Pure wave mechanics and the very idea of empirical adequacy

Louis de Broglie

Erwin Schrödinger

Cocco, Susanna

Everett’s Relative State Formulation is one of the most famous and debated interpretations of Quantum Theory. Further deepening of the debates has been made possible by the discovery of his unpublished notes and manuscripts. \nMy purpose is to examine Everett’s ideas about physical theories, and show that his understanding of actual experience can be put into correspondence with the latest forms of constructive empiricism and empirical adequacy: the problem of ‘extra structure’, which is the reason for metaphysical interpretations, can be solved by using a pragmatic criterion to choose in which way the theory should correspond to empirical evidence. \nA quantitative justification for probabilities in Everettian context is given in terms of typicality.

Louis de Broglie

Jeffrey Alan Barrett

Abstract Everett thought of the quantum measurement problem as one of providing a consistent description of nested measurement. He proposed solving the measurement problem by simply supposing that all physical systems whatsoever always obey the linear dynamics and hence never collapse. Dropping the collapse dynamics immediately solves the measurement problem, but it introduces two new problems: explaining determinate measurement records and explaining quantum probabilities. In addition to these, we also consider the problem of empirical coherence in the context of pure wave mechanics. We then discuss how Everett himself understood determinate records and probabilities in his relative-state formulation of pure wave mechanics. What he ultimately provided was an argument that his formulation of quantum mechanics was consistent and empirically faithful. We will see why this is a relative weak standard by which to judge the empirical adequacy of a physical theory.

Jeffrey Alan Barrett

Abstract We consider a number of radically different ways that Everett’s pure wave mechanics has been understood. Each of these reconstructions aims to provide a stronger variety of empirical adequacy than Everett’s own formulation of the theory. Among the alternative formulations of quantum mechanics we consider are splitting worlds, decohering worlds, many minds, many threads, and many maps. Each of these differs in its metaphysical commitments and, hence, in how it explains determinate measurement records and probabilities. We focus, in particular, on the problem of accounting for the standard quantum probabilities. To this end, we consider the relationship between typicality and probability and contrast synchronic and forward-looking probabilities. We conclude with a brief discussion of epistemological, pragmatic, and information-theoretic formulations of quantum mechanics. A recurring issue in this chapter concerns what it should mean for a physical theory to be empirically adequate.