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  • Near a black hole space and time do some very strange things because the black holes are probably the most

  • violent places we know of in the universe. This river provides a beautiful analogy of what happens

  • to space and time as you get closer and closer to the black hole.

  • Now upstream the water is flowing pretty slowly.

  • Let's imagine that it is flowing at three kilometers per hour

  • and I can swim at 4, so I can swim faster than the flow and can easily escape

  • But as you go further, further down the stream towards

  • the waterfall in the distance, the river flows faster and faster.

  • Imagine that I decided to jump in the river just there at the edge of the falls

  • The water is flowing far faster than I could swim.

  • So, no matter what I did, no matter how hard I tried

  • I would not be able to swim back upstream

  • I would be carried inextricably towards the edge and I would vanish over the falls

  • Well, it's the same close to the black hole,

  • because the space flows faster, faster and faster

  • towards the black hole.

  • Literally, this stuff, my space that I am in, flowing over the edge into the black hole.

  • And then, at a very special point, called the event horizon, the space is flowing

  • at the speed of light into the black hole.

  • Light itself, travelling at 300.000km per second is not going fast enough to escape the flow

  • and light itself will plunge into the black hole.

  • Well, as you fall into the black hole, across the event horizon, then if you were going feet first, your feet will be

  • accelerating faster than your head, so you'll be stretched

  • and you'll be quite literally spaghettified.

  • Now as you get right into the center,

  • Then our understanding of the laws of physics breaks down.

  • Our best theory of space and time, Einstein's theory of general relativity

  • says that space and time become infinitely curved, that

  • the center of the hole becomes infinitely dense

  • That place is called the singularity and it is the place

  • where our understanding of the Universe stops.

Near a black hole space and time do some very strange things because the black holes are probably the most


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B1 中級

ブラックホール - 宇宙の不思議。落下 - BBC 2 (Black Holes - Wonders of the Universe: Falling - BBC Two)

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    VoiceTube に公開 2021 年 01 月 14 日