This document is a set of notes I took on QFT as a graduate student at the University of Pennsylvania, mainly inspired in lectures by Burt Ovrut, but also working through Peskin and Schroeder (1995), as well as David Tong’s lecture notes available online. They take a slow pedagogical approach to introducing classical field theory, Noether’s theorem, the principles of quantum mechanics, scattering theory, and culminating in the derivation of Feynman diagrams.

Effective Field Theory (EFT) is the successful paradigm underlying modern theoretical physics, including the "Core Theory" of the Standard Model of particle physics plus Einstein's general relativity. I will argue that EFT grants us a unique insight: each EFT model comes with a built-in specification of its domain of applicability. Hence, once a model is tested within some domain (of energies and interaction strengths), we can be confident that it will continue to be accurate within that domain. (...) Currently, the Core Theory has been tested in regimes that include all of the energy scales relevant to the physics of everyday life (biology, chemistry, technology, etc.). Therefore, we have reason to be confident that the laws of physics underlying the phenomena of everyday life are completely known. (shrink)

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 science, but debates over its ontology are vexed. Rather than taking a stand on these matters, the structural realist can embrace QFT as an example of just the kind of theory SR should lead us to expect. Yet, it is not clear that QFT meets the structuralist's positive expectation by providing a structure for the world. In particular, the problem of unitarily inequivalent representations threatens to undermine the possibility of QFT providing a unique structure for the world. In response to this problem, I suggest that the structuralist should endorse pluralism about structure. (shrink)

The hard problem of consciousness arises in most incarnations of present day physicalism. Why should certain physical processes necessarily be accompanied by experience? One possible response is that physicalism itself should be modified in order to accommodate experience: But, modified how? In the present work, we investigate whether an ontology derived from quantum field theory can help resolve the hard problem. We begin with the assumption that experience cannot exist without being accompanied by a subject of experience (...) (SoE). While people well versed in Indian philosophy will not find that statement problematic, it is still controversial in the analytic tradition. Luckily for us, Strawson has elaborately defended the notion of a thin subject—an SoE which exhibits a phenomenal unity with different types of content (sensations, thoughts etc.) occurring during its temporal existence. Next, following Stoljar, we invoke our ignorance of the true physical as the reason for the explanatory gap between present day physical processes (events, properties) and experience. We are therefore permitted to conceive of thin subjects as related to the physical via a new, yet to be elaborated relation. While this is difficult to conceive under most varieties of classical physics, we argue that this may not be the case under certain quantum field theory ontologies. We suggest that the relation binding an SoE to the physical is akin to the relation between a particle and (quantum) field. In quantum field theory, a particle is conceived as a coherent excitation of a field. Under the right set of circumstances, a particle coalesces out of a field and dissipates. We suggest that an SoE can be conceived as akin to a particle—a SelfOn—which coalesces out of physical fields, persists for a brief period of time and then dissipates in a manner similar to the phenomenology of a thin subject. Experiences are physical properties of selfons with the constraint (specified by a similarity metric) that selfons belonging to the same natural kind will have similar experiences. While it is odd at first glance to conceive of subjects of experience as akin to particles, the spatial and temporal unity exhibited by particles as opposed to fields and the expectation that selfons are new kinds of particles, paves the way for cementing this notion. Next, we detail the various no-go theorems in most versions of quantum field theory and discuss their impact on the existence of selfons. Finally, we argue that the time is ripe for a rejuvenated Indian philosophy to begin tackling the three-way relationship between SoEs (which may become equivalent to jivas in certain Indian frameworks), phenomenal content and the physical world. With analytic philosophy still struggling to come to terms with the complex worlds of quantum field theory and with the relative inexperience of the western world in arguing the jiva-world relation, there is a clear and present opportunity for Indian philosophy to make a worldcentric contribution to the hard problem of experience. (shrink)

Many attempts have been made to provide Quantum Field Theory with conceptually clear and mathematically rigorous foundations; remarkable examples are the Bohmian and the algebraic perspectives respectively. In this essay we introduce the dissipative approach to QFT, a new alternative formulation of the theory explaining the phenomena of particle creation and annihilation starting from nonequilibrium thermodynamics. It is shown that DQFT presents a rigorous mathematical structure, and a clear particle ontology, taking the best from the mentioned (...) perspectives. Finally, after the discussion of its principal implications and consequences, we compare it with the main Bohmian QFTs implementing a particle ontology. (shrink)

