The observed spatial flatness |Ω_K| < 0.005 (Planck 2018) implies that at the Planck epoch the total density had to equal the critical density to one part in 10⁶⁰. Any tiny deviation would have grown exponentially as the universe evolved, producing either rapid recollapse or runaway expansion before structure could form (Liddle & Lyth 2000). Inflation was proposed to resolve this, but inflation itself requires fine-tuned initial conditions on the inflaton potential.
The standard model assumes a hot dense singular origin at the Planck scale with arbitrary curvature. Under that history, any departure from Ω_K = 0 grows mechanically over cosmic time, so achieving today's near-flatness demands extraordinary tuning at t = 0. Inflation defers the tuning into the inflaton sector but does not remove it.
SCT replaces the hot-dense-center with a superluminal collision between two pre-existing parent pockets. From this single change, there is no Planck-epoch starting point at which curvature could be arbitrarily set. 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 volume settles into, not what initial curvature was set in some t = 0 singularity.
The collision overlap virializes through the multi-stage cascade (P22, P36, P37, P38), with energy distributed across the cumulative thermalization rather than concentrated at one moment. The cascade terminates well before t ≈ 1 second (P40), leaving a thermalized region whose geometry is the mechanical consequence of virialization. The virial condition 2K + U = 0 (P69, applied hierarchically to the virializing remnant) generically produces near-flat geometry, with curvature corrections of order (R_pocket / R_universe)² that sit far below current observational sensitivity. Flatness is the expected outcome of virialization, not a fine-tuned initial condition.
The same M1 mechanism that dissolves the flatness problem also dissolves the horizon problem (the entire overlap volume thermalized simultaneously during the superluminal intersection, before any internal signal could traverse it — P22, P24, P43), the hierarchy problem (recid 6), and the question of why structure exists at all without inflation. There is no need for an inflaton field, an inflationary potential, or a Lyth bound. Flatness is what virialized self-gravitating systems do.
Detection of primordial inflationary B-modes at tensor-to-scalar ratio r > 0.005 (LiteBIRD, CMB-S4) would re-introduce the inflationary picture and refute SCT's virialization-flatness explanation. Independently, any observation requiring the universe to have passed through Planck-scale energies (GUT-scale relics, monopoles at observable abundance) would refute the no-Planck-epoch claim.