Time was, using the rules of general relativity, you could imagine a fairly simple black hole consisting of an infinitely-dense singularity surrounded by a gravitational zone of no-escape called the “event horizon”. Even the speed of light was no match for the event horizon, hence the "black" in black hole. Whatever goes in, never comes out.
This rather simple description was a fairly decent description of what was going on inside a black hole. But in the 1970′s, the inconsistencies began to trouble the likes of British theoretical physics scientist Stephen Hawking who theorized evaporating black holes, which went a long ways to clearing up some of the more troubling inconsistencies.
Now, as an extension to his original theory, Hawking thinks that black holes aren’t the one-way street the textbooks have led us to believe.