2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/92907Using an elementary example based on two simple harmonic oscillators, we show how a relational time may be defined that leads to an approximate Schrodinger dynamics for subsystems, with corrections leading to an intrinsic decoherence in the energy eigenstates of the subsystem.Contribution to the Int. J. of Quant. Info. issue dedicated to the memory of Asher PeresQuantum PhysicsGeneral Relativity and Quantum Cosmologytext