NASA probe proves that Einstein was right

THEORY OF RELATIVITY:：Four decades in the making and launched in 2004, Gravity Probe B confirmed Einstein’s predictions on the geodetic effect and frame dragging


Fri, May 06, 2011 - Page 7

Huge objects in the universe distort space and time with the force of their gravity, scientists said on Wednesday 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 US space agency’s longest-running projects.

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

“In Einstein’s universe, space and time are warped by gravity. The Earth distorts the space around it very slightly by its gravity,” Everitt said, explaining the physicist’s theory devised nearly 100 years ago.

“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,” Everitt said.

“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.”

The satellite carried four advanced gyroscopes to measure the 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, 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,” NASA said in a statement.

The probe’s measurements came remarkably close to Einstein’s projections, according to the findings published in the journal 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 US Department of Defense, dreamed up a satellite that would orbit the Earth and test the notion.


“Forty-one years later, the satellite was launched into orbit about 400 miles [644km] above Earth,” NASA said.

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


Hundreds of university students and dozens of high school students have worked on the project, including Sally Ride, the first US female astronaut in space, and Nobel Laureate Eric Cornell.