Wayne C. Myrvold

On peaceful coexistence: is the collapse postulate incompatible with relativity?

Abstract In this paper, it is argued that the prima facie conflict between special relativity and the quantum-mechanical collapse postulate is only apparent, and that the seemingly incompatible accounts of entangled systems undergoing collapse yielded by different reference frames can be regarded as no more than differing accounts of the same processes and events. Attention to the transformation properties of quantum-mechanical states undergoing unitary, non-collapse evolution points the way to a treatment of collapse evolution consistent with the demands of relativity.

A Bayesian account of the virtue of unification

A Bayesian account of the virtue of unification is given. On this account, the ability of a theory to unify disparate phenomena consists in the ability of the theory to render such phenomena informationally relevant to each other. It is shown that such ability contributes to the evidential support of the theory, and hence that preference for theories that unify the phenomena need not, on a Bayesian account, be built into the prior probabilities of theories.

Modal Interpretations and Relativity

A proof is given, at a greater level of generality than previous “no-go” theorems, of the impossibility of formulating a modal interpretation that exhibits “serious” Lorentz invariance at the fundamental level. Particular attention is given to modal interpretations of the type proposed by Bub.

On some early objections to Bohm's theory

Recent literature on Bohms alternative to mainstream quantum mechanics may create the misleading impression that, except for perfunctory dismissals, the theory was ignored by the physics community in the years immediately following its proposal. As a matter of fact, Einstein, Pauli, and Heisenberg all published criticisms of Bohms theory, explaining their reasons for not accepting the theory. These criticisms will be discussed and evaluated in this article.

Deterministic Laws and Epistemic Chances

In this paper, a concept of chance is introduced that is compatible with deterministic physical laws, yet does justice to our use of chance-talk in connection with typical games of chance, and in classical statistical mechanics. We take our cue from what Poincare called “the method of arbitrary functions,” and elaborate upon a suggestion made by Savage in connection with this. Comparison is made between this notion of chance, and David Lewis’ conception.

Model Selection, Simplicity, and Scientific Inference

The Akaike Information Criterion can be a valuable tool of scientific inference. This statistic, or any other statistical method for that matter, cannot, however, be the whole of scientific methodology. In this paper some of the limitations of Akaikean statistical methods are discussed. It is argued that the full import of empirical evidence is realized only by adopting a richer ideal of empirical success than predictive accuracy, and that the ability of a theory to turn phenomena into accurate, agreeing measurements of causally relevant parameters contributes to the evidential support of the theory. This is illustrated by Newton’s argument from orbital phenomena to the inverse‐square law of gravitation.

What is a Wavefunction

Much of the the discussion of the metaphysics of quantum mechanics focusses on the status of wavefunctions. This paper is about how to think about wavefunctions, when we bear in mind that quantum mechanics—that is, the nonrelativistic quantum theory of systems of a fixed, finite number of degrees of freedom—is not a fundamental theory, but arises, in a certain approximation, valid in a limited regime, from a relativistic quantum field theory. We will explicitly show how the wavefunctions of quantum mechanics, and the configuration spaces on which they are defined, are constructed from a relativistic quantum field theory. Two lessons will be drawn from this. The first is that configuration spaces are not fundamental, but rather are derivative of structures defined on ordinary spacetime. The second is that wavefunctions are not as much like classical fields as might first appear, in that, on the most natural way of constructing wavefunctions from quantum field-theoretic quantities, the value assigned to a point in configuration space is not a local fact about that point, but rather, depends on the global state.

A Loophole in Bell`s Theorem? Parameter Dependence in the Hess-Philipp Model

The hidden‐variables model constructed by Karl Hess and Walter Philipp is claimed by its authors to exploit a “loophole” in Bells theorem; according to Hess and Philipp, the parameters employed in their model extend beyond those considered by Bell. Furthermore, they claim that their model satisfies Einstein locality and is free of any “suspicion of spooky action at a distance.” Both of these claims are false; the Hess‐Philipp model achieves agreement with the quantum‐mechanical predictions, not by circumventing Bells theorem, but via Parameter Dependence.

On the Evidential Import of Unification

There are two senses in which a hypothesis may be said to unify evidence: (1) ability to increase the mutual information of a set of evidence statements; (2) explanation of commonalities in phenomena by positing a common origin. On Bayesian updating, only Mutual Information Unification contributes to incremental support. Defenders of explanation as a confirmatory virtue that makes independent contribution must appeal to some relevant difference between humans and Bayesian agents. I argue that common origin unification has at best a limited heuristic role in confirmation. Finally, Reichenbachian common cause hypotheses are shown to be instances of Mutual Information Unification.

On the Debate Concerning the Proper Characterization of Quantum Dynamical Evolution

There has been a long-standing and sometimes passionate debate between physicists over whether a dynamical framework for quantum systems should incorporate not completely positive (NCP) maps in addition to completely positive (CP) maps. Despite the reasonableness of the arguments for complete positivity, we argue that NCP maps should be allowed, with a qualification: these should be understood, not as reflecting ‘not completely positive’ evolution, but as linear extensions, to a system’s entire state space, of CP maps that are only partially defined. Beyond the domain of definition of a partial-CP map, we argue, much may be permitted.