Testing Unified Substrate Theory: Harmonic Structure and Predictions for Redshift Drift

This study tests for the harmonic structure predicted by Unified Substrate Theory in the Pantheon Type Ia supernova sample. Fixed β ≃ 9 and 2β modes are examined in the mean Hubble residuals and intrinsic variance against a family of smooth null models. The analysis finds strong harmonic structure conditional on the adopted statistical framework and derives a corresponding oscillatory prediction for future redshift-drift measurements.