If the collapsed star is greater than about three times the solar mass, then
nothing that we know of in nature can withstand the force of its gravity, and
it crumples inexorably into a black hole. It's a mysterious place
where gravity has become so powerful that the velocity that an object would need to
escape its grip is greater than the 670,000,000-mile-per-hour speed of light,
which means that not even light can escape. Hence its simple but deeply
evocative name, black hole.