The Path of the Light Beam in a Rotating Optical Resonator: An Analysis of the Eisele et al.\ (2009) Experiment

This article analyzes the path of the light beam in one of the cavities (arms) of the rotating optical resonator apparatus described by Antonini et al. (2005) and Eisele et al. (2009), which test the isotropy of the speed of light with extremely high precision. The analysis applies L-ARF (Light – Absolute Reference Framework), based on the principle t = s/c, to calculate the expected resonance frequency in the arm as a function of the apparatus's absolute velocity and orientation, covering all nine combinations of longitudinal and transverse motion relative to the arm's axis. The resulting prediction is compared with the Robertson–Mansouri–Sexl (RMS) test theory and with the experimentally measured result in Eisele et al. (2009). The analysis finds a sharp discrepancy between the L-ARF prediction and the observed null result, and identifies an open question regarding how resonance is maintained under continuous transverse velocity — a question left for future work.