天文学家的理论是，当一个巨大的物体在其自身的引力作用下灾难性地收缩，只留下一个强大的引力场，且没有任何东西能逃脱时，黑洞就形成了。

Astronomers theorize that a black hole forms when a massive object shrinks catastrophically under its own gravity, leaving only a gravitational field so strong that nothing escapes it.

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大量尘埃积聚的区域里，彼此间引力作用导致星云快速的塌陷。

Large collections of dust are corralled together where the mutual gravity of the cloud causes it to rapidly collapse.

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就是说，有较弱的引力作用。

That is, there'd be a weak attraction.

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Everything -- gold, silver, diamonds, particles -- everything accelerates the same way in a gravitational field, due to this remarkable fact.

所有东西,金,银,钻石,粒子,所有东西,在引力场作用下都以相同的方式加速,原因就是这个显著的事实

耶鲁公开课 - 基础物理课程节选

If nothing is touching the body, there are no forces on it, with one exception which is, of course, gravity.

如果没有实体接触,那么它就不受作用力,当然一个例外那就是引力

耶鲁公开课 - 基础物理课程节选

Gravity is one force that acts on a body without the source of the force actually touching it.

引力是一种受力物体收到了力的作用,但却没有接触施力物体的力

耶鲁公开课 - 基础物理课程节选