Statistics of Local Value in Quantum Mechanics

J.G. Muga, J.P. Palao, R. Sala

Leon W. Cohen

CHRISTOF WETTERICH

We formulate incomplete classical statistics for situations where the knowledge about the probability distribution outside a local region is limited. The information needed to compute expectation values of local observables can be collected in a quantum mechanical state vector, whereas further statistical information about the probability distribution outside the local region becomes irrelevant. The translation of the available information between neighboring local regions is expressed by a Hamilton operator. A quantum mechanical operator can be associated to each local observable, such that expectation values of ``classical'' observables can be computed by the usual quantum mechanical rules. The requirement that correlation functions should respect equivalence relations for local obeservables induces a non-commutative product in classical statistics, in complete correspondence to the quantum mechanical operator product. We also discuss the issue of interference and the complex structure of quantum mechanics within our classical statistical setting.

CHRISTOF WETTERICH

The quantum mechanical concepts of states and operators arise naturally from the question how expectation values of observables can be computed in classical statistical systems where only incomplete local information about the probability distribution is available. The notions of evolution and time are related to the translation of the available information between neighboring local regions. The complex structure of quantum mechanics, the superposition of states and the interference effects characteristic for quantum statistics find a simple origin. This suggests the emergence of quantum mechanics from classical statistics with infinitely many degrees of freedom.

Michael J. Creutz, Barry A. Freedman

Jeffrey Bub, Vandana Shiva

The conceptually puzzling features of quantum mechanics as a statistical theory all have their source in the impossibility of relating the probability assignments defined by the quantum state to distributions over determinate values of the physical magnitudes. While some interpretations of quantum mechanics, as well as “hidden variable” modifications of the theory, have proposed several constructions for assigning values to magnitudes (beyond the value assignments defined by the quantum state alone), a variety of theorems exist which impose severe restrictions on such theoretical constructions. This note will deal with Bell's proof (in [2]), that any hidden variable theory satisfying a physically reasonable locality condition is characterized by an inequality which is inconsistent with the quantum statistics. Bell's result has initiated a series of experiments designed to refute the entire class of local hidden variable theories. We show that Bell's inequality actually characterizes a feature of hidden variable theories which is much weaker than locality in the sense considered physically motivated.