05/26/2015

Built to look for gravitational waves, the ripples in the fabric of space itself that were predicted by Einstein in 1916, the Laser Interferometer Gravitational-Wave Observatory (LIGO) is the most ambitious project ever funded by the National Science Foundation. LIGO consists of two L-shaped interferometers with four-kilometer-long arms; at their ends hang mirrors whose motions are measured to within one-thousandth the diameter of a proton. Managed jointly by Caltech and MIT, Initial LIGO became operational in 2001; the second-generation Advanced LIGO was dedicated on May 19.
Barry Barish is the Roland and Maxine Linde Professor of Physics, Emeritus. He was LIGO's principal investigator from 1994 to 1997, and director from 1997 to 2006. Stan Whitcomb (BS '73) was an assistant professor of physics at Caltech from 1980 to 1985. He returned to campus as a member of the professional staff in 1991 and has served the LIGO project in various capacities ever since. We talked with each of them about how LIGO came to be.

Image:
(Left) One of the dual instruments of the Laser Interferometer Gravitational-Wave Observatory sprawls across the desert near Hanford, Washington, each arm extending four kilometers and meeting at the corner of an L. The support buildings at the corner house laboratories as well as electronic and optical equipment, which will send a laser beam, split in two, back and forth down the two arms to intercept the infinitesimally small signal of a gravitational wave.
(Right) No, its not the Trans-Alaska Pipeline, but two-and-a-half miles of stainless steel tubing, protected by concrete arches, reaching across a desert in the Pacific Northwest. Inside, a laser beam, bouncing between mirrors on either end (and in the adjoining arm) will try to pick up an almost imperceptible signal, when the Laser Interferometer Gravitational-Wave Observatory turns on in the year 2002.