2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/36219Motivated by the consistent histories approach to quantum mechanics, we examine a simple model of hydrodynamic coarse-graining for a scalar field. It consists in averaging the field over spatial regions of size L and constructing the evolution equation for the coarse grained quantities, thus identifying dissipation and noise.17 pages, LATEXGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext