How Did Our View of the Universe Change?발음듣기
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How Did Our View of the Universe Change?
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인도네시아어 번역 1명 참여
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Some say perhaps a multicolored serpent was traveling through the land and as it did so, it created the mountains and the rivers and the streams and maybe even the stars and maybe even you and me.발음듣기
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Some say there was a sort of committee of gods that created the world or perhaps the one true God created the world.발음듣기
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They change. They change over time because new information comes in, new evidence, and the explanations have to change.발음듣기
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Now, what we're going to look at in this unit is how the modern, scientific answer to that great question emerged.발음듣기
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We'll begin by going back 500 years to Europe and this is because modern science first flourished in Europe.발음듣기
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And the Christian church, like most religions, had its own answers to that question, "How did everything begin?"발음듣기
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And the Christian church's answer was that God created the Universe several thousand years ago,발음듣기
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but they tied that answer to a great model of the Universe that had been constructed about 1,900 years ago by an astronomer called Ptolemy, who lived in Alexandria in Egypt.발음듣기
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And that realm consisted of several concentric transparent spheres and those spheres carried the Sun, the Moon, the stars,발음듣기
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People accepted it not just because the Church said they should, but also because there was a lot of evidence for it.발음듣기
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And this was because astronomers in his time - or astronomers in the 16th century, I should say, and in Ptolemy's time - were studying the Earth using the naked eye.발음듣기
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If you were studying the Universe using just the naked eye, just looking directly at the skies,발음듣기
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you might be very tempted to think that the Universe revolves around the Earth, mightn't you?발음듣기
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Between 1550 and 1700, new evidence began to kick in, some of it supplied by new technologies.발음듣기
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Some astronomers, for example, pointed out that every year, the planets, as they orbit the Earth, seem to move backwards for a period.발음듣기
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The astronomer Copernicus in the 16th century pointed out that if you imagine that it's actually the Sun that's at the center of the Universe instead of the Earth, you could solve that problem quite easily.발음듣기
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Then another astronomer, Kepler, found that the orbits of the planets are actually not perfect circles as Ptolemy had imagined.발음듣기
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Third, an Italian astronomer called Galileo began to use what was the hot new technology of the time, the telescope.발음듣기
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And he was one of the first astronomers to actually look at the heavens through the telescope.발음듣기
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And if you look at Jupiter, you find it's not a single planet, it's got little moons, lots of moons orbiting it.발음듣기
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And notice how new technologies, new evidence and logic have begun to undermine a traditional explanation of how the Universe works.발음듣기
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Late in the 17th century, the great English scientist Isaac Newton began to argue that it wasn't concentric spheres that held together all the bodies of the Universe.발음듣기
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It was actually a mysterious force that pervaded the entire Universe that was called gravity and it pulled everything together.발음듣기
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They now came to believe there were no edges to the Universe, there were no spheres or perhaps, the entire Universe was infinite in size and infinitely old and just held together by this force of gravity.발음듣기
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This is, in fact, the first model of the Universe that was scientific in the sense that it was based primarily on evidence.발음듣기
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Notice how scientists in different parts of the world communicate with each other, share their information, share their evidence to construct a new story.발음듣기
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Most astronomers accepted it until in the 19th century problems began to emerge as new forms of evidence appeared and new technologies.발음듣기
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Now, I'm going to describe this new evidence and how it undermined Ptolemy's Universe very briefly.발음듣기
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So let's go. What 19th century astronomers were really interested in was trying to map the Universe.발음듣기
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It's not easy at all. But in fact, the Greeks, who were really good at thinking about the Universe logically and rationally had already figured out how you do it.발음듣기
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Let me try and explain. Now, take your finger, put it right in front of your nose, and now, hold the finger steady and waggle your head and notice that the finger moves against the background.발음듣기
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Okay? Now, move the finger away, do the same thing and what you'll notice is the finger seems to move far less against the background.발음듣기
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By figuring out how much it moves, you ought to be able to calculate how far away it is using trigonometry, which is the math all surveyors use.발음듣기
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The Greeks simply didn't have the technology to make precise enough measurements and the movements of stars, even the very nearest, are absolutely tiny.발음듣기
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So it was not until the 19th century when new, better telescopes emerged that we were able to make the first parallax measurements and the first measurements of the distance to nearby stars.발음듣기
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And what she found out is that from the way they vary you can tell exactly how bright they really are.발음듣기
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Now, if you know how bright they really are, you can figure out how far away they are because you can figure out how much light has been lost in between.발음듣기
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Now, astronomers also began to figure out ways of measuring whether stars are moving away from us or towards us.발음듣기
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Now, astronomers figured out that the same thing happens with the light from distant stars or galaxies.발음듣기
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So astronomers say it's "redshifted." Now, if you find a distant galaxy is redshifted, that means it's moving away from us.발음듣기
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In the 1920s, an American astronomer, Edwin Hubble, used the Mount Wilson Telescope in L.A. to make an astonishing discovery.발음듣기
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What he did was he used all the information we've just been describing and what he found was first, that most galaxies seem to be moving away from the Earth.발음듣기
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What could that possibly mean? Well, it seemed to mean first that Newton's model of the Universe simply doesn't work.발음듣기
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Instead, it's expanding. Now, for most astronomers, that was a quite remarkable and unexpected conclusion because if it's expanding now, think about the past.발음듣기
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That's what the Belgian astronomer Lemaitre called the "primordial atom" from which everything came.발음듣기
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And what it meant was that the Universe, like you and me, has a history of change over time.발음듣기
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