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Date Posted: 23:34:09 10/22/04 Fri
Author: Scientists-at-large
Subject: Warped Satellites Prove Einstein Theory -Scientists

Warped Satellites Prove Einstein Theory
-Scientists/Oct 21 2004

By Maggie Fox,
Health and Science Correspondent

WASHINGTON- Einstein was right - again. Satellites that have been pulled slightly off their orbits show that the Earth is indeed twisting the fabric of space-time as it rotates, scientists said on Thursday.

They said their findings are the first to directly measure and prove an important aspect of Albert Einstein's General Theory of Relativity -- that a rotating body warps and twists the "fabric" that combines the three dimensions of space and the fourth dimension of time.

"As the Earth turns, it is actually twisting space-time with it. Near Earth, the twisting is greater," said Michael Salamon, a physicist at NASA (news - web sites) in Washington.

"This twisting of space-time, which is also referred to as frame-dragging, has never been directly observed before," Salamon told reporters in a telephone briefing.

"This is the first real, solid, direct evidence we have for the twisting of space-time caused by the spinning of a rotating body."

Erricos Pavlis of the Joint Center for Earth System Technology at NASA and the University of Maryland and colleagues observed two satellites orbiting the Earth and found that they did shift as the planet pulled on space.

"We measured the distance from the Earth to the satellite with the accuracy of millimeters," Pavlis said. Their research was reported in the journal Nature.

The Laser Geodynamics Satellite I or LAGEOS I, a NASA spacecraft, and LAGEOS II, a joint NASA/Italian Space Agency satellite, are basically hunks of metal covered with reflectors that make them easy to follow and measure from the ground.


Their butterfly-shaped orbits are meant to simulate the movement of a spinning gyroscope. Einstein's theory predicts that a nearby spinning body -- such as the Earth -- will pull on space and cause a gyroscope to shift slightly on its axis.

There is no proof that some other force is not acting on the satellites, Pavlis said, but it is unlikely.

"It would have to be a very smart force to exactly mimic general relativity," he said.

"We have eliminated all of the forces that we do know -- tidal forces, et cetera and so forth, as well as gravitational model errors."

Pavlis likens the effect to a spoon twisting in a jar of molasses.

"Similarly, as the Earth rotates, it pulls space-time in its vicinity around itself. This will shift the orbits of satellites near Earth," he said.

Salamon said indirect evidence has been seen of frame-dragging, but this is the first direct measurement.

In April, NASA launched Gravity Probe B, a probe carrying four gyroscopes, which the scientists say should prove Einstein's theory with even higher accuracy when its results are reported next year.


Wow..

:-/

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