Gravitational Wave Detection

A century after their prediction by Albert Einstein, gravitational waves were directly detected by the two Michelson interferometers that form the Laser Interferometer Gravitational-Wave Observatory (LIGO). LIGO, along with the European detector Virgo, are the start of a global network of gravitational wave detectors that begin the era of gravitational wave astronomy. With arm lengths of 3 km for Virgo and 4 km for LIGO, these detectors can measure a relative displacement of the interferometers’ arm lengths of 10 −18 m. Presented here is a description of the exquisite optical properties of these Michelson interferometers that can measure disturbances of spacetime created by merging binary black holes more than a billion light-years away.