UnBorn: Probability in Bohmian Mechanics

Why are quantum probabilities encoded in measures corresponding to wave functions, rather than by a more general (or more specific) class of measures? Whereas orthodox quantum mechanics has a compelling answer to this question, Bohmian mechanics might not

UnBorn: Probability in Bohmian Mechanics

Why are quantum probabilities encoded in measures corresponding to wave functions, rather than by a more general (or more specific) class of measures? Whereas orthodox quantum mechanics has a compelling answer to this question, Bohmian mechanics might not

Infinite Idealizations in Science: An Introduction

We offer a framework for organizing the literature regarding the debates revolving around infinite idealizations in science, and a short summary of the contributions to this special issue

Author Meets Critics: Jill North, Physics, Structure and Reality

Commentary and responses from 2022 Eastern APA book symposium for Jill North's Physics, Structure and Reality

A Matter of Degree: Putting Unitary Equivalence to Work

A characteristic feature of quantum field theory is the availability of unitarily inequivalent representations of its canonical commutation relations. Under the prima facie reasonable assumption that unitary equivalence is a necessary condition for physical equivalence, this availability implies that there are many physically inequivalent quantizations of any classical field theory. To explore this dramatic non-uniqueness, and its implications for our understanding of how physical theories delimit physical possibility, I examine some of the uses to which unitarily inequivalent representations are put in another setting in which they arise: the thermodynamic limit of quantum statistical mechanics

When the Concrete is Hard

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/169283/1/phpr12817_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/169283/2/phpr12817.pd

Why Be Normal?

A normal state on a von Neumann algebra defines a countably additive probability measure over its projection lattice. The von Neumann algebras familiar from ordinary QM are algebras of all the bounded operators on a Hilbert space H, aka Type I factor von Neumann algebras. Their normal states are density operator states, and can be pure or mixed. In QFT and the thermodynamic limit of QSM, von Neumann algebras of more exotic types abound. Type III von Neumann algebras, for instance, have no pure normal states; the pure states they do have fail to be countably additive. I will catalog a number of temptations to accord physical significance to non-normal states, and then give some reasons to resist these temptations: (1) pure though they may be, non-normal states on non-Type I factor von Neumann algebras can\u27t do the interpretive work we\u27ve come to expect from pure states on Type I factors; (2) our best accounts of state preparation don\u27t work for the preparation of non-normal states; (3) there is a sense in which non-normal states fail to instantiate the laws of quantum mechanics