1998/07/27 by L. Vaidman
Physics and Astronomy · #quant-ph
published as Found.Phys. 29 (1999) 755-765 · This is a preprint from July 97 and it has partial overlap with quant-ph/9609007 and quant-ph/9802042. It is submitted now, in part because the paper (accepted for publication) by R. Kastner, quant-ph/9806002 addresses this manuscript
arxiv created 1998/07/27 · arxiv updated 2009/12/01
Recently, several authors have criticized the time-symmetrized quantum theory originated by the work of Aharonov et al. (1964). The core of this criticism was a proof, appearing in various forms, which showed that the counterfactual interpretation of time-symmetrized quantum theory cannot be reconciled with standard quantum theory. I argue here that the apparent contradiction is due to a logical error. I analyze the concept of counterfactuals in quantum theory and introduce time-symmetrized counterfactuals. These counterfactuals do not lead to any contradiction with the predictions of quantum theory. I discuss applications of time-symmetrized counterfactuals to several surprising examples and show the usefulness of the time-symmetrized quantum formalism.