In the first part I argue that Buddhism and Hinduism can be unified by a Pure Consciousness thesis, which says that the nature of ultimate reality is an unconditioned and pure consciousness and that the phenomenal world is a mere appearance of pure consciousness. In the second part I argue that the Pure Consciousness thesis can be supported by an argument from quantum physics. According to our best scientific theories, the fundamental nature of reality consists of quantum fields, (...) and it seems that quantum fields have merely particle-like appearances—particles seem to be mere epiphenomena. This interpretation can be generalized. There appear to be individual entities, small and large, and their ontological reality is precisely what it appears to be—they are mere appearances. (shrink)

We discuss the fate of the correspondence principle beyond quantum mechanics, specifically in quantum field theory and quantum gravity, in connection with the intrinsic limitations of the human ability to observe the external world. We conclude that the best correspondence principle is made of unitarity, locality, proper renormalizability (a refinement of strict renormalizability), combined with fundamental local symmetries and the requirement of having a finite number of fields. Quantum gravity is identified in an essentially (...) unique way. The gauge interactions are uniquely identified in form. Instead, the matter sector remains basically unrestricted. The major prediction is the violation of causality at small distances. (shrink)

In this work, we attempt to define a notion of compositeness compatible with Quantum Field Theory. Considering the analytic properties of the S-matrix, we conclude that there is no satisfactory definition of compositeness compatible with Quantum Field Theory. Without this notion, one must claim that all bound states are equally fundamental, that is, one cannot rigorously claim that everyday objects are made of atoms or that atoms are made of protons and neutrons. I then (...) show how an approximate notion of compositeness may be recovered in the regime where the mass of a bound state is close to a multi-particle threshold. -/- Finally, we see that rejecting compositeness solves several of the "problems of everyday objects" encountered in an undergraduate metaphysics course. (shrink)

The most part of the debates on Quantum Mechanics (QM) interpretation come out from the remains of a classical language based upon waves and particles. Such problems can find a decisive clarification in Quantum Field Theory (QFT), where the concept of “classical object” is replaced by an interaction networks. On the other hand, it is simpler to discuss about non-locality in QM than in QFT. We propose here the concept of transaction as a connection between theQM (...) and QFT language as well as the possibility to introduce quantum non-locality ab initio.We also mention the cosmological consequence of a non-local archaic vacuum here defined. (shrink)

This unpublished paper, written in 2005 in the PhD philosophy program at Notre Dame, argues that algebraic structural realism faces a potentially fatal difficulty raised by the existence of inequivalent representations in quantum field theory.

A new non-Archimedean approach to interacted quantum fields is presented. In proposed approach, a field operator φ(x,t) no longer a standard tempered operator-valued distribution, but a non-classical operator-valued function. We prove using this novel approach that the quantum field theory with Hamiltonian P(φ)_4 exists and that the corresponding C^*­ algebra of bounded observables satisfies all the Haag-Kastler axioms except Lorentz covariance. We prove that the λ(φ^2n )_4,n≥2 quantum field theory models are Lorentz (...) covariant. (shrink)

Functional analysis works with TVS (Topological Vector Spaces), classically over archimedean fields like
and .Canonical non-Archimedean functional analysis, where alternative but equally valid number systems such as p-adic numbers p etc. are fundamental, is a fast-growing discipline. This paper deals with TVS over non-classical non-Archimedean fields.

The elementary particles of relativistic quantum field theory are not simple field quanta, as has long been assumed. Rather, they supplement quantum fields, on which they depend but to which they are not reducible, as shown here with particles defined instead as a unified collection of properties that appear in both physical symmetry group representations and field propagators. This notion of particle provides consistency between the practice of particle physics and its basis in (...) class='Hi'>quantum field theory. (shrink)

A fully micro realistic, propensity version of quantum theory is proposed, according to which fundamental physical entities - neither particles nor fields - have physical characteristics which determine probabilistically how they interact with one another . The version of quantum "smearon" theory proposed here does not modify the equations of orthodox quantum theory: rather, it gives a radically new interpretation to these equations. It is argued that there are strong general reasons for preferring (...) class='Hi'>quantum "smearon" theory to orthodox quantum theory; the proposed change in physical interpretation leads quantum "smearon" theory to make experimental predictions subtly different from those of orthodox quantum theory. Some possible crucial experiments are considered. (shrink)

The ontology behind quantum mechanics has been the subject of endless debate since the theory was formulated some 100 years ago. It has been suggested, at one time or another, that the objects described by the theory may be individual particles, waves, fields, ensembles of particles, observers, and minds, among many other possibilities. I maintain that these disagreements are due in part to a lack of precision in the use of the theory’s various semantic designators. In (...) particular, there is some confusion about the role of representation, reference, and denotation in the theory. In this article, I first analyze the role of the semantic apparatus in physical theories in general and then discuss the corresponding ontological implications for quantum mechanics. Subsequently, I consider the extension of the theory to quantum fields and then analyze the semantic changes of the designators with their ontological consequences. In addition to the classical arguments to rule out a particle ontology in the case of non-relativistic quantum field theory, I show how the existence of black holes makes the proposal of a particle ontology in general spacetimes unfeasible. I conclude by proposing a provisional pluralistic ontology of fields and spacetime and discussing some prospects for possible future ontological economies. (shrink)

