid mist or fine powder to treat the problem at its source . they come in two forms . there are reliever medications , which treat symptoms immediately and contain beta-agonists . beta-agonists relax constricted muslces , allowing the airways to widen so more air can travel into and out of the lungs . the other form of inhalers serve as preventive medications , which treat asthma symptoms over the long term , and contain corticosteroids . corticosteroids reduce airway sensitivity and inflammation , so asthma can be kept under control . they 're also crucial in preventing long-term damage from chronic inflammation , which can cause scarring of the airways . inhalers are known to be very effective , and have helped many people live better lives . although we 've come a long way in improving how we treat and diagnose asthma , we still do n't know its exact causes . we currently believe that a combination of genetic and environmental factors play a role , potentially acting during early childhood . recent research has even linked poverty to asthma incidents . this may be due to reasons ranging from exposure to additional pollutants and environmental irritants to difficulties in obtaining medical care or treatment . as our understanding of asthma improves , we can continue to find better ways to keep people 's airways happy and healthy .
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corticosteroids reduce airway sensitivity and inflammation , so asthma can be kept under control . they 're also crucial in preventing long-term damage from chronic inflammation , which can cause scarring of the airways . inhalers are known to be very effective , and have helped many people live better lives .
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long-term damage of the respiratory system ’ s airways can happen in asthma due to _____ .
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try to measure a circle . the diameter and radius are easy , they 're just straight lines you can measure with a ruler . but to get the circumference , you 'd need measuring tape or a piece of string , unless there was a better way . now , it 's obvious that a circle 's circumference would get smaller or larger along with its diameter , but the relationship goes further than that . in fact , the ratio between the two , the circumference divided by the diameter , will always be the same number , no matter how big or small the circle gets . historians are n't sure when or how this number was first discovered , but it 's been known in some form for almost 4,000 years . estimates of it appear in the works of ancient greek , babylonian , chinese , and indian mathematicians . and it 's even believed to have been used in building the egyptian pyramids . mathematicians estimated it by inscribing polygons in circles . and by the year 1400 , it had been calculated to as far as ten decimal places . so , when did they finally figure out the exact value instead of just estimating ? actually , never ! you see , the ratio of a circle 's circumference to its diameter is what 's known as an irrational number , one that can never be expressed as a ratio of two whole numbers . you can come close , but no matter how precise the fraction is , it will always be just a tiny bit off . so , to write it out in its decimal form , you 'd have an on-going series of digits starting with 3.14159 and continuing forever ! that 's why , instead of trying to write out an infinite number of digits every time , we just refer to it using the greek letter pi . nowadays , we test the speed of computers by having them calculate pi , and quantum computers have been able to calculate it up to two quadrillion digits . people even compete to see how many digits they can memorize and have set records for remembering over 67,000 of them . but for most scientific uses , you only need the first forty or so . and what are these scientific uses ? well , just about any calculations involving circles , from the volume of a can of soda to the orbits of satellites . and it 's not just circles , either . because it 's also useful in studying curves , pi helps us understand periodic or oscillating systems like clocks , electromagnetic waves , and even music . in statistics , pi is used in the equation to calculate the area under a normal distribution curve , which comes in handy for figuring out distributions of standardized test scores , financial models , or margins of error in scientific results . as if that were n't enough , pi is used in particle physics experiments , such as those using the large hadron collider , not only due to its round shape , but more subtly , because of the orbits in which tiny particles move . scientists have even used pi to prove the illusive notion that light functions as both a particle and an electromagnetic wave , and , perhaps most impressively , to calculate the density of our entire universe , which , by the way , still has infinitely less stuff in it than the total number of digits in pi .
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in fact , the ratio between the two , the circumference divided by the diameter , will always be the same number , no matter how big or small the circle gets . historians are n't sure when or how this number was first discovered , but it 's been known in some form for almost 4,000 years . estimates of it appear in the works of ancient greek , babylonian , chinese , and indian mathematicians .
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it has been known for 4,000 years that what ratio is always the same ?
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translator : jessica ruby reviewer : caroline cristal russia , with the largest territory in the world , has roughly the same total population as nigeria , a country 1/16 its size . but this similarity wo n't last long . one of the populations is rapidly growing , while the other is slowly declining . what can this tell us about the two countries ? population statistics are some of the most important data social scientists and policy experts have to work with . but understanding a country 's situation and making accurate predictions requires knowing not just the total size of the population but its internal characteristics , such as age and gender distribution . so , how can we keep track of all that data in a way that makes it easy to comprehend ? complex data is more easily interpreted through visualization , and one of the ways that demographers represent the internal distribution of a population is the population pyramid . here , the data is divided by gender with females on one side and males on the other . the population numbers are shown for each five-year age interval , starting from 0-4 and continuing up to 100 and up . these intervals are grouped together into pre-reproductive ( 0-14 ) , reproductive ( 15-44 ) , and post-reproductive years ( 45 and up ) . such a population pyramid can be a powerful predictor of future population trends . for example , rwanda 's population pyramid shows it to be a fast-growing country , with most of the population being in the youngest age groups at the bottom of the pyramid . the number will grow rapidly in the coming years . as today 's children reach their reproductive years and have children of their own , the total population is almost certain to double within the next few decades . for our second example , let 's look at canada , where most of the population is clustered around the middle of the graph . because there are less people in the pre-reproductive age groups than there are in the reproductive ones , the population will grow more slowly , as the number of people reaching their reproductive years decreases . finally , let 's look at japan . because the majority of its population is in its post-reproductive years and the number of people is smaller at each younger interval , this means that at current rates of reproduction the population will begin to decline as fewer and fewer people reach reproductive age . comparing these three population pyramids side by side shows us three different stages in a demographic transition , as a country moves from a pre-industrial society to one with an industrial or post-industrial economy . countries that have only recently begun the process of industrialization typically see an increase in life expectancy and a fall in child mortality rates as a result of improvements in medicine , sanitation , and food supply . while birth rates remain constant , leading to a population boom . developing countries that are farther along in the industrialization process begin to see a fall in birth rates , due to factors such as increased education and opportunities for women outside of child-rearing and a move from rural to urban living that makes having large families less economically advantageous . finally , countries in advanced stages of industrialization reach a point where both birth and death rates are low , and the population remains stable or even begins to decline . now , let 's take a look at the projected population pyramids for the same three countries in 2050 . what do these tell us about the expected changes in each country 's population , and what kinds of factors can alter the shape of these future pyramids ? a population pyramid can be useful not only as a predictor of a country 's future but as a record of its past . russia 's population pyramid still bears the scars of world war ii , which explains both the fewer numbers of elderly men compared to elderly women and the relatively sudden population increase as soldiers returned from the war and normal life resumed . china 's population pyramid reflects the establishment of the one child policy 35 years before , which prevented a population boom such as that of rwanda but also led to sex-selective abortions , resulting in more male children than female children . finally , the pyramid for the united states shows the baby boom that followed world war ii . as you can see , population pyramids tell us far more about a country than just a set of numbers , by showing both where it 's been and where it 's headed within a single image . and in today 's increasingly interconnected world , facing issues such as food shortages , ecological threats , and economic disparities , it is increasingly important for both scientists and policy makers to have a rich and complex understanding of populations and the factors affecting them .
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these intervals are grouped together into pre-reproductive ( 0-14 ) , reproductive ( 15-44 ) , and post-reproductive years ( 45 and up ) . such a population pyramid can be a powerful predictor of future population trends . for example , rwanda 's population pyramid shows it to be a fast-growing country , with most of the population being in the youngest age groups at the bottom of the pyramid . the number will grow rapidly in the coming years .
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as a country slows in population growth , its pyramid shape will
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think back to a really vivid memory . got it ? okay , now try to remember what you had for lunch three weeks ago . that second memory probably is n't as strong , but why not ? why do we remember some things , and not others ? and why do memories eventually fade ? let 's look at how memories form in the first place . when you experience something , like dialing a phone number , the experience is converted into a pulse of electrical energy that zips along a network of neurons . information first lands in short term memory , where it 's available from anywhere from a few seconds to a couple of minutes . it 's then transferred to long-term memory through areas such as the hippocampus , and finally to several storage regions across the brain . neurons throughout the brain communicate at dedicated sites called synapses using specialized neurotransmitters . if two neurons communicate repeatedly , a remarkable thing happens : the efficiency of communication between them increases . this process , called long term potentiation , is considered to be a mechanism by which memories are stored long-term , but how do some memories get lost ? age is one factor . as we get older , synapses begin to falter and weaken , affecting how easily we can retrieve memories . scientists have several theories about what 's behind this deterioration , from actual brain shrinkage , the hippocampus loses 5 % of its neurons every decade for a total loss of 20 % by the time you 're 80 years old to the drop in the production of neurotransmitters , like acetylcholine , which is vital to learning and memory . these changes seem to affect how people retrieve stored information . age also affects our memory-making abilities . memories are encoded most strongly when we 're paying attention , when we 're deeply engaged , and when information is meaningful to us . mental and physical health problems , which tend to increase as we age , interfere with our ability to pay attention , and thus act as memory thieves . another leading cause of memory problems is chronic stress . when we 're constantly overloaded with work and personal responsibilites , our bodies are on hyperalert . this response has evolved from the physiological mechanism designed to make sure we can survive in a crisis . stress chemicals help mobilize energy and increase alertness . however , with chronic stress our bodies become flooded with these chemicals , resulting in a loss of brain cells and an inability to form new ones , which affects our ability to retain new information . depression is another culprit . people who are depressed are 40 % more likely to develop memory problems . low levels of serotonin , a neurotransmitter connected to arousal , may make depressed individuals less attentive to new information . dwelling on sad events in the past , another symptom of depression , makes it difficult to pay attention to the present , affecting the ability to store short-term memories . isolation , which is tied to depression , is another memory thief . a study by the harvard school of public health found that older people with high levels of social integration had a slower rate of memory decline over a six-year period . the exact reason remains unclear , but experts suspect that social interaction gives our brain a mental workout . just like muscle strength , we have to use our brain or risk losing it . but do n't despair . there are several steps you can take to aid your brain in preserving your memories . make sure you keep physically active . increased blood flow to the brain is helpful . and eat well . your brain needs all the right nutrients to keep functioning correctly . and finally , give your brain a workout . exposing your brain to challenges , like learning a new language , is one of the best defenses for keeping your memories intact .
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these changes seem to affect how people retrieve stored information . age also affects our memory-making abilities . memories are encoded most strongly when we 're paying attention , when we 're deeply engaged , and when information is meaningful to us .
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which two factors contribute to memory loss as we age :
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so californium is another element which was first prepared at the berkeley labs in california . it ’ s got quite a few military applications , usually involving the word ‘ nuclear ’ . but what most people don ’ t realise is it ’ s actually used in various types of machines for detecting metal fatigue and stress in airplanes , so obviously it ’ s pretty important our planes don ’ t fall to bits in mid-air and they are used in the kind of instruments which scan for this and can spot any problems long before they become a serious issue . it ’ s also probably the only other actinide which has possibly routinely got its way into households which is that it ’ s also used in metal detectors .
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so californium is another element which was first prepared at the berkeley labs in california . it ’ s got quite a few military applications , usually involving the word ‘ nuclear ’ .
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what is the longest-lived isotope of californium and what is its half-life ?
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how much would you pay for a bouquet of tulips ? a few dollars ? a hundred dollars ? how about a million dollars ? probably not . well , how much would you pay for this house , or partial ownership of a website that sells pet supplies ? at different points in time , tulips , real estate and stock in pets.com have all sold for much more than they were worth . in each instance , the price rose and rose and then abruptly plummeted . economists call this a bubble . so what is exactly is going on with a bubble ? well , let 's start with the tulips to get a better idea . the 17th century saw the netherlands enter the dutch golden age . by the 1630s , amsterdam was an important port and commercial center . dutch ships imported spices from asia in huge quantities to earn profits in europe . so amsterdam was brimming with wealthy , skilled merchants and traders who displayed their prosperity by living in mansions surrounded by flower gardens . and there was one flower in particularly high demand : the tulip . the tulip was brought to europe on trading vessels that sailed from the east . because of this , it was considered an exotic flower that was also difficult to grow , since it could take years for a single tulip to bloom . during the 1630s , an outbreak of tulip breaking virus made select flowers even more beautiful by lining petals with multicolor , flame-like streaks . a tulip like this was scarcer than a normal tulip and as a result , prices for these flowers started to rise , and with them , the tulip 's popularity . it was n't long before the tulip became a nationwide sensation and tulip mania was born . a mania occurs when there is an upward movement of price combined with a willingness to pay large sums of money for something valued much lower in intrinsic value . a recent example of this is the dot-com mania of the 1990s . stocks in new , exciting websites were like the tulips of the 17th century . everybody wanted some . the more people who wanted the tulip , the higher the price could go . at one point , a single tulip bulb sold for more than ten times the annual salary of a skilled craftsman . in the stock market , the price of stock is based on the supply and demand of investors . stock prices tend to rise when it seems like a company will earn more in the future . investors might then buy more of the stock , raising the prices even further due to an increased demand . this can result in a feedback loop where investors get caught up in the hype and ultimately drive prices far above intrinsic value , creating a bubble . all that is needed for a mania to end and for a bubble to burst is the collective realization that the price of the stock , or a tulip , far exceeds its worth . that 's what happened with both manias . suddenly the demand ended . prices were pushed to staggering lows , and pop ! the bubbles burst , and the market crashed . today , scholars work long and hard trying to predict what causes a bubble and how to avoid them . tulip mania is an effective illustration of the underlying principles at work in a bubble and can help us understand more recent examples like the real estate bubble of the late 2000s . the economy will continue to go through phases of booms and busts . so while we wait for the next mania to start , and the next bubble to burst , treat yourself to a bouquet of tulips and enjoy the fact that you did n't have to pay an arm and a leg for them .
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tulip mania is an effective illustration of the underlying principles at work in a bubble and can help us understand more recent examples like the real estate bubble of the late 2000s . the economy will continue to go through phases of booms and busts . so while we wait for the next mania to start , and the next bubble to burst , treat yourself to a bouquet of tulips and enjoy the fact that you did n't have to pay an arm and a leg for them .
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gold , ipads , cell phones , and computers are all items that frequently go up and down in value . what do you think are the two main reasons this frequent change may occur ?
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yeah so neodymium is one my favourite f elements to work with . when you use it in compounds and you dissolve it , often you get colourful blue solutions from it . sometimes they are green as well , but often i have found that if concentration of the solution makes a really big difference to the colour of these solutions so you may have a compound which appears to be red but actually as you dilute it down eventually it ends up being blue , which is really pretty and sometimes if you cannula it from one flask to another and you can see through the cannula you can see it change colour as it goes through the cannula and then drops into the next solution again . so neodymium is one of the rare earths and it has a number of quite important applications . one of my favourite is in lasers , it ’ s used for example in this laser pointer and if you point the laser it makes this rather nice bright green colour . a little known use of neodymium is that the size and strength of volcanic eruptions can actually be judged from the composition of neodymium isotopes which are present . the first laser pointers were red . they didn ’ t use neodymium , and the green ones have become really quite fashionable among lecturers . so the way this works is that inside here there is a small crystal , of so-called neodymium yag , is the sum of the neodymium atoms that are isolated in the glass that contains yttrium and aluminium together to form so-called the g is for garnet , which describes the structure of the solid , and if you excite this the neodymium atoms can emit light in the infrared , like heat rays you can ’ t see them . and then further up here there is another crystal which turns this infrared light into green light so the green light comes out at the end . and also when neodymium is combined with iron and boron it can form a type of magnet which we call a ‘ permanent magnet ’ and it is extremely strong , one of the strongest that we actually know of . in order to get this doubling from the infrared to the green to work , you need to have pulses of light . so green lasers , although to the eye , look as if they are continuous are actually very rapid pulses which are very intense which is why these pointers are quite dangerous if you point them in the wrong direction in a lecture . because i wave my hands so much , i never use these in lectures . but i know that you the cameraman have also used… hello . …used neodymium , because neodymium is element number 60 and the cameraman ’ s future mother-in-law was 60 a few days ago and so we provided a sample of neodymium , element 60 , for him to present to her as a birthday present . happy birthday marion !
