黑洞(black hole)
一种天体，其引力极大，致使任何东西，甚至连光线也不能从中逸出。科学家们猜想它是在星体死亡并坍塌後形成的，开始时该星体的质量大约是太阳的十多倍。质量小些的星体演化为白矮星或中子星。黑洞结构的细节已根据爱因斯坦的广义相对论计算出来：零体积的「奇点」和无限大的密度将它周围由史瓦西半径所确定的视界之内的所有物质和能量都拉了进来。黑洞很小，而且不发射光，所以很难观察。然而，它们巨大的引力场影响着附近的物质，这些物质被拉入黑洞，而在视界外面以高速碰撞时会发射X射线。某些黑洞可能起源於非星体。许多天文学家都推测，在类星体和许多星系中心的超大质量黑洞是观察到的能量活动之源。霍金提出了大量小型黑洞的创生理论，在大爆炸之际，这些黑洞的质量可能比不上一个小行星大。这些原发性的「微型黑洞」会随时间推移而损失质量，最後消失，也就是霍金辐射的结果。从技术上看，黑洞还只是理论性的，但已经观察到符合理论所预期行为的一些现象。
English version：
black hole
Cosmic body with gravity (see gravitation) so intense that nothing, not even light, can escape. It is suspected to form in the death and collapse of a star that began with more than 10 times the sun's mass. Stars with less mass evolve into white dwarf stars or neutron stars. Details of a black hole's structure are calculated from Albert Einstein's general theory of relativity: a “singularity” of zero volume and infinite density pulls in all matter and energy that comes within an event horizon, defined by the Schwarzschild radius, around it. Black holes are hard to observe because they are small and emit no light. However, their enormous gravitational fields affect nearby matter, which is drawn in and emits X rays as it collides at high speed outside the event horizon. Some black holes may have nonstellar origins. Astronomers speculate that supermassive black holes at the centers of quasars and many galaxies are the source of energetic activity that is observed. Stephen W. Hawking has theorized the creation of numerous tiny black holes, possibly no more massive than an asteroid, during the big bang. These primordial “mini-black holes” lose mass over time and disappear as a result of Hawking radiation. Technically, black holes are still theoretical, but phenomena have been observed that match their predicted behavior.