PULLMAN, Wash. — LIGO, a project designed to detect cosmic gravity waves, will be the subject of a seminar by Fred Raab, director of the LIGO Hanford Observatory Tuesday, April 14, at WSU. The seminar is scheduled in the Webster Physical Science Building, Room 17, at 4:10 p.m.
LIGO, which stands for Laser Interferometer Gravitational-Wave Observatory, is expected to open a new window on the universe and become a new scientific tool for physicists and astronomers. Gravitational waves are described as “ripples in the fabric of space and time produced by violent events in the distant universe,” and, since Albert Einstein first predicted them in his general theory of relativity in 1916, they have only been indirectly detected. LIGO is the first effort, using modern technology, to directly measure the waves.
The project depends on twin units located at widely separated sites. The unit that Raab oversees is being completed at Hanford, and the other is being built in Livingston, Louisiana. The units operate in unison as a single facility and are expected to be operational by 2001. The Hanford unit is an L-shaped structure, consisting of two concrete arms, each two and one half miles long, which contain four-foot diameter ultra-high-vacuum tubes. Ultrastable laser beams traversing the vacuum pipes will measure the effect of gravitational waves on suspended masses located at the ends.
The facility is designed to detect very weak cosmic gravity waves such as those originating from the Big Bang and black holes, collisions of neutron stars and other violent cosmic events. The equipment is so sensitive that it can sense the pull of the moon on the ground beneath the tubes, micro-earthquakes, thunderstorms and cannon blasts at a firing range 25 miles away. Having two separated units permits the identification of false indications caused by such local disturbances and also allows calculations to determine the direction of origin of the incoming waves.
LIGO is a joint project of the California Institute of Technology and the Massachusetts Institute of Technology. Construction and testing of the project is funded by a $350 million grant from the National Science Foundation. The project will eventually make use of observatories in Italy, Germany, Australia and Japan.
The lecture will be preceded by a reception at 3:45 p.m. in Webster B8, and is sponsored by the Department of Physics.