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a little known use of neodymium is that the size and strength of volcanic eruptions can actually be judged from the composition of neodymium isotopes which are present . the first laser pointers were red . they didn ’ t use neodymium , and the green ones have become really quite fashionable among lecturers .
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as the professor explained , laser pointers of which color contain neodymium ?
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translator : andrea mcdonough reviewer : jessica ruby welcome to the department of plagiarism investigation . the d.p.i . has dealt with numerous complex cases in their effort to bring plagiarists to justice and to rescue purloined texts . the first form of plagiarism that the d.p.i . regularly encounters is known as brain child snatching , in honor of the latin word , plagiarius , from which plagiarism originates . brain child snatchers sneak up on innocent papers and copy and paste them without citing any sources , putting quotation marks around direct quotes or changing a word . they 've also been known to steal and hold particularly eloquent essays for ransom . when brain child snatchers get together , they form a kidnapping ring , which involves brain child snatching from multiple sources . some perpetrators have even been known to commit self-plagiarism , one of the laziest crimes in the annals of the d.p.i . also known as one-sided collaborators , these odd balls snatch up entire texts or small passages that they 've written before and present them as brand-new material . brain child snatchers and kidnapping rings are easy for the d.p.i . to catch . just paste a few passages into a search engine , and bam ! they 're caught red-handed . the more covert forms of plagiarism include the wild goose chase technique , in which plagiarists create fake authors , book titles , page numbers , or other information in order to cover up plagiarism . and the old synonym switcheroo in which plagiarists utilize a thesaurus as their main weapon . by substituting a synonym for nearly every word in the document and leaving the sentence structure and order of the ideas the same , plagiarists give legitimate paraphrasing a very bad name . shoddy paraphrasing is also a key part of variations on a smokescreen , a technique in which multiple passages are paraphrased , then pasted together into one . the thorniest issue that the d.p.i . deals with is the misconception that you can never be accused of plagiarism if you use quotes and cite your sources . this is most certainly not the case because a paper that is made up of passage upon passage of other people 's ideas is known as a wholly quotable document . this is considered plagiarism since there are no original thoughts in the work . similarly , passage after passage of too closely paraphrased text from multiple cited sources is also plagiarism of the pervasively paraphrased kind because the ideas still are n't one 's own . and lastly , the technique of revealing while concealing is plagiarism because it involves selective amnesia regarding one 's sources in an attempt to cover up wholly quotable and pervasively paraphrased issues in a text . some passages are meticulously documented , quoted , or paraphrased , while others are presented entirely as one 's own . as you can see , the d.p.i . has its hands full , tackling all sorts of academic mischief and mayhem , ranging from the petty to the outrageous . given the gravity of these transgressions , you might be wondering why you 've never heard of the department of plagiarism investigation 's victories . that 's because it does n't technically exist . but people , like you and me , can be our own d.p.i . agents to fight plagiarism and uphold the values of original thinking . we know that the best defense against plagiarism consists of writers who save themselves time , worry , and effort by taking the far easier road of just doing the work themselves .
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but people , like you and me , can be our own d.p.i . agents to fight plagiarism and uphold the values of original thinking . we know that the best defense against plagiarism consists of writers who save themselves time , worry , and effort by taking the far easier road of just doing the work themselves .
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renee , the daughter of a u.s. dpi secret agent , procrastinated all semester and started her creative writing project the night before . renee looked up a random poet online and copied and pasted her poems into her project , claiming them as her own original poems . renee engaged in the most egregious form of plagiarism , according to the dpi .
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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 .
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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 .
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boron compounds ( particularly perborate ) are used in laundry detergent . persil is a good example of one that contains perborate . but which compound , that can bleach clothes , forms in the washing machine when perborate is mixed with hot water ?
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imagine two people are listening to music . what are the odds that they are listening to the exact same playlist ? probably pretty low . after all , everyone has very different tastes in music . now , what are the odds that your body will need the exact same medical care and treatment as another person 's body ? even lower . as we go through our lives , each of us will have very different needs for our own healthcare . scientists and doctors are constantly researching ways to make medicine more personalized . one way they are doing this is by researching stem cells . stem cells are cells that are undifferentiated , meaning they do not have a specific job or function . while skin cells protect your body , muscle cells contract , and nerve cells send signals , stem cells do not have any specific structures or functions . stem cells do have the potential to become all other kinds of cells in your body . your body uses stem cells to replace worn-out cells when they die . for example , you completely replace the lining of your intestines every four days . stem cells beneath the lining of your intestines replace these cells as they wear out . scientists hope that stem cells could be used to create a very special kind of personalized medicine in which we could replace your own body parts with , well , your own body parts . stem cell researchers are working hard to find ways in which to use stem cells to create new tissue to replace the parts of organs that are damaged by injury or disease . using stem cells to replace damaged bodily tissue is called regenerative medicine . for example , scientists currently use stem cells to treat patients with blood diseases such as leukemia . leukemia is a form of cancer that affects your bone marrow . bone marrow is the spongy tissue inside your bones where your blood cells are created . in leukemia , some of the cells inside your bone marrow grow uncontrollably , crowding out the healthy stem cells that form your blood cells . some leukemia patients can receive a stem cell transplant . these new stem cells will create the blood cells needed by the patient 's body . there are actually multiple kinds of stem cells that scientists can use for medical treatments and research . adult stem cells or tissue-specific stem cells are found in small numbers in most of your body 's tissues . tissue-specific stem cells replace the existing cells in your organs as they wear out and die . embryonic stem cells are created from leftover embryos that are willingly donated by patients from fertility clinics . unlike tissue-specific stem cells , embryonic stem cells are pluripotent . this means that they can be grown into any kind of tissue in the body . a third kind of stem cells is called induced pluripotent stem cells . these are regular skin , fat , liver , or other cells that scientists have changed to behave like embryonic stem cells . like embryonic stem cells , they , too , can become any kind of cell in the body . while scientists and doctors hope to use all of these kinds of stem cells to create new tissue to heal your body , they can also use stem cells to help understand how the body works . scientists can watch stem cells develop into tissue to understand the mechnanisms that the body uses to create new tissue in a controlled and regulated way . scientists hope that with more research , they can not only develop specialized medicine that is specific to your body but also better understand how your body functions , both when it 's healthy and when it 's not .
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stem cell researchers are working hard to find ways in which to use stem cells to create new tissue to replace the parts of organs that are damaged by injury or disease . using stem cells to replace damaged bodily tissue is called regenerative medicine . for example , scientists currently use stem cells to treat patients with blood diseases such as leukemia .
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using stem cells to replace damaged bodily tissue is called…
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in 1800 , the explorer alexander von humboldt witnessed a swarm of electric eels leap out of the water to defend themselves against oncoming horses . most people thought the story so unusual that humboldt made it up . but fish using electricity is more common than you might think ; and yes , electric eels are a type of fish . underwater , where light is scarce , electrical signals offer ways to communicate , navigate , and find—plus , in rare cases , stun—prey . nearly 350 species of fish have specialized anatomical structures that generate and detect electrical signals . these fish are divided into two groups , depending on how much electricity they produce . scientists call the first group the weakly electric fish . structures near their tails called electric organs produce up to a volt of electricity , about two-thirds as much as a aa battery . how does this work ? the fish 's brain sends a signal through its nervous system to the electric organ , which is filled with stacks of hundreds or thousands of disc-shaped cells called electrocytes . normally , electrocytes pump out sodium and potassium ions to maintain a positive charge outside and negative charge inside . but when the nerve signal arrives at the electrocyte , it prompts the ion gates to open . positively charged ions flow back in . now , one face of the electrocyte is negatively charged outside and positively charged inside . but the far side has the opposite charge pattern . these alternating charges can drive a current , turning the electrocyte into a biological battery . the key to these fish 's powers is that nerve signals are coordinated to arrive at each cell at exactly the same time . that makes the stacks of electrocytes act like thousands of batteries in series . the tiny charges from each one add up to an electrical field that can travel several meters . cells called electroreceptors buried in the skin allow the fish to constantly sense this field and the changes to it caused by the surroundings or other fish . the peter ’ s elephantnose fish , for example , has an elongated chin called a schnauzenorgan that 's riddled in electroreceptors . that allows it to intercept signals from other fish , judge distances , detect the shape and size of nearby objects , and even determine whether a buried insect is dead or alive . but the elephantnose and other weakly electric fish do n't produce enough electricity to attack their prey . that ability belongs to the strongly electric fish , of which there are only a handful of species . the most powerful strongly electric fish is the electric knife fish , more commonly known as the electric eel . three electric organs span almost its entire two-meter body . like the weakly electric fish , the electric eel uses its signals to navigate and communicate , but it reserves its strongest electric discharges for hunting using a two-phased attack that susses out and then incapacitates its prey . first , it emits two or three strong pulses , as much as 600 volts . these stimulate the prey 's muscles , sending it into spasms and generating waves that reveal its hiding place . then , a volley of fast , high-voltage discharges causes even more intense muscle contractions . the electric eel can also curl up so that the electric fields generated at each end of the electric organ overlap . the electrical storm eventually exhausts and immobilizes the prey , and the electric eel can swallow its meal alive . the other two strongly electric fish are the electric catfish , which can unleash 350 volts with an electric organ that occupies most of its torso , and the electric ray , with kidney-shaped electric organs on either side of its head that produce as much as 220 volts . there is one mystery in the world of electric fish : why do n't they electrocute themselves ? it may be that the size of strongly electric fish allows them to withstand their own shocks , or that the current passes out of their bodies too quickly . some scientists think that special proteins may shield the electric organs , but the truth is , this is one mystery science still has n't illuminated .
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cells called electroreceptors buried in the skin allow the fish to constantly sense this field and the changes to it caused by the surroundings or other fish . the peter ’ s elephantnose fish , for example , has an elongated chin called a schnauzenorgan that 's riddled in electroreceptors . that allows it to intercept signals from other fish , judge distances , detect the shape and size of nearby objects , and even determine whether a buried insect is dead or alive .
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what is the function of the schnauzenorgan in the peters ' elephantnose fish ?
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check this out : here 's a grid , nothing special , just a basic grid , very grid-y . but look closer , into this white spot at the center where the two central vertical and horizontal lines intersect . look very closely . notice anything funny about this spot ? yeah , nothing . but keep looking . get weird and stare at it . now , keeping your gaze fixed on this white spot , check what 's happening in your peripheral vision . the other spots , are they still white ? or do they show weird flashes of grey ? now look at this pan for baking muffins . oh , sorry , one of the cups is inverted . it pops up instead of dipping down . wait , no spin the pan . the other five are domed now ? whichever it is , this pan 's defective . here 's a photo of abraham lincoln , and here 's one upside down . nothing weird going on here . wait , turn that upside down one right side up . what have they done to abe ? those are just three optical illusions , images that seem to trick us . how do they work ? are magical things happening in the images themselves ? while we could certainly be sneaking flashes of grey into the peripheral white spots of our animated grid , first off , we promise we are n't . you 'll see the same effect with a grid printed on a plain old piece of paper . in reality , this grid really is just a grid . but not to your brain 's visual system . here 's how it interprets the light information you call this grid . the white intersections are surrounded by relatively more white on all four sides than any white point along a line segment . your retinal ganglion cells notice that there is more white around the intersections because they are organized to increase contrast with lateral inhibition . better contrast means it 's easier to see the edge of something . and things are what your eyes and brain have evolved to see . your retinal ganglion cells do n't respond as much at the crossings because there is more lateral inhibition for more white spots nearby compared to the lines , which are surrounded by black . this is n't just a defect in your eyes ; if you can see , then optical illusions can trick you with your glasses on or with this paper or computer screen right up in your face . what optical illusions show us is the way your photo receptors and brain assemble visual information into the three-dimensional world you see around you , where edges should get extra attention because things with edges can help you or kill you . look at that muffin pan again . you know what causes confusion here ? your brain 's visual cortex operates on assumptions about the lighting of this image . it expects light to come from a single source , shining down from above . and so these shading patterns could only have been caused by light shining down on the sloping sides of a dome , or the bottom of a hole . if we carefully recreate these clues by drawing shading patterns , even on a flat piece of paper , our brain reflexively creates the 3d concave or convex shape . now for that creepy lincoln upside down face . faces trigger activity in areas of the brain that have specifically evolved to help us recognize faces . like the fusiform face area and others in the occipital and temporal lobes . it makes sense , too , we 're very social animals with highly complex ways of interacting with each other . when we see faces , we have to recognize they are faces and figure out what they 're expressing very quickly . and what we focus on most are the eyes and mouth . that 's how we figure out if someone is mad at us or wants to be our friend . in the upside down lincoln face , the eyes and mouth were actually right side up , so you did n't notice anything was off . but when we flipped the whole image over , the most important parts of the face , the eyes and mouth , were now upside down , and you realized something fishy was up . you realized your brain had taken a short cut and missed something . but your brain was n't really being lazy , it 's just very busy . so it spends cognitive energy as efficiently as possible , using assumptions about visual information to create a tailored , edited vision of the world . imagine your brain calling out these edits on the fly : `` okay , those squares could be objects . let 's enhance that black-white contrast on the sides with lateral inhibition . darken those corners ! dark grey fading into light grey ? assume overhead sunlight falling on a sloping curve . next ! those eyes look like most eyes i 've seen before , nothing weird going on here . '' see ? our visual tricks have revealed your brain 's job as a busy director of 3d animation in a studio inside your skull , allocating cognitive energy and constructing a world on the fly with tried and mostly -- but not always -- true tricks of its own .
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darken those corners ! dark grey fading into light grey ? assume overhead sunlight falling on a sloping curve .
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improving the contrast of an image ( making the dark regions darker and the light regions lighter ) helps us to identify :
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your cell phone is mainly made of plastics and metals . it 's easy to appreciate the inventive process by which those elements are made to add up to something so useful and entertaining . but there 's another story we do n't hear about as much . how did we get our raw ingredients in the first place from the chaotic tangle of materials that is nature ? the answer is a group of clever hacks known as separation techniques . they work by taking advantage of the fundamental properties of things to disentangle them from each other . simple separation techniques apply to many physical scenarios , like separating cream from milk , extracting water from soil , or even sifting out flecks of gold from river sand . but not all mixtures are so easy to unravel . in some of those cases , we can exploit the differences between physical properties within a mixture , like particle size , density , or boiling point to extract what 's required . take petroleum , a mixture of different types of hydrocarbons . some of these are valuable as fuels , and others make good raw materials for generating electric power . to separate them , experts rely on one important feature : different hydrocarbons boil at different temperatures . during the boiling process , each type vaporizes at a precise point , then gets separately funneled into a container and collected as a liquid as it cools . separation techniques also take us to the sea . in some drought-stricken countries , the ocean is the only available water source . but of course , humans ca n't drink salt water . one way to get around this problem is to remove salt from sea water with reverse osmosis , a process that separates water 's ingredients by size . a membrane with pores bigger than water particles , but smaller than salt particles , only lets fresh water pass through , transforming what was once undrinkable into a life saver . meanwhile in the medical world , blood tests are a vital tool for evaluating a person 's health , but doctors typically ca n't examine blood samples until they 've separated the solid blood cells from the liquid plasma they 're dissolved in . to do that , a powerful rotational force is exerted on the test tube , causing heavier substances with higher density , like blood cells , to move away from the rotational axis . meanwhile , lighter substances with lower density , like plasma , move to its center . the tube 's contents divide clearly , and the blood cells and liquid plasma can be tested independently . but sometimes , unlike oil , seawater , and blood , the parts of mixtures that we want to separate share the same physical properties . in these cases , the only way to isolate ingredients is by chemical separation , a complex process that relies on unique interactions between components within a mixture and another material . one of these methods is chromatography , a tool forensic scientists use to examine crime scenes . they dissolve gathered evidence in a gas , and can monitor and analyze the ingredients as they separate and move at varying speeds due to their unique chemical properties . that information then tells scientists precisely what was present at the scene , often helping to identify the culprit . separation techniques are not just about industry , infrastructure , medicine , and justice . one of the most technically ambitious projects in human history is a separation technique aimed at answering the fundamental question , `` what is the universe made of ? '' by accelerating particles to extremely high speeds and smashing them into each other , we can break them into their constituent parts ever so briefly . and if we succeed at that , what 's next ? is there a most elementary particle ? and if so , what 's it made of ?
