Understanding the gravity of a situation

Barry Barish, director of the Laser Interferometer Gravitational-Wave Observatory (LIGO), discusses gravity waves and and how to detect them at a Director's Colloquium last Thursday in the Physics Building Auditorium at Technical Area 3. Barish discussed how gravitational waves disrupt the fabric of space-time in the universe and discussed how the LIGO observatory on Earth is making progress in the quest to detect and measure gravitational waves. Gravitational waves are emitted by accelerating masses much as electromagnetic waves are produced by accelerating charges. These ripples in the space-time fabric travel toward Earth, bringing with them information about their cataclysmic origins, as well as invaluable clues as to the nature of gravity. Albert Einstein predicted the existence of these gravitational waves in his 1916 general theory of relativity, but only now in the 21st century has technology advanced to enable their detection and study by science. The LIGO facility is dedicated to detecting gravitational waves by use of two laboratories (see aerial photo) -- one located in at Hanford, Wash., the other located on a tree farm in rural Louisiana. The two laboratory facilities are huge L-shaped detectors. Each uses two perpendicular axes of laser beam tunnels that are 2.6 miles long. When gravitational waves from objects such as a rotating binary star system collide with the Earth, they stretch one axis slightly while compressing the other. These deformations of the axes are tiny -- a distance just one one-hundred-millionth of the diameter of a hydrogen atom. The greatest challenge to the facility right now is calibrating equipment to be able to detect such an infinitesimally small change in the length of the detector tunnels. If successful, LIGO has the potential to enrich researchers' understanding of the universe. LIGO is a collaboration between the California Institute of Technology and the Massachussets Institute of Technology. It receives funding from the National Science Foundation. Inset photo: Barish talks with technical host Rajan Gupta of Elementary Particles and Field Theory (T-8) before he delivered his talk. Photos by James E. Rickman, Public Affairs

Aerial view of the Laser Interferometer Gravitational-Wave Observatory facility at Hanford, Wash. Photo courtesy of LIGO

Other Headlines