Measuring the Frame-Dragging Effect
April 12, 2010: Researchers at Stanford University recently made the most precise test of Einstein's general theory of relativity there has ever been by measuring the frame-dragging effect. Frame-dragging is an extremely tiny warp in spacetime that occurs near rotating masses such as planets. To measure it, a satellite was launched into Earth orbit in 2004 with four spherical gyroscopes onboard. The electronic control for the gyroscopes' suspension had previously undergone comprehensive testing, including a test setup consisting of a DS1005 Processor Board, diverse I/O boards and the experiment software ControlDesk® (as reported in dSPACE NEWS 1/2002). According to Einstein, if the spin axis of each gyroscope is aligned with a guide star at the start, after a full year in orbit it will show a minimal deviation. This is caused by various relativity effects, including frame-dragging, which makes a difference of approx. 1/40,000,000th of a degree. To give an idea of size: 1/40,000,000th of a degree is the angle of a pin head seen from 1000 km away. After several years of evaluating data, the researchers finally succeeded in detecting this microscopically small change in the gyroscopes' angle at the end of 2009. They had verified the existence of the frame-dragging effect.
Further information: http://einstein.stanford.edu