Gravitational waves are disturbances in the curvature of
spacetime, generated by accelerated masses,
that propagate as waves outward from their source at the speed of
They were proposed by Henri Poincaré in 1905
and subsequently predicted in 1916 by Albert Einstein on the
basis of his general theory of relativity.
On 11 February 2016, the LIGO and Virgo Scientific Collaboration
they had made the first direct observation of gravitational waves.
The observation was made five months earlier, on 14 September
using the Advanced LIGO detectors. The gravitational waves
originated from a pair of merging black holes.