CMB and large-scale structure measurements indicate the spatial geometry is flat to within roughly 0.4% (|Ω_k| ≈ 0). Without inflation, achieving this 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 from Ω_k = 0 grows rapidly over cosmic history (Guth 1981; Planck 2020).
The standard model assumes a hot dense Planck-epoch origin where any initial curvature grows exponentially as the universe evolves. Inflation was added to flatten that curvature, but inflation itself requires its own tuning of inflaton potential and field initial conditions. The flatness problem is deferred, not resolved.
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, and the relevant geometric question is what shape that overlap settles into through the cascade, not what curvature was set in some t = 0 singularity.
For the cascade to have produced an extended thermalized region capable of becoming our observable universe, the parent pockets must have intersected on nearly antiparallel trajectories (P22, P24); otherwise the overlap volume would have been small and asymmetric, and the resulting plasma would not have produced the observed isotropic CMB. Antiparallel parent-pocket trajectories produce an overlap volume whose virialized remnant satisfies 2K + U = 0 (P69, applied hierarchically), generically delivering near-flat geometry as the mechanical outcome of self-gravitating relaxation. The cascade does not require fine-tuning to produce flatness; it requires only that the parent pockets approached on nearly antiparallel paths, which is a geometric selection effect on which collisions produce observers, not a tuning condition.
The same mechanism dissolves the flatness problem (recid 10), the Ω_k bound (recid 11), the horizon problem (recid 14), and the hierarchy problem (recid 6). 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, an inflationary potential, or anthropic selection across a multiverse landscape.
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 Ω_k outside the |Ω_k| < 0.005 envelope at greater than 5σ that cannot be attributed to parent-frame embedding would refute the virialization-driven flatness mechanism.