Watch videos with subtitles in your language, upload your videos, create your own subtitles! Click here to learn more on "how to Dotsub"

Adam Savage räägib ideedest ja teadusest

0 (0 Likes / 0 Dislikes)
TED Education One of the funny things about owning a brain is that you have no control over the things that it gathers and holds onto, the facts and the stories. And as you get older, it only gets worse. Things stick around for years sometimes before you understand why you're interested in them, befor you understand their imoprt to you. Here's tree of mine. When Richard Feynman was a young boy in Queens, he went for a walk with his dad and his wagon and a ball. And he noticed that when he pulled the wagon, the ball went to the back of the wagon. And hi asked his dad, "Why does the ball go back of the wagon." And his dad said. "That's inertia." He said, "What's inertia?" And his dad said "Ah, Inertia is the name that scientist give to the phenomenon of the ball going to the back of the wagon. But in truth, nobody really knows." Feynman went on to earn degrees at MIT, Princeton, he solved the Challenger disaster, he ended up winning Nobel Prize in Physics for his Feynman diagrams describing the movement of subatomic particles. And he credits that convesation with his father as giving him a sense that the simplest questions could carry you out to the edge of human knowledge, and that that's where he wanted to play. And play hi did. Now Eratosthenes was the third librarian at the great Library at Alexandria, and he made many contributions to science. But the one he is most rememberd for began in a letter that he recived as the librarian, from the town of Swenet, wich was south of Alexandria. The letter included this fact that struck in Eratosthenes' mind, and the fact was that the writer said at noon on the solstice, when he looked down this deep well, he could see his reflection at the bottom, and he could also see that his head was blocking the sun. Now, I should tell you -- the idea, that Christopher Columbus discoverd that the world is spherical is total bull. It's not true at all. In fact, everyone who was educated understood that the word was spherical since Aristotle's time, and Aristotle had proved it with a simple observation. He noticed that every time you saw the Earth's shadow on the Moon it was circular, and the only shape that constantly creates a circular shadow is a sphere, Q.E.D. the Earth is round. but nobody knew, how big it was until Eratosthenes got this letter with this fact. So he undersood that sun was directly above the city of Swenet, because looking down a well, it was a staight line all the way down the well, riht past the guy's head up to the sun. Eratosthenes knew another fact. He knew that a stick stuck in the ground in Alexandria at the same time and same day, at noon, the sun's zenith, on the solstice, the sun cast a shadow that showed that it was 7.2 degrees off-axis. Now. if you know the cirumference of a circle, and you have two points on it, all you need to know is the distance between those two points, and you can extrapolate the circumference. Three hundred and sixty degrees divided by 7.2 equals 50. I know it's a little bit of a round number, and it makes me suspicious of the story too, but it's a good story, so we'll continue with it. He needed to know the distance between Swenet and Alexandria, wich is good because Eratosthenes was good in geography in fact, he invented the word geography. The raod between Swenet and Alexandria was the raod of commerce, and commerce needed to know how long it took to get there. It needed to know the exaxt distance, so he knew very precisely that the distance between the two cities was 500 miles. Multiply that times 50, you get 25,000 witch is within one percent of the actual diameter of the Earth. He did this 2,200 years ago. Now, we live in an age where multi-billion-dollar pieces of machinery are looking for Higgs boson. We're discovering particles that may travel faster than the speed of light, and all of these discoveries are made possible by technology that's been developed in the last few decades. But for most of human history, we had to discover these things using our eyes and our ears and our minds. Armand Fizeau was an experimental physicist in Paris. His speciality was actually refining and confirming other people's results, and this might sound like a bit of an also-ran, but in fact this is the soul of science, because there is no such thing as a fact that cannot be independently corroborated. And he was familiar with Galileo's experiments in trying to determine whether or not light had a speed. So, Galileo had worked out this really wonderful experiment where hi and his assistant had a lamp, each one of them was holding a lamp. And Galileo would open his lamp, and his assistant would open his lamp. And they got the timing down really good. They just knew their timing. And then they stood at two hilltops, two miles distant, and they did the same thing, on the assumption from Galileo that if light had a discernable speed, he'd notice a delay in the light coming back from assistant's lamp. But light was too fast for Galileo. He was off by sevaral orders of magnitude when he assumed that light was roughly 10 times as fast as speed of sound. Fizeau was aware of this experiment. He lived in Paris. And he set up two experimental stations, roughly five and a half miles distant, in Paris. And he solved this problem of Galileo's. and he did it with a really relatively trivial piece of equipment. He did it with one of these. I'm going to put away the clicker for a second because I want to engage your brains in this. This is a toothed wheel. It's got a bunch of notches and it's got a bunch of teeth. This was Fizeau's solution to sending discrete pulses of light. He put a beam behind one of these notches. If I point a beam through this notch at a mirror, five miles away, that beam is bouncing off the mirror and coming back to me through this notch. But something interesting happens as he spins the wheel faster. He notices that it seems like a door is starting to close on the light beam that's coming back to his eye. Why is that? It's because the pulse of light, it's not coming back to the same notch. It's actually hitting a tooth. And he spins the wheel fast enough and he fully occludes the light. And then, based on the distance between the two stations and the speed of his wheel and the nuber of notches in the wheel, he calculates the speed of light to within two percent of its actual value. And he does this in 1849. This is what really gets me going about science. Whenever I'm having trouble understanding a concept, I go back and I research the people that discoverd that concept. I look at the story of how they came to understand it. And what happens when you look at what the discoverers were thinking about when they made their discoveries, is you understand that they are not so different from us. We are all bags of meat and water. We all start with the same tools. I love the idea that different branches of science are called fields of study. Most people think of science as a closed, black box, when in fact it is an open field. And we are all explorers. The people that made these discoveries just thought a little bit harder about what they were looking at, and they were a little bit more curious. And their curiosity changed the way people thought about the world. and thus it changed the world. They changed the world, and so can you. Thank you.

Video Details

Duration: 7 minutes and 31 seconds
Year: 2012
Country: United States
Language: English
Genre: None
Views: 283
Posted by: jnpvr on Mar 15, 2012

Adam Savage räägib sellest, miks on tore omada aju ja kanda sellega aastaid kaasas mõnd tähendusrikast ideed. Kolm toredat näidet.

Caption and Translate

    Sign In/Register for Dotsub to translate this video.