What Are Intermediate-Mass Black Holes?
Black holes have long served as fodder for science fiction and for good reason. These unimaginably dense objects contain so much matter trapped in such a small volume that their gravity is strong enough to prevent even light from escaping their surfaces.Although the first prediction of a black hole was made nearly 250 years ago by the English philosopher and clergyman John Michell, the first black hole candidate, Cygnus X-1, wasn't discovered until 1971.