arXiv subjects
Publications and source records attributed to J. Finkelstein.
There has been considerable discussion of the claim by Stapp [Am. J. Phys. 65, 300 (1997)] that quantum theory is incompatible with locality. In this note I analyze the meaning of some of the statements used in this discussion.
Macroscopic objects appear to have definite positions. In a many-worlds interpretation of quantum theory, this appearance is an illusion; the correct view is the "view from outside" in which even macroscopic objects are in general in a superposition of different positions. In the Bohm model, objects really are in definite positions. This additional aspect of reality is accessible only from the "inside"; thus in the Bohm model the view from inside can be more correct than is the view from outside.
Interpretational questions that arise in the Consistent Histories formulation of quantum mechanics are illustrated by the familiar example of a beam passing through multiple slits.
Widom, Srivastava, and Sassaroli have published [Phys. Lett. A 203, 255 (1995)] a calculation which purports to show that "future events can affect present events". In this note an error in their calculation is identified.
A brief discussion is given of measurement within the context of a theory of "beables", e.g. theories of de Broglie, Bohm, Bell, Vink, and also "modal" theories. It is shown that even in an ideal von Neumann measurement of a beable, the measured value may not agree with the value which the beable had prior to the measurement.
We discuss an interpretation of the projection postulate that implies collapse of the wavefunction along the lightcone.
We examine the relationship between the decoherence of quantum-mechanical histories of a closed system (as discussed by Gell-Mann and Hartle) and environmentally-induced diagonalization of the density operator for an open system. We study a definition of decoherence which incorporates both of these ideas, and show that it leads to a consistent probabilistic interpretation of the reduced density operator.