Status of the Search for Gravitational Waves with LIGO

Einstein predicted the existence of gravitational waves, ripples of space-time, in 1916; but they are so faint that they have yet to be observed. Gravitational waves are produced by the most energetic events in the universe: collisions between black holes, supernovas, and the Big Bang itself. The observation of gravitational waves would be a spectacular confirmation of Einstein's prediction, and would permit powerful new tests of General Relativity. More importantly, it will open up a new and totally different window on the universe, and inaugurate a radically new field of astrophysics. The LIGO project is part of a worldwide observatory network capable of detecting gravitational waves from astrophysical sources. It began taking scientific data in 2002. We will describe the physics and astrophysics of gravitational waves, discuss the principles of the LIGO detectors, and review at the status of the detectors, the data analysis, and first results.