Peak Heights

The heights of the acoustic peaks in the CMB temperature power spectrum encode the competition between gravitational compression and radiation pressure in the baryon-photon fluid. ΛCDM fits the observed peak heights well with six parameters, but subtle discrepancies in the relative heights — particularly the ratio of even to odd peaks, which measures the baryon-to-photon momentum ratio, and the overall damping envelope — have been noted in high-resolution analyses. SCT's thermalization mechanism produces a baryon-photon plasma whose initial conditions are determined by the collision kinetics rather than by inflation's adiabatic perturbations, but the subsequent acoustic evolution is identical to ΛCDM once the plasma state is established. The pre-existing matter in the colliding pockets provides a slightly different baryon-to-photon ratio than pure primordial nucleosynthesis would produce, potentially shifting the even-odd peak height ratio.

The angular momentum deposited by the collision also leaves a subtle imprint on peak heights through its effect on the large-scale tidal environment that modulates baryon loading across different sky directions. Regions aligned with the collision axis experienced slightly different baryon compression amplitudes than perpendicular regions, producing a direction-dependent peak height modulation that is averaged over in standard isotropic power spectrum analyses but contributes to the observed scatter in peak height measurements between different CMB experiments covering different sky patches. SCT predicts that this peak height variation is correlated with the CMB anomaly axis direction — a testable prediction that would distinguish it from instrument noise or foreground systematics.