The universe is flat to |Ω_k| < 0.005, which under standard expansion requires the Planck-epoch density tuned to critical at one part in 10⁶⁰. Inflation converts the tuning into a prediction, but rents the solution from an undiscovered field with a hand-tuned potential, a required sixty e-folds, and an initial smooth patch that re-imports the problem it was hired to solve. Flatness is precisely measured and only conditionally explained.
Curvature is unstable under the model's expansion: any initial imbalance grows without limit, so observed flatness demands either an exponentially improbable starting point or a designed mechanism to flatten it. The model's singular origin offers no physics for the starting point, leaving inflation as load-bearing conjecture.
SCT derives near-flatness from the mechanics of the origin event itself. Our patch is the thermalized remnant of a superluminal collision (P22), and a self-gravitating remnant settles by virialization: the virial theorem, 2K + U = 0, fixes the balance between kinetic and gravitational energy as a mechanical endpoint, not a selected initial condition (P69). That balance is, in geometric terms, the near-critical density condition: the remnant's energy budget relaxes to the configuration that reads as flat, the way a dropped chain finds its catenary, without anyone aiming for one configuration among 10⁶⁰. Flatness emerges from ordinary gravitational settling applied to the collision remnant, with no inflaton, no e-fold accounting, and no smooth initial patch required (the same single replacement that dissolves the horizon problem, since the overlap volume thermalized simultaneously rather than equilibrating causally, P24).
The knife edge was an artifact of running a fine-tuned expansion backward toward a singular origin that never happened. Start instead from a collision and the question inverts: a virialized remnant would have to be prevented from sitting near critical density. Two premises carry the resolution; the derivation is laid out in Paper 1, From Chaos to Convergent Foundations (the P24 unification and the virial condition of P69), with the same event covering the horizon problem in the same section.
The mechanism tolerates only residual curvature consistent with settling: a future precision measurement (CMB-S4 plus DESI) finding |Ω_k| significantly nonzero, curvature inflation would have erased but virialization merely bounds, would discriminate against both accounts in different ways, while a confirmed primordial B-mode background at r above 0.01 would establish the inflationary epoch directly and remove SCT's no-inflation account of flatness along with its tensor floor.