Using everyday language, spatial concepts, visualizations and his renowned "Feynman diagrams," the author clearly and humorously communicates the substance and spirit of QED (quantum electodynamics).

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)

There are two distinct interpretations of the role that Feynman diagrams play in physics: (i) they are calculational devices, a type of notation designed to keep track of complicated mathematical expressions; and (ii) they are representational devices, a type of picture. I argue that Feynman diagrams not only have a calculational function but also represent: they are in some sense pictures. I defend my view through addressing two objections and in so doing I offer an account (...) of representation that explains why Feynman diagrams represent. The account that I advocate is a version of that defended by Kendall Walton, which provides us with a basic characterization of the way that representations in general work and is particularly useful for understanding distinctively pictorial representations - in Walton's terms, depictions. The question of the epistemic function of Feynman diagrams as pictorial representations is left for another time. (shrink)

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.

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)

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.

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)

A blue-ribbon panel convened by the National Council for Accreditation of Teacher Education (NCATE) concluded in 2010 that teacher education in the United States must be “turned upside down,” with practical experience at its center and academic content woven around the practical. It might seem that the new clinical model based on medical education, which has been adopted by eight states, would be well-aligned with a Deweyan inquiry-based pedagogy. Dewey himself recognized a paradox, however: preparation for the combination of rigor (...) and flexibility needed for inquiry-based pedagogical skills absolutely requires immersion in clinical settings, even as immersion in the teaching environment that prevails in U.S. public schools systematically socializes new teachers to a very different set of skills than those needed for this model of effective pedagogy. Recent scholarship by Kuhnian scholars provides practical guidance for an alternative understanding of how changes in practice occur and may be transmitted to future generations. (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)

Feynman diagrams: conceptual tools for theoretical physicists Content Type Journal Article Category Book Review Pages 1-4 DOI 10.1007/s11016-011-9580-y Authors Laurie M. Brown, Department of Physics and Astronomy, Northwestern University, Evanston, IL 60201, USA Journal Metascience Online ISSN 1467-9981 Print ISSN 0815-0796.

Hans Reichenbach’s posthumous book The Direction of Time ends somewhere between Socratic aporia and historical irony. Prompted by Feynman’s diagrammatic formulation of quantum electrodynamics, Reichenbach eventually abandoned the delicate balancing between the macroscopic foundation of the direction of time and microscopic descriptions of time order undertaken throughout the previous chapters in favor of an exclusively macroscopic theory that he had vehemently rejected in the 1920s. I analyze Reichenbach’s reasoning against the backdrop of the history of Feynman diagrams (...) and the current practice of particle physics. Building upon the debates about processes and conserved quantities between Wesley Salmon and Phil Dowe in the 1990s, and the exchange between Reichenbach and the gestalt theorist Kurt Lewin during the 1920s about topology and genidentity, I investigate whether the aporia about local time order could be avoided by following a strategy that Reichenbach adopted elsewhere in the book and develop a notion of functional genidentity that captures the practice of present-day elementary particle physics and the fact that Feynman diagrams have to be understood in the context of a complex mathematical description of scattering processes. (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.

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)

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)

Arguably, the development of Feynman diagrams not only resulted in a useful tool for calculations but also brought about deep conceptual changes in the theory of quantum electrodynamics. Starting from this thesis, I try to bring to the fore a particular aspect of it. I maintain that the function of Feynman diagrams is not exhausted by their use in the application of the finished theory to concrete cases. Rather, Feynman diagrams are one of the (...) results of Feynman's more general search for appropriate means of representation. Accordingly, the development of Feynman diagrams is a characteristic example of Feynman's heuristics. (shrink)

The law of gravitation, an example of physical law The relation of mathematics to physics The great conservation principles Symmetry in physical law The distinction of past and future Probability and uncertainty: the quantum mechanical view of nature Seeking new laws.

The physical limitations, due to quantum mechanics, on the functioning of computers are analyzed.

