SEATTLE, Jan. 7, 2003 — Albert Einstein can rest a little
easier: The first effort to measure how quickly gravity exerts
its influence indicates that it more or less matches the speed
of light, scientists reported Tuesday. If the results had come
out differently, it would have cast new doubt on Einstein’s view
of general relativity — and in fact, some doubters contend that
the latest measurement by no means closes the case. The
measurement, presented at this week’s meeting of the American
Astronomical Society in Seattle, was made by analyzing how radio
waves from a quasar nearly 9 billion light-years from Earth were
bent as they passed through Jupiter’s gravitational field on
Sept. 8. Scientists have known for decades that gravity bends
waves of electromagnetic radiation: The phenomenon played a key
role in the first test of general relativity during a 1919 solar
eclipse. But it’s only been in the last few years that
astronomers have worked on putting a number to the propagation
speed of gravity’s effect. Thi