Researchers have spent 10 years improving the massive detectors they use to catch shockwaves from colliding black holes, and now the science is precise enough to test one of Stephen Hawking's key ideas.

Scientists say they've found evidence of a very long gravitational wave that could open a window onto supermassive black holes — and perhaps even other extreme, unseen objects in the universe.

Before scientists were even sure black holes existed, an Indian astrophysicist did the math behind Einstein's predictions of what would happen if two black holes collided.