英语听力文摘467 星星的遗迹
黑洞是一种引力极强的天体，就连光也不能逃脱。当恒星的史瓦西半径小到一定程度时，就连垂直表面发射的光都无法逃逸了。这时恒星就变成了黑洞。说它“黑”，是指它就像宇宙中的无底洞，任何物质一旦掉进去，“似乎”就再不能逃出。由于黑洞中的光无法逃逸，所以我们无法直接观测到黑洞。然而，可以通过测量它对周围天体的作用和影响来间接观测或推测到它的存在。黑洞引申义为无法摆脱的境遇。
The Remains of a Star
星星的遗迹
What is a black hole,anyway? Oh,come on,everyone knows what a black hole is.
Do they? Everybody thinks they know because of science fiction.But where do they really come from?
They come from stars. A black hole is what you get when a really big star uses up all its fuel. Gravity is always trying to push all the stuff that makes up a star into its center.
But as long as the star has enough nuclear fuel in its core to keep burning, it pushes back. It’s only when it runs out of fuel that everything gets crushed down into the middle of the star.
If the star is big enough, gravity just keeps squeezing and squeezing until everything that made up the star is compressed into a tiny point.
And get this — the gravitational attraction of that tiny point will be so strong anything that comes too close will be sucked in, never to return! Not even light can escape. Even a passing beam of light will be pulled right in.
黑洞是什么?拜托，大家都知道黑洞。
他们真的知道吗?大家都只是通过科幻小说知道黑洞的。但是黑洞到底是怎么来的呢?
黑洞是由恒星形成的。当一颗大的恒星燃料耗尽黑洞就产生了。由于地心引力的作用，组成恒星的所有物质被压缩到核心位置。
但是，只要恒星的核心有足够的核燃料一直燃烧，就会往外推。只有等燃料耗尽，所有物质才会向中心坍塌。
如果这颗恒星足够大，地心引力会不断挤压直到所有物质被压缩成一个密实的星体。
得明白这一点：这个小星体的引力非常大，任何靠近它的物质都会被吸进去，永远也出不来。甚至连光都不能逃脱。一束经过的光线也会被吸入。
