First scientific results from LIGO

First scientific results from LIGO (the Laser Interferometer Gravitational-Wave Observatory). Essentially a giant strain gauge to measure the local distortion in spacetime of a passing gravitational wave, LIGO has detectors in Hanford, Washington, and Livingston, Louisiana. (For more on LIGO’s operation, see Physics Today, October 1999, page 44.) The ripples in spacetime radiated, for example, by the collapsing inspiral of two neutron stars are predicted to produce a strain in LIGO of perhaps one part in 10²⁰, which would change the distance between mirrors some 4 km apart by about 10⁻¹⁸ meters, a displacement 1000 times smaller than a proton. At the April APS meeting, the LIGO team reported its first official results from the initial science run, conducted over 17 days in the late summer of 2002. Gary Sanders (Caltech) and Erik Katsavounidis (MIT) reported that, as expected, no gravitational-wave events were seen, but...