Macroscopic Superpositions, Decoherent Histories and the Emergence of Hydrodynamic Behaviour

摘要: Macroscopic systems are described most completely by local densities (particle number, momentum and energy) yet the superposition states of such physical variables, indicated Everett interpretation, not observed. In order to explain this, it is argued that histories energy density approximately decoherent when coarse-grained over sufficiently large volumes. Decoherence arises directly from proximity these variables exactly conserved quantities (which decoherent), environmentally-induced decoherence. We discuss approach equilibrium subsequent emergence hydrodynamic equations for densities. The results general but we focus on a chain oscillators as specific example in which explicit calculations may be carried out. relationships between conservation-induced decoherence present unified view two mechanisms.