## Philosophy of Quantum Field Theory

### Taking Particle Physics Seriously: A critique of the algebraic approach to quantum field theory (April 2011)

*Studies in the History and Philosophy of Modern Physics* 42 (2011) pp.116-125

I argue against the currently-prevalent view in philosophy of physics that algebraic quantum field theory (AQFT) is the correct framework for philosophy of quantum field theory and that "conventional" quantum field theory (CQFT), of the sort used in mainstream particle physics, is not suitable for foundational study. In doing so, I defend the position that AQFT and CQFT, understood in an appropriate sense, ought to be understood as rival programs to resolve the mathematical and physical pathologies of renormalization theory, and that CQFT has succeeded in this task and AQFT has failed. I also defend CQFT from recent criticisms made by Doreen Fraser.

- PDF of published version (requires subscription)
- preprint PDF

### QFT, Antimatter, and Symmetry (March 2009)

*Studies in the History and Philosophy of Modern Physics* 40 (2009) pp. 209-222.

A systematic analysis is made of the relations between the symmetries of a classical field and the symmetries of the one-particle quantum system that results from quantizing that field in regimes where interactions are weak. The results are applied to gain a greater insight into the phenomenon of antimatter.

- PDF of published version (requires subscription)
- Preprint PDF
- Preprint PostScript

### In defence of naivete: the conceptual status of Lagrangian QFT (December 2001)

*Synthese* 151 (2006) pp. 33-80.

I analyse the conceptual and mathematical foundations of Lagrangian quantum field theory (that is, the "naive" quantum field theory used in mainstream physics, as opposed to algebraic quantum field theory). The objective is to see whether Lagrangian quantum field theory has a sufficiently firm conceptual and mathematical basis to be a legitimate object of foundational study, or whether it is too ill-defined. The analysis covers renormalisation and infinities, inequivalent representations, and the concept of localised states; the conclusion is that Lagrangian QFT (at least as described here) is a perfectly respectable physical theory, albeit somewhat different in certain respects from most of those studied in foundational work.

- PDF of published version (requires subscription)
- Preprint PDF
- Preprint PostScript

### Emergence of particles from bosonic quantum field theory (December 2001)

#### Unpublished (cite the arxiv.org URL)

An examination is made of the way in which particles emerge from linear, bosonic, massive quantum field theories. Two different constructions of the one-particle subspace of such theories are given, both illustrating the importance of the interplay between the quantum-mechanical linear structure and the classical one. Some comments are made on the Newton-Wigner representation of one-particle states, and on the relationship between the approach of this paper and those of Segal, and of Haag and Ruelle.

(**Note:** this was actually accepted by *Studies in the History and Philosophy of Modern Physics,* pending minor revisions,
back in 2003 or so. For various reasons I never got around to making the revisions; by now, I'd probably need to rewrite it quite a lot,
since my views have shifted a bit, more in terms of presentation than actual content).