The Laser Interferometer Gravitational-wave Observatory (LIGO) is an ambitious project that has launched a new kind of astronomy. Our group at Stanford is a founding member of the LIGO Scientific Collaboration, and we are proud that our work on lasers, material science, and seismic isolation is evident in key components of the LIGO detectors.
Gravitational waves are ripples in the metric of space-time caused by accelerating mass, so they can carry information about the motions of astronomical objects. On September 14, 2015, the detection of gravitational waves by Advanced LIGO (aLIGO) was a dramatic confirmation of Einstein’s General Theory of Relativity. These waves were produced by the inspiral and merger of two black holes, an event never before observed, inaugurating a new era of astronomy. This detection gave the first evidence of stellar mass black holes heavier than 20 solar masses and the first evidence of binary stellar mass black hole systems. As the aLIGO observatories approach their design sensitivity, more binary black hole mergers will be detected. We also look forward to detections of other sources of gravitational waves including binary neutron star in-spirals, stellar collapses, pulsars, low mass X-ray binaries, and a stochastic background of radiation from the early universe. New and unexpected sources will almost certainly be found as well.