Laser Interferometer Gravitational Wave Observatory
- Instrument for observing gravitational waves by detecting the change in the interference pattern produced by interacting laser beams. Two sets of equipment would be used to allow spurious events observed at only one to be eliminated. Work on LIGO was due to start in 1995 but the project, involving identical instruments at sites in Washington State and Louisiana in the United States, had many technical, financial and political problems. It was finally built in 1999.