Chapter 45: The Threshold Ladder: From Baryogenesis to Recombination

The universe cools. As the boundary characters decrease along the α-orbit, the physical readout passes through a sequence of qualitative transitions — moments when the dominant physics changes from one regime to another. In orthodox cosmology, these are called phase transitions: the electroweak transition, the QCD transition, nucleosynthesis, recombination. In Category τ, they are thresholds — character-level crossings where one sector’s contribution to the source term T drops below a critical value and another sector takes over.

This chapter constructs the canonical threshold ladder: the ordered sequence of regime transitions from the electroweak threshold through baryogenesis, the neutron threshold, nucleosynthesis, hydrogen formation, and recombination. Each threshold is defined intrinsically — as a crossing condition on the boundary characters — not as a temperature or energy scale. The neutron threshold L_N is identified as a kernel invariant: the refinement depth at which the η-sector (Strong) confines and stable composite nucleons appear.

The chapter includes two honest scope boundaries: the τ-sphaleron question (baryon number violation, Sakharov conditions) is flagged as an open question, and the precise baryogenesis mechanism remains conjectural.