Gravitational wave

Gravitational waves are waves of spacetime curvature produced by the relative motion of gravitating masses and which propagate away at the speed of light. They were first predicted by Albert Einstein as a consequence of his general theory of relativity, appearing as "ripples in spacetime curvature".

Hundreds of these gravitational waves have since then been observed, first indirectly using binary-pulsar observations and, since 2015, directly through dedicated observatories.

Gravitational waves transport energy as gravitational radiation, a form of radiant energy similar to electromagnetic radiation. Newton's law of universal gravitation, part of classical mechanics, does not provide for their existence, instead asserting that gravity has instantaneous effect everywhere. Gravitational waves therefore stand as an important relativistic phenomenon that is absent from Newtonian physics.

Gravitational-wave astronomy has the advantage that, unlike electromagnetic radiation, gravitational waves are not affected by intervening matter. Sources that can be studied this way include binary star systems composed of white dwarfs, neutron stars, and black holes; events such as supernovae; and the formation of the early universe shortly after the Big Bang.

The first indirect evidence for the existence of gravitational waves came in 1974 from the observed orbital decay of the Hulse–Taylor binary pulsar, which matched the decay predicted by general relativity for energy lost to gravitational radiation. In 1993, Russell Alan Hulse and Joseph Hooton Taylor Jr.