Friday, 6 May 2011

Einstein Was A Clever Boy

In 1959, some boffins at Stanford University dreamed up an experiment for testing Einstein's Theory of General Relativity which predicted that the Earth (or any other large mass) distorts space-time by virtue of its gravity and movement. The experiment was adopted by NASA and has received other independent funding too, and it has now delivered its final results which prove conclusively that Mr Einstein was right.
The experiment has taken so long because the boffins have had to wait for technology to catch up with their ideas, but it is basically simple:
"Gravity Probe B (GP-B) is a NASA physics mission to experimentally investigate Einstein’s 1916 general theory of relativity - his theory of gravity. GP-B uses four spherical gyroscopes and a telescope, housed in a satellite orbiting 642 km (400 miles) above the Earth, to measure, with unprecedented accuracy, two extraordinary effects predicted by the general theory of relativity:
1) the geodetic effect - the amount by which the Earth warps the local spacetime in which it resides; and
2) the frame-dragging effect - the amount by which the rotating Earth drags its local spacetime around with it.
GP-B tests these two effects by precisely measuring the precession (displacement) angles of the spin axes of the four gyros over the course of a year and comparing these experimental results with predictions from Einstein’s theory."
(Two-page .pdf with more info here).
So I guess it's not a Theory any longer. And it shows that what we think of as time is affected by gravity. And time is not an absolute. (More on that story later).
Note: Opportunity Cost Analysis: This experiment has cost about $750 million, which is about £460 million, spread over 52 years. This equates to about six weeks' worth of war in Afghanistan for the UK and about nine days of air strikes/cruise missiles launched by the USA against Libya.

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