Ligo
LIGO (Laser Interferometer Gravitational-Wave Observatory) is a large-scale physics experiment designed to detect gravitational waves—ripples in spacetime caused by accelerating massive objects. The observatory consists of two facilities located in the United States, in Livingston, Louisiana and Hanford, Washington, which operate in tandem to identify and characterize gravitational wave signals through laser interferometry. By comparing measurements from both sites, LIGO can triangulate the location of gravitational wave sources and distinguish genuine signals from local noise.
Detection and Discoveries
Since its first confirmed detection in 2015, LIGO has identified gravitational waves from numerous astronomical events, primarily from the merger of binary black holes and neutron star systems. These observations have provided direct evidence for phenomena predicted by Einstein’s general relativity and have opened a new observational window into the universe. Among LIGO’s detections are signals from sub-solar mass objects—bodies smaller than the Sun—which have implications for understanding primordial black holes and the early universe.
Methodology
LIGO employs laser interferometry to measure infinitesimal changes in the relative lengths of two perpendicular arms, each several kilometers long. When a gravitational wave passes through Earth, it causes minute distortions in spacetime that alter the light travel time between mirrors at the ends of each arm. By analyzing these phase shifts in laser light, researchers can infer the properties of the source event, including the masses and orbital parameters of colliding objects.