It's a sad day for physics crackpots bent on disproving relativity, because once again, it turns out that Einstein was right.
The last bits of data collected several years ago by NASA's Gravity Probe B satellite have been analyzed, and the result is a resounding confirmation of two critical predictions of the general theory of relativity.
Perhaps you're thinking, "Wait a minute - NASA has a satellite up there testing the predictions of relativity?" Yes it does! NASA launched Gravity Probe B in April 2004, and these new results are the culmination of more than 50 years of effort.
Per Isaac Newton, the spin axis of a perfect gyroscope orbiting the Earth would remain unchanged for all eternity. But Newton saw gravity as a force between objects. Einstein re-envisioned gravity as arising from the warping of spacetime. That's the central tenet of General Relativity, and Einstein made several predictions that could be used to test the accuracy of his theory.
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One was confirmed right away: Einstein said that a ray of light passing near the sun would be deflected by a certain degree, because the sun's mass would warp the surrounding spacetime and the light ray would follow that curvature.
This effect would be observable during a solar eclipse, when the sun's light was temporarily blocked. In May 1919, two separate scientific expeditions - one in Brazil and another on an island off the coast of West Africa - observed just such a deflection during a solar eclipse.
Einstein also predicted that the Earth's mass would warp its surrounding spacetime, and that it would "drag" the fabric of spacetime by a certain degree as it rotates. Those last two predictions are the reason Gravity Probe B was first conceived in 1959 by two Stanford scientists named George Pugh and Leonard Schiff.
The idea was to precisely measure the displacement angles of the spin axes of four different gyroscopes-in-space over the course of a year and then compare that data with Einstein's predictions.
Basically, the gyroscope orbits the Earth in a state of perfect free-fall because the body of the craft shields it from outside disturbances like friction and magnetic fields. But we didn't have the instrumentation and associated technologies to build such a complicated system for several decades.
After its launch, NASA pointed Gravity Probe B at a single star, IM Pegasi, and collected tons of data to see if the on-board gyroscopes would continue to point in that same direction forever - as Newton expected - or whether there would be tiny changes in the direction of their spin in response to Earth's gravitational pull.