"LIGO and its Quest for Gravitational Waves" 	
Laura Cadonati (MIT)
  	
The Laser Interferometer Gravitational-wave Observatory (LIGO) has the ambitious
goal of performing the first direct detection of gravitational waves. As 
predicted by General Relativity, gravitational waves are ripples in the fabric 
of space-time that can be produced by a wide range of sources, both inside and 
outside our galaxy, such as black hole collisions, supernova explosions, and 
rotating pulsars. Their detection will provide a fundamental new tool for the 
understanding of our universe.

To achieve this goal, LIGO uses three Michelson laser interferometers, two in 
Hanford, WA, and one in Livingston, LA. Each interferometer monitors changes in 
the relative separation of mirrors at the ends of each of two perpendicular arms
of km-scale length, in response to the space-time distortions induced by the 
passage of gravitational waves. The goal for the initial phase of LIGO is to 
measure differences in length of one part in 10 21 , or 10 -18 m, one thousand 
times smaller than the nuclear diameter. The detectors have now reached this 
design sensitivity and the LIGO Scientific Collaboration is actively searching 
for gravitational wave signatures in the interferometers' data.
This talk will present the physics targeted by LIGO, with an overview of 
possible gravitational wave sources, data analysis methods, current results and 
the expected reach of the initial and advanced LIGO configuration.