Black Holes

摘要

Nothing is stranger than a black hole. The darkened corpse of a former sun from which not even light can escape, a black hole forms when a massive, dying star crumples under its own gravity. It shrinks until all of its mass is contained in an infinitely dense point, called a singularity. Its gravity is so intense, if anything ventures within an invisible border around the singularity, called the event horizon, it cannot escape.