Gravitational-wave astronomy

Gravitational-wave astronomy is an emerging branch of observational astronomy which aims to use gravitational waves (minute distortions of spacetime predicted by Einstein's theory of general relativity) to collect observational data about objects such as neutron stars and black holes, events such as supernovae, and processes including those of the early universe shortly after the Big Bang.

Gravitational waves have a solid theoretical basis, founded upon the theory of relativity. They were first predicted by Einstein in 1916; although a specific consequence of general relativity, they are a common feature of all theories of gravity that obey special relativity. Indirect observational evidence for their existence first came in 1974 from measurements of the Hulse–Taylor binary pulsar, whose orbit evolves exactly as would be expected for gravitational wave emission.Richard Hulse and Joseph Taylor were awarded the 1993 Nobel Prize in Physics for this discovery. Subsequently, many other binary pulsars (including one double pulsar system) have been observed, all fitting gravitational-wave predictions.

On 11 February 2016 it was announced that LIGO had directly observed the first gravitational waves in September 2015. The second observation of gravitational waves was made on 26 December 2015 and announced on 15 June 2016.

Ordinary gravitational waves frequencies are very low and much harder to detect, while higher frequencies occur in more dramatic events and thus have become the first to be observed.

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