Science: A Victory for Relativity

After Mariners 6 and 7 photographed Mars last year and went into perpetual orbits around the sun, scientists at Pasadena's Jet Propulsion Laboratory conducted an important test. Using NASA's giant 210-ft. Goldstone antenna in the California desert, they beamed powerful radio signals past the sun toward the little unmanned spacecraft. When they reached the Mariners some 250 million miles away, the signals were automatically amplified on board and transmitted back to earth. The entire round trip took only about 43 minutes, but the results may be momentous for all of physics. Last week, at a conference on gravity at Caltech, the...