Effective Entropy, Decoherence, Thermality, and Relational Time from Deterministic Dynamics under Restricted Access

Abstract

This manuscript presents a finite-dimensional Page–Wootters clock–system–environment construction in which entropy growth and long-lived saturation emerge from strictly unitary global dynamics under restricted access. The model provides an explicit relational-time benchmark illustrating entanglement-driven mixedness and equilibration in clock-conditioned reduced states. The work is situated within quantum foundations and relational approaches to time. Supplementary numerical implementations and scripts will be made available following journal publication.