核聚变是太阳和恒星的能量来源。

Fusion is the energy source of the sun and the stars.

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在我们的星系中，超过10亿颗恒星已经耗尽了它们的内部能量来源，因此无法再产生恒星所需的热量来对抗向内的引力。

Upwards of a billion stars in our galaxy have burnt up their internal energy sources, and so can no longer produce the heat a star needs to oppose the inward force of gravity.

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戴森提出这样的文明将能够使用卫星群围封住一颗恒星从而获取它的能量。

Dyson proposed that such a civilization would be capable of encapsulating a star with a swarm of satellites to harvest its energy.

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And even in astrophysics, when you talk about stars, black holes, etcetera you're moving energy around.

即使在天文学中，当你谈论恒星，黑洞等时,你能量的转移。

麻省理工公开课 - 热力学与动力学课程节选