clarinews@clarinet.com (02/03/90)
STANFORD, Calif. (UPI) -- If Albert Einstein was right, the earth doesn't rotate around the sun but moves in a straight line in a space-time curved by the solar mass. This is an aspect of Einstein's general theory of relativity to be tested in the near future by a $4 million space probe unveiled Friday by scientists at Stanford University. If all goes according to plan, the probe with four pure quartz gyroscopes coated with superconducting material and spinning in a pure vacuum would be first tested on the ground and in a space shuttle before being launched into orbit as a research satellite in 1996 or 1997. Scientists will be watching the experiment with a tinge of trepidation since a large part of modern physics is based on Einstein's theories concerning the structure and origin of the universe. If the probe finds Einstein was not completely correct, says project scientist and principal investigator Francis Everitt, ``all hell will break loose.'' Einstein's most famous theory, based on the equation that energy equals mass times the speed of light squared -- which launched the atomic age -- isn't being challenged by the experiment because it has been verified as accurate in linear accelerators. The 1916 general theory, which added gravity to the equations, has never been completely verified because of its complexity. Everitt says many distinguished physicists are convinced that the general theory is incomplete based on modern advances in quantum mechanics. Einstein himself stubbornly refused to embrace the latter theory, putting him at odds with some colleagues, including Niels Bohr and Robert Oppenheimer. ``Some physicists think it quite likely that the result of the test for one of the two effects being measured by our experiment may give a result that is in disagreement with Einstein's predictions,'' Everitt said. Einstein saw gravity as a curvature in the basic fabric of time and space caused by the presence of a gravitating object. The theory upset a world described by Isaac Newton, who said gravity was a force, something one object exerted on another. In Einstein's theory, the earth does not rotate around the sun because of the sun's gravity but actually moves in a straight line in a space-time curved by the mass of the sun. Under Newton's theory, a gyroscope in orbit would spin with its axis always pointing in the same direction. Scientists said that using Einstein's equations, the gyroscope would tilt forward, or precess, as it spun, because it moves through curved time-space around the earth. Calculations done in the 1950s by Stanford physicist Leonard Schiff predicted that the precession would amount to 6.6 arc-seconds per year, or 360 degrees every 200,000 years. Thus, a satellite launched in the time of Moses would have tilted 6.5 degrees by now. The Stanford space probe experiment will measure this ``geodetic effect,'' as well as attempt to measure another unexplored aspect deduced by Einsteinian physics -- the gravitomagnetic field or frame-dragging effect -- described by scientists in the axiom, ``As the earth rotates, it drags space and time around with it.'' Until recently, the technology wasn't available to launch such an experiments, said Everitt, because the gyroscopes must be put in orbit without touching anything as they spin and have no interference from friction. They also have to be near-perfect to an extent once believed to be impossible.