The main concept of quantum field theory is the conviction that all the phenomena in the universe are created by the underlying structure of the quantum fields. Fields represent dynamical spatial properties that can be described with the help of geometrical concepts. Therefore it is possible to describe the mathematical origin of the structure of the creating fields and show the mathematical origin of the law of conservation of energy, Planck’s constant and the constant speed of (...) light within a non-local universe. (shrink)

In this paper I put forward a new micro realistic, fundamentally probabilistic, propensiton version of quantum theory. According to this theory, the entities of the quantum domain - electrons, photons, atoms - are neither particles nor fields, but a new kind of fundamentally probabilistic entity, the propensiton - entities which interact with one another probabilistically. This version of quantum theory leaves the Schroedinger equation unchanged, but reinterprets it to specify how propensitons evolve when no (...) probabilistic transitions occur. Probabilisitic transitions occur when new "particles" are created as a result of inelastic interactions. All measurements are just special cases of this. This propensiton version of quantum theory, I argue, solves the wave/particle dilemma, is free of conceptual problems that plague orthodox quantum theory, recovers all the empirical success of orthodox quantum theory, and at the same time yields as yet untested predictions that differ from those of orthodox quantum theory. (shrink)

The quantum-dynamic theory of musical forms redefines music as an ontological and noematic phenomenon, extending beyond its traditional auditory interpretation. This theory proposes that music represents the acoustic expression of thought vibrations, where each melody and harmony serves as a direct manifestation of universal noetic structures. Tonal forms are conceptualized as carriers of metaphysical and philosophical truths, bridging the gap between human discursiveness and the divine. Through specific examples, such as Bach's Toccata and Fugue in D Minor (...) and Beethoven's Pastoral Symphony, the theory illustrates how music encapsulates theological and philosophical principles, such as the theology of creation and Schelling's philosophy of nature. The theory emphasizes music's infinite hermeneutic potential, positioning it as a medium for translating noematic content into discursive narratives. It regards composers as intermediaries who channel noetic inspiration into audible forms, rendering music a divine and ontological artifact. Drawing parallels with Hermann Hesse's The Glass Bead Game, the theory frames music as a central element of universal synthesis, capable of connecting art, science, and philosophy. Ultimately, music is viewed as an aesthetic-ontological phenomenon that transcends the category of meaning, revealing the sanctity and preciousness of existence. This theory not only deepens our understanding of music but also illuminates the fundamental essence of the universe, offering a framework for exploring the translation of noematic content into tonal forms. (shrink)

I argue that our sensory fields are photon fields. The philosophical foundation here is informed by mind/brain identity theory, such as we find in Russell, Feigl, Lockwood and Chalmers. In brief, given Dyson's observation that all material things consist of quantum fields, and given an identity of mind and brain, our sensory fields are then most plausibly photon fields.

With the present paper I maintain that the group field theory (GFT) approach to quantum gravity can help us clarify and distinguish the problems of spacetime emergence from the questions about the nature of the quanta of space. I will show that the mechanism of phase transition suggests a form of indifference between scales (or phases) and that such an indifference allows us to black-box questions about the nature of the ontology of the fundamental levels of the (...) theory. I consider the GFT approach to quantum gravity which derives spacetime as an emergent property from abstract non-geometrical tetrahedra through a processes of phase transition. Because the physical interpretation of the tetrahedra is problematic in view of their (non)-spatiotemporal nature, I will apply the considerations about phase transitions to GFT and conclude that the fundamental ontology of the theory and the mechanism of spacetime emergence can and should be treated separately. (shrink)

Einstein's theory of Relativity describes variances of the volume of our universe in a model that is known as "spacetime". Quantum field theory describes the volume of our universe as a composition of a limited number of basic quantum fields. Both models exclude each other.

