[ExI] NASA space probe proves Einstein correct

[Damien Broderick]

NASA space probe proves Einstein correct
Thursday, 5 May 2011

by Kerry Sheridan
Agence France-Presse


WASHINGTON: Huge objects in the universe distort space and time with the 
force of their gravity, scientists said after a NASA probe confirmed two 
key parts of Albert Einstein's theory of general relativity.

"Einstein survives," chuckled Francis Everitt, Stanford University 
physicist and principal investigator for Gravity Probe B (GP-B), one of 
the U.S. space agency's longest running projects.

The physics experiment was more than four decades in the making, and 
finally launched in 2004.

The Earth in honey

"In Einstein's universe, space and time are warped by gravity. The Earth 
distorts the space around it very slightly by its gravity," he said, 
explaining the Jewish physicist's theory devised nearly 100 years ago, 
long before the technology existed to test it.

"Imagine the Earth as if it were immersed in honey. As the planet 
rotates, the honey around it would swirl, and it's the same with space 
and time," said Everitt.

"GP-B confirmed two of the most profound predictions of Einstein's 
universe, having far-reaching implications across astrophysics 
research," he said, predicting the mission would "have a lasting legacy 
on Earth and in space."

Confirmation of Einstein's theory

The satellite carried four advanced gyroscopes to measure geodetic 
effect, or the warping of space and time around a gravitational body, 
and frame-dragging, or how much a spinning object pulls space and time 
with it when it turns.

If Einstein's theory were disproved, the "gyroscopes would point in the 
same direction forever while in orbit", NASA said.

"But in confirmation of Einstein's general theory of relativity, the 
gyroscopes experienced measurable, minute changes in the direction of 
their spin as they were pulled by Earth's gravity."

Remarkably close to projections

The probe's measurements came remarkably close to Einstein's 
projections, according to the findings published in Physical Review 
Letters. The satellite, which wrapped up its data mission last year, was 
first envisioned in 1959.

Leonard Schiff, head of Stanford's physics department, and George Pugh 
of the Defense Department, dreamed up a satellite that would orbit the 
Earth and test the notion. Everitt joined the project in 1962, followed 
by NASA in 1963. "Forty-one years later, the satellite was launched into 
orbit about 400 miles above Earth," NASA said.

The technologies created in the development of the gravity probe have 
been used in making precise global position systems (GPS) and in gauging 
the background radiation of the universe.

"That measurement is the underpinning of the 'big bang theory' and led 
to the Nobel Prize for NASA's John Mather," NASA said.