The received view in philosophical studies of quantum field theory is that Feynman diagrams are simply calculational devices. Alongside this view we have the one that takes virtual quanta to be also simply formal tools. This received view was developed and consolidated in philosophy of physics by Mario Bunge, Paul Teller, Michael Redhead, Robert Weingard, Brigitte Falkenburg, and others. In this article I present an alternative to the received view.

Since its inception in the late 1920s and 30s, the main problem of quantum electrodynamics had been that any interaction or scattering event involved processes of a higher order that arose from vacuum polarization, the creation and subsequent annihilation of particle-antiparticle pairs, and the mutual interactions of all those short-lived entities.1 These processes posed two kinds of conceptual problems. First, they were not detectable individually, but had a measurable effect on the energy of the overall process. Even in simple quantum (...) systems, such as the hydrogen atom, they showed up, for instance, in the form of a further splitting up of spectral lines, most prominently the Lamb shift and measurements of... (shrink)

One way visual representations might function in scientific reasoning is to convey content that is true or false, analogous to making a claim. An alternative way that visual representations might function is as an object that may make statements true or false, but is not itself true or false, analogous to a scientific model. In this paper I evaluate the most recent and extended defense of this latter position and show that the case study involved does not in fact support (...) the view that the diagrams discussed function as truth-makers rather than truth bearers. (shrink)

According to the received view Feynman diagrams are a bookkeeping device in complex perturbative calculations. Thus, they do not provide a representation or model of the underlying physical process. This view is in apparent tension with scientific practice in high energy physics, which analyses its data in terms of “channels”. For example the Higgs discovery was based on the observation of the decay H → γγ – a process which can be easily represented by the corresponding Feynman diagrams. I take (...) issue with this tension and show that on closer analysis the story of the Higgs discovery should be told differently. (shrink)

Meynell’s contention is that feminists should attend to pictures in science as distinctive bearers of epistemic content that cannot be reduced to propositions. Remarks on the practice and function of medical illustration—specifically, images Nancy Tuana used in her discussion of the construction of ignorance of women’s sexual function (2004)—show pictures to be complex and powerful epistemic devices. Their affinity with perennial feminist concerns, the relation between epistemic subject and object, and the nature of social knowledge, are of particular interest.

In "Why Feynman Diagrams Represent", I argued that Feynman diagrams have two distinct functions: they are both calculational devices, developed to keep track of the long mathematical expressions of quantum electrodynamics,1 and they are pictorial representations. This challenges the common view that FDs are calculational devices alone and that it is misleading, if not an outright error, to think of them as pictorial. Following Kendall Walton's account of representation, I drew out what it means to think of FDs as pictures, (...) which in turn explained why FDs represent. However, my defence conceded an important point: not all of... (shrink)

This paper motivates, explains, and defends a new account of the content of thought experiments. I begin by briefly surveying and critiquing three influential accounts of thought experiments: James Robert Brown’s Platonist account, John Norton’s deflationist account that treats them as picturesque arguments, and a cluster of views that I group together as mental model accounts. I use this analysis to motivate a set of six desiderata for a new approach. I propose that we treat thought experiments primarily as aesthetic (...) objects, specifically fictions, and then use this analysis to characterize their content and ultimately assess their epistemic success. Taking my starting point from Kendall Walton’s account of representation (Mimesis as make-believe, Harvard University Press, Cambridge, 1990), I argue that the best way to understand the content of thought experiments is to treat them as props for imagining fictional worlds. Ultimately, I maintain that, in terms of their form and content, thought experiments share more with literary fictions and pictorial representations than with either argumentation or observations of the Platonic realm. Moreover, while they inspire imaginings, thought experiments themselves are not mental kinds. My approach redirects attention towards what fixes the content of any given thought experiment and scrutinizes the assumptions, cognitive capacities and conventions that generate them. This view helps to explain what seems plausible about Brown’s, Norton’s, and the mental modelers’ views. (shrink)

