MACROSCOPIC MATTER IN LORENTZ TESTS

Abstract

The Michelson-Morley experiment, originally performed 1881 in Potsdam,’ was the first experiment to test Lorentz symmetry. A light ray is split into two, run along two interferometer arms, and interfered thereafter; a differential change in the times required to transverse the arms connected to a rotation in space would move the interference fringes and indicate Lorentz violation. Very early, it was noted that such a change might be caused not only by a shift in the speed of light c, but also in the arm length L, maybe depending on the material used for the interferometer. For example, Morley and Miller2 used an interferometer out of sandstone to test whether Michelson’s famous null result was just a cancellation between simultaneous shifts in c and L for Michelson’s choice of material. Indeed, solids are bonded by electromagnetic forces, so Lorentz violation in electrodynamics should change the length of a crystaL3 Furthermore, the solid consists of electrons and protons (the uncharged neutrons play a minor role here), so Lorentz violation in the fermionic equations of motion will likely distort crystal^.^?^ These effects modify the sensitivity of interferometer or cavity experiments. Moreover, they allow new tests for fermionic Lorentz violation.