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meanwhile in the medical world , blood tests are a vital tool for evaluating a person 's health , but doctors typically ca n't examine blood samples until they 've separated the solid blood cells from the liquid plasma they 're dissolved in . to do that , a powerful rotational force is exerted on the test tube , causing heavier substances with higher density , like blood cells , to move away from the rotational axis . meanwhile , lighter substances with lower density , like plasma , move to its center . the tube 's contents divide clearly , and the blood cells and liquid plasma can be tested independently .
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in centrifugation , _______ substances with ______ density move away from the rotational axis , while _____ substances with ______ density move to its center .
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how fast are you moving right now ? that seems like an easy question . the first tempting answer is , `` i 'm not moving . '' upon further reflection , you realize that maybe the earth 's motion counts . so , a second tempting answer is , `` 19 miles/second around the sun . '' but then you recall learning that the sun moves around the center of the milky way galaxy , and the milky way moves within the local group of galaxies , and the local group moves within the virgo cluster , and the virgo cluster moves within ... `` how fast are you moving ? '' is not an easy question . when mission control tells astronauts how fast they 're going , there 's always an assumed standard of rest . at the start of the voyage , speeds are given relative to the launchpad . but later , when the launchpad is just one more arbritrary place down there on earth 's spinning surface , speeds are given relative to the idealized , non-spinning pinpoint center of earth . on their way to the moon , apollo astronauts had a hard time answering the question , `` how fast are you moving ? '' speed away from earth was one thing , and speed toward the moon was quite another . that 's because the earth and the moon move relative to one another . ah , of course ! speed is a relative quantity . when captain kirk ask lieutenant sulu if the starship enterprise has reached a speed of warp 7 , sulu should reply , `` relative to what , captain ? '' such a sassy reply may get subordinate starfleet officers in trouble , but it is the only good answer to the question , `` how fast are you moving ? '' this is basic relatively talking . not fancy einsteinian relativity , but good old fashioned ( and still correct ) galilean relativity . galileo seems to have been the first person to realize that there is no such thing as an absolute speed . speeds are relative . this means that speeds only have meaning when they are referred to a reference frame . presumably that reference frame is itself at rest . but then we have to ask again , `` at rest relative to what ? '' because even the concept of rest has lost any hint of absolute meaning . speed is relative , and rest is relative . earth 's speed is 19 miles/second relative to the sun . the enterprise 's speed is warp 7 relative to the center of the milky way galaxy . your speed is zero relative to your easy chair . but depending on where you sit , it is hundreds of miles/hour relative to earth 's center . when we furrow a brow and ask , `` but how fast is earth really moving ? '' we imagine spaceship earth plowing through the ocean of space as it orbits the sun . but space is not an ocean . it has no substance as water does . space is not a thing ; space is nothing . space is no thing . you can move between two points in space , say between earth and mars , but you ca n't move through space . there 's nothing to move through . it 's like trying to say how much a hole weighs . a hole weighs exactly nothing because a hole is nothing . it 's a void , and so is space . to move relative to nothing is meaningless . the concepts of speed and of rest have only relative meaning . they are absolutely meaningless . they mean something only with respect to arbitrarily chosen , artificial frames of reference . if , someday , you are buckled into your spaceship , and you see from the side window , say , a space station whizz by at constant speed , there is no way to know which of you is really moving . neither of you is really moving because there is no deep reality about constant speed . constant speed in a straight line has only relative meaning , a kind of relative reality . does this mean that all motion is relative ? no ! some motions have only relative meaning , but some motions have absolute meaning , are absolutely real . for example , constant speed is relative , but change in speed is absolute . calling something absolute in science means that arbitrary standards are not used in its measurement . it is unambiguously measurable . when your spaceship fires its engines , your change in speed is beyond doubt . you feel it in your stomach , and your ship 's sensors can measure it . outside your window , the passing space station may seem to be changing speed , but the beings inside the station will not feel it . and no sensors can measure it . you are really changing speed , and they are really are not . there 's something absolutely real about changes in speed . the same goes for rotation . if your spaceship is spinning , you can feel it , and your ship 's sensors can measure it . the space station outside may seem to be going around you , but it is you who feels queasy , not the folks in the space station . you are really spinning , and they really are not . there 's something absolutely real about rotation . so , some motions are relative , and some are not . there is no deep reality about constant speed , but changes in speed are deeply real , and so are rotations . we have to be thoughtful in our analysis of everyday experience in order to identify what is deeply real . since we can be fooled by perceptions as basic as speed , maybe every perception deserves careful scrutiny . this is what inspired einstein to his incredible insights about the speed of light and forward time travel . knowing how to identify what is deeply real is tough and important work . if a police officer ever pulls you over for speeding and asks , & amp ; amp ; quot ; do you know how fast you were going ? & amp ; amp ; quot ; an insightful , though perhaps unwise , reply would be , `` relative to what ? '' and then , as you sit in the backseat of the police car and feel it accelerate toward jail , you can add , & amp ; amp ; quot ; but some things are absolute ! & amp ; amp ; quot ;
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but depending on where you sit , it is hundreds of miles/hour relative to earth 's center . when we furrow a brow and ask , `` but how fast is earth really moving ? '' we imagine spaceship earth plowing through the ocean of space as it orbits the sun .
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why have we grown so accustomed to saying that we ’ re “ at rest ” when , specifically , we ’ re not moving over earth ’ s surface ?
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what do charles darwin , michael jordan , and yoda have in common ? they , like many other historical and fictive individuals , are bald , in some cases by their own choice . for centuries , a shining dome has been a symbol of intelligence , but despite this , many balding people still wish their hair would return . scientists have long pondered , `` why do some people lose their hair , and how can we bring it back ? '' the full-headed among us have about 100,000 to 150,000 hairs on our scalps , and scientists have discovered two things about this dense thicket . firstly , the sprouting hair we see is mostly made up of keratin , the protein leftover from dead cells that are forced upwards as new cells grow beneath them . secondly , the structures that drive hair growth are called hair follicles , a network of complex organs that forms before we 're born , and grows hair in an everlasting cycle . this cycle has three main phases . the first is anagen , the growth phase , which up to 90 % of your hair follicles are experiencing right now , causing them to push up hair at a rate of one centimeter per month . anagen can last for two to seven years , depending on your genes . after this productive period , signals within the skin instruct some follicles to enter a new phase known as catagen , or the regressing stage , causing hair follicles to shrink to a fraction of their original length . catagen lasts for about two to three weeks and cuts blood supply to the follicle , creating a club hair , meaning it 's ready to be shed . finally , hairs enter telogen , the resting phase , which lasts for ten to twelve weeks , and affects about 5-15 % of your scalp follicles . during telogen , up to 200 club hairs can be shed in a day , which is quite normal . then , the growth cycle begins anew . but not all heads are hairy , and , in fact , some of them grow increasingly patchy over time in response to bodily changes . 95 % of baldness in men can be attributed to male pattern baldness . baldness is inherited , and in people with this condition , follicles become incredibly sensitive to the effects of dihydrotestosterone , a hormonal product made from testosterone . dht causes shrinkage in these overly sensitive follicles , making hair shorter and wispier . but loss is n't sudden . it happens gradually , along a metric known as the norwood scale , which describes the severity of hair loss . first , hair recedes along the temples , then hair on the crown begins to thin in a circular pattern . at the highest rating on the scale , these balding areas meet and expand dramatically , eventually leaving only a ring of sparse hair around the temples and the back of the head . genetics is n't all that drives hair loss . long periods of stress can release signals that shock follicles and force them into the resting phase prematurely . some women experience this after childbirth . follicles might also lose the ability to go into anagen , the growth phase . people going through chemotherapy treatment temporarily experience this . but while balding may look permanent , scientific investigation has revealed the opposite . below the skin 's surface , the roots that give rise to our hair actually remain alive . using this knowledge , scientists have developed drugs that shorten the resting phase , and force follicles into anagen . other drugs combat male pattern baldness by blocking the conversion of testosterone to dht so that it does n't affect those sensitive follicles . stem cells also play a role in regulating the growth cycle , and so scientists are investigating whether they can manipulate the activity of these cells to encourage follicles to start producing hair again . and in the meantime , while scientists hone their hair-reviving methods , anyone going bald , or considering baldness , can remember that they 're in great company .
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other drugs combat male pattern baldness by blocking the conversion of testosterone to dht so that it does n't affect those sensitive follicles . stem cells also play a role in regulating the growth cycle , and so scientists are investigating whether they can manipulate the activity of these cells to encourage follicles to start producing hair again . and in the meantime , while scientists hone their hair-reviving methods , anyone going bald , or considering baldness , can remember that they 're in great company .
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hair follicle stem cells play a key role in regulating the cycles of the hair follicle . how can research on stem cells be used to develop new drugs to reverse baldness ?
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it can strike without warning , at any moment . you may be walking across a soft carpet and reaching for the door knob when suddenly ... zap ! to understand static electricity , we first need to know a bit about the nature of matter . all matter is made up of atoms that consist of three types of smaller particles : negatively charged electrons , positively charged protons , and neutral neutrons . normally , the electrons and protons in an atom balance out , which is why most matter you come across is electrically neutral . but electrons are tiny and almost insignificant in mass , and rubbing or friction can give loosely bound electrons enough energy to leave their atoms and attach to others , migrating between different surfaces . when this happens , the first object is left with more protons than electrons and becomes positively charged , while the one with more electrons accumulates a negative charge . this situation is called a charge imbalance , or net charge separation . but nature tends towards balance , so when one of these newly charged bodies comes into contact with another material , the mobile electrons will take the first chance they get to go where they 're most needed , either jumping off the negatively charged object , or jumping onto the positively charged one in an attempt to restore the neutral charge equilibrium . and this quick movement of electrons , called static discharge , is what we recognize as that sudden spark . this process does n't happen with just any objects . otherwise you 'd be getting zapped all the time . conductors like metals and salt water tend to have loosely bound outer electrons , which can easily flow between molecules . on the other hand , insulators like plastics , rubber and glass have tightly bound electrons that wo n't readily jump to other atoms . static build-up is most likely to occur when one of the materials involved is an insulator . when you walk across a rug , electrons from your body will rub off onto it , while the rug 's insulating wool will resist losing its own electrons . although your body and the rug together are still electrically neutral , there is now a charge polarization between the two . and when you reach to touch the door knob , zap ! the metal door knob 's loosely bound electrons hop to your hand to replace the electrons your body has lost . when it happens in your bedroom , it 's a minor nuisance . but in the great outdoors , static electricity can be a terrifying , destructive force of nature . in certain conditions , charge separation will occur in clouds . we do n't know exactly how this happens . it may have to do with the circulation of water droplets and ice particles within them . regardless , the charge imbalance is neutralized by being released towards another body , such as a building , the earth , or another cloud in a giant spark that we know as lightning . and just as your fingers can be zapped over and over in the same spot , you better believe that lightning can strike the same place more than once .
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normally , the electrons and protons in an atom balance out , which is why most matter you come across is electrically neutral . but electrons are tiny and almost insignificant in mass , and rubbing or friction can give loosely bound electrons enough energy to leave their atoms and attach to others , migrating between different surfaces . when this happens , the first object is left with more protons than electrons and becomes positively charged , while the one with more electrons accumulates a negative charge . this situation is called a charge imbalance , or net charge separation .
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how does friction between two materials cause electrons to jump from one and stick to another ?
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translator : jessica ruby reviewer : caroline cristal let 's say that it would take you ten minutes to solve this puzzle . how long would it take if you received constant electric shocks to your hands ? longer , right ? because the pain would distract you from the task . well , maybe not ; it depends on how you handle pain . some people are distracted by pain . it takes them longer to complete a task , and they do it less well . other people use tasks to distract themselves from pain , and those people actually do the task faster and better when they 're in pain than when they 're not . some people can just send their mind wandering to distract themselves from pain . how can different people be subjected to the exact same painful stimulus and yet experience the pain so differently ? and why does this matter ? first of all , what is pain ? pain is an unpleasant sensory and emotional experience , associated with actual or potential tissue damage . pain is something we experience , so it 's best measured by what you say it is . pain has an intensity ; you can describe it on a scale from zero , no pain , to ten , the most pain imaginable . but pain also has a character , like sharp , dull , burning , or aching . what exactly creates these perceptions of pain ? well , when you get hurt , special tissue damage-sensing nerve cells , called nociceptors , fire and send signals to the spinal cord and then up to the brain . processing work gets done by cells called neurons and glia . this is your grey matter . and brain superhighways carry information as electrical impulses from one area to another . this is your white matter . the superhighway that carries pain information from the spinal cord to the brain is our sensing pathway that ends in the cortex , a part of the brain that decides what to do with the pain signal . another system of interconnected brain cells called the salience network decides what to pay attention to . since pain can have serious consequences , the pain signal immediately activates the salience network . now , you 're paying attention . the brain also responds to the pain and has to cope with these pain signals . so , motor pathways are activated to take your hand off a hot stove , for example . but modulation networks are also activated that deliver endorphins and enkephalins , chemicals released when you 're in pain or during extreme exercise , creating the runner 's high . these chemical systems help regulate and reduce pain . all these networks and pathways work together to create your pain experience , to prevent further tissue damage , and help you to cope with pain . this system is similar for everyone , but the sensitivity and efficacy of these brain circuits determines how much you feel and cope with pain . this is why some people have greater pain than others and why some develop chronic pain that does not respond to treatment , while others respond well . variability in pain sensitivities is not so different than all kinds of variability in responses to other stimuli . like how some people love roller coasters , but other people suffer from terrible motion sickness . why does it matter that there is variability in our pain brain circuits ? well , there are many treatments for pain , targeting different systems . for mild pain , non-prescription medications can act on cells where the pain signals start . other stronger pain medicines and anesthetics work by reducing the activity in pain-sensing circuits or boosting our coping system , or endorphins . some people can cope with pain using methods that involve distraction , relaxation , meditation , yoga , or strategies that can be taught , like cognitive behavioral therapy . for some people who suffer from severe chronic pain , that is pain that does n't go away months after their injury should have healed , none of the regular treatments work . traditionally , medical science has been about testing treatments on large groups to determine what would help a majority of patients . but this has usually left out some who did n't benefit from the treatment or experienced side effects . now , new treatments that directly stimulate or block certain pain-sensing attention or modulation networks are being developed , along with ways to tailor them to individual patients , using tools like magnetic resonance imaging to map brain pathways . figuring out how your brain responds to pain is the key to finding the best treatment for you . that 's true personalized medicine .
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and brain superhighways carry information as electrical impulses from one area to another . this is your white matter . the superhighway that carries pain information from the spinal cord to the brain is our sensing pathway that ends in the cortex , a part of the brain that decides what to do with the pain signal .
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what are the different roles of gray matter and white matter ?
