p2pnet.net News:- OK. This is just a little bit off-topic. But …

NASA is ready to measure Earth’s drag on space-time, says a story from the NewScientist.com news service here.

“NASA has a launch window of just one second early on 19 April to launch Gravity Probe B into a polar orbit precisely aligned with a reference star,” it says, going on:

“The gyros, a million times more accurate than the best on Earth, will measure how the rotating Earth drags on the fabric of space-time.”

A 1976 NASA mission sent an atomic clock 10,000 kilometres into space, confirming the Einstein General Theory of Relativity prediction that gravity slows the flow of time, the report states.

Now, “Gravity Probe B aims to measure a weaker and even stranger effect called ‘frame dragging’, a warping of space-time by the gravity and angular momentum of a spinning body. In principle, it is possible to measure it by monitoring the spin axis of a gyroscope orbiting the Earth. The axis should change its orientation relative to that of a distant star.”

Francis Everitt, Gravity Probe B’s principal investigator at Stanford University, is quoted as saying, “It’s hard to imagine a simpler experiment. The difficult part is making gyroscopes with the extraordinary precision needed to measure changes of just 0.041 arcsecond a year while in a polar orbit 640 km above the Earth.”

The probe should measure frame-dragging to within 1% and will also measure a much larger space-warping effect called the geodetic effect to one part in 10,000,” the most precise test yet of any relativistic effect,” says New Scientist.

This entry was posted on Tuesday, April 13th, 2004 at 5:11 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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