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Whose Theory Predicted Gravitational Waves?

PhysicsAstronomy

Quick Answer

Albert Einstein predicted gravitational waves in 1916 as a consequence of his general theory of relativity — ripples in spacetime caused by accelerating massive objects, confirmed experimentally 100 years later by LIGO.

The Full Story

Einstein general theory of relativity (1915) describes gravity not as a force but as the curvature of spacetime caused by mass and energy. The field equations predict that accelerating massive objects — orbiting black holes, colliding neutron stars, supernovae — produce ripples in the fabric of spacetime that propagate outward at the speed of light: gravitational waves. Einstein himself doubted they could ever be detected because the effect is extraordinarily tiny. On 14 September 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected gravitational waves from two black holes merging 1.3 billion light-years away. The signal, lasting 0.2 seconds, caused a length change of about 10^-18 metres (one-thousandth the diameter of a proton) in LIGO 4-km detector arms. Rainer Weiss, Kip Thorne, and Barry Barish received the 2017 Nobel Prize in Physics for the detection.

Key Facts

1.LIGO first detection measured a spacetime distortion of about 10^-18 metres — one-thousandth the diameter of a proton — in its 4-km-long laser interferometer arms.
2.The two merging black holes detected in 2015 had masses of about 36 and 29 solar masses and produced a final black hole of 62 solar masses — the "missing" 3 solar masses were radiated away as gravitational wave energy.
3.The gravitational wave signal GW150914 released more power in 0.2 seconds than all the stars in the observable universe combined.

YouTube Angle

Suggested video title for this topic:

"Gravitational Waves — Einstein Prediction Confirmed After 100 Years"