Scientists have detected the collision of two massive black holes merging beyond the Milky Way. The two black holes, each with a mass more than 100 times that of the sun, had been circling each other for a while before finally colliding to form an even bigger black hole about 10 billion light years from Earth.

The event is the most massive black hole merger ever recorded by gravitational wave detectors and has forced physicists to rethink their models of how the enormous objects form. The signal was recorded when it hit detectors on Earth sensitive enough to detect shudders in space-time thousands of times smaller than the width of a proton.