Science: Slow Time

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One of the bizarre predictions of Einstein's General Relativity is that time runs more slowly in a strong gravitational field. The effect is slight and hard to detect but Astronomer Daniel Popper of U.C.L.A. believes that he has caught time in the act of running slow.

A result of the slowing of time: light that originates in a slow-time region appears, when observed on the earth, to have slightly longer waves than local light. Motion away from the earth has the same effect, so the speed of the body from which the light is coming must be known accurately.

Dr. Popper studied the faint "white dwarf" star, 40 Eridani B, which is 40% as heavy as the sun but only about as big as Mars. Its high concentration of mass forms a powerful gravitational field at the star's surface, where its light comes from. Besides, 40 Eridani B is a member of a double-star system, which allows its speed to be measured accurately.

After analyzing 37 spectrograms of his star's light, Dr. Popper found that its wave lengths are, as he had hoped, slightly longer than is normal. This meant that white-dwarf time really does run slow, just as Einstein predicted. The difference is not much. A man living on 40 Eridani B would fall behind by about six earthly seconds a day.