Upgrades to the hardware and software of the advanced observatory should allow astrophysicists to detect much fainter gravitational waves than before.

The theory of gravity may need to be altered.

Gravity is something every person on Earth intuitively understands: It is what keeps you on the ground. But how come gravity pulls down, rather than pushes up? Einstein came up with the answer.

Roger Penrose helped resurrect Einstein's general theory of relativity, and Reinhard Genzel and Andrea Ghez showed there was a black hole in the middle of our galaxy.