A gyroscope's gravity-defying feat.

A gyroscope's gravity-defying feat

T Japanese scientists have conducted an experiment suggesting that under certain circumstances a spinning gyroscope may partially counter the Earth's gravitational pull. Their startling results, published in the Dec. 18 PHYSICAL REVIEW LETTERS, show that a small gyroscope spinning in one direction suffers a weight decrease of a few milligrams, with the weight loss increasing as the spin rate increases. In contrast, a gyroscope spinning in the opposite direction loses no weight. "The experimental result cannot be explained by the usual theories," conclude Hideo Hayasaka and Sakae Takeuchi of Tohoku University in Sendai.

Physicists who have seen the report express skepticism. Although the experiment, as described in the report, appears to have no obvious sources of experimental error, most experts say they expect that intense scrutiny and attempts to replicate the experiment will show the results to be incorrect.

"I looked at it carefully because it's very puzzling," says Eric G. Adelberger of the University of Washington in Seattle. "I can't see any particular thing that they didn't do or that they did wrong, but there are things that suggest there is something clearly wrong." For one, he notes, the way in which the weight loss depends on the spin direction is unlike any other known physical effect.