Quantum Mechanics, Propensities, and Realism
Dissertation, The Johns Hopkins University (
1990)
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Abstract
The goal of the dissertation is, first, to develop in the tradition of conventional quantum mechanics what I call a propensity view of quantum properties, and to examine its coherence. Conventional quantum mechanics assumes the completeness of quantum mechanics. Taking the ontic version of the completeness assumption, which says that a state vector completely describes an individual quantum system as it is, I argue that the propensity view of quantum properties, i.e., the attribution of certain irreducible propensities to a quantum system, is not only demanded but also can be coherently maintained. ;Second, I evaluate the relation between a propensity view of quantum properties and the demands of Einstein's program of realism, the backbone of which is the requirement that physical systems, as described by a theory, have properties independently of measurement. In doing so, I argue for a non-relational version of the quantum propensity view, which amounts to attributions propensities to individual quantum systems, and claim that conventional quantum mechanics together with the non-relational propensity view of quantum properties realizes physical realism, which is a particular version of Einstein's realist thesis and which reads that a physical system, as described by a theory, has at least some of its extrinsic properties independently of measurement. ;Third, quantum mechanics, in spite of its empirical success, has suffered from certain well-known conceptual puzzles, viz., the measurement problem and the problem of nonlocality as it arises in the Einstein-Podolsky-Rosen paradox. So we ask whether the propensity view of quantum properties can help us the resolve these problems. I argue that the so-called reduction of the wave packet is the source of both problems and suggest that there is a sense in which the propensity view of quantum properties explains the reduction of the wave packet and its nonlocal nature. On the other hand, the propensity view by itself fails to resolve the question of when or in what circumstances the reduction of the wave packet occurs, indicating that we do not as yet possess a complete understanding of quantum propensities