这个实验在以后的年代里一直在做，结果越来越精确。这个人在写文章的时候为什么不调研一下？贴一段：
http://en.wikipedia.org/wiki/Michelson-Morley
In recent times versions of the Michelson–Morley experiment have become commonplace. Lasers and masers amplify light by repeatedly bouncing it back and forth inside a carefully tuned cavity, thereby inducing high-energy atoms in the cavity to give off more light. The result is an effective path length of kilometers. Better yet, the light emitted in one cavity can be used to start the same cascade in another set at right angles, thereby creating an interferometer of extreme accuracy.

The first such experiment was led by Charles H. Townes, one of the co-creators of the first maser. Their 1958 experiment put an upper limit on drift, including any possible experimental errors, of only 30 m/s. In 1974 a repeat with accurate lasers in the triangular Trimmer experiment reduced this to 0.025 m/s, and included tests of entrainment by placing one leg in glass. In 1979 the Brillet-Hall experiment put an upper limit of 30 m/s for any one direction, but reduced this to only 0.000001 m/s for a two-direction case (i.e., still or partially entrained aether). A year long repeat known as Hils and Hall, published in 1990, reduced the limit of anisotropy to 2x10-13.
另外，相对论的推论有很多，目前为止实验上还没有观测到不符合。反倒是有不少远离直觉匪夷所思的结论，却都被观测证实，比如E=mc2