Just as Maxwell’s equations imply that an accelerating charge produces electromagnetic radiation, Einstein’s theory of general relativity predicts that an accelerating mass produces gravitational radiation. As a gravitational wave propagates at the speed of light, it stretches space in one direction and compresses it in another. But because gravity is so weak, those distortions are minuscule, and extraordinary sensitivity is required to detect them.
The Laser Interferometer Space Antenna (LISA) is a proposed mission to look for gravitational waves through their effect on the distances between three spacecraft. The spacecraft would form, in essence, a Michelson interferometer 5 million kilometers on a side—more than 10 times the distance from Earth to the Moon. Researchers hope to be able to measure oscillations as small as 10 picometers in the interferometer’s arm lengths.
Many technical challenges stand in LISA’s way. One of the biggest has involved laser phase noise: Even with the...