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whether you 're watching an entire netflix series in one sitting , or playing the newest zelda from start to finish , most of us spend a significant time in front of screens . but is binge watching bad for your brain and body ? in the past , it may have actually been deadly . in 1967 , an error in manufacturing led to the selling of tvs which emitted harmful x-rays with radiation levels 100,000 times higher than what is considered safe today . but even modern televisions cause a strain on your eyes . under normal circumstances , humans blink around 18 times per minute , but when staring at a screen , this rate decreases drastically causing sore and tired eyes . fortunately , these symptoms are generally short-term . in children , however , simply spending extended hours indoors can have developmental effects . a condition called myopia , where the eyes can not focus properly , is seen much more frequently in children who spend more time inside . not only are you constantly forced to focus on nearby objects as opposed to far off landscapes and distances , but scientists believe that the sun itself may actually play a role in healthy eye regulation . and while tv may feel like a nice way to relax your body and brain , that may not always be a good thing . not only is a sedentary lifestyle a major contributor to obesity , but studies have shown that people who watch less tv tend to burn more calories , even if they are n't doing more physical activity . simply doing more mentally rigorous tasks like reading , playing a board game , or simple household activities , requires more energy and burns more calories . and if you want to truly relax , tv before bed may also be hurting you . studies have shown that it may actually reduce the hours of quality sleep , contributing to chronic sleep debt . it may also affect other bedtime activities . researchers have found that those who watch more than 20 hours of tv a week have , on average , a 44 % reduction in sperm . but perhaps the most significant findings relate directly to your life span . not only is there a documented correlation between tv viewing time and risk for diabetes and heart disease , but as shocking as it may be , multiple studies have found a correlation between tv viewing time and all causes of death . one study concluded that every hour spent in front of the tv may cut as much as 22 minutes off your life . of course , correlation does not equal causation , and you can have a healthy relationship with tv if consumed in moderation like anything else . at the root of many of these claims is the physical inactivity associated with prolonged tv watching . ultimately , the more you move , the more you live . be sure to check out our newest videos by clicking the screen or using the links in the description , and subscribe for more weekly science videos every thursday .
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in children , however , simply spending extended hours indoors can have developmental effects . a condition called myopia , where the eyes can not focus properly , is seen much more frequently in children who spend more time inside . not only are you constantly forced to focus on nearby objects as opposed to far off landscapes and distances , but scientists believe that the sun itself may actually play a role in healthy eye regulation .
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myopia , a condition that causes you to have trouble focusing your eyes , is seen more in children that spend too much time inside . what is one reason for this ?
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all animals communicate . crabs wave their claws at each other to signal that they 're healthy and ready to mate . cuttlefish use pigmented skin cells called chromatophores to create patterns on their skin that act as camouflage or warnings to rivals . honeybees perform complex dances to let other bees know the location and quality of a food source . all of these animals have impressive communication systems , but do they have language ? to answer that question , we can look at four specific qualities that are often associated with language : discreteness , grammar , productivity , and displacement . discreteness means that there is a set of individual units , such as sounds or words , that can be combined to communicate new ideas , like a set of refrigerator poetry magnets you can rearrange to create different phrases . grammar provides a system of rules that tells you how to combine those individual units . productivity is the ability to use language to create an infinite number of messages . and displacement is the ability to talk about things that are n't right in front of you , such as past , future , or fictional events . so , does animal communication exhibit any of these qualities ? for crabs and cuttlefish , the answer is no . they do n't combine their signals in creative ways . those signals also do n't have to be in a grammatical order , and they only communicate current conditions , like , `` i am healthy , '' or `` i am poisonous . '' but some animals actually do display some of these properties . bees use the moves , angle , duration , and intensity of their waggle dance to describe the location and richness of a food source . that source is outside the hive , so they exhibit the property of displacement . they share that language trait with prairie dogs , which live in towns of thousands , and are hunted by coyotes , hawks , badgers , snakes , and humans . their alarms calls indicate the predator 's size , shape , speed , and , even for human predators , what the person is wearing and if he 's carrying a gun . great apes , like chimps and gorillas , are great communicators , too . some have even learned a modified sign language . a chimpanzee named washoe demonstrated discreteness by combining multiple signs into original phrases , like , `` please open . hurry . '' coco , a female gorilla who understands more than 1000 signs , and around 2000 words of spoken english referred to a beloved kitten that had died . in doing so , she displayed displacement , though it 's worth noting that the apes in both of these examples were using a human communication system , not one that appeared naturally in the wild . there are many other examples of sophisticated animal communication , such as in dolphins , which use whistles to identify age , location , names , and gender . they can also understand some grammar in a gestural language researchers use to communicate with them . however , grammar is not seen in the dolphin 's natural communication . while these communication systems may have some of the qualities of language we 've identified , none display all four . even washoe and coco 's impressive abilities are still outpaced by the language skills of most three-year-old humans . and animals ' topics of conversation are usually limited . bees talk about food , prairie dogs talk about predators , and crabs talk about themselves . human language stands alone due to the powerful combination of grammar and productivity , on top of discreteness and displacement . the human brain can take a finite number of elements and create an infinite number of messages . we can craft and understand complex sentences , as well as words that have never been spoken before . we can use language to communicate about an endless range of subjects , talk about imaginary things , and even lie . research continues to reveal more and more about animal communication . it may turn out that human language and animal communication are n't entirely different but exist on a continuum . after all , we are all animals .
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bees use the moves , angle , duration , and intensity of their waggle dance to describe the location and richness of a food source . that source is outside the hive , so they exhibit the property of displacement . they share that language trait with prairie dogs , which live in towns of thousands , and are hunted by coyotes , hawks , badgers , snakes , and humans .
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displacement is a quality found in the communication of both honeybees and in humans . displacement means :
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translator : bedirhan cinar why do we cringe when we hear `` shakespeare ? '' if you ask me , it 's usually because of his words . all those thines and thous and therefores and wherefore-art-thous can be more than a little annoying . but you have to wonder , why is he so popular ? why have his plays been made and remade more than any other playwright ? it 's because of his words . back in the late 1500s and early 1600s , that was the best tool that a person had , and there was a lot to talk about . however , most of it was pretty depressing . you know , with the black plague and all . shakespeare does use a lot of words . one of his most impressive accomplishments is his use of insults . they would unify the entire audience ; and no matter where you sat , you could laugh at what was going on onstage . words , specifically dialogue in a drama setting , are used for many different reasons : to set the mood of the scene , to give some more atmosphere to the setting , and to develop relationships between characters . insults do this in a very short and sharp way . let 's first go to `` hamlet . '' right before this dialogue , polonius is the father of ophelia , who is in love with prince hamlet . king claudius is trying to figure out why prince hamlet is acting so crazy since the king married prince hamlet 's mother . polonius offers to use his daughter to get information from prince hamlet . then we go into act ii scene 2 . polonius : `` do you know me , my lord ? '' hamlet : `` excellent well . you 're a fishmonger . '' polonius : `` not i , my lord . '' hamlet : `` then i would you were so honest a man . '' now , even if you did not know what `` fishmonger '' meant , you can use some contextual clues . one : polonius reacted in a negative way , so it must be bad . two : fish smell bad , so it must be bad . and three : `` monger '' just does n't sound like a good word . so from not even knowing the meaning , you 're beginning to construct some characterization of the relationship between hamlet and polonius , which was not good . but if you dig some more , `` fishmonger '' means a broker of some type , and in this setting , would mean like a pimp , like polonius is brokering out his daughter for money , which he is doing for the king 's favor . this allows you to see that hamlet is not as crazy as he 's claiming to be , and intensifies the animosity between these two characters . want another example ? `` romeo and juliet '' has some of the best insults of any of shakespeare 's plays . it 's a play about two gangs , and the star-crossed lovers that take their own lives . well , with any fisticuffs you know that there is some serious smack talk going on . and you are not disappointed . in act i scene 1 , right from the get-go we are shown the level of distrust and hatred the members of the two families , the capulets and montagues , meet . gregory : `` i will frown as i pass by , and let them take it as they list . '' sampson : `` nay , as they dare , i will bite my thumb at them , which is a disgrace to them , if they bear it . '' enter abraham and balthasar . abraham : `` do you bite your thumb at us , sir ? '' sampson : `` i do bite my thumb , sir . '' abraham : `` do you bite your thumb at us , sir ? '' okay , so how does this development help us understand mood or character ? well , let 's break it down to the insult . biting your thumb today may not seem like a big deal , but sampson says it is an insult to them . if they take it so , it must have been one . this begins to show us the level of animosity between even the men who work for the two houses . and you normally would not do anything to someone unless you wanted to provoke them into a fight , which is exactly what 's about to happen . looking deeper , biting your thumb in the time in which the play was written is like giving someone the finger today . a pretty strong feeling comes with that , so we now are beginning to feel the tension in the scene . later on in the scene , tybalt , from the house of the capulets , lays a good one on benvolio from the house of the montagues . tybalt : `` what , art thou drawn among these heartless hinds ? turn thee , benvolio , and look upon thy death . '' benvolio : `` i do but keep the peace ; put up thy sword , or manage it to part these men with me . '' tybalt : `` what , drawn and talk of peace ! i hate the word , as i hate hell , all montagues , and thee . have at thee , coward ! '' okay , heartless hinds . we know that once again , it 's not a good thing . both families hate each other , and this is just adding fuel to the fire . but just how bad is this stinger ? a heartless hind is a coward , and calling someone that in front of his own men , and the rival family , means there 's going to be a fight . tybalt basically calls out benvolio , and in order to keep his honor , benvolio has to fight . this dialogue gives us a good look at the characterization between these two characters . tybalt thinks that the montagues are nothing but cowardly dogs , and has no respect for them . once again , adding dramatic tension to the scene . okay , now here 's a spoiler alert . tybalt 's hotheadedness and severe hatred of the montagues is what we literature people call his hamartia , or what causes his downfall . oh , yes . he goes down at the hands of romeo . so when you 're looking at shakespeare , stop and look at the words , because they really are trying to tell you something .
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they would unify the entire audience ; and no matter where you sat , you could laugh at what was going on onstage . words , specifically dialogue in a drama setting , are used for many different reasons : to set the mood of the scene , to give some more atmosphere to the setting , and to develop relationships between characters . insults do this in a very short and sharp way .
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what is the purpose of dialogue in drama ?
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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 .
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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 .
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what are other inventions that you foresee becoming obsolete or outlawed due to new technology or the material used in their construction ?
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okay , i 've got a piece of crystalline bismuth , so you can actually take sort of pellets of bismuth , metal , and heat it up , i 've seen photos of people doing that on their home cookers , their ovens and things , but you can make them in the lab so you get crystals of bismuth out which look like this which is actually really really pretty and there are websites of people who 've made these crystals and they 're selling them for collectors and things which is quite nice . bismuth is interesting because it is the heaviest element that is not radioactive . you can imagine the nucleus , the center of the atom , rather like a drop of water , and if you imagine a drop of water as it gets bigger and bigger it becomes unstable and will usually split into two , and it just happens that bismuth is the largest size that 's not radioactive . - the interesting thing about bismuth actually is that it 's long been regarded , bismuth 209 has long been regarded as the heaviest non-radioactive element , and technically actually that 's not true . it was actually found i think about 5 years ago now , it was actually proven to be an alpha emitter , so it 's actually a radioactive element , that emits alpha particles . - so here is a very old sample of bismuth . this is a bismuth rod and as you can see it 's packed up really quite nicely , but if we open this then we can go in and see what it is in here . let 's see . here if we pull it out carfully . - but actually it 's kind of a little bit pedantic i suppose because the half life of this bismuth 209 they 've found is actually 1.9x10 to the power of 19 years . its half life , that 's the time it takes a kilo of bismuth , for 500 grams of it to decompose to its daughter element which i think is thalium 205 if i 'm right , and so that half life is actually longer than the current age of the universe , so for all intents and purposes , it 's still quite stable and i think they actually call it meta stable . - it is used particularly in an alloy which they call woods metal , which is a very low melting alloy , will even melt in boiling water , and there are endless practical jokes where you can buy woods metal spoons and give it to somebody to stir their tea and it melted in their tea and they look suprised . - bismuth . really old sample from johnson matthey and let 's see if we can find out what the purity is , so it 's 99.9 % , really a quite nice sample of a bismuth rod . - bismuth suprisingly is not very poisonous compared to the fact that led is very poisonous , and so there are some suggestions that we should be exploring more the chemistry of bismuth as a catalist because if it works well then it can be used in chemical processes with much less danger than some of these other materials . - so if we can push it out from this old paper package then you can see it 's packaged really quite nicely , here you can see the bismuth metal itself , bismuth is used in catalysis to attenuate selective reactions so perhaps we might use bismuth with a platinum group metal like paladium or platinum even to make chemistry work even more selectively , it 's a really beautiful element then . really nice , so we 'll pop that back in there nice and safe . - what have you got there , where did that come from ? - i bought it because it 's so pretty , i bought it from a shop , i ca n't remember actually which shop now , but i collect these sorts of things . these very big pretty looking sort of metallic things and crystals and as you can see it 's really nice and irradescent so it 's got a tarnished oxide layer and it shines like all the colors of the rainbow which is really really pretty in my opinion . lovely ! captions by www.subply.com
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- it is used particularly in an alloy which they call woods metal , which is a very low melting alloy , will even melt in boiling water , and there are endless practical jokes where you can buy woods metal spoons and give it to somebody to stir their tea and it melted in their tea and they look suprised . - bismuth . really old sample from johnson matthey and let 's see if we can find out what the purity is , so it 's 99.9 % , really a quite nice sample of a bismuth rod .
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what is the color of bismuth crystals ?
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grammatical tense is how languages talk about time without explicitly naming time periods by , instead , modifying verbs to specify when action occurs . so how many different tenses are there in a language like english ? at first , the answer seems obvious : there 's past , present , and future . but thanks to something called grammatical aspect , each of those time periods actually divides further . there are four kinds of aspect . in the continuous or progressive aspect , the actions are still happening at the time of reference . the perfect aspect describes actions that are finished . the perfect progressive aspect is a combination , describing a completed part of a continuous action . and finally , there 's the simple aspect , the basic form of the past , present , and future tense where an action is not specified as continuous or discreet . that 's all a little hard to follow , so let 's see how it works in action . let 's say your friends tell you they went on a secret naval mission to collect evidence of a mysterious sea creature . the tense sets the overall frame of reference in the past , but within that , there are many options . your friends might say a creature attacked their boat , that 's the past simple , the most general aspect , which gives no further clarification . they were sleeping when it happened , a continuous process underway at that point . they might also tell you they had departed from nantucket to describe an action completed even earlier . that 's an example of the past perfect . or that they had been sailing for three weeks , something that was ongoing up until that point . in the present , they tell you that they still search for the creature today , their present simple activity . perhaps they are preparing for their next mission continuously as they speak . and they have built a special submarine for it , a completed achievement . plus , if they have been researching possible sightings of the creature , it 's something they 've been doing for a while and are still doing now making it present perfect progressive . so what does this next mission hold ? you know it still has n't happened because they will depart next week , the future simple . your friends will be searching for the elusive creature , an extended continuous undertaking . they tell you the submarine will have reached uncharted depths a month from now . that 's a confident prediction about what will be achieved by a specific point in the future , a point at which they will have been voyaging for three weeks in the future perfect progressive . the key insight to all these different tenses is that each sentence takes place in a specific moment , whether it 's past , present , or future . the point of aspects is that they tell you as of that moment the status of the action . in total , they give us twelve possibilities in english . what about other languages ? some , like french , swahili , and russian take a similar approach to english . others describe and divide time differently . some have fewer grammatical tenses , like japanese , which only distinguishes past from non-past , buli and tukang basi , which only distinguish future from non-future , and mandarin chinese with no verb tenses at all , only aspect . on the other hand , languages like yagwa split past tense into multiple degrees , like whether something happened hours , weeks , or years ago . in others , tenses are intertwined with moods that can convey urgency , necessity , or probability of events . this makes translation difficult but not impossible . speakers of most languages without certain tenses can express the same ideas with auxiliary words , like would or did , or by specifying the time they mean . are the variations from language to language just differents ways of describing the same fundamental reality ? or do their diverse structures reflect different ways of thinking about the world and even time itself ? and if so , what other ways of conceiving time may be out there ?
