Reeh-Schlieder Defeats Newton-Wigner: On alternative localization schemes in relativistic quantum field theory

Many of the "counterintuitive" features of relativistic quantum field theory have their formal root in the Reeh-Schlieder theorem, which in particular entails that local operations applied to the vacuum state can produce any state of the entire field. It is of great interest, then, that I.E. Segal and, more recently, G. Fleming (in a paper entitled "Reeh-Schlieder Meets Newton-Wigner") have proposed an alternative "Newton-Wigner" localization scheme that avoids the Reeh-Schlieder theorem. In this paper, I reconstruct the Newton-Wigner localization scheme and clarify the limited extent to which it avoids the counterintuitive consequences of the Reeh-Schlieder theorem. I also argue that neither Segal nor Fleming has provided a coherent account of the physical meaning of Newton-Wigner localization.Comment: 25 pages, LaTe

A note on information theoretic characterizations of physical theories

Clifton, Bub, and Halvorson [Foundations of Physics 33, 1561 (2003)] have recently argued that quantum theory is characterized by its satisfaction of three information-theoretic axioms. However, it is not difficult to construct apparent counterexamples to the CBH characterization theorem. In this paper, we discuss the limits of the characterization theorem, and we provide some technical tools for checking whether a theory (specified in terms of the convex structure of its state space) falls within these limits.Comment: 16 pages, LaTeX, Contribution to Rob Clifton memorial conferenc

Momentum and Context

A sentence's meaning may depend on the state of motion of the speaker. I argue that this context-sensitivity blocks the inference from special relativity to four-dimensionalism

There is no invariant, four-dimensional stuff

Some philosophers say that in special relativity, four-dimensional stuff is invariant in some sense that three-dimensional stuff is not. I show that this claim is false

Are Rindler Quanta Real? Inequivalent particle concepts in quantum field theory

Philosophical reflection on quantum field theory has tended to focus on how it revises our conception of what a particle is. However, there has been relatively little discussion of the threat to the "reality" of particles posed by the possibility of inequivalent quantizations of a classical field theory, i.e., inequivalent representations of the algebra of observables of the field in terms of operators on a Hilbert space. The threat is that each representation embodies its own distinctive conception of what a particle is, and how a "particle" will respond to a suitably operated detector. Our main goal is to clarify the subtle relationship between inequivalent representations of a field theory and their associated particle concepts. We also have a particular interest in the Minkowski versus Rindler quantizations of a free Boson field, because they respectively entail two radically different descriptions of the particle content of the field in the very same region of spacetime. We shall defend the idea that these representations provide complementary descriptions of the same state of the field against the claim that they embody completely incommensurable theories of the field.Comment: 62 pages, LaTe

Morita Equivalence

Logicians and philosophers of science have proposed various formal criteria for theoretical equivalence. In this paper, we examine two such proposals: definitional equivalence and categorical equivalence. In order to show precisely how these two well-known criteria are related to one another, we investigate an intermediate criterion called Morita equivalence.Comment: 30 page

Mutual Translatability, Equivalence, and the Structure of Theories

This paper presents a simple pair of first-order theories that are not definitionally (nor Morita) equivalent, yet are mutually conservatively translatable and mutually 'surjectively' translatable. We use these results to clarify the overall geography of standards of equivalence and to show that the structural commitments that theories make behave in a more subtle manner than has been recognized