Most Precise Test Yet of Einstein's Gravitational Redshift

[n2doc]

ScienceDaily (Feb. 18, 2010) — While airplane and rocket experiments have proved that gravity makes clocks tick more slowly -- a central prediction of Albert Einstein's general theory of relativity -- a new experiment in an atom interferometer measures this slowdown 10,000 times more accurately than before, and finds it to be exactly what Einstein predicted.

Cesium atom matter waves oscillate more slowly along the lower path because the gravitational field is stronger, which means time passes more slowly. In the experiment, laser pulses kicked half the atoms 0.1 mm higher than the others; a second laser sent them on a course to merge; and a third laser measured the phase difference between the interfering matter waves. (Credit: Courtesy of Nature)

The result shows once again how well Einstein's theory describes the real world, said Holger Müller, an assistant professor of physics at the University of California, Berkeley.

"This experiment demonstrates that gravity changes the flow of time, a concept fundamental to the theory of general relativity," Müller said. The phenomenon is often called the gravitational redshift because the oscillations of light waves slow down or become redder when tugged by gravity.

A report describing the experiment appears in the Feb. 18 issue of the journal Nature.

http://www.sciencedaily.com/releases/2010/02/100217131125.htm

[Political Heretic]

1. Damn, I love science!

[DrDan]

2. incredible

"If we used our best clocks, with 17-digit precision, in global positioning satellites, we could determine position to the millimeter," he said. "But lifting a clock by 1 meter creates a change in the 16th digit."