Finite-Capacity Thermodynamics of Causal Horizons

This work proposes that fundamental physics remains unchanged, but its local classical representability is limited by the finite entropic capacity of causal horizons. Geometric entanglement entropy is treated as a thermodynamic potential, and horizons as finite-capacity information systems. When this capacity is saturated, local semiclassical descriptions break down without affecting underlying unitary dynamics. This defines a representational, not dynamical, transition, where configurations persist but cannot be locally encoded. This work formalizes this limit of representation as an intrinsic entropic bound.