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 the kind of matter being considered. Although we cannot (...) get by without attributing energy to the electromagnetic field, matter may still have electromagnetic potential energy. Indeed, if we take the matter to be represented by the Dirac field, then it will possess potential energy. Thus, potential energy reappears. Upon field quantization, the potential energy of the Dirac field becomes an interaction term in the Hamiltonian operator of quantum electrodynamics. (shrink)

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 spin and (...) self-interaction as compared to a classical particle model, and the space of field wave functionals appears to be larger than the space of particle wave functions. The article also describes two important tasks facing proponents of a field approach: legitimize or excise the use of Grassmann numbers for fermionic field values and in wave functional amplitudes, and describe how quantum fields give rise to particle-like behavior. (shrink)

Matthias Egg argues that scientific realism can be reconciled with quantum mechanics and its foundational underdetermination by focusing realist commitments on ‘effective’ ontology. I argue in general terms that Egg’s effective realism is ontologically overly promiscuous. I illustrate the issue in relation to both Newtonian mechanics and quantum mechanics.