Argumenta el autor que ciencia no es lo que han dicho los filósofos y tampoco lo que dicen las guías del profesor. ¿Qué es? Y afirma: durante toda mi vida he hecho ciencia y sé lo que es, pero me siento incapaz de decirlo. Y lo ejemplifica con el maravilloso número pi, diciendo: lo importante para mí no era el número, sino la idea de que existía un misterio. Pero finalmente se arriesga: dudar de la veracidad de lo que nos (...) es trasmitido del pasado y tratar de determinar ab initio nuevamente esas situaciones a partir de la experiencia, en vez de admitir las experiencias del pasado tal como nos llegan, esto es la ciencia. (shrink)

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.

Feynman diagrams have fascinated physicists and philosophers since they were introduced to the world about 70 years ago. Clearly, they help in calculation; they have allowed nearly impossible problems to be solved with relative ease. This is agreed by all, but that is probably where the consensus ends. Are they pictures of physical processes? Are they just devices for keeping track of mathematical formulae, that do the real work? Are they some sort of mix of both?They are almost (...) as famous as representations of the Bohr atom, even though most people could not give even a sketchy account of what they do. In spite of this they have taken on a role as a cultural icon. Feynman used them to decorate his own van.... (shrink)

In 1927, Paul Dirac first explicitly introduced the idea that electrodynamical processes can be evaluated by decomposing them into virtual (modern terminology), energy non-conserving subprocesses. This mode of reasoning structured a lot of the perturbative evaluations of quantum electrodynamics during the 1930s. Although the physical picture connected to Feynman diagrams is no longer based on energy non-conserving transitions but on off-shell particles, emission and absorption subprocesses still remain their fundamental constituents. This article will access the introduction and the (...) initial reception of this picture of subsequent transitions (PST) by conceiving of concepts, models, and their representations as tools for the practitioners. I will argue for a multi-factorial explanation of Dirac’s initial, verbally explicit introduction: the mathematical representation he had developed was highly suggestive and already partly conceptualized; Dirac was philosophical flexible enough to talk about transitions when no actual transitions, according to the general interpretation of quantum mechanics of the time, occurred; and, importantly, Dirac eventually used the verbal exposition in the same paper in which he introduced it. The direct impact of PST on the conception of quantum electrodynamical processes will be exemplified by its reflection in diagrammatical representations. The study of the diverging ontological commitments towards PST immediately after its introduction opens up the prehistory of a philosophical debate that stretches out into the present: the dispute about the representational and ontological status of the physical picture connected to the evaluation of the perturbative series of QED and QFT. (shrink)

Review of Drawing Theories Apart: The Dispersion of Feynman Diagrams in Postwar Physics, by David Kaiser. University of Chicago Press. 2005.

The paper is concerned with explaining some of the principal theoretical developments in elementary particle physics and discussing the associated methodological problems both in respect of heuristics and appraisal. Particular reference is made to relativistic quantum field theory, renormalization, Feynman diagram techniques, the analytic S-matrix and the Chew — Frautschi bootstrap.

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.

Quantum field theories are notoriously difficult to understand, physically as well as philosophically. The aim of this paper is to contribute to a better conceptual understanding of gauge quantum field theories, such as quantum chromodynamics, by discussing a famous physical limit, the ’t Hooft limit, in which the theory concerned often simplifies. The idea of the limit is that the number N of colours goes to infinity. The simplifications that can happen in this limit, and that we will consider, are: (...) the theory’s Feynman diagrams can be drawn on a plane without lines intersecting ; and the theory, or a sector of it, becomes integrable, and indeed corresponds to a well-studied system, viz. a spin chain. Planarity is important because it shows how a quantum field theory can exhibit extended, in particular string-like, structures; in some cases, this gives a connection with string theory, and so with its representation of gravity. Previous philosophical literature about how one theory might be emergent from, and-or reduced to, another one has tended to emphasize cases, such as occur in statistical mechanics, where the system before the limit has finitely many degrees of freedom. But here, our quantum field theories, including those on the way to the ’t Hooft limit, will have infinitely many degrees of freedom. Nevertheless, we will show how a recent schema by Butterfield and taxonomy by Norton apply to the quantum field theories we consider; and we will classify three physical properties of our theories in these terms. These properties are planarity and integrability, as in and above; and the behaviour of the beta-function reflecting, for example, asymptotic freedom. Our discussion of these properties, especially the beta-function, will also relate to recent philosophical debate about the propriety of assessing quantum field theories, whose rigorous existence is not yet proven. (shrink)

