How it works
Measuring ripples in spacetime
LIGO doesn't capture light from distant objects. It measures spacetime itself, using laser light split down two enormous perpendicular arms.
The instrument
An interactive interferometer
Drag the slider to watch a gravitational wave stretch one arm while squeezing the other.
Drag the slider to simulate a passing wave. As spacetime stretches one arm, it squeezes the other. The recombined laser light shifts, and the detector reads out that tiny change as a signal.
Key principles
What makes it possible
Detects waves, not light
LIGO senses gravitational waves — tiny ripples in spacetime from violent cosmic events — rather than electromagnetic light.
Laser interferometers
Each detector splits a laser beam down two perpendicular 4 km arms and measures minute differences when they recombine.
Two US detectors
The American observatories sit in Hanford, Washington and Livingston, Louisiana, roughly 3,000 km apart.
A global network
LIGO works with Virgo, KAGRA, and future LIGO-India so detections can be confirmed and located across the sky.
Sources