Abstract

The Space Interferometry Mission (SIM), due for launch by NASA in 2007, will be able to determine directly whether length contraction exists. As the Earth orbits the sun, its velocity against a given field of background stars changes by 30 km/sec every three months. According to special relativity, this changing velocity introduces a contraction or expansion of the relative spacing between stars of as much as 18 microarcseconds per degree of separation. With a resolution of 1 microarcsecond per degree, more than 100 times more sensitive than any mission to date, SIM's resolution far exceeds the expected relativistic effect. This project represents the first direct test of relativistic length contraction, just in time for the 100 year anniversary of that theory's introduction.