LIGO (Laser Interferometer Gravity-Wave Observatory)

LIGO is a joint project operated by the California Institute of Technology and MIT and funded by the National Science Foundation. Its purpose is to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool.

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a facility dedicated to the detection of cosmic gravitational waves and the measurement of these waves for scientific research. It consists of two widely separated installations within the United States, operated in unison as a single observatory. This observatory is available for use by the world scientific community, and is a vital member in a developing global network of gravitational wave observatories.

Funded by the National Science Foundation (NSF), LIGO was designed and constructed by a team of scientists from the California Institute of Technology, the Massachusetts Institute of Technology, and by industrial contractors. LIGO is the largest and most ambitious project ever funded by NSF.

The international LIGO Scientific Collaboration (LSC) is a growing group of researchers, some 600 individuals at roughly 40 institutions, working to analyze the data from LIGO and other detectors, and working toward more sensitive future detectors.

LIGO's mission is to directly observe gravitational waves of cosmic origin. These waves were first predicted by Einstein's Theory of General Relativity in 1916, when the technology necessary for their detection did not yet exist.

LIGO operates two gravitational wave observatories in unison: the LIGO Livingston Observatory in Livingston, Louisiana and the LIGO Hanford Observatory, on the Hanford Nuclear Reservation, located near Richland, Washington. Construction of the facilities was completed in 1999. Initial operation of the detectors began in 2001.

By detecting changes in distance between finely calibrated mirrors, LIGO's instruments measure tiny distortions in the fabric of space-time. Although LIGO is the world's most sensitive gravitational wave project, scientists estimate that currently it has a chance of only a few percent per year of detecting a source for the waves. Scientists just have to wait and hope that a violent enough event will occur close enough to the Earth to be noticeable. But LIGO physicists think they now have the technology to turn the corner.

Advanced LIGO

The Advanced LIGO Project, an upgrade in sensitivity for LIGO (Laser Interferometer Gravitational-wave Observatories), was approved by the National Science Board in its meeting on March 27, 2008. The National Science Foundation will fund the $205.12 million, seven-year project, starting with $32.75 million in 2008. This major upgrade will increase the sensitivity of the LIGO instruments by a factor of 10, giving a one thousand-fold increase in the number of astrophysical candidates for gravitational wave signals.

The Advanced LIGO detector, to be installed at the LIGO Observatories in Hanford, Washington, and Livingston, Louisiana, using the existing infrastructure, will replace the present detector, and will transform gravitational wave science into a real observational tool.

The change of more than a factor of 10 in sensitivity comes also with a change in the bandwidth of high sensitivity, and the ability to tune the instrument for specific astrophysical sources. This will allow Advanced LIGO to look at the inspiral, coalescence, and ringdown of pairs of black holes up to 50 solar masses, and to pinpoint periodic signals from the many known pulsars which radiate in the range from 500-1000 Hertz. Recent results from the WMAP satellite have shown the rich information that comes from looking at the photon, or infrared cosmic background, which comes from some 400,000 years after the Big Bang. Advanced LIGO can be optimized for the search for the gravitational cosmic background - allowing tests of theories for the development of the universe at only 10-35 seconds after the Big Bang.

Advanced LIGO will pioneer a new form of astronomy utilizing gravitational waves to observe and interpret some of the most violent events happening in the universe. Construction on this stage will begin early in 2008, with first observations using the Advanced LIGO configuration scheduled to commence in 2014.