英語聽力文摘467 星星的遺跡
黑洞是一種引力極強的天體，就連光也不能逃脫。當恒星的史瓦西半徑小到一定程度時，就連垂直表面發(fā)射的光都無法逃逸了。這時恒星就變成了黑洞。說它“黑”，是指它就像宇宙中的無底洞，任何物質一旦掉進去，“似乎”就再不能逃出。由于黑洞中的光無法逃逸，所以我們無法直接觀測到黑洞。然而，可以通過測量它對周圍天體的作用和影響來間接觀測或推測到它的存在。黑洞引申義為無法擺脫的境遇。
The Remains of a Star
星星的遺跡
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。
他們真的知道嗎?大家都只是通過科幻小說知道黑洞的。但是黑洞到底是怎么來的呢?
黑洞是由恒星形成的。當一顆大的恒星燃料耗盡黑洞就產生了。由于地心引力的作用，組成恒星的所有物質被壓縮到核心位置。
但是，只要恒星的核心有足夠的核燃料一直燃燒，就會往外推。只有等燃料耗盡，所有物質才會向中心坍塌。
如果這顆恒星足夠大，地心引力會不斷擠壓直到所有物質被壓縮成一個密實的星體。
得明白這一點：這個小星體的引力非常大，任何靠近它的物質都會被吸進去，永遠也出不來。甚至連光都不能逃脫。一束經過的光線也會被吸入。
