Cluster centers split sharply into cool cores that should cool catastrophically but do not, and non-cool cores that mergers should produce but cannot, with the middle ground nearly empty (Fabian 2012; McDonald 2018). The feedback loop must regulate perfectly for gigayears, the mergers must disrupt resilient cores, and the bimodality itself fits no continuous process.
The model builds every cluster center the same way, gravitational collapse plus cooling plus feedback, so central diversity must be generated by history: merger luck and AGN duty cycles. A sharp two-family split with empty middle ground is the signature of an initial condition, which is the one ingredient the assembled-center picture does not stock.
SCT supplies the initial condition. Cluster centers inherit their thermodynamic state from the collision-cascade deposits that seeded them: the relic entropy stamped at thermalization is conserved adiabatically thereafter (P29, P30), the same registered mechanism behind the universal entropy floor and the steepened luminosity-temperature relation (recid 126). Deposit geometry is naturally bimodal in its central outcome, compact low-J deposits build dense low-entropy centers that become cool cores, while higher-impact-parameter and multi-stage depositions leave flatter high-entropy centers that present as non-cool cores (P22, P25), so the two families are two deposit classes, the empty middle ground reflecting the geometry's preference rather than improbable history.
The maintenance problems ease on both sides: cool-core resilience is expected because the core state is a conserved initial condition rather than a fragile equilibrium, and the cooling-flow regulation asks less of AGN feedback because the relic entropy floor (the registered K₀ near 100 to 300 keV cm²) sets a conserved thermodynamic baseline beneath the cooling. The registered discriminants travel with the floor: CC/NCC fractions should be roughly stable with redshift rather than merger-tracking, and the core families should appear equally in AGN-quiet and AGN-active systems. The relic-entropy mechanics are in Paper 6, From Chaos to Cosmic Collisions, Section 7.
Keystone economy: P29 conserves the deposit's stamp, P22 makes the stamp bimodal. The two families were born, not made.
The registered kills track the initial-condition claim: Athena-class X-ray surveys finding the CC/NCC fractions evolving strongly with redshift in lockstep with merger rates, or core states correlating tightly with current AGN activity rather than appearing in quiet and active systems alike, would restore the assembled-center picture. The floor cuts with it: relic entropy demands K₀(z = 2) comparable to K₀(z = 0); strong evolution of the entropy floor refutes the conserved-deposit reading directly.