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the tense sets the overall frame of reference in the past , but within that , there are many options . your friends might say a creature attacked their boat , that 's the past simple , the most general aspect , which gives no further clarification . they were sleeping when it happened , a continuous process underway at that point . they might also tell you they had departed from nantucket to describe an action completed even earlier .
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in the sentence `` they were sleeping when the creature attacked the boat , '' we use the past continuous form `` were sleeping '' to show that the heroes :
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hi , i ’ m john green . this is crash course world history and today we ’ re going to talk about world war ii . finally , a war with some color film ! so , here at crash course we try to make history reasonably entertaining , and fortunately , world war ii was hilarious ... said no one ever . mr. green , mr. green ! is this , like , gon na be one of the unfunny ones where you build to the big melodramatic conclusion about how i have to imagine the world more complexly ? me from the past , as long as you have that eighth rate soup-strainer , i ’ m not even going to acknowledge your existence . [ theme music ] right , so you ’ ve probably heard a lot about world war ii from movies and books , the history channel , before it decided that swamp people were history , the incessant droning of your grandparents , etc . we ’ re not gon na try to give you a detailed synopsis of the war today . instead , we ’ re going to try to give a bit of perspective on how the most destructive war in human history happened , and why it still matters globally . so one of the reasons history classes tend to be really into wars is that they ’ re easy to put on tests . they start on one day and they end on another day . and they ’ re caused by social , political , and economic conditions that can be examined in a multiple choice kind of manner . except , not really . like , when did world war ii start ? in september 1939 , when the nazis invaded poland ? i ’ d say no - it actually started when japan invaded manchuria in 1931 , or at the very latest when the japanese invaded china in 1937 , because they didn ’ t stop fighting until 1945 . then again , you could also argue 1933 , when hitler took power , or 1941 , when america started fighting . it ’ s complicated . but anyway , in china the fighting was very brutal , as exemplified by the infamous rape of nanking , which featured the slaughter of hundreds of thousands of chinese people and is still so controversial today that : 1 . it affects relations between japan & amp ; amp ; china and 2 . even though i have not described it in detail , you can rest assured that there will be angry comments about my use of the word “ slaughter. ” but the world war ii we know the most about from movies and tv is primarily the war in the european theater , the one that adolf hitler started . hitler is the rare individual who really did make history - specifically he made it worse - and if he hadn ’ t existed , it ’ s very unlikely that world war ii would ’ ve ever happened . but he did exist , and after coming to power in 1933 , with the standard revolutionary promises to return the homeland to its former glory , infused with quite a bit of paranoia and anti-semitism , germany saw rapid re-militarization and eventually , inevitably , war . in the beginning , it was characterized by a new style of combat made possible by the mechanized technology of tanks , airplanes , and especially , trucks . this was the blitzkrieg , a devastating tactic combining quick movement of troops , tanks , and massive use of air power to support infantry movements . and in the very early years of the war , it was extremely effective . the nazis were able to roll over poland , norway , denmark , the netherlands , and then all of france , all within about 9 months between the fall of 1939 and the summer of 1940 . so after knocking out most of central europe , the nazis set their sights on great britain , but they didn ’ t invade the island , choosing instead to attack it with massive air strikes . i mean , you look at this poster and think , “ man , the queen wants me to finish my term paper , so i can do it , ” but when this poster was first produced in 1939 , it was to quell terror in the face of bombardment . the battle of britain was a duel between the royal air force and the luftwaffe , and while the raf denied the nazis total control of british airspace , the nazis were still able to bomb great britain over and over again in what ’ s known as the blitz . stan , no . no jokes this time . yes , the blitz . meanwhile , europeans were also fighting each other in north africa . the desert campaigns started in 1940 and lasted through 1942 - this is where british general “ monty ” montgomery outfoxed german general irwin “ the desert fox ” rommel . it ’ s also the place where americans first fought nazis in large numbers . but most importantly , it ’ s where indiana jones discovered the ark of the covenant . okay , let ’ s go to the thought bubble . 1941 was a big year for world war ii . first , the nazis invaded russia , breaking a non-aggression pact that the two powers had signed in 1939 . this hugely escalated the war , and also made allies of the most powerful capitalist countries and the most powerful communist one , an alliance that would stand the test of time and never end ... until like three seconds after the defeat of the nazis . the nazi invasion of russia opened the war up on the so-called eastern front , although if you were russian , it was the western front , and it led to millions of deaths , mostly russian . also , 1941 saw a day that would `` live in infamy '' when the japanese bombed pearl harbor , hoping that such an audacious attack would frighten the united states into staying neutral , which was a pretty stupid gamble because : 1 . the u.s. was already giving massive aid to the allies and was hardly neutral and 2 . the united states is not exactly famed for its pacifism or political neutrality . 1941 also saw japan invading much of southeast asia , which made australia and new zealand understandably nervous . as part of the british commonwealth , they were already involved in the war , but now they could fight the japanese closer to home . and shut up about how i never talk about you australians . i just gave you 1.5 sentences . but by the time the americans and australians started fighting the japanese , it was already a world war . sometimes this meant fighting or starving or being bombed ; other times , it meant production for the war - you don ’ t think of argentina as being a world war ii powerhouse , for instance , but they were vital to the allies , supplying 40 % of british meat during world war ii . thanks , thought bubble . so , not to sound jingoistic , but the entry of the u.s. into the war really did change everything , although i doubt the nazis could ’ ve taken russia regardless . no one conquers russia in the wintertime , unless you are - wait for it - the mongols . okay , we ’ re going to skip most of the big battles of 1942 - like the battle of midway , which effectively ended japan ’ s chance of winning the war - and focus on the battle of stalingrad . the german attack on stalingrad , now known as volgograd because stalin sucks , was one of the bloodiest battles in the history of war , with more than two million dead . the germans began by dropping more than 1,000 tons of bombs on stalingrad , and then the russians responded by “ hugging ” the germans , staying as close to their front lines as possible so that german air support would kill germans and russians alike . this kind of worked , although the germans still took most of the city . but then , a soviet counterattack left the sixth army of the nazis completely cut off . and after that , due partly to hitler ’ s overreaching megalomania and partly to lots of people being scared of him , the sixth army slowly froze and starved to death before finally surrendering . and of the 91,000 axis pows from stalingrad , only about 6,000 ever returned home . stalingrad turned the war in europe and by 1944 , the american strategy of “ island hopping ” in the pacific was taking gis closer and closer to japan . rome was liberated in june by americans and canadians ; and the successful british , canadian , and american d-day invasion of normandy was the beginning of the end for the nazis . oh , it ’ s time for the open letter ? an open letter to canada . but first , let ’ s see what ’ s in the secret compartment today . oh , it ’ s canadian mittens . i wan na thank the canadian crash course fans , who sent us these mittens . canadians are just so nice , stan . like , all we ever do on this show is make fun of them , and they ’ re just like , “ it ’ s so kind of you to mention us . here ’ s some mittens ! ” dear canada , we ’ re not always nice to you here on crash course , but you are awesome . i ’ m pointing , but you can ’ t tell because i ’ m wearing mittens . 45,000 canadians died fighting for the allies in world war ii , which means that , per capita , canada lost more people than the united states . you fought with the royal air force to defend great britain from the beginning of the war and you were there on d-day , successfully invading juno beach . and , as many of you have pointed out in comments , you defeated the united states in the war of 1812 , meaning that , arguably , canada , you are the greater military power . plus , you have lumberjacks , and excellent beer , and hockey , and universal healthcare , and justin bieber . i ’ m jealous ! that 's what it is - i 'm jealous ! best wishes , john green . so , by the end of 1944 , the allies were advancing from the west and the russian red army was advancing from the east and then , the last-ditch german offensive at the battle of the bulge in the winter of 1944-1945 failed . mussolini was executed in april of 1945 . hitler committed suicide at the end of that month . and , on may 8 , 1945 the allies declared victory in europe after germany surrendered unconditionally . three months later , the united states dropped the only two nuclear weapons ever deployed in war , japan surrendered , and world war ii was over . the war had a definite cause : unbridled military expansion by germany , japan , and , to a small extent , italy . now , it ’ s easy to claim that hitler was crazy or evil , and , in fact , he was certainly both , but that doesn ’ t explain the nazis decision to invade russia , and it sure doesn ’ t explain japan ’ s decision to bomb pearl harbor . and there are many possible explanations beyond mere evil ; but the most interesting one , to me , involves food . hitler had a number of reasons for wanting to expand germany ’ s territory , but he often talked about lebensraum or living space for the german people . german agriculture was really inefficiently organized into lots of small farms , and that meant that germany needed a lot of land in order to be self-sufficient in food production . the plan was to take poland , the ukraine , and eastern russia , and then resettle that land with lots of germans , so that it could feed german people . this was called the hunger plan because the plan called for 20 million people to starve to death . many would be the poles , ukrainians , and russians who ’ d previously lived on the land . the rest would be europe ’ s jews , who would be worked to death . six million jews were killed by the nazis , many by starvation , but many through a chillingly planned effort of extermination in death camps . these death camps can be distinguished from concentration camps or labor camps in that their primary purpose was extermination of jews , roma people , communists , homosexuals , disabled people , and others that the nazis deemed unfit . some historians believe that the nazis opened the death camps because the jews weren ’ t dying as fast as the hunger plan had intended . this was a sickening plan , but it made a kind of demented sense . rather than becoming more involved in global trade , as the british had , the germans would feed themselves by taking land and killing the people who ’ d previously lived there . similarly , japan , at the beginning of the war , was suffering from an acute fear of food shortage because its agricultural sector was having trouble keeping up with population growth . and the japanese too , sought to expand their agricultural holdings by , for instance , resettling farmers in korea . so while it ’ s tempting to say that world war ii was about the allies fighting for democratic ideals against the totalitarian militaristic imperialism of the fascist axis powers , it just doesn ’ t hold up to scrutiny . for instance , a hugely important allied power , stalin ’ s soviet union , was , like , the least democratic place , ever . stan just said that was hyperbole , but it ’ s not . stalin ’ s soviet union is tied with all of the other completely undemocratic countries for last place on the democracy scale . it ’ s a big community there , at last place , but they ’ re definitely in there somewhere . and , by far , the biggest imperialists of the war were the british . they couldn ’ t have fed or clothed themselves - or resisted the nazis - without their colonies and commonwealth . so , why is world war ii so important ? well first , it proved the old roman adage homo homini lupus : man is a wolf to man . this is seen most clearly in the holocaust , but all the statistics are staggering . more than a million indian british subjects died , mainly due to famine that could have been avoided if the british had redistributed food . and their failure to do so helped convince indians that the so-called superior civilization of the british was a sham . more than a million vietnamese died , mainly due to famine . 418,000 americans . more than a million noncombatants in both germany and japan . and 20 million people in the soviet union , most of them civilians . these civilians were targeted because they helped sustain the war , mostly through industrial and agricultural production . in a total war , when a nation is at war , not just its army , there is no such thing as a non-military target . from the firebombing of dresden to tokyo to hiroshima , the line between soldier and civilian blurred . and then , of course , there is the holocaust , which horrifies us because the elements of western progress - record-keeping , industrial production , technology - were used to slaughter millions . world war ii saw modern industrial nations , which represented the best of the enlightenment and the scientific revolution , descend into once unimaginable cruelty . and what makes world war ii such a historical watershed is that in its wake , all of us - in the west or otherwise - were forced to question whether western dominance of this planet could , or should , be considered progress . thanks for watching . i ’ ll see you next week . crash course is produced and directed by stan muller . our script supervisor is meredith danko . our 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 . last week ’ s phrase of the week was “ an end to history. ” if you want to guess at this week ’ s phrase of the week or suggest future ones , you can do so in comments , where you can also ask questions about today ’ s video that will be answered by our team of historians . if you enjoy crash course , make sure you ’ re subscribed . thanks for watching , and as we say in my hometown , don ’ t forget to be awesome .
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except , not really . like , when did world war ii start ? in september 1939 , when the nazis invaded poland ?
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why do you think the battle of stalingrad helped turn world war ii in the allies ' favor ?
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what if i told you there were trillions of tiny bacteria all around you ? it 's true . microorganisms called bacteria were some of the first life forms to appear on earth . though they consist of only a single cell , their total biomass is greater than that of all plants and animals combined . and they live virtually everywhere : on the ground , in the water , on your kitchen table , on your skin , even inside you . do n't reach for the panic button just yet . although you have 10 times more bacterial cells inside you than your body has human cells , many of these bacteria are harmless or even beneficial , helping digestion and immunity . but there are a few bad apples that can cause harmful infections , from minor inconveniences to deadly epidemics . fortunately , there are amazing medicines designed to fight bacterial infections . synthesized from chemicals or occurring naturally in things like mold , these antibiotics kill or neutralize bacteria by interrupting cell wall synthesis or interfering with vital processes like protein synthesis , all while leaving human cells unharmed . the deployment of antibiotics over the course of the 20th century has rendered many previously dangerous diseases easily treatable . but today , more and more of our antibiotics are becoming less effective . did something go wrong to make them stop working ? the problem is not with the antibiotics but the bacteria they were made to fight , and the reason lies in darwin 's theory of natural selection . just like any other organisms , individual bacteria can undergo random mutations . many of these mutations are harmful or useless , but every now and then , one comes along that gives its organism an edge in survival . and for a bacterium , a mutation making it resistant to a certain antibiotic gives quite the edge . as the non-resistant bacteria are killed off , which happens especially quickly in antibiotic-rich environments , like hospitals , there is more room and resources for the resistant ones to thrive , passing along only the mutated genes that help them do so . reproduction is n't the only way to do this . some can release their dna upon death to be picked up by other bacteria , while others use a method called conjugation , connecting through pili to share their genes . over time , the resistant genes proliferate , creating entire strains of resistant super bacteria . so how much time do we have before these superbugs take over ? well , in some bacteria , it 's already happened . for instance , some strands of staphylococcus aureus , which causes everything from skin infections to pneumonia and sepsis , have developed into mrsa , becoming resistant to beta-lactam antibiotics , like penicillin , methicillin , and oxacillin . thanks to a gene that replaces the protein beta-lactams normally target and bind to , mrsa can keep making its cell walls unimpeded . other super bacteria , like salmonella , even sometimes produce enzymes like beta-lactams that break down antibiotic attackers before they can do any damage , and e. coli , a diverse group of bacteria that contains strains that cause diarrhea and kidney failure , can prevent the function of antibiotics , like quinolones , by actively booting any invaders that manage to enter the cell . but there is good news . scientists are working to stay one step ahead of the bacteria , and although development of new antibiotics has slowed in recent years , the world health organization has made it a priority to develop novel treatments . other scientists are investigating alternate solutions , such as phage therapy or using vaccines to prevent infections . most importantly , curbing the excessive and unnecessary use of antibiotics , such as for minor infections that can resolve on their own , as well as changing medical practice to prevent hospital infections , can have a major impact by keeping more non-resistant bacteria alive as competition for resistant strains . in the war against super bacteria , deescalation may sometimes work better than an evolutionary arms race .
