A century-old prediction confirmed: gravitational waves
LIGO directly detected ripples in spacetime from two colliding black holes — exactly as Einstein predicted in 1916.
On 11 February 2016 the LIGO collaboration announced the first direct detection of gravitational waves, recorded on 14 September 2015. The signal came from two black holes spiralling together 1.3 billion light-years away — and matched general relativity beautifully.
Einstein had predicted these waves in 1916 but doubted they would ever be measured, since they stretch space by less than the width of a proton. Their detection, a century later, opened a brand-new way of observing the universe and earned the 2017 Nobel Prize in Physics.