Experiments in particle physics have hitherto failed to produce any significant evidence for the many explicit models of physics beyond the Standard Model (BSM) that had been proposed over the past decades. As a result, physicists have increasingly turned to model-independent strategies as tools in searching for a wide range of possible BSM effects. In this paper, we describe the Standard Model Effective Field Theory (SM-EFT) and analyse it in the context of the philosophical discussions about models, theories, (...) and (bottom-up) effective field theories. We find that while the SM-EFT is a quantum field theory, assisting experimentalists in searching for deviations from the SM, in its general form it lacks some of the characteristic features of models. Those features only come into play if put in by hand or prompted by empirical evidence for deviations. Employing different philosophical approaches to models, we argue that the case study suggests not to take a view on models that is overly permissive because it blurs the lines between the different stages of the SM-EFT research strategies and glosses over particle physicists' motivations for undertaking this bottom-up approach in the first place. Looking at EFTs from the perspective of modelling does not require taking a stance on some specific brand of realism or taking sides in the debate between reduction and emergence into which EFTs have recently been embedded. (shrink)

In this chapter I examine seven clues to the nature of consciousness and explore what they reveal about the underlying physical substrate of consciousness. The consciousness clues are: it impacts upon the world; it is a property of living brains but no other structure; brain activity may be conscious or unconscious; the conscious mind appears to be serial; learning requires consciousness but recall doesn’t; conscious information is bound; and consciousness correlates with synchronous firing of neurons. I discuss field theories (...) of consciousness and introduce the conscious electromagnetic field (CEMI) theory that suggests that consciousness is a product of the brain’s electromagnetic field. I show that the CEMI field theory successfully accounts for each of the seven clues to the nature of consciousness. Finally, I show that although current quantum mechanical theories of consciousness are also field theories, they are physical untenable and should be discarded. (shrink)

The fields of application of general relativity (GR) and quantum field theory (QFT) are different, so most situations require the use of only one of the two theories. The overlaps occur in regions of extremely small size and high mass, such as the black hole or the early universe (immediately after the Big Bang). This conflict is supposed to be solved only by unifying gravity with the other three interactions, to integrate GR and QFT into one (...) class='Hi'>theory. At the cosmological level, the standard cosmological model contains Einstein's theory of gravity as part of the "hard core". Dark matter, dark energy, and inflation were added to the theory in response to observations. None of these ancillary hypotheses have yet been confirmed. DOI: 10.13140/RG.2.2.34318.72008. (shrink)

This paper explores the phenomena of "dark matter" and "black holes" within the framework of infinite quantum field theory, presenting them as interconnected and complementary aspects of cosmic dynamics. "Dark matter" arises from the interference between discrete particle orbits and indiscernible distant energy states, manifesting as a diffuse yet pervasive energetic presence. Its continuous growth reflects the expansive nature of the quantum field's self-modifying processes. Conversely, "black holes" are portrayed as loci of energy concentration and (...) reintegration, counterbalancing the expansive energy of "dark matter." These phenomena embody a dynamic equilibrium: "dark matter" represents outward expansion, while "black holes" serve as inward, transformative processes that stabilize the infinite quantum field. The study highlights the ontological and philosophical implications of these phenomena, emphasizing their complementarity and their role in maintaining universal harmony. Additionally, it proposes mathematical and experimental directions to model the interference mechanism of "dark matter" and the transformative dynamics within "black holes." This synthesis redefines these cosmic phenomena as emergent processes within the infinite quantum field, bridging the domains of quantum physics, cosmology, and philosophy. (shrink)

The cosmological constant problem stems from treating quantum field theory and general relativity as an effective field theory. We argue that the problem is a reductio ad absurdum, and that one should reject the assumption that general relativity can generically be treated as an EFT. This marks a failure of naturalness, and an internal signal that EFT methods do not apply in all spacetime domains. We then take an external view, showing that the assumptions for (...) using EFTs are violated in general relativistic domains where Λ is relevant. We highlight some ways forward that do not depend on naturalness. (shrink)

This essay explores the phenomenon of death through the lens of quantum-idealist theory, presenting it not as an end but as a transformative event—a reintegration of individual consciousness into the infinite quantum field. Death is conceptualized as a moment of absolute extension where particularized consciousness dissolves into universal plenitude, achieving harmony between the original modality (absolute plenitude) and the modificational modality (individual consciousness). The theory highlights the teleological nature of death, emphasizing its role in reconciling (...) the individual with the universal, evaluating the contributions of individual existence to the universal quantum field, and catalyzing the evolution of cosmic patterns. It introduces noetic intelligence and noematic structures as key elements shaping the transition from life to death, with death seen as a reflective process integrating all experiences into the infinite field. Moreover, death is framed as a gateway to ontological supremacy, revealing life’s inherent value, the interconnectedness of all beings, and the eternal process of becoming. The essay also examines the spiritual dimensions of death, portraying it as a sacred act guided by the “Holy Spirit,” enriching the universal field with unique contributions from each life. This theory invites a reimagining of mortality, encouraging the celebration of life’s transience, the cultivation of inner reflection, and the acknowledgment of death as an essential part of the cosmic order. It ultimately affirms the sacredness of existence and the infinite potential within the quantum field, offering profound insights into the eternal interplay between life and death. (shrink)

