The aim of this paper is to examine one of several candidates for the ontology of today’s most basic theory in physics, quantum field theory (QFT). I will begin by outlining some problems we encounter when we look at different conceptions for the basic entities to which QFT refers. The candidate ontology I wish to consider in this paper is process ontology. I shall characterize process ontology mainly in a negative manner as opposed to substance ontology. The central part will consist in a case study about how the interpretation of Feynman diagrams – the use of which is crucial in QFT – depends on whether we adhere to substance or process ontology. In conclusion I will evaluate my results and point towards some problems faced by process ontology as such.
The aim of this paper is to examine one of several candidates for the ontology of today’s most basic theory in physics, quantum field theory (QFT). I will begin by outlining some problems we encounter when we look at different conceptions for the basic entities to which QFT refers. The candidate ontology I wish to consider in this paper is process ontology. I shall characterize process ontology mainly in a negative manner as opposed to substance ontology. The central part will consist in a case study about how the interpretation of Feynman diagrams – the use of which is crucial in QFT – depends on whether we adhere to substance or process ontology. In conclusion I will evaluate my results and point towards some problems faced by process ontology as such.
The core of my doctoral thesis consists in the establishment and evaluation of different ontological interpretations of quantum field theory. I thus seek for an ontological picture of the most fundamental level of the physical world, under the assumption that quantum field theory provides a true description. I defend the view that algebraic quantum field theory is the most important formulation when ontological questions are concerned. Some of my more extensive studies deal with different substance ontologies as well as with process-ontological approaches. Eventually, I propose a dispositional trope ontology, according to which particularized properties and not substances are the most basic entities, in terms of which all other entities are to be analysed.
Approaches to Ontology: Candidate General Ontologies for Situating Quantum Field (P Simons) 'Quanta', Tropes, or Processes: Ontologies for QFT Beyond the Myth of Substance (J Seibt) Analytical Ontologists in Action: A Comment on Seibt and Simons (M Kuhlmann) How Do Field Theories Refer to Entities in a Field? (S Y Auyang) Field Ontologies for QFT: A Naive View of the Quantum Field (A Wayne) Comments on Paul Teller's Book, An Interpretive Introduction to Quantum Field Theory (G Fleming) So What Is the Quantum Field? (P Teller) Relativity, Measurement and Renormalization: On the Nature of Measurement Records in Relativistic Quantum Field (J A Barrett) No Place for Particles in Relativistic Quantum Theories? (H Halvorson & R Clifton) Events and Covariance in the Interpretation of Quantum Field (D Dieks) Measurement and Ontology: What Kind of Evidence Can We Have for Quantum Fields? (B Falkenburg) Renormalization and the Disunity of Science (N Huggett) Gauge Symmetries and the Vacuum: The Interpretation of Gauge Symmetry (M Redhead) Comment on Redhead: The Interpretation of Gauge Symmetry (M Drieschner et al.) Is the Zero-Point Energy Real? (S Saunders) Two Comments on the Vacuum in Algebraic Quantum Field (M Redei).
Quantum field theory (QFT) can be analyzed in terms of its mathematical structure, its conceptual system for physical descriptions, or its basic ontology. The analysis can be done logically or historically. In this chapter, only the genesis of the conceptual foundations of QFT relevant to its basic ontology will be treated; no discussion of its mathematical structures or its epistemological underpinnings will be given. Some conceptual problems, such as those related to probability and measurement, will be discussed, but only because of their relevance to the basic ontology of QFT, rather than their intrinsic philosophical interest. Here, by basic ontology I mean the irreducible entities that QFT is invented to describe. The often mentioned candidates for the basic ontology of QFT, in fact of the physical world, are the discrete particle and the continuous field. Another possible candidate (the spacetime point) has also been suggested recently (Redhead, 1983). Since the aim of this chapter is to analyze the historical process in which the conceptual foundations of QFT were laid down, rather than the logical structure of QFT which philosophers of the present day treat, no discussion of the last possibility will be given. The content of this chapter involves the formation and interpretation, in a roughly chronological order, of the concepts of the wave function, quantization, quantization of the field, the vacuum, interactions between fields, and renormalization. The first two topics will be discussed in relation to the quantization of the field, with their role being taken as the starting point of the conceptual development of QFT.
