Measurement of the Isotropy of the Maximum Attainable Speed

The tests of the special relativity (SR) postulate of the universal value of the speed of light, or the maximum attainable speed, are motivated by the important role of SR in modern physics, predictions of the Lorentz Invariance (LI) violation in string theories, and a fundamental concept of quantum gravity (QG). An anisotropy of the one-way speed of light, which is the least restricted possible violation of SR by the experimental data, will be discussed in the talk. I will outline a new proposal to search for a LI violation using CESR beams. The projected sensitivity of the proposed search approaches the onset of the QG effects.