The CMB temperature is uniform to one part in 100,000 across regions that, in a hot Big Bang without inflation, were never in causal contact and could not have thermally equilibrated through light-speed signal exchange. Inflation solves this by stretching a small causally connected patch to enormous size, but the inflaton potential and inflationary initial conditions require their own fine-tuning (Guth 1981; Kolb & Turner 1990).
The standard model assumes thermal equilibration was achieved by light-speed-limited causal communication between widely-separated regions of the post-Big-Bang plasma. Under that assumption, regions outside each other's particle horizons cannot share temperature, so an additional mechanism (inflation) is needed to put them in prior contact.
SCT replaces the hot-dense-center with a superluminal collision between two pre-existing parent pockets. From this single change, thermal equilibration was never constrained by light-speed signal propagation to begin with. When two pockets with v_rel > 2c intersect, the intersection front sweeps through the entire overlap volume faster than any internal signal can traverse it (P22, P43). The full overlap volume is engulfed and thermalized essentially simultaneously by the junction-condition stress-energy deposit, before any internal causal communication is needed.
This does not violate special relativity. SR's speed limit applies to objects accelerated through a single inertial frame by local forces (P20). It does not constrain the relative velocity between two pockets that were never in the same inertial frame and whose relative velocity was never built up by any local acceleration (P20, P21). The collision's phase-velocity front carries no information faster than c — group velocity remains subluminal throughout (P43) — but the geometric simultaneity of thermalization across the overlap volume happens regardless. The resulting plasma evolves under standard physics from a thermodynamically uniform initial state, naturally producing the observed CMB uniformity to one part in 10⁵.
The same M1 mechanism dissolves the flatness problem (recid 10), the hierarchy problem (recid 6), and the constellation of pre-inflationary tunings. Where ΛCDM had to invent inflation as a separate epoch with its own fine-tuned potential, SCT obtains the equivalent observational result as a generic property of how superluminal collisions thermalize. There is no need for an inflaton field, an inflationary potential, or a Lyth bound on tensor-to-scalar ratio.
Detection of a CMB region with statistically incompatible temperature evolution from the rest of the sky — evidence that the overlap volume was NOT thermalized as one geometrically simultaneous event — would refute the M1 simultaneous-thermalization mechanism. Independently, detection of inflationary B-modes at tensor-to-scalar r > 0.005 (LiteBIRD, CMB-S4) would re-introduce inflation and refute the no-inflation framework.