Planck CMB observations constrain the spatial curvature parameter to |Ω_K| < 0.001 (Guth 1981; Planck 2018), the observational expression of the flatness problem. Without inflation, achieving this value from arbitrary initial conditions at the Planck epoch requires fine-tuning the early density to the critical density at one part in 10⁶⁰ or better, since any departure grows exponentially across cosmic history.
The standard model assumes a hot dense singular origin where the spatial curvature was set arbitrarily, and the model has no mechanism to flatten that curvature except by adding inflation as a separate epoch. Inflation, in turn, demands its own tuning of inflaton potential and field initial conditions, so the curvature problem is never truly resolved, only relocated.
SCT replaces the hot-dense-center with a superluminal collision between two pre-existing parent pockets. From this single change, Ω_K stops being a primordial initial condition. The thermalized debris field that became our visible universe was deposited by the collision overlap volume, which virializes naturally through the multi-stage cascade (P22, P36, P37, P38). The virial condition 2K + U = 0 (P69, applied hierarchically) generically produces near-flat geometry as the mechanical outcome of self-gravitating relaxation, not as a tuned starting point.
Two parent pockets intersecting at superluminal v_rel deposit kinetic energy across the entire overlap volume essentially simultaneously (P22, P24). The cascade then thermalizes that deposit through progressively decelerating stages, terminating well before t ≈ 1 second (P40). What remains is a virialized remnant whose curvature is the geometric consequence of virialization, with corrections of order (R_pocket / R_universe)² sitting far below the |Ω_K| < 0.001 observational bound. The observed near-flatness is not a 1-in-10⁶⁰ coincidence; it is what virialized debris fields look like.
This is the same mechanism that dissolves the flatness fine-tuning (recid 10), the horizon problem, the hierarchy problem (recid 6), and the entire constellation of pre-inflationary tunings. Should Ω_K ever be measured to be detectably nonzero at sub-horizon scales, the parsimonious SCT reading is gravitational embedding of our largest comoving frame within parent-structure potential wells (P11, P13, P58, P59, P60), not a closed 3-sphere or hyperbolic saddle global topology. There is no need for an inflaton field or an inflationary potential.
Detection of inflationary B-modes at tensor-to-scalar ratio r > 0.005 (LiteBIRD, CMB-S4) would refute the no-inflation virialization explanation. Independently, a confirmed measurement of Ω_K outside the |Ω_K| < 0.005 envelope at > 5σ that cannot be attributed to parent-frame embedding would refute the virialization-driven flatness mechanism.