Entropy as Physical Exclusion: A Boltzmannian Ontology of Irreversibility

This paper proposes an ontological interpretation of entropy in which irreversibility is understood as a process of physical exclusion rather than probabilistic disorder or epistemic ignorance. Entropy increase is identified with the irreversible loss of causal accessibility to prior microstates, enforced by objective physical limits on information recovery. By grounding irreversibility in established principles—Landauer’s bound on information processing, the Bekenstein bound on information density, and relativistic causal structure—the framework resolves classical paradoxes such as Loschmidt’s paradox, Maxwell’s demon, and Poincaré recurrence without modifying the dynamical laws of physics. The result is a physically constrained ontology in which the past is fixed because the states required to reconstruct it are no longer energetically or causally reachable.