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I argue that algebraic quantum field theory (AQFT) permits an undisturbed view of the right ontology for fundamental physics, whereas standard (or Lagrangian) QFT offers different mutually incompatible ontologies.My claim does not depend on the mathematical inconsistency of standard QFT but on the fact that AQFT has the same concerns as ontology, namely categorical parsimony and a clearly structured hierarchy of entities. 



This article discusses the peculiar features of quantum entanglement and quantum nonlocality within the algebraic approach to relativistic quantum field theory (RQFT). The debate on the ontology of RQFT is considered in the light of these wellknown but little discussed features. In particular, this article examines the ontic structural realist understanding of quantum entanglement and quantum nonlocality and its contribution to this debate. 

A major obstacle facing interpreters of quantum field theory is a proliferation of different theoretical frameworks. This article surveys three of the main available options—Lagrangian, Wightman, and algebraic QFT—and examines how they are related. Although each framework emphasizes different aspects of QFT, leading to distinct strengths and weaknesses, there is less tension between them than commonly assumed. Given the limitations of our current knowledge and the need for creative new ideas, I urge philosophers to explore puzzles, tools, and techniques from (...) 

Approaches to the interpretation of physical theories provide accounts of how physical meaning accrues to the mathematical structure of a theory. According to many standard approaches to interpretation, meaning relations are captured by maps from the mathematical structure of the theory to statements expressing its empirical content. In this paper I argue that while such accounts adequately address meaning relations when exact models are available or perturbation theory converges, they do not fare as well for models that give rise to (...) 

Quantum gravity is understood as a theory that, in some sense, unifies general relativity (GR) and quantum theory, and is supposed to replace GR at extremely small distances (highenergies). It may be that quantum gravity represents the breakdown of spacetime geometry described by GR. The relationship between quantum gravity and spacetime has been deemed ``emergence'', and the aim of this thesis is to investigate and explicate this relation. After finding traditional philosophical accounts of emergence to be inappropriate, I develop a (...) 

In this paper I elicit a prediction from structural realism and compare it, not to a historical case, but to a contemporary scientific theory. If structural realism is correct, then we should expect physics to develop theories that fail to provide an ontology of the sort sought by traditional realists. If structure alone is responsible for instrumental success, we should expect surplus ontology to be eliminated. Quantum field theory (QFT) provides the framework for some of the best confirmed theories in (...) 

The problem of theoretical equivalence is traditionally understood as the problem of specifying when superficially dissimilar accounts of the world are reformulations of a single underlying theory. One important strategy for answering this question has been to appeal to formal relations between theoretical structures. This article presents two reasons to think that such an approach will be unsuccessful and suggests an alternative account of theoretical equivalence, based on the notion of interpretive equivalence, in which the problem is merely an instance (...) 



Quantum mechanics, and classical mechanics, are framework theories that incorporate many different concrete theories which in general cannot be arranged in a neat hierarchy, but discussion of ‘the ontology of quantum mechanics’ tends to proceed as if quantum mechanics were a single concrete theory, specifically the physics of nonrelativistically moving point particles interacting by longrange forces. I survey the problems this causes and make some suggestions for how a more physically realistic perspective ought to influence the metaphysics of quantum mechanics. 

Theories of scientific representation, following Chakrawartty's categorization, are divided into two groups. Whereas cognitivefunctional views emphasize agents' intentions, informational theories stress the objective relation between represented and representing. In the first part, a modified structuralist theory is introduced that takes into account agents' intentions. The second part is devoted to dismissing a criticism against the structural account of representation on which similarity as the backbone of representation raises serious problems, since it has definite logical features, i.e. reflexivity, symmetry and transitivity, (...) 

I give an introduction to the conceptual structure of quantum field theory as it is used in mainstream theoretical physics today, aimed at nonspecialists. My main focuses in the article are the common structure of quantum field theory as it is applied in solidstate physics and as it is applied in highenergy physics; the modern theory of renormalisation. 

I describe some interpretive strategies used by physicists in the development of quantum electrodynamics in the 1930s and 1940s, using Wimsatt's account of how to reason with false models as a guide. I call these “interpretive” strategies because they were used not just to derive empirical predictions, but also to derive information about the world besides the aforementioned predictions. These strategies were regarded as mathematically unrigorous, yet they were crucial to the development of a better theory of quantum electrodynamics. I (...) 

The perturbative approach to quantum field theory has long been viewed with suspicion by philosophers of science. This paper 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 (...) 

I argue that a common philosophical approach to the interpretation of physical theories—particularly quantum field theories—has led philosophers astray. It has driven many to declare the quantum field theories employed by practicing physicists, socalled ‘effective field theories’, to be unfit for philosophical interpretation. In particular, such theories have been deemed unable to support a realist interpretation. I argue that these claims are mistaken: attending to the manner in which these theories are employed in physical practice, I show that interpreting effective (...) 

This paper attempts to make sense of a notion of ``approximation on certain scales'' in physical theories. I use this notion to understand the classical limit of ordinary quantum mechanics as a kind of scaling limit, showing that the mathematical tools of strict quantization allow one to make the notion of approximation precise. I then compare this example with the scaling limits involved in renormalization procedures for effective field theories. I argue that one does not yet have the mathematical tools (...) 

PhD dissertation addressing what can be called conceptualmathematical 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 (...) 

I argue against the currentlyprevalent view in philosophy of physics that algebraic quantum field theory is the correct framework for philosophy of quantum field theory and that "conventional" quantum field theory, 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 (...) 

I argue against the currently prevalent view 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 that position that AQFT and CQFT should 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 (...) 

The framework of effective field theory is a natural one in which to understand the claim that the spacetime of general relativity is an emergent lowenergy phenomenon. I argue for a pragmatic understanding of EFT, given that the appropriate conception of emergence it suggests is necessarily epistemological in a sense. Analogue models of spacetime are examples of the topdown approach to EFT. They offer concrete illustrations of spacetime emergent within an EFT, and lure us toward a strong analogy between condensed (...) 

We provide a careful development and rigorous proof of the CPT theorem within the framework of mainstream quantum field theory. This is in contrast to the usual rigorous proofs in purely axiomatic frameworks, and nonrigorous proofsketches in the mainstream approach. We construct the CPT transformation for a general field directly, without appealing to the enumerative classification of representations, and in a manner that is clearly related to the requirements of our proof. Our approach applies equally in Minkowski spacetimes of any (...) 

In this article I present the extracts and summary of heuristic and speculative observations on various aspects I feel are problematic in the practice of modern physics, the definitions and methods of which are the premise for the whole of Science. The illustrations will be fully developed in a later, more extensive and indepth work in which some theoretical solutions will also be put forward; therefore in the interests of brevity all assertions will not be demonstrated fully in this article. (...) 

Howard argues that the existence of unitarily inequivalent representations in Quantum Field Theory presents a problem for structural realism in this context. I consider two potential ways round this problem: 1), follow Wallace in adopting the 'naive' Lagrangian form of QFT with cutoffs; 2), adapt Ruetsche's 'Swiss Army Knife' approach. The first takes us into the current debate between Wallace and Fraser on conventional vs. algebraic QFT. The second involves consideration of the role of inequivalent representations in understanding spontaneous symmetry (...) 

Further arguments are offered in defence of the position that the variant of quantum field theory (QFT) that should be subject to interpretation and foundational analysis is axiomatic quantum field theory. I argue that the successful application of renormalization group (RG) methods within alternative formulations of QFT illuminates the empirical content of QFT, but not the theoretical content. RG methods corroborate the point of view that QFT is a case of the underdetermination of theory by empirical evidence. I also urge (...) 