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fortunately , there are amazing medicines designed to fight bacterial infections . synthesized from chemicals or occurring naturally in things like mold , these antibiotics kill or neutralize bacteria by interrupting cell wall synthesis or interfering with vital processes like protein synthesis , all while leaving human cells unharmed . the deployment of antibiotics over the course of the 20th century has rendered many previously dangerous diseases easily treatable .
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which of the following is not a method by which antibiotics attempt to kill bacteria ?
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chat with a friend about an established scientific theory and she might reply , `` well , that 's just a theory . '' but a conversation about an established scientific law rarely ends with , `` well , that 's just a law . '' why is that ? what is the difference between a theory and a law , and is one better ? scientific laws and theories have different jobs to do . a scientific law predicts the results of certain initial conditions . it might predict your unborn child 's possible hair colors , or how far a baseball travels when launched at a certain angle . in contrast , a theory tries to provide the most logical explanation about why things happen as they do . a theory might invoke dominant and recessive genes to explain how brown-haired parents ended up with a red-headed child , or use gravity to shed light on the parabolic trajectory of a baseball . in simplest terms , a law predicts what happens while a theory proposes why . a theory will never grow up into a law , though the development of one often triggers progress on the other . in the 17th century , johannes kepler theorized cosmic musical harmonies to explain the nature of planetary orbits . he developed three brilliant laws of planetary motion while he was studying decades of precise astronomical data in an effort to find support for his theory . while his three laws are still in use today , gravity replaced his theory of harmonics to explain the planets ' motions . how did kepler get part of it wrong ? well , we were n't handed a universal instruction manual . instead , we continually propose , challenge , revise , or even replace our scientific ideas as a work in progress . laws usually resist change since they would n't have been adopted if they did n't fit the data , though we occasionally revise laws in the face of new unexpected information . a theory 's acceptance , however , is often gladiatorial . multiple theories may compete to supply the best explanation of a new scientific discovery . upon further research , scientists tend to favor the theory that can explain most of the data , though there may still be gaps in our understanding . scientists also like when a new theory successfully predicts previously unobserved phenomena , like when dmitri mendeleev 's theory about the periodic table predicted several undiscovered elements . the term scientific theory covers a broad swath . some theories are new ideas with little experimental evidence that scientists eye with suspicion , or even ridicule . other theories , like those involving the big bang , evolution , and climate change , have endured years of experimental confirmation before earning acceptance by the majority of the scientific community . you would need to learn more about a specific explanation before you 'd know how well scientists perceive it . the word theory alone does n't tell you . in full disclosure , the scientific community has bet on the wrong horse before : alchemy , the geocentric model , spontaneous generation , and the interstellar aether are just a few of many theories discarded in favor of better ones . but even incorrect theories have their value . discredited alchemy was the birthplace of modern chemistry , and medicine made great strides long before we understood the roles of bacteria and viruses . that said , better theories often lead to exciting new discoveries that were unimaginable under the old way of thinking . nor should we assume all of our current scientific theories will stand the test of time . a single unexpected result is enough to challenge the status quo . however , vulnerability to some potentially better explanation does n't weaken a current scientific theory . instead , it shields science from becoming unchallenged dogma . a good scientific law is a finely-tuned machine , accomplishing its task brilliantly but ignorant of why it works as well as it does . a good scientific theory is a bruised , but unbowed , fighter who risks defeat if unable to overpower or adapt to the next challenger . though different , science needs both laws and theories to understand the whole picture . so next time someone comments that it 's just a theory , challenge them to go nine rounds with the champ and see if they can do any better .
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chat with a friend about an established scientific theory and she might reply , `` well , that 's just a theory . '' but a conversation about an established scientific law rarely ends with , `` well , that 's just a law . ''
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which of the following might be an example of a theory ?
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when ultraviolet sunlight hits our skin , it affects each of us a little differently . depending on skin color , it will take only minutes of exposure to turn one person beetroot-pink , while another requires hours to experience the slightest change . so what 's to account for that difference and how did our skin come to take on so many different hues to begin with ? whatever the color , our skin tells an epic tale of human intrepidness and adaptability , revealing its variance to be a function of biology . it all centers around melanin , the pigment that gives skin and hair its color . this ingredient comes from skin cells called melanocytes and takes two basic forms . there 's eumelanin , which gives rise to a range of brown skin tones , as well as black , brown , and blond hair , and pheomelanin , which causes the reddish browns of freckles and red hair . but humans were n't always like this . our varying skin tones were formed by an evolutionary process driven by the sun . in began some 50,000 years ago when our ancestors migrated north from africa and into europe and asia . these ancient humans lived between the equator and the tropic of capricorn , a region saturated by the sun 's uv-carrying rays . when skin is exposed to uv for long periods of time , the uv light damages the dna within our cells , and skin starts to burn . if that damage is severe enough , the cells mutations can lead to melanoma , a deadly cancer that forms in the skin 's melanocytes . sunscreen as we know it today did n't exist 50,000 years ago . so how did our ancestors cope with this onslaught of uv ? the key to survival lay in their own personal sunscreen manufactured beneath the skin : melanin . the type and amount of melanin in your skin determines whether you 'll be more or less protected from the sun . this comes down to the skin 's response as sunlight strikes it . when it 's exposed to uv light , that triggers special light-sensitive receptors called rhodopsin , which stimulate the production of melanin to shield cells from damage . for light-skin people , that extra melanin darkens their skin and produces a tan . over the course of generations , humans living at the sun-saturated latitudes in africa adapted to have a higher melanin production threshold and more eumelanin , giving skin a darker tone . this built-in sun shield helped protect them from melanoma , likely making them evolutionarily fitter and capable of passing this useful trait on to new generations . but soon , some of our sun-adapted ancestors migrated northward out of the tropical zone , spreading far and wide across the earth . the further north they traveled , the less direct sunshine they saw . this was a problem because although uv light can damage skin , it also has an important parallel benefit . uv helps our bodies produce vitamin d , an ingredient that strengthens bones and lets us absorb vital minerals , like calcium , iron , magnesium , phosphate , and zinc . without it , humans experience serious fatigue and weakened bones that can cause a condition known as rickets . for humans whose dark skin effectively blocked whatever sunlight there was , vitamin d deficiency would have posed a serious threat in the north . but some of them happened to produce less melanin . they were exposed to small enough amounts of light that melanoma was less likely , and their lighter skin better absorbed the uv light . so they benefited from vitamin d , developed strong bones , and survived well enough to produce healthy offspring . over many generations of selection , skin color in those regions gradually lightened . as a result of our ancestor 's adaptability , today the planet is full of people with a vast palette of skin colors , typically , darker eumelanin-rich skin in the hot , sunny band around the equator , and increasingly lighter pheomelanin-rich skin shades fanning outwards as the sunshine dwindles . therefore , skin color is little more than an adaptive trait for living on a rock that orbits the sun . it may absorb light , but it certainly does not reflect character .
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so what 's to account for that difference and how did our skin come to take on so many different hues to begin with ? whatever the color , our skin tells an epic tale of human intrepidness and adaptability , revealing its variance to be a function of biology . it all centers around melanin , the pigment that gives skin and hair its color . this ingredient comes from skin cells called melanocytes and takes two basic forms . there 's eumelanin , which gives rise to a range of brown skin tones , as well as black , brown , and blond hair , and pheomelanin , which causes the reddish browns of freckles and red hair .
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variation in skin color is a function of :
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you know , back in the '40s and '50s , the original standard television had a 4 to 3 width to height ratio . that shape was chosen to be a slight rectangle , but still mostly square , thus having the maximal screen area for the given dimensions . and that 's still the ratio on many tvs and computer monitors in today 's homes . the problem is , hardly anybody today treats video content in a 4 to 3 ratio . see , this whole problem started when people wanted to watch movies from the theater in the comfort of their own homes . movie screens are considerably larger than our home television . more important , the screen is completely different rectangle and ca n't mathematically fit on our tv screens without manipulation . a typical tv is one and a third times wider than it is tall some movie screens could be up to three times as wide as it is tall . so what 're we going to do to make it fit ? well , we have all kinds of options . well , we could squeeze and stretch and mangle everything onto the screen , to make it all fill up , and everyone would look ridiculously thin and compressed . the good news is the sound would be just fine , although i do n't think people would be too happy about that option , particularly the actors in the movie . we could just cut a chunk of the original movie like a cookie cutter and just see that frame of the movie . the problem with that would be people and objects would be speaking from off the screen , or , even worse , they might be cut in half . some movie editors use what 's called the `` pan and scan '' technique to allow the full height of the tv screen to be used , but pick and choose what section of the original movie should be shown on your screen thus eliminating the annoying cutting of people . imagine that job : staring at a 4 to 3 hole watching movies all day , deciding for everyone which piece of the screen is the most important part for people to see . now let 's do a little quick math . if we compare a major cinematic film produced on a 2.35 to 1 aspect frame with my standard 4 to 3 tv screen , we find out that only 55 % of the movie can actually fit on the screen at any one time . just over half ! you 've seen the disclaimer at the beginning of the movie on tv or dvd that says , `` this film has been modified from its original format to fit on your tv screen . '' well , what it should say is , `` we are only displaying 55 % of the movie of our choosing . '' now for all the full-screen tv lovers , this is your dilemma : do you want to see all the movie , or is 55 % good enough ? how about new tvs ? around the start of the century , some widescreen tvs emerged in a 16 to 9 , or 1.78 times wider than it is tall . well , this screen fits the movie a little better , but still only shows 75 % of the original movie at one time . suppose someone made a tv for your living room that was actually 2.35 to 1 to show those full movies ? well , the tv with the same height as the most current 50-inch tvs - that tv would be close to six feet long . and on top of that , you 'd only use the full screen when you watched movies . most of the other content would have to be stretched , or have empty space on the sides of the screen . of course , there is one more option . we can just shrink the movie screen proportionally , to fit the width of your home television . we can mathematically scale the original to fit exactly the width of the screen and this 'll preserve the entire movie screen , but show the infamous black bars along the top and bottom that so many television watchers abhor . of course , now you can argue that we 're only using 75 % of that screen . and that is where the real question is : do you want your full screen , or do you want to see the entire movie ? most likely , you just need a bigger tv .
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and that 's still the ratio on many tvs and computer monitors in today 's homes . the problem is , hardly anybody today treats video content in a 4 to 3 ratio . see , this whole problem started when people wanted to watch movies from the theater in the comfort of their own homes .
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when did it become a real problem to have a 4:3 width to height ratio ?
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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 .
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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 .
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worm bins can only handle small amounts of organic waste , therefore large scale vermicomposting is difficult to impossible .
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muhammad ali spent years training to become the greatest boxer the world had ever seen , but only moments to create the shortest poem . ali captivated harvard 's graduating class in 1975 with his message of unity and friendship . when he finished , the audience wanted more . they wanted a poem . ali delivered what is considered the shortest poem ever . `` me , we . '' or is it `` me , weeee '' ? no one 's really sure . regardless , if these two words are a poem , then what exactly makes a poem a poem ? poets themselves have struggled with this question , often using metaphors to approximate a definition . is a poem a little machine ? a firework ? an echo ? a dream ? poetry generally has certain recognizable characteristics . one - poems emphasize language 's musical qualities . this can be achieved through rhyme , rhythm , and meter , from the sonnets of shakepeare , to the odes of confucius , to the sanskrit vedas . two - poems use condensed language , like literature with all the water wrung out of it . three - poems often feature intense feelings , from rumi 's spiritual poetry to pablo neruda 's `` ode to an onion . '' poetry , like art itself , has a way of challenging simple definitions . while the rhythmic patterns of the earliest poems were a way to remember stories even before the advent of writing , a poem does n't need to be lyrical . reinhard döhl 's “ apfel ” and eugen gomringer 's `` silencio '' toe the line between visual art and poetry . meanwhile , e.e . cummings wrote poems whose shapes were as important as the words themselves , in this case amplifying the sad loneliness of a single leaf falling through space . if the visual nature of poetry faded into the background , perhaps we 'd be left with music , and that 's an area that people love to debate . are songs poems ? many do n't regard songwriters as poets in a literary sense , but lyrics from artists like paul simon , bob dylan , and tupac shakur often hold up even without the music . in rap , poet elements like rhyme , rhythm , and imagery are inseparable from the form . take this lyric from the notorious b.i.g . `` i can hear sweat trickling down your cheek your heartbeat sound like sasquatch feet thundering , shaking the concrete . '' so far , all the examples we 've seen have had line breaks . we can even imagine the two words of ali 's poem organizing in the air - me , we . poetry has a shape that we can usually recognize . its line breaks help readers navigate the rhythms of a poem . but what if those line breaks disappeared ? would it lose its essence as a poem ? maybe not . enter the prose poem . prose poems use vivid images and wordplay but are formatted like paragraphs . when we look at poetry less as a form and more as a concept , we can see the poetic all around us : spiritual hymns , the speeches of orators like martin luther king , jr. , jfk , and winston churchill , and surprising places like social media . in 2010 , journalist joanna smith tweeted updates from the earthquake in haiti . `` was in b-room getting dressed when heard my name . tremor . ran outside through sliding door . all still now . safe . roosters crowing . '' smith uses language in a way that is powerful , direct , and filled with vivid images . compare her language to a haiku , the ancient japanese poetic form that emphasizes bursts of brief intensity with just three lines of five , seven , and five syllables . the waters of poetry run wide and deep . poetry has evolved over time , and perhaps now more than ever , the line between poetry , prose , song , and visual art has blurred . however , one thing has not changed . the word poetry actually began in verb form , coming from the ancient greek poiesis , which means to create . poets , like craftsman , still work with the raw materials of the world to forge new understandings and comment on what it is to be human in a way only humans can . dartmouth researchers tested this idea by asking robots to pen poetry . a panel of judges sorted through stacks of sonnets to see if they could distinguish those made by man and machine . you may be happy to know that while scientists have successfully used artificial intelligence in manufacturing , medicine , and even journalism , poetry is a different story . the robots were caught red-handed 100 % of the time .
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smith uses language in a way that is powerful , direct , and filled with vivid images . compare her language to a haiku , the ancient japanese poetic form that emphasizes bursts of brief intensity with just three lines of five , seven , and five syllables . the waters of poetry run wide and deep .
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what is a haiku ?
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it 's easy to forget how vast and deep the ocean really is . about 60 % of it is actually a cold and dark region known as the deep ocean . and it reaches down to 11,000 meters . yet , this remote zone is also one of the greatest habitats on earth , harboring a huge diversity of life , from giant squids and goblin sharks to minuscule animals smaller than a millimeter . how do so many species thrive in this underwater world ? over the decades , intrepid scientists have ventured there to find out . traveling down through the water column , pressure increases and light begins to wane . at 200 meters , photosynthesis stops and temperature decreases from surface temperatures by up to 20 degrees celsius . by 1000 meters , normal sunlight has disappeared altogether . without light , life as we know it seems impossible . that 's why in 1844 , the naturalist edward forbes wrote his azoic theory , azoic , meaning without animals . forbes was sure that nothing could survive below 600 meters on account of the lack of light . of course , the discovery of deep-sea species proved him wrong . what forbes failed to take into account is something called marine snow , which sounds much nicer than it is . marine snow is basically organic matter , things like particles of dead algae , plants , and animals , drifting down into the depths and acting as food for deep-sea animals . largely thanks to that , abundant life forms exist in the darkness , adapting to a harsh reality where only the weird and wonderful can survive . fish with cavernous mouths , spiky teeth jutting from their jaws , and lamp-like structures protruding from their heads , like the anglerfish which entices prey with its misleading glow . several sea creatures have perfected this lightning technique known as bioluminescence , using it to lure prey , distract predators , or attract mates . some creatures use it for camoflauge . in parts of the water column where only faint blue light filters through , animals bioluminesce to match the glow . predators or prey looking up from below are deceived by this camoflauge , unable to see the creatures silhouette . such otherworldly adaptations also arise from the need to locate and snatch up food before it drifts away . some sea animals , like jellyfish , comb jellies and salps can migrate between depths partially because their 90 % water consistency allows them to withstand immense pressure . but they 're the exception . most deep-sea creatures are confined to a narrow range in the water column where nutrients are scarce since the food drifting downwards from the surface rapidly sinks to the sea floor . plunging all the way down , we find more exotic creatures . some take on dwarfism , a trait that transforms them into miniature versions of animals we see closer to the surface . it 's thought that reduced food availability causes the shrinkage . only a tiny fraction of the food produced at the surface reaches the sea floor , so being small gives animals a low energy requirement and an adaptive advantage . and yet , the sea is also the land of giants . here , gargantuan squids can reach 18 meters long . isopods scuttle around the sea floor like enormous wood lice . there are long-limbed japanese spider crabs , and oarfish , whose bodies stretch to 15 meters . this trait is known as gigantism , and it 's something of a mystery . it 's thought that high oxygen levels may drive extreme growth in some species , while the colder temperatures promote longer life spans , giving animals the opportunity to grow massive . many of these exotic sea beasts will never experience sunlight . some will venture up through the water column to feed , and a few will actually break the waves , reminding us at the surface about the incredible survival skills of the ocean 's deepest inhabitants . humans still have an astounding 95 % of the ocean left to explore . so those depths remain a great mystery . what other untold wonders lie far below , and which ones will we discover next ?
