Chapter 64: Decidable Regimes and the NFL Theorem

What distinguishes an Euler flow from a Navier–Stokes flow? Physically, the answer is dissipation: Euler flows conserve energy exactly, while NS flows lose energy to heat. In τ³, this distinction acquires a precise algebraic formulation. The NFL-boundary theorem shows that a step in the defect dynamics is non-dissipative if and only if it acts as an automorphism of the boundary character algebra H_∂. Dissipation—viscosity, friction, turbulent decay—corresponds to strict endomorphisms that push information deeper into the primorial filtration. This chapter proves the NFL theorem, establishes a universal decidability meta-theorem for all ten defect-tuple regimes, and instantiates it for each regime individually.