It sounds like something from The X-Files, but levitation is raising eyebrows--and interest at NASA
Floating on air? It's possible. Just chill a ceramic superconductor below 90K (-300F) and place it on a magnet. The superconductor will levitate. It's called the Meissner effect, and it might one day lead to an ''antigravity'' machine.
John H. Schnurer, director of applied sciences at Physics Engineering in Yellow Springs, Ohio, thinks he might have taken a first step in that direction last fall. After chilling a 1-inch-diameter superconducting disk, he threw a switch that sent an electrical current surging through a set of coils positioned around the disk. Above the disk was a plastic sample hanging from one end of a homemade balance scale containing no metal parts. The plastic sample rose ever so slightly--corresponding to an apparent 5% loss in the weight of the sample. ''Great fun,'' said Schnurer--his restrained way of shouting ''Eureka!''
WEAK FORCE. Many physicists are sure antigravity is a delusion. Even if it does exist, it can't be more than one-millionth as strong as gravity, says Eric G. Adelberger, a professor of physics at the University of Washington who studies gravity. And because gravity itself is such a weak force, tiny magnetic fields and temperature changes can cause spurious results. Adelberger says it's crucial to control temperatures to one-thousandth of a degree--way beyond the scope of Schnurer's setup.
At least two scientists theorize that the apparent weight loss is real. Giovanni Modanese, a physicist at the Italian National Agency for Nuclear & High Energy Physics in Trento, agrees antigravity is unlikely--but a ''gravity shield'' is something else. It would produce an unseen tunnel above the disk, and inside it things would weigh less because exotic quantum-physics reactions would be absorbing some of gravity's pull.
Ning Li, a senior research scientist at the University of Alabama's Huntsville campus, believes that under the proper conditions, the minuscule force fields of superconducting atoms can ''couple,'' compounding in strength to the point where they can produce antigravity. Li and Modanese have been debating each other since the early 1990s, when Eugene E. Podkletnov, a Russian materials scientist then at Tampere University of Technology in Finland, reported strange gravity-attenuation effects in his experiments.
FINE-TUNING. To settle the issue, researchers at NASA's Marshall Space Flight Center in Huntsville, Ala., and two national laboratories are setting up experiments. NASA physicist David A. Noever was so eager to get going he paid his own fare to Denver to borrow a gravitometer, an ultrasensitive gadget for measuring gravity. ''It shows you how excited these people are. They're working their rear ends off,'' says L. Whitt Brantley, chief of NASA's Advanced Concepts Office.
So far, Schnurer has replicated his weight-loss experiment 12 times. He points out that the balance doesn't move when he turns on the juice without the disk--or when the disk isn't in the Meissner state. Still, Schnurer admits, his setup is crude, and he is now making other refinements.
To spread the fun around, Schnurer has formed the Gravity Society, with Podkletnov and Modanese as charter members. It now has a bare-bones Web page (http://www.gravity.org) and should soon offer scientific papers from the trio.
Until NASA or one of the national labs can determine why superconductors cause balances to tilt, skeptics will have an easy time denying Schnurer's results. He cheerfully admits he's no theoretician, just an inveterate tinkerer. ''I can't even understand Giovanni's math,'' he says. ''But this is big fun.''
By Otis Port in New York
Updated Feb. 6, 1997 by bwwebmaster
Copyright 1997, by The McGraw-Hill Companies Inc. All rights reserved.