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what forbes failed to take into account is something called marine snow , which sounds much nicer than it is . marine snow is basically organic matter , things like particles of dead algae , plants , and animals , drifting down into the depths and acting as food for deep-sea animals . largely thanks to that , abundant life forms exist in the darkness , adapting to a harsh reality where only the weird and wonderful can survive .
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which other adaptations might deep sea animals have ?
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here at scishow hq we have a little food area for the employees - sometimes there are donuts . sometimes there are nuts . sometimes dried mango . but the one thing that never sticks around and is gone as soon as we can buy it is the wonderful , beautiful , noble banana . unfortunately for us , they may not be around forever . [ intro music ] first , the good : bananas are healthy , packed with nutrition and energy , they fit in your hand and give nice little cues when they 're perfectly ripe , and are easy to peel and eat ; shocking statistic , the banana is wal-mart 's number one selling item . not the potato chip , not coca-cola , not fifty shades of grey , bananas . they appear to be so perfect for human consumption that kirk cameron attempted to use them to prove the existence of god . of course this banana was not created by god , or really even nature . bananas , at least the ones that you see at the store , were created by people . do n't get me wrong , there are wild banana plants - lots of them - they 're native to south and southeast asia , and there are dozens of species and thousands of varieties . they 're just not the ones we eat . some those species , as you might suspect , have seeds , 'cause that 's what fruits are , they 're fleshy bodies containing seeds . so you might wonder , why have you never eaten a banana seed ? well , you have ... kinda . in cultivated bananas the seeds have pretty much stopped existing . if you look closely you can see tiny black specks . those are all that 's left , and they 're not fertile seeds . if you plant them , nothing grows . today 's bananas are sterile mutants . i 'm not trying to be mean , that 's just the truth . unless you were alive in the 1960 's ( hats off to all those older scishow viewers out there ) every banana you have ever eaten was pretty much genetically identical . this is a cavendish , the virtually seedless variety that we all eat today , but it was n't always our banana of choice . until the 1960s , everyone was eating the same banana , it was just a different banana - the gros michel , a bigger , sweeter fruit with thicker skin . you might notice that banana flavored things do n't really taste like bananas . well they do - they taste like the gros michel . the genetic monotony of the gros michel crop was its undoing . a fungicide resistant pathogen called the panama disease began infecting gros michel crop . by the time growers understood how vulnerable their crops were , the gros michel variety was all but extinct . the entire banana industry had to be retooled for the cavendish . since they 're seedless , the only way to reproduce them is to transplant part of the plant stem , and for the last 50 years we 've been good with the cavendish , 'cause it 's more resistant to the panama disease . however somewhat terrifyingly a strain of panama disease that affects the cavendish strain that we all eat has been identified . a global monoculture of genetically identical individuals is a beautiful sight to a pathogen . the fungus only has to figure out how to infect and destroy a single individual , and suddenly there is no diversity to stop it , or even slow it down . that 's led to a lot of scientists worrying about or even predicting the outright demise of the cavendish . this wonderful most popular of fruits might completely cease existence . the good news is we now have a much better understanding of genetics , epidemics , fungi , and pathology . scientists and growers have already taken steps to protect the cavendish . some growers are creating genetically different bananas that might replace the cavendish crop if it fails , while scientists are attempting to genetically engineer cavendish plants with immunity to panama disease . plus we learned a lot from the gros michel debacle . infected fields are quickly being destroyed and new crops are grown from pathogen-free lab-grown plant stock . so thanks to the people who work tirelessly to grow and harvest bananas and bring them to us so that we can offer them inexpensively to our employees , and thanks to the growers and scientists working tirelessly to make sure that they do n't go the way of the gros michel . thanks for watching this episode of scishow , if you have any questions , comments or suggestions for us , you can find us on facebook , twitter or in the comments below , and if you want to continue getting smarter this year at scishow , you can go to youtube.com/scishow and subscribe . [ banana eating noises ] [ music ]
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of course this banana was not created by god , or really even nature . bananas , at least the ones that you see at the store , were created by people . do n't get me wrong , there are wild banana plants - lots of them - they 're native to south and southeast asia , and there are dozens of species and thousands of varieties .
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4. since the 1960 's , all the bananas that people have eaten have been :
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honeybees are fascinating creatures for a number of reasons : their incredible work ethic , the sugary sweet syrup they produce and their intricate social structure . but another reason is that honeybees are , in fact , excellent mathematicians . scientists claim the tiny insects can calculate angles , and can even comprehend the roundness of the earth . but there 's particular mathematical bee genius behind the most important aspect of honeybee life : the hive . just like humans , bees need food and shelter to stay alive . the hive is not only the bees ' home , but doubles as a place to store their honey . since it 's so central to survival , honeybees have to perfect the hive 's architectural design . if you examine any piece of honeycomb , you 'll see that it 's constructed from tightly packed hexagonal , or six-sided , cells . of all the possible designs , why do honeybees choose this one ? to understand , you need to think like a bee . bees need a secure place for their entire colony to live . similarly , there needs to be a place where their nectar can be stored and ripened suitably until it turns into honey . that means there 's a need for some serious space efficiency . a good solution is to build little storage units , or cells , just big enough for a bee to fit into , which can also double as the containers in which nectar is stored : the bees ' very own honey jars . the next thing , is to decide what the little cells should be made out of . bees do n't have beaks or arms to pick up things , but they are capable of producing wax . the thing is , producing it is a lot of hard work . bees have to consume 8 ounces of honey to produce just 1 ounce of wax . so they do n't want to waste it . so , they need a design that allows them to store the largest possible amount of honey using the least amount of wax . what shape does that ? imagining for a minute that all bees had to attend architecture academy and go to math class . let 's say they asked their geometry teacher , `` what shape would give us the most space to store our honey , but require the least amount of wax ? '' and then geometry teacher replied , `` the shape that you 're seeking is the circle . '' leaving the bees to return to their trial construction site and begin building their honeycomb using circular cells . after a while , some of them might have noticed a problem with their design : small gaps between the cells . `` we ca n't even fit in there ! that 's wasted space ! '' they might have thought . so , ignoring the geometry lesson , and taking matters into their own hands , the bees went back to the drawing board to rethink their beehive design . one suggested triangles , `` we can use triangles . look ! they fit together perfectly . '' another bee suggested squares . finally , a third bee piped up and said , `` pentagons do n't seem to work , but hexagons do ! we want the one that will use the least amount of wax and be able to store the most amount of honey . yes , i think that 's the hexagon . '' `` why ? '' `` it looks more like the circle than the others . '' `` but how do we know for sure ? '' to find out , the industrious insect architects calculated the areas of the triangle , the square and the hexagon and found that the hexagon was , in fact , the shape that gave them the most storage space . they agreed on an ideal size and returned to work . the space efficient comb that is a bee 's trademark today , is probably the result of this trial and error , but over long periods of evolutionary history . however , it paid off . peek into any hive -- with your protective goggles and netting on , of course -- and you 'll see the end result : a beautiful compact honeycomb that any architect would have be proud to design .
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look ! they fit together perfectly . '' another bee suggested squares .
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repeating shapes so that they fit together without spaces in between them is called a _________________ .
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translator : bedirhan cinar why do we cringe when we hear `` shakespeare ? '' if you ask me , it 's usually because of his words . all those thines and thous and therefores and wherefore-art-thous can be more than a little annoying . but you have to wonder , why is he so popular ? why have his plays been made and remade more than any other playwright ? it 's because of his words . back in the late 1500s and early 1600s , that was the best tool that a person had , and there was a lot to talk about . however , most of it was pretty depressing . you know , with the black plague and all . shakespeare does use a lot of words . one of his most impressive accomplishments is his use of insults . they would unify the entire audience ; and no matter where you sat , you could laugh at what was going on onstage . words , specifically dialogue in a drama setting , are used for many different reasons : to set the mood of the scene , to give some more atmosphere to the setting , and to develop relationships between characters . insults do this in a very short and sharp way . let 's first go to `` hamlet . '' right before this dialogue , polonius is the father of ophelia , who is in love with prince hamlet . king claudius is trying to figure out why prince hamlet is acting so crazy since the king married prince hamlet 's mother . polonius offers to use his daughter to get information from prince hamlet . then we go into act ii scene 2 . polonius : `` do you know me , my lord ? '' hamlet : `` excellent well . you 're a fishmonger . '' polonius : `` not i , my lord . '' hamlet : `` then i would you were so honest a man . '' now , even if you did not know what `` fishmonger '' meant , you can use some contextual clues . one : polonius reacted in a negative way , so it must be bad . two : fish smell bad , so it must be bad . and three : `` monger '' just does n't sound like a good word . so from not even knowing the meaning , you 're beginning to construct some characterization of the relationship between hamlet and polonius , which was not good . but if you dig some more , `` fishmonger '' means a broker of some type , and in this setting , would mean like a pimp , like polonius is brokering out his daughter for money , which he is doing for the king 's favor . this allows you to see that hamlet is not as crazy as he 's claiming to be , and intensifies the animosity between these two characters . want another example ? `` romeo and juliet '' has some of the best insults of any of shakespeare 's plays . it 's a play about two gangs , and the star-crossed lovers that take their own lives . well , with any fisticuffs you know that there is some serious smack talk going on . and you are not disappointed . in act i scene 1 , right from the get-go we are shown the level of distrust and hatred the members of the two families , the capulets and montagues , meet . gregory : `` i will frown as i pass by , and let them take it as they list . '' sampson : `` nay , as they dare , i will bite my thumb at them , which is a disgrace to them , if they bear it . '' enter abraham and balthasar . abraham : `` do you bite your thumb at us , sir ? '' sampson : `` i do bite my thumb , sir . '' abraham : `` do you bite your thumb at us , sir ? '' okay , so how does this development help us understand mood or character ? well , let 's break it down to the insult . biting your thumb today may not seem like a big deal , but sampson says it is an insult to them . if they take it so , it must have been one . this begins to show us the level of animosity between even the men who work for the two houses . and you normally would not do anything to someone unless you wanted to provoke them into a fight , which is exactly what 's about to happen . looking deeper , biting your thumb in the time in which the play was written is like giving someone the finger today . a pretty strong feeling comes with that , so we now are beginning to feel the tension in the scene . later on in the scene , tybalt , from the house of the capulets , lays a good one on benvolio from the house of the montagues . tybalt : `` what , art thou drawn among these heartless hinds ? turn thee , benvolio , and look upon thy death . '' benvolio : `` i do but keep the peace ; put up thy sword , or manage it to part these men with me . '' tybalt : `` what , drawn and talk of peace ! i hate the word , as i hate hell , all montagues , and thee . have at thee , coward ! '' okay , heartless hinds . we know that once again , it 's not a good thing . both families hate each other , and this is just adding fuel to the fire . but just how bad is this stinger ? a heartless hind is a coward , and calling someone that in front of his own men , and the rival family , means there 's going to be a fight . tybalt basically calls out benvolio , and in order to keep his honor , benvolio has to fight . this dialogue gives us a good look at the characterization between these two characters . tybalt thinks that the montagues are nothing but cowardly dogs , and has no respect for them . once again , adding dramatic tension to the scene . okay , now here 's a spoiler alert . tybalt 's hotheadedness and severe hatred of the montagues is what we literature people call his hamartia , or what causes his downfall . oh , yes . he goes down at the hands of romeo . so when you 're looking at shakespeare , stop and look at the words , because they really are trying to tell you something .
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want another example ? `` romeo and juliet '' has some of the best insults of any of shakespeare 's plays . it 's a play about two gangs , and the star-crossed lovers that take their own lives .
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in the scene from romeo and juliet , what is heightened by the use of insults ?
