Title: Discovery Of Gravitational Waves
Course: Relativity > Section: Module 23: Discovery Of Gravitational Waves

Discovery of Gravitational Waves

Gravitational waves were first predicted by Albert Einstein in 1916 as part of his General Theory of Relativity. However, they remained unobserved for nearly a century due to their extremely weak nature.

The first direct detection of gravitational waves occurred on September 14, 2015, by the LIGO (Laser Interferometer Gravitational-Wave Observatory) collaboration. This groundbreaking event was caused by the merger of two black holes, about 1.3 billion light-years away from Earth. The detection marked a monumental moment in physics and astronomy, confirming a key prediction of Einstein’s theory.

Instruments and Techniques

LIGO employs a technique called laser interferometry to detect gravitational waves. The apparatus consists of two long arms (each 4 kilometers) set at right angles to each other. When a gravitational wave passes through, it causes slight changes in the lengths of these arms. LIGO measures these minuscule changes—on the order of a fraction of the width of a proton—by analyzing the interference pattern of laser beams split and recombined.

Significance in Astrophysics