Decoherence and the Emergence of Classicality

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We consider the claim that decoherence explains the emergence of classicality in quantum systems, and conclude that it cannot. We show that, given a universe composed of a variety of subsystems, some of which are macroscopic and subject to decoherence-inducing interactions, and some of which are microscopic, the macroscopic subsystems do not display any distinctively classical behavior. Therefore, a universe in which macroscopic and microscopic do display distinct behavior must be in a very special, highly nongeneric quantum state.


A presentation at the Philosophy of Quantum Field Theory Workshop, which was held at The University of Western Ontario on April 24-26, 2009

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