Testing Quantum Gravity With Bosons in an Elevator Shaft

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By Lisa Grossman June 17, 2010 | 2:04 pm | Categories: Physics

Dropping ultra-cold quantum gas down an elevator shaft could help prove Einstein wrong. Scientists have shown that it’s possible to keep sufficiently close tabs on quantum mechanical objects in free fall to tell whether two such objects experience gravity the same way.

In 1907, Einstein suggested that if you were in a windowless elevator that was plunging towards Earth in free fall, you would feel the same weightlessness as if you were floating in outer space.

This notion, known as the equivalence principle, laid the foundation for general relativity. It explains why a pebble and a piano fall at the same speed if dropped from the same roof, despite their different masses. It’s also a necessary first step toward describing the effects of gravity as curvature in spacetime.

“It’s a very important cornerstone,” said physicist Ernst Rasel of the Leibniz University of Hannover in Germany. But, he added, the equivalence principle “is just a postulate — it’s not coming out of a law.”

So of course, physicists have spent the past century trying to break it. Earlier tests used man-made, macroscopic objects like rotating pendulums to make sure two elements of different masses fall toward Earth at the same speed. Physicists also have bounced laser light off mirrors left on the moon in the 1960s to make sure the Earth and the moon feel the same acceleration from the sun’s gravity. So far, to the limits of the experiments’ accuracy, Einstein’s idea has held up.



Read More http://www.wired.com/wiredscience/2010/06/quantum-gravity-in-an-elevator/

[sharp_stick]

1. I thought they were dropping navy guys

down elevator shafts with that title. ;-)

[Thor_MN]

2. I'd rather use those overpriced Yankees

What? BosoNs, not Bosox? Nevermind.