General Relativity as the Equation of State of a Finite-Capacity Causal-Informational Substrate

We argue that General Relativity is not a fundamental microscopic law, but the local equilibrium equation of state of a nite-capacity causal-informational substrate. In the Causal-Informational Spectral (CIS) framework, each nite causal interval carries a graph Laplacian, a normalized spectral state, and a spectral entropy, while local dynamics are governed by variationally selected updates subject to bounded local capacity. In the homogeneous near-equilibrium continuum-supporting phase, we show that the rst variation of spectral entropy is boundary-supported and that the corresponding coarse-grained entropy variation matches the form required by Jacobson's thermodynamic construction. Einstein's equations therefore emerge as the Clausius relation of the substrate. Finite capacity also reinterprets singularities as failures of continuum validity rather than fundamental in nities. Essay written for the Gravity Research Foundation 2026 Awards for Essays on Gravitation.