Relationships between current theories, and relationships between current theories and the sought theory of quantum gravity (QG), play an essential role in motivating the need for QG, aiding the search for QG, and defining what would count as QG. Correspondence is the broad class of inter-theory relationships intended to demonstrate the necessary compatibility of two theories whose domains of validity overlap, in the overlap regions. The variety of roles that correspondence plays in the search for QG are (...) illustrated, using examples from specific QG approaches. Reduction is argued to be a special case of correspondence, and to form part of the definition of QG. Finally, the appropriate account of emergence in the context of QG is presented, and compared to conceptions of emergence in the broader philosophy literature. It is argued that, while emergence is likely to hold between QG and general relativity, emergence is not part of the definition of QG, and nor can it serve usefully in the development and justification of the new theory. (shrink)

Rudolf Haag’s Local Quantum Physics (LQP) is an alternative framework to conventional relativistic quantum field theory for combining special relativity and quantum theory based on first principles, making it of great interest for the purposes of conceptual analysis despite currently being relatively limited as a tool for making experimental predictions. In LQP, the elementary particles are defined as species of causal link between interaction events, together with which they comprise its most fundamental entities. This (...) notion of particle has yet to be independently assessed as such. Here, it is captured via a set of propositions specifying particle characteristics and then compared to previous particle notions. Haag’s particle differs decisively with respect to mechanical intuitions about particles by lacking, among other things, even an approximate independent space–time location. This notion is thus found to differ greatly even from those of relativistic quantum mechanics and quantum field theory, which have been applied to the known elementary particles. (shrink)

In quantum field theory, the main obstacle is the occurrence of the untreatable infinities in the interactions of the particles due to the possibility of arbitrary distances between the point particles. Strings, as extended objects, provide a better framework, which allows finite calculations. String theory is part of a research program in which point particles in particle physics are replaced by one-dimensional objects called strings. It describes how these strings propagate through space and interact with one (...) another. The purpose of string theory was to replace elementary particles with one-dimensional strings in order to unify quantum physics and gravity. DOI: 10.13140/RG.2.2.18894.82240. (shrink)

String theory, a framework that aims to reconcile general relativity and quantum mechanics, holds a unique position in the field of quantum gravity. In quantum field theory, the main obstacle is the occurrence of the untreatable infinities in the interactions of the particles due to the possibility of arbitrary distances between the point particles. Strings, as extended objects, provide a better framework, which allows finite calculations. In the realm of theoretical physics, where theories (...) often push the boundaries of human understanding, examining the epistemology of a theory becomes crucial. This article delves into the epistemological aspects of string theory’s role in our quest for a unified theory of quantum gravity, exploring the challenges it presents and the insights it offers. (shrink)

Quantum theory offers mathematical descriptions of measurable phenomena with great facility and accuracy, but it provides absolutely no understanding of why any particular quantum outcome is observed. It is the province of genuine explanations to tell us how things actually work—that is, why such descriptions hold and why such predictions are true. Quantum theory is long on the what, both mathematically and observationally, but almost completely silent on the how and the why. What is even (...) more interesting is that, in some sense, this state of affairs seems to be a necessary consequence of the empirical adequacy of quantum descriptions. One of the most noteworthy achievements of quantum theory is the accurate prediction of phenomena that, on pain of experimental contradiction, have no physical explanation. It is the purpose of this essay to make clear why quantum mechanics and quantum field theory are complete physical descriptions that describe the metaphysical incompleteness of the physical world, then to press the negative implications of this fact for naturalistic metaphysics. (shrink)

In this paper, I introduce an intrinsic account of the quantum state. This account contains three desirable features that the standard platonistic account lacks: (1) it does not refer to any abstract mathematical objects such as complex numbers, (2) it is independent of the usual arbitrary conventions in the wave function representation, and (3) it explains why the quantum state has its amplitude and phase degrees of freedom. -/- Consequently, this account extends Hartry Field’s program outlined in (...) Science Without Numbers (1980), responds to David Malament’s long-standing impossibility conjecture (1982), and establishes an important first step towards a genuinely intrinsic and nominalistic account of quantum mechanics. I will also compare the present account to Mark Balaguer’s (1996) nominalization of quantum mechanics and discuss how it might bear on the debate about “wave function realism.” In closing, I will suggest some possible ways to extend this account to accommodate spinorial degrees of freedom and a variable number of particles (e.g. for particle creation and annihilation). -/- Along the way, I axiomatize the quantum phase structure as what I shall call a “periodic difference structure” and prove a representation theorem as well as a uniqueness theorem. These formal results could prove fruitful for further investigation into the metaphysics of phase and theoretical structure. -/- (For a more recent version of this paper, please see "The Intrinsic Structure of Quantum Mechanics" available on PhilPapers.). (shrink)

