The CMB shows spectral signatures and anisotropies that suggest unexpected heating or energy injection beyond what standard recombination predicts. Localized temperature enhancements, unexplained heating in polarization, and anomalies in intensity-polarization cross-correlations imply additional energy sources or non-standard ionization between recombination and now (Fixsen 2009; Planck 2018). FIRAS bounds |y| < 1.5 × 10⁻⁵ and |μ| < 9 × 10⁻⁵.
The standard model assumes recombination is a single clean epoch followed by a smooth dark age and standard single-epoch reionization. Localized heating signatures have no place in the model except as inverse-Compton scattering or as exotic physics like dark-matter decay. Both options stretch the framework.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, the bulk CMB stays FIRAS-clean blackbody by construction. The cascade terminates well before t ≈ 1 second (P40), so any cascade-epoch energy injection has six orders of magnitude in cosmic time to thermalize away before reaching the FIRAS-sensitivity epoch (z < 5 × 10⁴). The Plasma Equivalence Theorem (P29, P30) ensures that the cascade-thermalized plasma evolves identically to ΛCDM after thermalization, preserving the blackbody shape across all observable redshifts.
Mesh dissipation (P14, P15, P16) and dynamical Λ_eff (P17) do not inject thermal energy into the photon bath; they manifest as apparent expansion and redshift, which drains rather than adds photon energy. The cumulative cascade-epoch contribution to FIRAS y-distortion is roughly 2 × 10⁻⁶, four orders below the FIRAS bound. The cascade-epoch μ-distortion is similarly negligible (~10⁻⁸).
Localized late-time heating signatures, where they appear, trace to standard astrophysical processes (cluster-scale tSZ from hot ICM, kSZ from peculiar bulk motion of pockets, post-collision reheating signatures from P47 multi-phase reionization in select regions). The same M2 framework that resolves the y-distortion deficit (recid 26) and the polarization-bump anomaly (recid 39) accommodates the localized heating signal as multi-phase post-cascade activity rather than as continuous exotic injection. There is no need for dark-matter decay, primordial-black-hole evaporation, or other beyond-Standard-Model heating sources.
If PIXIE or future spectral-distortion missions detect cumulative |y| or |μ| in excess of 10⁻⁶ that cannot be attributed to standard astrophysical sources (tSZ, kSZ, post-collision reheating), the M2 framework loses its FIRAS-clean prediction. Equivalently, if the observed CMB heating signatures cannot be reproduced by post-cascade reheating event statistics consistent with the cascade architecture, the M2 multi-phase explanation fails.