Glossary

Gravitational Waves

Gravitational waves are ripples in the fabric of spacetime, produced when massive objects accelerate, predicted by Einstein in 1916 and first detected by LIGO in 2015. The most powerful sources are colliding black holes and neutron stars, whose final merger sends a chirp of waves outward at the speed of light. Detectors measure distortions thousands of times smaller than a proton. Pulsar timing arrays have since revealed a low-frequency background hum thought to come from supermassive black hole pairs across the cosmos.

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