This article probes the question of what interpretations of quantum mechanics actually accomplish. In other domains, which are briefly considered, interpretations serve to make alien systematizations intelligible to us. This often involves clarifying the status of their implicit ontology. A survey of interpretations of non-relativistic quantum mechanics supports the evaluation that these interpretations make a contribution to philosophy, but not to physics. Interpretations of quantum field theory are polarized by the divergence between the Lagrangian (...) class='Hi'>field theory that led to the Standard Model of Particle physics and the Algebraic quantum field theory, that discounts an ontology of particles. Ruetsche's interpretation, it is argued, offers a potential for loosening the sharp polarization that presently obtains. A brief evaluation focuses on the functional ontology of quantum field theory considered as an effective theory. (shrink)

I propose a gentle reconciliation of Quantum Theory and General Relativity. It is possible to add small, but unshackling constraints to the quantum fields, making them compatible with General Relativity. Not all solutions of the Schrodinger's equation are needed. I show that the continuous and spatially separable solutions are sufficient for the nonlocal manifestations associated with entanglement and wavefunction collapse. After extending this idea to quantum fields, I show that Quantum Field Theory can (...) be defined in terms of partitioned classical fields. One key element is the idea of integral interactions, which also helps clarifying the quantum measurement and classical level problems. The unity of Quantum Theory and General Relativity can now be gained with the help of the partitioned fields' energy-momentum. A brief image of a General Relativistic Quantum Standard Model is outlined. (shrink)

The sciences occasionally generate discoveries that undermine their own assumptions. Two such discoveries are characterized here: the discovery of apophenia by cognitive psychology and the discovery that physical systems cannot be locally bounded within quantum theory. It is shown that such discoveries have a common structure and that this common structure is an instance of Priest’s well-known Inclosure Schema. This demonstrates that science itself is dialetheic: it generates limit paradoxes. How science proceeds despite this fact is briefly discussed, (...) as is the connection between our results and the realism-antirealism debate. We conclude by suggesting a position of epistemic modesty. (shrink)

Singularities in general relativity and quantum field theory are often taken not only to motivate the search for a more-fundamental theory (quantum gravity, QG), but also to characterise this new theory and shape expectations of what it is to achieve. Here, we first evaluate how particular types of singularities may suggest an incompleteness of current theories. We then classify four different 'attitudes' towards singularities in the search for QG, and show, through examples in the (...) physics literature, that these lead to different scenarios for the new theory. Two of the attitudes prompt singularity resolution, but only one suggests the need for a theory of QG. Rather than evaluate the different attitudes, we close with some suggestions of factors that influence the choice between them. (shrink)

Three accounts of effective realism (ER) have been advanced to solve three problems for scientific realism: Fraser and Vickers (forthcoming) develop a version of ER about non-relativistic quantum mechanics that they argue is compatible with all the main realist versions (‘interpretations’) of quantum mechanics avoiding the problem of underdetermination among them; Williams (2019) and Fraser (2020b) propose ER about quantum field theory as a response to the problems facing realist interpretations; Robertson and Wilson (forthcoming) propose (...) ER to deal with the dubious ontological status of the entities belonging to superseded theories. This paper argues for the unification of these proposals based on realism about modal structure and the idea of scale relativity of ontology developed by ontic structural realists. This solves problems some or all the accounts of ER face, especially that of making explicit in what way they are realist. Furthermore, we respond to a recent critique that has been raised against the ontic structural realist account of quantum mechanics that we employ. (shrink)

The aim of this thesis is to propose a deflationary approach towards the ontological analysis of physical theories. Such an approach sustains that the development of ontologies for physical theories must be neutral relatively to the debate between realists and anti-realists in philosophy of physics. Mainly, our attention will be oriented towards what we called "quantum domain", which includes the non-relativistic Quantum Mechanics and variants of the Quantum Field Theory. This meta-ontological approach consists in an (...) attempt to provide a methodology for the development of specific ontologies for physical theories. With this aim we suggest the separation between physical phenomena and physical theories on one side, and physical theories and ontologies on the other side. This separation intends to endorse the idea that physical theories can provide all the informative contents required for the development of the ontologies associated with them. The result is a defense of the idea that physical theories can positively contribute for the constitution of the ontologies in physics. Additionally, we present a critical analysis of four different ontological approaches to QM and QFT. Each one of these interpretations deals with a different ontological category (tropes, events and processes). At the end of the thesis we will analyze the concepts of interaction and commutation in QFT in order to exemplify the main lines of the deflationary approach suggested here. (shrink)

