•  10
    Eliminating Electron Self-repulsion
    Foundations of Physics 53 (4): 1-15. 2023.
    Problems of self-interaction arise in both classical and quantum field theories. To understand how such problems are to be addressed in a quantum theory of the Dirac and electromagnetic fields (quantum electrodynamics), we can start by analyzing a classical theory of these fields. In such a classical field theory, the electron has a spread-out distribution of charge that avoids some of the problems of self-interaction facing point charge models. However, there remains the problem that the electr…Read more
  •  199
    Absorbing the Arrow of Electromagnetic Radiation
    Studies in History and Philosophy of Science Part A 99 (C): 10-27. 2023.
    We argue that the asymmetry between diverging and converging electromagnetic waves is just one of many asymmetries in observed phenomena that can be explained by a past hypothesis and statistical postulate (together assigning probabilities to different states of matter and field in the early universe). The arrow of electromagnetic radiation is thus absorbed into a broader account of temporal asymmetries in nature. We give an accessible introduction to the problem of explaining the arrow of radia…Read more
  •  10
    In electrostatics, we can use either potential energy or field energy to ensure conservation of energy. In electrodynamics, the former option is unavailable. To ensure conservation of energy, we must attribute energy to the electromagnetic field and, in particular, to electromagnetic radiation. If we adopt the standard energy density for the electromagnetic field, then potential energy seems to disappear. However, a closer look at electrodynamics shows that this conclusion actually depends on th…Read more
  •  40
    The fundamentality of fields
    Synthese 200 (5): 1-28. 2022.
    There is debate as to whether quantum field theory is, at bottom, a quantum theory of fields or particles. One can take a field approach to the theory, using wave functionals over field configurations, or a particle approach, using wave functions over particle configurations. This article argues for a field approach, presenting three advantages over a particle approach: particle wave functions are not available for photons, a classical field model of the electron gives a superior account of both…Read more
  •  11
    Locating Oneself in a Quantum World
    Dissertation, University of Michigan. 2015.
    There appear to be multiple mathematically and physically distinct theories that successfully reproduce the empirical predictions of quantum mechanics, so-called "interpretations" of quantum mechanics. This dissertation uses the tools of formal epistemology to investigate which of the theories that have been put forward really are empirically adequate and what alternatives can be devised. The first chapter introduces a novel theory that incorporates aspects of two well-developed alternatives, Bo…Read more
  •  21
    Within quantum chemistry, the electron clouds that surround nuclei in atoms and molecules are sometimes treated as clouds of probability and sometimes as clouds of charge. These two roles, tracing back to Schrödinger and Born, are in tension with one another but are not incompatible. Schrödinger’s idea that the nucleus of an atom is surrounded by a spread-out electron charge density is supported by a variety of evidence from quantum chemistry, including two methods that are used to determine ato…Read more
  •  24
    Particles, fields, and the measurement of electron spin
    Synthese 198 (12): 11943-11975. 2020.
    This article compares treatments of the Stern–Gerlach experiment across different physical theories, building up to a novel analysis of electron spin measurement in the context of classical Dirac field theory. Modeling the electron as a classical rigid body or point particle, we can explain why the entire electron is always found at just one location on the detector but we cannot explain why there are only two locations where the electron is ever found. Using non-relativistic or relativistic qua…Read more
  •  15
    Putting positrons into classical Dirac field theory
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 70 8-18. 2020.
  •  40
    How electrons spin
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 68 40-50. 2019.
  •  31
    Electromagnetism as Quantum Physics
    Foundations of Physics 49 (4): 365-389. 2019.
    One can interpret the Dirac equation either as giving the dynamics for a classical field or a quantum wave function. Here I examine whether Maxwell’s equations, which are standardly interpreted as giving the dynamics for the classical electromagnetic field, can alternatively be interpreted as giving the dynamics for the photon’s quantum wave function. I explain why this quantum interpretation would only be viable if the electromagnetic field were sufficiently weak, then motivate a particular app…Read more
  •  53
    The Mass of the Gravitational Field
    British Journal for the Philosophy of Science 73 (1): 211-248. 2022.
    By mass-energy equivalence, the gravitational field has a relativistic mass density proportional to its energy density. I seek to better understand this mass of the gravitational field by asking whether it plays three traditional roles of mass: the role in conservation of mass, the inertial role, and the role as source for gravitation. The difficult case of general relativity is compared to the more straightforward cases of Newtonian gravity and electromagnetism by way of gravitoelectromagnetism…Read more
  •  106
    GRW theory offers precise laws for the collapse of the wave function. These collapses are characterized by two new constants, \ and \ . Recent work has put experimental upper bounds on the collapse rate, \ . Lower bounds on \ have been more controversial since GRW begins to take on a many-worlds character for small values of \ . Here I examine GRW in this odd region of parameter space where collapse events act as natural disasters that destroy branches of the wave function along with their occup…Read more
  •  765
    A longstanding issue in attempts to understand the Everett (Many-Worlds) approach to quantum mechanics is the origin of the Born rule: why is the probability given by the square of the amplitude? Following Vaidman, we note that observers are in a position of self-locating uncertainty during the period between the branches of the wave function splitting via decoherence and the observer registering the outcome of the measurement. In this period it is tempting to regard each branch as equiprobable,…Read more
  •  478
    Many Worlds, the Born Rule, and Self-Locating Uncertainty
    In Daniele C. Struppa & Jeffrey M. Tollaksen (eds.), Quantum Theory: A Two-Time Success Story, Springer. pp. 157-169. 2014.
    We provide a derivation of the Born Rule in the context of the Everett (Many-Worlds) approach to quantum mechanics. Our argument is based on the idea of self-locating uncertainty: in the period between the wave function branching via decoherence and an observer registering the outcome of the measurement, that observer can know the state of the universe precisely without knowing which branch they are on. We show that there is a uniquely rational way to apportion credence in such cases, which lead…Read more
  •  15
    Constructing and constraining wave functions for identical quantum particles
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 56 48-59. 2016.
  •  42
    Forces on fields
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 63 1-11. 2018.
  •  75
    Quantum Mechanics as Classical Physics
    Philosophy of Science 82 (2): 266-291. 2015.
    Here I explore a novel no-collapse interpretation of quantum mechanics that combines aspects of two familiar and well-developed alternatives, Bohmian mechanics and the many-worlds interpretation. Despite reproducing the empirical predictions of quantum mechanics, the theory looks surprisingly classical. All there is at the fundamental level are particles interacting via Newtonian forces. There is no wave function. However, there are many worlds.