Gravity

A satellite spotted a burst of light just as gravitational waves rolled in from the collision of two black holes. Was the flash a cosmic coincidence, or do astrophysicists need to rethink what black holes can do?

The path from a revolutionary set of equations to the detection of gravitational waves was strewn with obstacles and controversy, explains the physicist Daniel Kennefick — and the struggle continues.

Ripples in space-time have been detected a century after Einstein predicted them, launching a new era in astronomy.