Universität Konstanz and Heinrich Heine Universität Düsseldorf, both in Germany, a group has tested the predictions of relativity with a high-tech update of the Michelson-Morley experiment using two crossed cryogenic optical resonators injected with stabilized Nd:YAG lasers, yielding higher accuracy than previous experiments. The researchers reported their results at the 2002 Conference on Lasers and Electro-Optics in Long Beach, Calif., in May.

The sapphire resonators display a thermal expansion coefficient two orders of magnitude better than the cavities used in previous tests. The team reported an upper limit for the anisotropy of space of 8.7±13 x 10^-10.