We now have the means to watch the fabric of space-time as it ripples. At a
ceremony last week, physicists celebrated the completed construction of the
Laser Interferometer Gravitational-Wave Observatory (LIGO).
At sites in Louisiana and Washington State, LIGO will use lasers to track the
motion of suspended test weights with incredible accuracy. Gravitational
waves—ripples in space-time predicted by general relativity— should
cause the weights to move. LIGO should be fully operational by 2001.