Reviewed by: Quantum Processes: A Whiteheadian Interpretation of Quantum Field Theory Henry J. Folse Quantum Processes: A Whiteheadian Interpretation of Quantum Field Theory. Frank Hättich . Munster: Agenda Verlag, 2004. xiv + 280 pp. Euro 29.90, pbk.3-89688-204-x. Many philosophers and physicists—including the current reviewer—have argued that Whitehead's process philosophy provides a conceptual framework better suited for understanding the quantum theoretical account of the atomic domain than does the substance ontology that has dominated Western metaphysics. However, apart from calling attention to this issue, few (with the notable exceptions of Henry Stapp and Jorge Nobo) have attempted to do anything about it. Frank Hättich has now changed this situation by providing a sustained analysis of quantum field theory (QFT) in terms of Whitehead's ontological scheme. The result is interesting for two reasons: (1) by extending the match between Whitehead's specific metaphysical proposals and the mathematics of algebraic QFT to a level of detail never before attempted, Hättich greatly strengthens the hope that process ontology can help resolve quantum mysteries; and (2) in noting the points of noncompatibility between QFT and Whitehead's metaphysical conclusions, he suggests ways of revising Whitehead's pioneering effort to enhance the match between speculative ontological scheme and contemporary physical theory. Hättich's book is in three unequal parts: the first two are exegetical, and the third, constituting nearly half the book, is synthetic. Part I presents a "simplified version" of those parts of Whitehead's ontology pertinent to the interpretation of QFT to be presented, and Part II presents an algebraic formulation of [End Page 283] QFT susceptible to that interpretation. Although Part I is "self-contained" from the point of view of its intended application, it is unlikely that a reader wholly ignorant of Whitehead's process ontology would gain enough enlightenment to appreciate much of the author's argumentation; but it is equally unlikely that such a person would be reading this book. Part II presumes considerable mathematical sophistication and familiarity with the formalism of at least quantum mechanics and some knowledge of field theory. It is "introductory" only in the sense that it introduces the particular version of QFT, algebraic QFT (AQFT), to which process ontology is to be applied. Of course, both Whitehead's metaphysics and quantum theory have been subjected to many and various rival interpretations, and in selecting among them Hättich has clearly, and reasonably, been led by choices that maximize the connections he wishes to explore. It is misleading to see the goal here as developing yet another argument for why quantum theory must (or must not) be interpreted realistically. Rather, this investigation presupposes a realist interpretation and then gets to work constructing an ontological framework to show how this is possible, thereby suggesting that those who have argued that a realist interpretation of quantum theory is conceptually impossible have done so because they remain committed to ontological presuppositions moored in classical physics. In presenting the ontological framework for his project in Part III, Hättich accounts for the process of each occasion's creative concrescence from pure potentiality to determined actuality in terms of three Whiteheadian concepts: (1) the extensive continuum; (2) eternal objects; and (3) the underlying activity. Each one of these ontological elements is then matched up with an aspect of the mathematical formalism by which AQFT represents the quantum state of a region in spacetime. Hättich then shows that given these identifications, various consequences of the mathematical formalism imply that some of the ontological claims made by Whitehead are either inconsistent or incompatible with the presumption that AQFT gives us a true account of the world. Thus although the final conclusions of this investigation are critical of Whitehead's specific metaphysical conclusions, the extent of the applicability of his ontological categories to quantum mechanics and QFT provides persuasive grounds for hoping that future realist interpretations of quantum theory can learn much from process metaphysics. For this reason, Hättich is to be commended for keeping the project of process ontology alive by proposing specific reasons for revising Whiteheadian conclusions based on our best scientific theories of the microdomain, rather than arguing...
One of the foundational challenges in both Quantum Field Theory and the philosophy of physics lies in the traditional binary classification of entities as either real or unreal. The classical view posits that material entities are real, while mental constructs or theoretical entities are unreal. However, quantum phenomena such as virtual particles challenge this simplistic dichotomy. These unobservable entities, by influencing measurable phenomena, raise profound questions about the nature and modes of existence. To address this, we propose a four-level ontological hierarchy that spans from the quantum vacuum and the virtual level to the quantum level and phenomenal reality, providing a coherent continuum from potentiality to actualization. This framework not only clarifies the interpretation of quantum theory but also offers a unified perspective linking the unobservable with the observable. In QFT, virtual particles play a crucial role in mediating forces and in correcting the measurable properties of real particles. They arise within the mathematical structure of Feynman diagrams and, despite being unobservable, produce real, measurable effects such as the Lamb shift and the Casimir effect. Philosophically, this raises deep ontological questions: if unobservable entities affect measurable phenomena, can they truly be dismissed as unreal? Conversely, if they are real, what mode of existence do they possess? The traditional dichotomy of real versus unreal is thus insufficient for interpreting the ontological implications of quantum processes. To overcome these limitations, we propose a four-level ontological hierarchy.