Content about “

gravity

”

You're unlikely to ever run into a black hole, but here's what it "looks" and "sounds" like when two black holes run into each other. The movie shows a simulation of the gravitational waves generated when two black holes collide and form a third, and the sound file shows what these waves would sound like if you cold hear them.

String theory is a theory of everything in which everything's made of strings — but why strings? What do they do? Find out in our equation-free introduction for beginners.