And yet, despite their apparent impossibility, they exist. But what if these gravitational monsters aren't black holes at all, but rather the cosmic equivalent of fuzzy, vibrating balls of string?
New research suggests that may be the case, and that with upcoming observations we may actually be able to see them.
Black holes appear in Einstein's theory of general relativity, and by all rights they simply shouldn't exist. In that theory, if a clump of matter crunches down into a tiny enough volume, then gravity can become overwhelmingly strong. This insane gravitational compression can out-compete any of the other four fundamental forces of nature — like the strong nuclear force that holds that clump of matter together. Once a certain critical threshold is reached, the clump of matter just squeezes and squeezes, compressing down into an infinitely tiny point.