Gravitational Waves

Gravitational waves were predicted by Albert Einstein in 1916 as part of his general theory of relativity. According to Einstein, massive accelerating objects, like merging black holes or neutron stars, create ripples in the fabric of spacetime that propagate outward at the speed of light.

These waves are incredibly faint—by the time they reach Earth, they stretch and compress space by less than one-thousandth the diameter of a proton. For decades, scientists searched for evidence of gravitational waves, but it wasn't until 2015 that the Laser Interferometer Gravitational-Wave Observatory (LIGO) made the first direct detection.

On September 14, 2015, LIGO detected gravitational waves from two black holes merging 1.3 billion light-years away. This historic event confirmed Einstein's century-old prediction and opened an entirely new way to observe the universe. The detection earned the 2017 Nobel Prize in Physics.

LIGO uses laser interferometry to measure tiny changes in distance between mirrors placed kilometers apart. When a gravitational wave passes, it slightly alters the distance, creating an interference pattern in the laser light. The sensitivity required is extraordinary—LIGO can detect changes smaller than one-ten-thousandth the diameter of a proton.

Gravitational wave astronomy has revolutionized our understanding of the universe. We've now detected mergers of black holes, neutron stars, and even a black hole-neutron star pair. Each detection reveals new information about these extreme objects and tests our understanding of gravity.

Future gravitational wave observatories, including space-based missions like LISA, will detect waves from supermassive black hole mergers and the earliest moments of the universe. Combined with traditional telescopes, gravitational waves provide a "multi-messenger" view of cosmic events, allowing us to study the universe through both light and spacetime ripples.