1995/03/31 by William G. Unruh, Robert M. Wald · 2 citations
Physics and Astronomy · #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.52.2176
published as Phys.Rev. D52 (1995) 2176-2182 · 19pages, RevTeX3, We have added a number of references and clarified the role of the Markovian approximation in the loss of energy conservation
arxiv created 1995/05/23 · arxiv updated 2009/11/30
It has been argued that any evolution law taking pure states to mixed states in quantum field theory necessarily gives rise to violations of either causality or energy-momentum conservation, in such a way as to have unacceptable consequences for ordinary laboratory physics. We show here that this is not the case by giving a simple class of examples of Markovian evolution laws where rapid evolution from pure states to mixed states occurs for a wide class of states with appropriate properties at the ``Planck scale", suitable locality and causality properties hold for all states, and the deviations from ordinary dynamics (and, in particular, violations of energy-momentum conservation) are unobservably small for all states which one could expect to produce in a laboratory. In addition, we argue (via consideration of other, non-Markovian models) that conservation of energy and momentum for all states is not fundamentally incompatible with causality in dynamical models in which pure states evolve to mixed states.