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carbon is a fantastically important element . there are probably , far more molecules that contain carbon , than any other element . the reason why you can get so many carbon compounds , is that carbon atoms , form chains very , very easily . sometimes millions of atoms long . if you just have atoms that will form one or two bonds then you ca n't build up huge numbers of molecules . if there 's no limit to the number of bonds you can make , you can make things that are really long . it 's like the difference between a lorry ; a truck which can pull if you 're lucky , one trailer or perhaps two and a train where you can put as many wagons or carriages as you want . so you can get really long train , so it 's just the same with carbon . so carbon it 's around us everywhere . we 're all carbon , there are lots of carbon in us , in all the hydrocarbons within our body . lots of that structures inside us and many many of the materials that we use every day . in fact the majority of us use carbon in the form of fuels every day to get to work or to go home . without carbon we could n't exist . you 're carbon , i 'm carbon , we have bones made that of calcium . but the important parts of our brains contain largely carbon . they contain nitrogen and oxygen and hydrogen as well , but carbon is the key . carbon is one of the very few elements ; that has given rise to a whole area of chemistry . organic chemistry ; the chemistry of carbon compounds , is almost a separate discipline from some of the areas of chemistry and most of the molecules that we use for plastics , for pharmaceutical products , for our food are all carbon compounds . carbon is an extremely common element but it comes in a number of different allotropes , so different forms and this one here ; this is actually some charcoal , which is just simple carbon . it 's very , very similar and very very in fresh into it to graphite . you can find lumps of carbon lying around . this is a piece here , that i found on a beach , on the northeast of england ; it 's a piece of coal . its not absolutely pure carbon , but it has a very high proportion of carbon and compared to other stones , of this sort of size , it 's really quite light more recently people have discovered diamonds , and of course graphite which is the black material that you get in pencils . people call them lead pencils but they actually contain the form of carbon called graphite so carbon comes graphite , as diamond , and also as as buckyballs or fullerenes so the carbon here which is a bit like the graphite ; it is very amorphous and it 's very very free-flowing so i 'm going to pour a little bit of carbon out onto the paper so you can see so you can see its a very light powder and you can see that it 's a very very nice , easily maneuverable and a really easy workable material . the thing that 's really exciting is that in the last 20 years people have discovered new forms of carbon ; now this is extraordinary ! people have known of carbon for thousands of years , even longer , and suddenly in the last 20 years the number of different types of carbon has grown enormously . i have a colleague who is a specialist in these new forms of carbon and i went and asked him for a model and he gave me a whole suitcase of models . let me show you . ... so , what did we get ? first of all , this is a model of graphite . the materials in the middle of pencils and it consists of layers of rings , hexagonal rings of carbon atoms . that six carbon atoms ; and they 're joined together in layers . can you see here ? there are purple bonds in between them . you can see they 're not very strong ; one is even broken here . very recently in the last 10 years its been discovered that using a piece of sellotape , you can pull off these layers ; and make single sheets of these carbon atoms . it 's called graphene . the 2-2010 nobel prize for physics , was given to two scientists for discovering graphene , there 's this structure here ; where each carbon atom is joined to 4 others , in this sort of tetrahedral pattern . tetrahedron is this group one in the middle with four rounded , and this–is diamond ; it 's really very strong . whichever way you squash it , it 's strong . you ca n't peel off layers of diamond with a piece of sellotape . diamonds are colorless ; and to understand why , you have to understand ; what gives rise to color , and the color of anything my tie , anything are caused by electrons in the molecules or material and they absorb energy and go from one level to another . in diamond , there are bonds between all the carbon atoms that use all the electrons . the electrons are very tightly bound and none of them can change their energy state , so you get no absorption . at least in the visible region of the spectrum . on the other hand with graphite , the electrons are less strongly bound . in fact it conducts electricity and it 's black because the electrons will absorb all wavelengths of visible light right from the blue to the red so that it looks black because none of the light is reflected from it . inside here we have the famous molecule , c60 like a football ( soccer ball us ) 60 carbon atoms and ray has put a little one inside here but forget that for a moment . so you can have this molecule c60 first discovered in the late 1980 's . and only isolated in the early 1990 's and there is a very similar molecule which looks a bit more squashed which is c70 . now these are also colored , but their color is rather different . have a look here . i 've got two samples one of c60 and one of c70 both of them dissolved up in the solvent toluene . so if you look here c70 is a sort of reddish brown color and c60 in the solvent has a beautiful color . i call it purple , other people call it magenta . back to the box ( suitcase ) ... and in here , we have the final form of carbon which are called nanotubes these are whole tubes ; made up of hexagons . you have two sorts one which is closed at the end and this one here which is open rather like a basket . you can put things inside it the final model is graphene this material that you can peel off graphite with a seller tape sticky tape and the reason that people get so excited is first of all this is a very thin material it 's only one atom thick and you can react the carbon atoms on here with all sorts of different molecules you can make very strong materials you can start making electronics carbon computers things like that many people believe that graphene is one of the materials of the future this is one of and raised exhibits he uses it in exhibitions to measure electrical conductivity to see if you take a piece of metal like this coin and you put the two electrodes on there you can see it conducts electricity all the lights light up and the needle goes across so he 's got different samples this one here is coal and this is graphite so there 's a track of this is a photo and this is a track of coal between two metal electrodes and you can see if we put the electrodes on here the coal does n't conduct electricity at all however if we take the graphite and do the same it conducts electricity not very well but you can see you do get some electricity going through on this other sheet he 's got a sample of c60 and here of the carbon nanotubes and you can see the c60 does n't conduct electricity either the electrons ca n't jump between one molecule and the other but when you come to the carbon nanotubes which are long molecules they conduct electricity really well not quite as well as a metal but pretty close
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carbon is one of the very few elements ; that has given rise to a whole area of chemistry . organic chemistry ; the chemistry of carbon compounds , is almost a separate discipline from some of the areas of chemistry and most of the molecules that we use for plastics , for pharmaceutical products , for our food are all carbon compounds . carbon is an extremely common element but it comes in a number of different allotropes , so different forms and this one here ; this is actually some charcoal , which is just simple carbon .
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what is the name of the discipline of chemistry that focuses on carbon compounds ?
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is teleportation possible ? could a baseball transform into something like a radio wave , travel through buildings , bounce around corners , and change back into a baseball ? oddly enough , thanks to quantum mechanics , the answer might actually be yes . sort of . here 's the trick . the baseball itself could n't be sent by radio , but all the information about it could . in quantum physics , atoms and electrons are interpreted as a collection of distinct properties , for example , position , momentum , and intrinsic spin . the values of these properties configure the particle , giving it a quantum state identity . if two electrons have the same quantum state , they 're identical . in a literal sense , our baseball is defined by a collective quantum state resulting from its many atoms . if this quantum state information could be read in boston and sent around the world , atoms for the same chemical elements could have this information imprinted on them in bangalore and be carefully directed to assemble , becoming the exact same baseball . there 's a wrinkle though . quantum states are n't so easy to measure . the uncertainty principle in quantum physics implies the position and momentum of a particle ca n't be measured at the same time . the simplest way to measure the exact position of an electron requires scattering a particle of light , a photon , from it , and collecting the light in a microscope . but that scattering changes the momentum of the electron in an unpredictable way . we lose all previous information about momentum . in a sense , quantum information is fragile . measuring the information changes it . so how can we transmit something we 're not permitted to fully read without destroying it ? the answer can be found in the strange phenomena of quantum entanglement . entanglement is an old mystery from the early days of quantum physics and it 's still not entirely understood . entangling the spin of two electrons results in an influence that transcends distance . measuring the spin of the first electron determines what spin will measure for the second , whether the two particles are a mile or a light year apart . somehow , information about the first electron 's quantum state , called a qubit of data , influences its partner without transmission across the intervening space . einstein and his colleagues called this strange communcation spooky action at a distance . while it does seem that entanglement between two particles helps transfer a qubit instantaneously across the space between them , there 's a catch . this interaction must begin locally . the two electrons must be entangled in close proximity before one of them is transported to a new site . by itself , quantum entanglement is n't teleportation . to complete the teleport , we need a digital message to help interpret the qubit at the receiving end . two bits of data created by measuring the first particle . these digital bits must be transmitted by a classical channel that 's limited by the speed of light , radio , microwaves , or perhaps fiberoptics . when we measure a particle for this digital message , we destroy its quantum information , which means the baseball must disappear from boston for it to teleport to bangalore . thanks to the uncertainty principle , teleportation transfers the information about the baseball between the two cities and never duplicates it . so in principle , we could teleport objects , even people , but at present , it seems unlikely we can measure the quantum states of the trillion trillion or more atoms in large objects and then recreate them elsewhere . the complexity of this task and the energy needed is astronomical . for now , we can reliably teleport single electrons and atoms , which may lead to super-secured data encryption for future quantum computers . the philosophical implications of quantum teleportation are subtle . a teleported object does n't exactly transport across space like tangible matter , nor does it exactly transmit across space , like intangible information . it seems to do a little of both . quantum physics gives us a strange new vision for all the matter in our universe as collections of fragile information . and quantum teleportation reveals new ways to influence this fragility . and remember , never say never . in a little over a century , mankind has advanced from an uncertain new understanding of the behavior of electrons at the atomic scale to reliably teleporting them across a room . what new technical mastery of such phenomena might we have in 1,000 , or even 10,000 years ? only time and space will tell .
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the two electrons must be entangled in close proximity before one of them is transported to a new site . by itself , quantum entanglement is n't teleportation . to complete the teleport , we need a digital message to help interpret the qubit at the receiving end .
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one of the postulates in albert einstein ’ s special theory of relativity asserts that nothing can move faster than the speed of light . does quantum teleportation violate this postulate ? why or why not ?
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all the material objects around you are composed of submicroscopic units we call molecules . and molecules in turn are composed of individual atoms . molecules frequently break apart and then form new molecules . on the other hand , virtually all the atoms you come in to contact with through the course of your life , the ones in the ground beneath you , the air you breath , the food you eat , those that make up every living thing , including you , have existed for billions of years and were created in places very unlike our planet . how those atoms came about is what i want to share with you . it all started 14 billion years ago with an event we call the big bang , which resulted in a universe consisting of gas alone . there were no stars and no planets . the gas was made up only of atoms belonging to the simplest elements . it was about 75 percent hydrogen and almost all the rest was helium . no elements like carbon , oxygen or nitrogen existed . no iron , silver or gold . in some places , the density of this gas was slightly higher than in others . due to gravity , those places attracted even more gas , which further strengthened the pull of gravity , which then drew more gas in , and so on . eventually , large dense gas balls formed , shrinking under their own gravity and consequently heating up on the inside . at some point , the core of such a ball gets hot enough that nuclear fusion occurs . hydrogen atoms smash together to form helium , accompanied by a great release of energy , strong enough to counteract the shrinking force of the gravity . when the energy pushing out from the fusion reactions matches the gravity pulling all the gas inwards , an equilibrium occurs . from this a star is born . over its lifetime , the fusion reactions in the core of a massive star will produce not only helium , but also carbon , oxygen , nitrogen and all the other elements in the periodic table up to iron . but eventually , the core 's fuel runs out , leaving it to collapse completely . that causes an unbelievably powerful explosion we call a supernova . now there are two things to note about how supernovas create elements . first , this explosion releases so much energy that fusion goes wild forming elements with atoms even heavier than iron like silver , gold and uranium . second , all the elements that had been accumulating in the core of the star , like carbon , oxygen , nitrogen , iron , as well as all of those formed in the supernova explosion , are ejected in to interstellar space where they mix with the gas that 's already there . history then repeats itself . gas clouds , now containing many elements besides the original hydrogen and helium , have higher density areas that attract more matter , and so on . as before , new stars result . our sun was born this way about 5 billion years ago . that means that the gas it arose from had itself been enriched with many elements from supernova explosions since the universe began . so that 's how the sun wound up with all the elements . it 's still mostly hydrogen at 71 percent , with most of the rest being helium at 27 percent . but bear in mind that while the first stars were made up of hydrogen and helium alone , the remaining elements in the periodic table make up two percent of the sun . and what about earth ? planets form as an incidental process to star formation out of the same gas cloud as the star itself . small planets like ours do n't have enough gravity to hold on to much hydrogen or helium gas since both of those are very light . so , even though carbon , nitrogen , oxygen and so on made up only two percent of the gas cloud from which earth was formed , these heavier elements form the bulk of our planet and everything on it . think about this : with the exception of hydrogen and some helium , the ground you walk on , the air you breath , you , everything is made of atoms that were created inside stars . when scientists first worked this out over the first half of the 20th century , the famous astronomer harlow shapley commented , `` we are brothers of the boulders , cousins of the clouds . ''
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as before , new stars result . our sun was born this way about 5 billion years ago . that means that the gas it arose from had itself been enriched with many elements from supernova explosions since the universe began .
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our sun was formed ________ .
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[ why do n't we eat bugs ? ] for centuries , people have consumed bugs , everything from beetles to caterpillars , locusts , grasshoppers , termites , and dragonflies . the practice even has a name : entomophagy . early hunter-gatherers probably learned from animals that foraged for protein-rich insects and followed suit . as we evolved and bugs became part of our dietary tradition , they fulfilled the role of both staple food and delicacy . in ancient greece , cicadas were considered luxury snacks . and even the romans found beetle larvae to be scrumptious . why have we lost our taste for bugs ? the reason for our rejection is historical , and the story probably begins around 10,000 bc in the fertile crescent , a place in the middle east that was a major birthplace of agriculture . back then , our once-nomadic ancestors began to settle in the crescent . and as they learned to farm crops and domesticate animals there , attitudes changed , rippling outwards towards europe and the rest of the western world . as farming took off , people might have spurned bugs as mere pests that destroyed their crops . populations grew , and the west became urbanized , weakening connections with our foraging past . people simply forgot their bug-rich history . today , for people not accustomed to entomophagy , bugs are just an irritant . they sting and bite and infest our food . we feel an `` ick factor '' associated with them and are disgusted by the prospect of cooking insects . almost 2,000 insect species are turned into food , forming a big part of everyday diets for two billion people around the world . countries in the tropics are the keenest consumers , because culturally , it 's acceptable . species in those regions are also large , diverse , and tend to congregate in groups or swarms that make them easy to harvest . take cambodia in southeast asia where huge tarantulas are gathered , fried , and sold in the marketplace . in southern africa , the juicy mopane worm is a dietary staple , simmered in a spicy sauce or eaten dried and salted . and in mexico , chopped jumiles are toasted with garlic , lemon , and salt . bugs can be eaten whole to make up a meal or ground into flour , powder , and paste to add to food . but it 's not all about taste . they 're also healthy . in fact , scientists say entomophagy could be a cost-effective solution for developing countries that are food insecure . insects can contain up to 80 % protein , the body 's vital building blocks , and are also high in energy-rich fat , fiber , and micronutrients like vitamins and minerals . did you know that most edible insects contain the same amount or even more mineral iron than beef , making them a huge , untapped resource when you consider that iron deficiency is currently the most common nutritional problem in the world ? the mealworm is another nutritious example . the yellow beetle larvae are native to america and easy to farm . they have a high vitamin content , loads of healthy minerals , and can contain up to 50 % protein , almost as much as in an equivalent amount of beef . to cook , simply sauté in butter and salt or roast and drizzle with chocolate for a crunchy snack . what you have to overcome in `` ick factor , '' you gain in nutrition and taste . indeed , bugs can be delicious . mealworms taste like roasted nuts . locusts are similar to shrimp . crickets , some people say , have an aroma of popcorn . farming insects for food also has less environmental impact than livestock farms do because insects emit far less greenhouse gas and use up less space , water , and food . socioeconomically , bug production could uplift people in developing countries since insect farms can be small scale , highly productive , and yet relatively inexpensive to keep . insects can also be turned into more sustainable food for livestock and can be reared on organic waste , like vegetable peelings , that might otherwise just end up rotting in landfills . feeling hungry yet ? faced with a plate of fried crickets , most people today would still recoil , imagining all those legs and feelers getting stuck between their teeth . but think of a lobster . it 's pretty much just a giant insect with legs and feelers galore that was once regarded as an inferior , repulsive food . now , lobster is a delicacy . can the same paradigm shift happen for bugs ? so , give it a try ! pop that insect into your mouth , and savor the crunch .
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what you have to overcome in `` ick factor , '' you gain in nutrition and taste . indeed , bugs can be delicious . mealworms taste like roasted nuts .
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when did our attitude towards eating bugs begin to change ?
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lanthanum is the first element in a series called the ‘ rare earths ’ . they are not terribly rare but never-the-less they are called rare earths and they all have rather similar names so there is quite an amusing little rhyme , mnemonic , that people learn to remember the names which at the first two letters of each word tell you this chemical symbol the elements so this goes ‘ language centres praise ned ’ s promise of small european garden tubs . dinosaurs hobble erotically thrumming yellow lutes ’ , which takes us from lanthanum all the way to lutetium . lanthanum is the largest of the lanthanides . it ’ s a prototype for the lanthanide series and because it is the largest it is the most reactive . it ’ s a strange metal in that you can actually cut it with a knife . so it ’ s not actually that hard . i haven ’ t worked much with lanthanum but one of my students or a russian visitor did some rather interesting experiments with making a compound of lanthanum and copper , so-called lanthanum cuprate , which is quite an interesting catalyst . lanthanum ’ s got quite a few technological uses . it ’ s used in , of all things , lighting in hollywood studios . lanthanum can also be used in hydrogen storage though obviously the hydrogen economy is becoming a very important issue with the energy crisis and so on and so forth ; and it ’ s , in certain circumstances , it ’ s very effective as what we called a hydrogen sponge so it can suck up all of the hydrogen and then hopefully you could use it as a fuel source . but because it ’ s quite heavy it might not be actually that useful in the end , but it ’ s good to know that it can do that .
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i haven ’ t worked much with lanthanum but one of my students or a russian visitor did some rather interesting experiments with making a compound of lanthanum and copper , so-called lanthanum cuprate , which is quite an interesting catalyst . lanthanum ’ s got quite a few technological uses . it ’ s used in , of all things , lighting in hollywood studios . lanthanum can also be used in hydrogen storage though obviously the hydrogen economy is becoming a very important issue with the energy crisis and so on and so forth ; and it ’ s , in certain circumstances , it ’ s very effective as what we called a hydrogen sponge so it can suck up all of the hydrogen and then hopefully you could use it as a fuel source .
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where did steve say we can find lanthanum in hollywood studios ?
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