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In this note, I briefly review Lyre’s (2008) analysis and interpretation of the Higgs mechanism. Contrary to Lyre, I maintain that, on the proper understanding of the term, the Higgs mechanism refers to a physical process in the course of which gauge bosons acquire a mass. Since also Lyre’s worries about imaginary masses can be dismissed, a realistic interpretation of the Higgs mechanism seems viable. While it may remain an open empirical question whether the Higgs mechanism did actually occur in the early history of the universe and what the details of the mechanism are, I claim that the term can certainly refer to a physical process.

I reconstruct the discovery of the Higgs boson by the ATLAS collaboration at CERN as the application of a series of inferences from effects to causes. I show to what extent such diagnostic causal inferences can be based on well established knowledge gained in previous experiments. To this extent, causal reasoning can be used to infer the existence of entities, rather than just causal relationships between them. The resulting account relies on the principle of causality, attributes only a heuristic role to the theory’s predictions, and shows how, and to what extent, data selection can be used to exclude alternative causes, even “unconceived” ones.

A fair amount of recent scholarship has been concerned with correcting a supposedly wrong, but wide-spread, assessment of the consequences of the empirical falsification of Bell-type inequalities. In particular, it has been claimed that Bell-type inequalities follow from “locality tout court” without additional assumptions such as “realism” or “hidden variables”. However, this line of reasoning conflates restrictions on the spatio-temporal relation between causes and their effects (“locality”) and the assumption of a cause for every event (“causality”). It thus fails to recognize a substantial restriction of the class of theories that is falsified through Bell-type inequalities.

One of the first publications by the ATLAS collaboration using data from the Large Hadron Collider at CERN dealt with the measurement of the production cross section of the W boson. The collaboration “rediscovered” the W in order to, among other things, check whether the detector and analysis methods were working well. Originally, the discovery of the W had been announced in 1983 by the CERN management, referring mainly to work done by its UA1 collaboration. In both the discovery and the “rediscovery”, the convergence of two distinct sets of criteria of data selection was an important concern of the researchers. In 1983, this concern figured prominently in the published paper whereas in 2010 it was mainly dealt with inside the collaboration.

I give a brief introduction to how Feynman diagrams are used. I review arguments to the effect that they are only used as calculation tools and should not be interpreted as representations of physical processes. Against these arguments, I propose to regard Feynman diagrams as visual models that explain, in some respects, how elementary particles interact.

If one compares Feynman diagrams with other diagrammatic representations of the same phenomena, one can discern the change in the conception and representation of the phenomena that silently occurred while Feynman diagrams were being developed by Feynman and then systematized by Freeman J. Dyson. In some publications, diagrammatic representations occupy centre stage, which testifies to their importance in the context of quantum electrodynamics (QED). In this section we will see that some authors even explicitly mention that improving diagrammatic representations was one of their principal goals.

In the light of recent discussions we present the main results of our project, the aim of which was to derive a Bell-type inequality from the weakest possible assumptions. A principal outcome of the project is that a Bell-type inequality can be derived from the assumption of separate common causes, even without the assumption of perfectly anticorrelating event types. We also address the critique that in Grashoff, Portmann and Wuthrich we implicitly assume a common common cause.

Feynman gave the first public presentation of his alternative formulation of quantum electrodynamics (QED) at a “conference on physics” that was sponsored by the National Academy of Sciences and held at Pocono Manor, Pennsylvania, United States, from 30 March to 1 April 1948.1 It proved to be a complete disaster! The audience failed to understand how Feynman could possibly justify his results, even if it was agreed that the results were correct.

In the early 1940s, when Feynman was a graduate student, one of the most pressing problems facing theoretical physicists of the time was the fact that infinite and, therefore, uninterpretable quantities arose from some of the principles of electrodynamics—in both classical electrodynamics as well as in the early attempts to establish a quantum theory.1 Roughly, the problem was as follows: an extended electron could not be stable because the charges distributed over its volume would repel each other. On the other hand, a point-like electron would imply that the energy contained in the electron’s electrostatic field would be infinite, since the field energy e/r diverges in the limit of vanishing radius r of the spatial distribution of the charge e.2

“Like the silicon chip of more recent years, the Feynman diagram was bringing computation to the masses.” Thus Julian Schwinger, displaying a hint of both disdain and admiration, appraises the enormous impact of Feynman diagrams as a mathematical tool on the daily work of theoretical physicists. And indeed, since Richard P. Feynman (1918–1988) invented them, around the year 1948, and Freeman J. Dyson subsequently systematized them, these diagrams have undeniably become an indispensable tool for performing calculations in modern quantum field theory. They are omnipresent in the theoretical treatments of an important class of elementary particle phenomena, in particular quantum electrodynamics (QED). In modern textbooks on quantum field theory—I will quote from one of them below—they take centre stage, while the teaching of their use is one of the essential components in courses on the subject.

In this chapter I will show how Feynman used diagrams to represent and modify physical models of electrons (and later their interaction) and how he used these representations to derive quantitative expressions that are “true of the model”.

From the time of his thesis and during his struggle to understand the Dirac equation, Feynman is preoccupied with finding the quantity that will determine the evolution of the wave function. While working on his thesis, he finds that the time evolution of the wave function is determined by the classical action, which is integrated along the possible paths that connect the start and end points of the particle. There is no classical action in the Dirac equation’s description of quantum electrodynamics (QED), since the equation introduced a new degree of freedom: spin. In RMP48, Feynman constructs an action that yields the Dirac equation using his quantization method. However, because he cannot justify the action independently, Feynman considers this treatment to be “purely formal” and unsatisfactory (see Section 3.5).

Two of the principal aims of this study were to reconstruct the route that led Feynman, between approximately 1946 and 1948, to devise his new method of diagrams and to evaluate what was achieved. In the preceding sections I showed how Feynman developed his diagrams in a series of comprehensible steps, and that his primary consideration was to solve important theoretical problems of the theory of quantum electrodynamics (QED) as it then stood. This goal was finally achieved to a satisfactory extent by Freeman J. Dyson’s systematization of Feynman’s results.