How was the speed of gravity measured in September 2002?
Ed Fomalont of the National Radio Astronomy Observatory and Sergei Kopeikin from the University of Missouri in Columbia, performed the experiment. They watched light from a faraway galaxy bend as the planet Jupiter passed almost directly between the galaxy and Earth. Their theory stated that the bending would occur due to the gravitational influence of Jupiter. By noting the extent of the bending, the researchers claimed to have measured whether gravity acted instantly or somewhat more slowly, at light-speed. Proving that gravity works at the speed of light would add support to Einstein’s General Theory of Relativity and place limits on fringe theories in cosmology. Most physicists are confident that this is the case, but no one has ever confirmed it by direct measurement.
