Philosophy of Physics Graduate Lunch Seminar (Monday - Week 3, HT19)

Philosophy of Physics

In the early 1980s a short argument concerning the proper definitions of field momentum and energy took place in the Physical Review journal. The argument was initiated by T. H. Boyer's criticism of the covariant definition of the field momentum and energy densities, suggested as a replacement of the classical definitions. A defense of the new definition was issued by F. Rohrlich, who was also one of its originators. Boyer argued against the new definition with the claim that the classical definition is a natural, conceptually clear way to define energy and momentum for the electromagnetic field; Boyer recapitulated the classical model of the electron as a body of finite-extension as an illustration of that claim. Rohrlich defended the covariant definition by arguing that it is improper for the energy and momentum of the electromagnetic field not to define a covariant 4-vector independently of the energy and momentum of any other auxiliary field - as is required in Boyer's approach. I will try to show that Boyer's approach coheres quite well with the dynamical interpretation of special relativity, while Rohrlich's approach can more adequately be based in the geometrical interpretation. I will also argue that consequently, Boyer's approach has some of the conceptual advantages of the former interpretation.