Context, spacetime loops, and the interpretation of quantum mechanics

Abstract

Three postulates are discussed: first that well-defined properties cannot be assigned to an isolated system, secondly that quantum unitary evolution is atemporal, and thirdly that some physical processes are never reversed. It is argued that these give useful insight into quantum behaviour. The first postulate emphasizes the fundamental role in physics of interactions and correlations, as opposed to internal properties of systems. Statements about physical interactions can only be framed in a context of further interactions. This undermines the possibility of objectivity in physics. However, quantum mechanics retains objectivity through the combination of the second and third postulates. A rule is given for determining the circumstances in which physical evolution is non-unitary. This rule appeals to the absence of spacetime loops in the future evolution of a set of interacting systems. A single universe undergoing non-unitary evolution is a viable interpretation.