We look into the ontology of quantum theory as distinct from that of the classical theory in the sciences. Theories carry with them their own ontology while the metaphysics may remain the same in the background. We follow a broadly Kantian tradition, distinguishing between the noumenal and phenomenal realities where the former is independent of our perception while the latter is assembled from the former by means of fragmentary bits of interpretation. Theories do not tell us how (...) the noumenal world is constituted but are conceptual constructs applying to models generated in the phenomenal world within limited contexts. -/- The ontology of quantum theory principally rests on the view that entities in the world are pervasively correlated with one another not by means of probabilities as in the case of the classical theory, but by means of probability amplitudes involving finely tuned phases characterising the oscillatory behaviour of quantum mechanical states. -/- The amplitude-dependent correlations (quantum entanglement) exist over and above the classical ones expressed in terms of probabilities. While the classical correlations are essentially local in nature, quantum correlations are shared globally in the process of environment-induced decoherence. The decoherence is an effectively random process that removes local correlations in the course of global sharing of entanglement—the removal being especially manifest in the case of systems that appear as classical ones. It is this aspect of the decoherence process that makes the so-called measurement postulate (one relating to wave function collapse) cohere with the rest of the principles of quantum theory where the latter implies a Schrodinger type time evolution of quantum mechanical systems. -/- The mathematical basis of the quantum correlations consists of the description of pure states of a system in terms of vectors in a linear vector space (a mixed state appears as an admixture of pure states with some probability distribution associated with it) and, in addition, the description of (pure) states of composite systems as vectors in the product space arising from the component sub-systems. -/- The crucial aspect of the decoherence process, of significance in the context of the apparent incompatibility of the measurement postulate with the unitary Schrodinger evolution, relates to the fact that it is almost instantaneous in the case of a classical object (one that is nevertheless amenable to a quantum description). Indeed, the decoherence time is, in all likelihood, of the order of the Planck scale, being driven by field fluctuations in the Planck regime. This points to factors of an unknown nature determining the finest details of the decoherence process since Planck scale physics remains an obscure terrain. -/- In other words, quantum theory is, to all intents and purposes, in the need of a radical revision, in keeping with the fact that all theories are defeasible and need revision as our domains of experience expand and get realigned in a complex manner. The context within which quantum theory (and quantum field theory too) is defined is set precisely by the Planck scale, across which a novel theoretical framework is likely to emerge. However, as in the case of theory revisions in general, that emerging theory will stand in an asymmetric relation of incommensurability with the present-day quantum theory, where the concepts of the latter will be comprehensible in terms of those of the former, but the converse will not hold. (shrink)

In this paper I outline my propensiton version of quantum theory (PQT). PQT is a fully micro-realistic version of quantum theory that provides us with a very natural possible solution to the fundamental wave/particle problem, and is free of the severe defects of orthodox quantum theory (OQT) as a result. PQT makes sense of the quantum world. PQT recovers all the empirical success of OQT and is, furthermore, empirically testable (although not as yet (...) tested). I argue that Einstein almost put forward this version of quantum theory in 1916/17 in his papers on spontaneous and induced radiative transitions, but retreated from doing so because he disliked the probabilistic character of the idea. Subsequently, the idea was overlooked because debates about quantum theory polarised into the Bohr/Heisenberg camp, which argued for the abandonment of realism and determinism, and the Einstein/Schrödinger camp, which argued for the retention of realism and determinism, no one, as a result, pursuing the most obvious option of retaining realism but abandoning determinism. It is this third, overlooked option that leads to PQT. PQT has implications for quantum field theory, the standard model, string theory, and cosmology. The really important point, however, is that it is experimentally testable. I indicate two experiments in principle capable of deciding between PQT and OQT. (shrink)

Meta-quantum idealism (MQI) proposes a novel framework for understanding the fundamental nature of reality. Rooted in the interplay of quantum field theory, geometry, and idealist metaphysics, MQI challenges traditional ontological assumptions by reimagining space, time, and matter as emergent phenomena arising from the dynamic self-modifications of an infinite quantum field. This paper articulates the foundational principles of MQI and explores its implications for physics, metaphysics, and mathematics.

