Extra dimensions, preferred frames and ether-drift experiments

TL;DR

This paper explores how extra dimensions and gravitational effects can induce a preferred frame in physics, proposing specific experimental tests with optical resonators and analyzing recent data for evidence of Lorentz invariance violation.

Contribution

It introduces a model linking extra dimensions to a refractive index effect, predicting observable modulations in ether-drift experiments, and compares these predictions with recent experimental results.

Findings

Predicted signal modulations due to Earth's motion.

Potential first evidence of a preferred frame.

Compatibility of experimental data with model predictions.

Abstract

Models with extra space-time dimensions produce, tipically, a 4D effective theory whose vacuum is not exactly Lorentz invariant but can be considered a physical medium whose refractive index is determined by the gravitational field. This leads to a version of relativity with a preferred frame and to look for experimental tests with the new generation of ether-drift experiments using rotating cryogenic optical resonators. Considering various types of cosmic motion, we formulate precise predictions for the modulations of the signal induced by the Earth's rotation and its orbital revolution around the Sun. We also compare with recent experimental results that might represent the first modern experimental evidence for a preferred frame.