Stochastic space-time and laser interferometry

Several theoretical arguments indicate that space-time may have the fundamental stochastic nature of a turbulent fluid. This view, where Lorentz symmetry represents an emergent phenomenon, has phenomenological implications for those `ether-drift' experiments that look for the possible existence of a preferred reference frame. In fact, numerical simulations show that, in present experiments with vacuum optical resonators, it becomes non trivial to understand if an irregular instantaneous signal is just spurious noise or has a genuine physical origin. To obtain further checks, experiments with light propagating in gaseous systems are particularly interesting. In fact, the transformation matrix, which connects the effective space-time metric for light propagation in the laboratory frame to the corresponding isotropic metric in the hypothetical preferred frame, is a two-valued function for refractive index N = 1+ɛ. This symmetry argument, when combined with the idea of a stochastic space-time, provides a new scheme where the small irregular residuals observed in all classical ether-drift experiments and in the 1963 MIT experiment with He-Ne lasers become consistent with the average Earth's velocity of 370 km/s which is obtained from the CMB observations. This remarkable agreement should motivate additional, precise tests with a new generation of laser interferometers.