http://www.washingtonpost.com/wp-dyn/articles/A46404-2004Apr2.html Isn’t science wonderful? Imagine explaining this to someone from another planet: to test a theory about how things move (Einstein’s theory of general relativity), earth people have spent about 40 years designing a device containing four small spheres (supposedly the most perfect spheres ever made). This device will be strapped to a rocket and shot 400 miles out into space whereupon the balls will be made really cold and then spun at 10,000rpm. If the balls slow down, or tilt, or something Einstein wins.
The main project page has a good pdf (note that superscripts are missing) describing the science involved, including how they’re going to suspend, spin and measure the sphere-gyroscopes. (Another page briefly describes the three (small) ways in which the predictions of Einstein’s and Newton’s theories diverge within the solar system.) 20:53
