Macroscopic quantum distinguishablity, identity and irreversibility (2502.20400v1)

Abstract: The basic characteristics of the classical many-particle (''macroscopic'') systems are notoriously hard to reproduce in quantum theory. In this paper we show that this is not the case for certain many-particle systems within the recently introduced theory of emergent local quantum times, the so-called, Local Time Scheme. For an isolated many-particle system consisting of large number of (approximately) isolated subsystems, distinguishability and individuality can be naturally and straightforwardly obtained. In effect, a single such many-particle system quickly evolves between the mutually approximately orthogonal states thus setting a trajectory in the state space that is not shared with any other such individual many-particle system. Irreversibility of such dynamical processes is justified for the individual systems but not for the statistical ensembles of such systems. As an application, we derive a genuine nonexponential law for decay of unstable systems, in accordance with some theoretical expectations. This, classically plausible, picture calls for detailed analysis regarding the relativistic causality and cosmological contexts.