The story behind your glasses - Eva Timothy

131,597 views ・ 2012-10-08

TED-Ed


Please double-click on the English subtitles below to play the video.

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Transcriber: tom carter Reviewer: Bedirhan Cinar
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Optics, or the enhancement of our natural vision,
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has been one of the biggest catalysts for science over the past 500 years,
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Interestingly, it wasn't scientific interest, but more practical matters that led to the initial advancements in optics,
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starting around 1440 when Johannes Gutenberg invented his printing press.
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In short order, books, which had been a rarity,
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were now becoming a widespread phenomenon.
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All that new reading material meant more knowledge was circulating,
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but it also meant that more people were straining their eyes,
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likely as they read by candlelight.
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And while spectacles had been invented in Italy around 1286,
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the need for reading glasses increased substantially.
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Now that people could use lenses to see things more clearly,
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they started wondering if vision could be enhanced to see things the human eye couldn't perceive by its own devices.
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Robert Hooke pursued microscopy, and 1665 he published his findings of worlds inside worlds,
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which he called "cells" in the book "Micrographia."
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At the other end of the spectrum,
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Galileo innovated with telescopic lenses,
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and in 1609, he had refined a telescope until he had an instrument powerful enough to see distant objects in the sky
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with an accuracy no one had before him.
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He found that the moon had craters and mountains,
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that Jupiter had moons of its own, and the whole system governing the earth and space was brought into question.
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Not everyone was thrilled with all the things Galileo saw though.
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For instance, it was taught at the time that the moon was a perfectly smooth sphere.
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Yet here was visual proof that was awfully hard to discount.
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Upon finding moons around Jupiter, he also verified what Johannes Kepler had surmised:
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that the earth was not the center of the universe,
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dispelling another central dogma of Galileo's day.
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Then almost exactly a year after Galileo died,
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Isaac Newton was born.
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A lot that had been unknown was visible by now,
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but much of it was simply the foundation for further questions.
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What was light anyway? And color, for that matter?
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What were the laws that governed the earth, and the heavens?
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And could we capture them through keen observation?
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Newton experimented extensively with optics,
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and came to understand light as something of substance,
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and colors as components of light at different frequencies.
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Before Newton, people widely believed that the color was due to different amounts of light,
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with red being lots of light, and blue being mostly dark.
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Newton's prism experiments showed that white light could not only be broken into its component colors with one prism,
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but that a second lens could recompose those colors back into white light again,
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thus showing that color was a matter of light's refraction rather than how light or dark it was.
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Newton's studies of optics led to the development of the reflecting telescope.
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This, together with his study of planetary motion, led to his theory of gravitation,
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one of the world's greatest examples of learning to see something invisible
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by observing its effect on things that are visible.
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So fast forward a few hundred years, and here we stand.
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We've evolved from a single lens to optics that reveal the birth of a star in another galaxy,
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or a child developing in the womb,
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or an electron whirling around an atom.
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At a time when so much is visible, how we see the world around us matters even more than what we see.
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Will we see a world where everything important has already been discovered?
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Or will we see one in which yesterday's discoveries are but a doorway to the breakthroughs of tomorrow?
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