The claim that at the so-called Planck scale our current physics breaks down and a new theory of quantum gravity is required is ubiquitous, but the evidence is shakier than the confidence of those assertions warrants. In this paper, I survey five arguments in favour of this claim - based on dimensional analysis, quantum black holes, generalised uncertainty principles, the nonrenormalisability of quantum gravity, and theories beyond the standard model - but find that none of them (...) succeeds. The argument from nonrenormalisability is the most convincing, yet it requires the unwarranted assumption that the same constant of action occurs in every quantum field theory. Therefore, our theories don’t (yet) predict that quantum gravity happens at the Planck scale. (shrink)

After about a century since the first attempts by Bohr, the interpretation of quantum theory is still a field with many open questions.1 In this article a new interpretation of quantum theory is suggested, motivated by philosophical considerations. Based on the findings that the ’weirdness’ of quantum theory can be understood to derive from a vanishing distinguishability of indiscernible particles, and the observation that a similar vanishing distinguishability is found for bundle theories in (...) philosophical ontology, the claim is made that quantum theory can be interpreted in an intelligible way by positing a bundle-theoretic view of objective idealism instead of materialism as the underlying fundamental nature of reality. (shrink)

The search for a new scientific theory is typically prompted by an encounter with something in the world that cannot be explained by current theories. This is not the case for the search for a theory of quantum gravity, which has been primarily motivated by theoretical and philosophical concerns. This Element introduces some of the motivations for seeking a theory of quantum gravity, with the aim of instigating a more critical perspective on how they are (...) used in defining and constraining the theory sought. These motivations include unification, incompatibilities between general relativity and quantum field theory, consistency, singularity resolution, and results from black hole thermodynamics. (shrink)

It is now well-known that Newton–Cartan theory is the correct geometrical setting for modelling the quantum Hall effect. In addition, in recent years edge modes for the Newton–Cartan quantum Hall effect have been derived. However, the existence of these edge modes has, as of yet, been derived using only orthodox methodologies involving the breaking of gauge-invariance; it would be preferable to derive the existence of such edge modes in a gauge-invariant manner. In this article, we employ recent (...) work by Donnelly and Freidel in order to accomplish exactly this task. Our results agree with known physics, but afford greater conceptual insight into the existence of these edge modes: in particular, they connect them to subtle aspects of Newton–Cartan geometry and pave the way for further applications of Newton–Cartan theory in condensed matter physics. (shrink)

Quantum entanglement, a phenomenon where two or more particles remain interconnected such that the state of one instantly influences the state of the other regardless of distance, challenges classical notions of locality and causality. From the perspective of the theory of the infinite quantum field, entanglement arises as a natural consequence of the harmonized auto-irritation of this field, where all particles are manifestations of an indivisible and unified reality. This theory posits that the infinite (...) quantum field is the ontological foundation of reality, homogeneous, continuous, and indivisible. All phenomena, including particles, space, and time, emerge as manifestations of this field. Localized excitations of the field, described as auto-solicitations, produce particles as dynamic expressions of the whole. When two particles are generated through auto-irritation of the same intensity, they remain harmonized due to their shared origin within the field. Their interconnectedness transcends spatial separation, as changes in one particle immediately reflect in the other, rooted in the intrinsic unity of the field. This perspective reframes entanglement as a manifestation of the universal interconnectedness of all phenomena through the infinite quantum field. It challenges classical interpretations of separability, offering a holistic framework that integrates quantum mechanics with a deeper ontological foundation. Empirical confirmations of entanglement, such as Bell's tests, support this unified view of reality, deepening our understanding of the cosmos as an integrated whole. (shrink)

The correspondence principle made of unitarity, locality and renormalizability has been very successful in quantum field theory. Among the other things, it helped us build the standard model. However, it also showed important limitations. For example, it failed to restrict the gauge group and the matter sector in a powerful way. After discussing its effectiveness, we upgrade it to make room for quantum gravity. The unitarity assumption is better understood, since it allows for the presence of (...) physical particles as well as fake particles (fakeons). The locality assumption is applied to an interim classical action, since the true classical action is nonlocal and emerges from the quantization and a later process of classicization. The renormalizability assumption is refined to single out the special role of the gauge couplings. We show that the upgraded principle leads to an essentially unique theory of quantum gravity. In particular, in four dimensions, a fakeon of spin 2, together with a scalar field, is able to make the theory renormalizable while preserving unitarity. We offer an overview of quantum field theories of particles and fakeons in various dimensions, with and without gravity. (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)

The monistic worldview aims at a uniform description of nature based on scientific models. Quantum physical systems are mutually part of the other quantum physical systems. An aperture distributes the subsystems and the wave front in all possible ways. The system only takes one of the possible paths, as measurements show. Conclusion from Bell's theorem: Before the quantum physical measurement, there is no point-like location in the universe where all the information that explains the measurement is available. (...) Distributed information is possible. Movement of the particle and measuring process are deterministic. The oscillation between location uncertainty and momentum uncertainty leads photons to determine their own location at short intervals. The uncertainty principle focuses the systems. The fields of the surrounding matter influence the location of the new formation. The effect of all fields is based on a common mechanism. (shrink)