Gravity wave discovery sends shockwaves through physics

The world of physics is reeling from the aftershocks of the announcement of the discovery of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US. The observatory has confirmed that on 14 September last year it detected a signal caused by two black holes colliding and coalescing, squeezing and stretching the fabric of space-time.

Gravitational waves were predicted by Albert Einstein in his theory of relativity in 1915, and were the last of the theory’s predictions to be proved true. Einstein said that all massive bodies distort space-time (famously, like a heavy ball denting a rubber sheet), and that those distortions give rise to the phenomenon we experience as gravity. Events involving very large masses – such as colliding black holes – should ripple space-time, he said. The problem is that gravity is such a feeble force on the scale of the universe that such ripples would be tiny and difficult to detect against the ‘noise’ of all the other signals in the universe.