The operation of fundamental forces in quantum field theory is explicated here as the exchange of particles, consistently with the standard methodology of particle physics. The particles involved are seen to bear little relation to any classical particle but, rather, comprise unified collections of compresent, conserved quantities indicated by propagators. The exchange particles, which supervene upon quantum fields, are neither more fundamental than fields nor replace them as has often previously been assumed in models of exchange forces. It is argued (...) that this explication of quantum field-theoretic exchange forces definitively improves upon its predecessors. (shrink)

The way from the path integral to Feynman diagrams is sketched. The emphasis is put on the decrease of complexity in this process, from infinite-dimensional integrals down to the apparent simplicity of child’s play. On the other hand, also the subsequent increase in complexity when using Feynman diagrams to make realistic physical predictions is described, thus illustrating the dialectic between the simplicity and clarity of Feynman diagrams, and the complexity in their practical applications.

This paper aims to give a substantive account of how Feynman used diagrams in the first lectures in which he explained his new approach to quantum electrodynamics. By critically examining unpublished lecture notes, Feynman’s use and interpretation of both "Feynman diagrams" and other visual representations will be illuminated. This paper discusses how the morphology of Feynman’s early diagrams were determined by both highly contextual issues, which molded his images to local needs and particular physical characterizations, and an overarching common diagrammatic (...) style, which facilitated Feynman’s movement between different diagrams despite their divergent forms and significance. (shrink)

The perturbative approach to quantum field theory has long been viewed with suspicion by philosophers of science. This article offers a diagnosis of its conceptual problems. Drawing on Norton’s discussion of the notion of approximation I argue that perturbative QFT ought to be understood as producing approximations without specifying an underlying QFT model. This analysis leads to a reassessment of common worries about perturbative QFT. What ends up being the key issue with the approach on this picture is not mathematical (...) rigour, or the threat of inconsistency, but the need for a physical explanation of its empirical success. 1Three Worries about Perturbative Quantum Field Theory2The Perturbative Formalism 2.1Expanding the S-matrix2.2Perturbative renormalization3Approximations and Models4Perturbative Quantum Field Theory Produces Approximations5The Real Problem. (shrink)

After a brief presentation of Feynman diagrams, we criticizise the idea that Feynman diagrams can be considered to be pictures or depictions of actual physical processes. We then show that the best interpretation of the role they play in quantum field theory and quantum electrodynamics is captured by Hughes' Denotation, Deduction and Interpretation theory of models, where “models” are to be interpreted as inferential, non-representational devices constructed in given social contexts by the community of physicists.

Feynman diagrams are now iconic. Like pictures of the Bohr atom, everyone knows they have something important to do with physics. Those who work in quantum field theory, string theory, and other esoteric fields of physics use them extensively. In spite of this, it is far from clear what they are or how they work. Are they mere calculating tools? Are they somehow pictures of physical reality? Are they models in any interesting sense? Or do they play some other kind (...) of role?It is safe to say they are linked to some sort of calculation tool, but after that it is far from clear. If you ask me how to get from Toronto to Montreal, I could respond two ways: I could tell you to drive north until you... (shrink)

In this paper we argue that the different positions taken by Dyson and Feynman on Feynman diagrams’ representational role depend on different styles of scientific thinking. We begin by criticizing the idea that Feynman Diagrams can be considered to be pictures or depictions of actual physical processes. We then show that the best interpretation of the role they play in quantum field theory and quantum electrodynamics is captured by Hughes' Denotation, Deduction and Interpretation theory of models (DDI), where “models” are (...) to be interpreted as inferential, non-representational devices constructed in given social contexts by the community of physicists. (shrink)

PhD dissertation addressing what can be called conceptual-mathematical anomalies in quantum electrodynamics. This work can be seen as following the line of philosophy of physics studies of quantum field theory that started to emerge in a systematic way in the early eighties of last century. One example is Teller’s work on standard quantum electrodynamics.In this work, by following a historical approach, I will return to the standard version of quantum electrodynamics, which is the only one available when we want to (...) get numbers out to compare with experimental results. This work spins around two main vectors. One is the divergence of the S-matrix series expansion, the other is the spatio-temporal description of physical processes in the theory. (shrink)