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Gravitational wave Created 2026-09-24 Updated 2026-10-18
A gravitational wave is a propagating disturbance of spacetime curvature produced by changing mass-energy multipole moments. In general relativity, its two transverse gravitational wave polarizations alternately stretch and squeeze freely falling separations. The leading radiation from a slowly moving source is governed by its mass quadrupole moment, rather than by its total mass alone.
The experimental breakthrough was GW150914: observed on 14 September 2015 and published on 11 February 2016. The LIGO Scientific Collaboration and Virgo Collaboration reported a merging pair of black holes, using the two LIGO detectors at Hanford and Livingston; Virgo was being upgraded and did not observe this event.[ref]
Observation of Gravitational Waves from a Binary Black Hole Merger by B. P. Abbott and others. Abstract; II Observation, pp. 1–3; received and publication dates on p. 1
The 2017 Nobel Prize in Physics recognized Rainer Weiss, Barry C. Barish and Kip S. Thorne for contributions to LIGO and gravitational wave observation. Rainer Weiss developed interferometric detection and its noise analysis; Barry C. Barish led the project into construction and operation; Kip S. Thorne developed its theoretical and astrophysical foundations. The experiment depended on a large collaboration.[ref]
Press release: The Nobel Prize in Physics 2017 by Royal Swedish Academy of Sciences. 3 October 2017 announcement, laureates and account of their complementary contributions
GW150914 2026-10-18
GW150914 is the first directly detected gravitational wave, interpreted as a binary black hole inspiral, merger and ringdown. Its discovery paper reports a peak projected gravitational wave strain of approximately and a combined matched filter signal-to-noise ratio of 24. The inferred source-frame component masses were and solar masses, with 90 percent credible intervals. These are model-dependent estimates from a detector network.[ref]
Observation of Gravitational Waves from a Binary Black Hole Merger by B. P. Abbott and others. Abstract; II Observation; VI Source discussion, Table I
The interesting measurement is a chain: curvature changes relative light travel times, wave interference turns those changes into a photodetector signal, calibrated records from separate sites constrain a common source, and statistical inference tests competing explanations. The following original models explain that chain; the plotted time series are stipulated calculations, never measured GW150914 data.