Abolhassan Mohammadi

A stone falls into a well, and a second later, a splash. A star falls into a black hole, and disappears beyond the horizon, leaving only a ripple in space. But what if the bottom of the well is not a dead end but a passage? In the usual picture, matter compresses into a point of infinite density — a singularity.

Gravitational waves from a tiny body falling into a black hole work like an X-ray image. Only instead of a bone, they illuminate the curved spacetime itself.