Science: Proof for Einstein

Einstein's theory of relativity was one of the giant leaps of the human intellect. So impressive was it that for years most physicists have accepted it as the fundamental law of the universe, even though no one had devised methods or machines sensitive enough to verify it completely. Last week its most basic concept triumphantly passed the most rigorous test yet.

Crucial in the theory of relativity is the nature and behavior of light. In the 19th century, the prevailing idea was that light is a wave motion, and therefore needs a medium to travel in, as sound waves travel in air....