This grant in mathematical physics will use the "consistent-history" approach to resolve some longstanding problems relating to the properties of a quantum mechanical system. First, the approach will be applied to the relation of quantum mechanics to the statistical irreversibility embodied in the second law of thermodynamics. Then it will be used to illuminate a collection of paradoxes in which quantum mechanics predicts violations of either Bell's inequality or common-sense notions of reality, locality and the like. A study of the consistency of various quantum mechanical histories will indicate where the sources of various conceptual problems are.