This new edition of work that has evolved over the past seven years completes the derivation of the form of The Standard Model from quantum theory and the extension of the Theory of Relativity to superluminal transformations. The much derided form of The Standard Model is established from a consideration of Lorentz and superluminal relativistic space-time transformations. So much so that other approaches to elementary particle theory pale in comparison. In previous work color SU(3) was derived from space-time considerations. This (...) book shows that the SU(2) U(1) Weak Interaction sector follows directly from the extension of Lorentz transformations to superluminal (faster-than-light) transformations. In fact, ElectroWeak symmetry is shown to have an SU(2) U(1) U(1) symmetry that naturally includes WIMPs (Weakly Interacting Massive Particles), a candidate for Dark Matter. Thus the form of the Standard Model is dictated by space-time considerations fulfilling a dream of Einstein. Using a new matrix formulation of Logic - Operator Logic - we show that Dirac-like equations can be constructed. This edition also derives broken SU(4) four fermion generations as well as a non-Higgsian (Dimensional Mass Generation) derivation of fermion and ElectroWeak gauge boson masses from GL(4). The program of the book is completed by reprinting the book Quantum Theory of the Third Kind, which describes Two-Tier quantum field theory. This theory yields finite results (No Feynman diagram calculations diverge!) in The Standard Model and Quantum Gravity calculations to all orders in perturbation theory. Lastly, the book also contains a description of Operator Logic, Probabilistic Operator Logic, Quantum Operator Logic (for q-number statements). A comprehensive derivation of the form of The Standard Model from geometric considerations. (shrink)

In this paper a few facts about Feynman diagrams and the perturbation expansion of the S-matrix are reviewed and discussed in connection with the question of the ontological status of virtual particles.

The problem of infinities in quantum field theory (QFT) is a longstanding problem in particle physics. To solve this problem, different renormalization techniques have been suggested but the problem persists. Here we suggest another approach to the elimination of infinities in QFT, which is based on non-Diophantine arithmetics – a novel mathematical area that already found useful applications in physics, psychology, and other areas. To achieve this goal, new non-Diophantine arithmetics are constructed and their properties are studied. In addition, non-Diophantine (...) integration is developed in these arithmetics. These constructions allow using constructed non-Diophantine arithmetics for computing integrals associated with Feynman diagrams. Although in the conventional QFT such integrals diverge, their non-Diophantine counterparts are convergent and rigorously defined. As the result, QFT becomes consistent with quantum experiments. (shrink)

The influential Berkeley theoretical physicist Geoffrey Chew renounced the reigning approach to the study of subatomic particles in the early 1960s. The standard approach relied on a rigid division between elementary and composite particles. Partly on the basis of his new interpretation of Feynman diagrams, Chew called instead for a “nuclear democracy” that would erase this division, treating all nuclear particles on an equal footing. In developing his rival approach, which came to dominate studies of the strong nuclear (...) force throughout the 1960s, Chew drew on intellectual resources culled from his own political activities and his attempts to reform how graduate students in physics would be trained. (shrink)

The rigid recoil of a crystal is the accepted mechanism for the Mössbauer effect. It’s at odds with the special theory of relativity which does not allow perfectly rigid bodies. The standard model of particle physics which includes QED should not allow any signals to be transmitted faster than the speed of light. If perturbation theory can be used, then the X-ray emitted in a Mössbauer decay must come from a single nuclear decay vertex at which the 4-momentum is exactly (...) conserved in a Feynman diagram. Then the 4-momentum of the final state Mössbauer nucleus must be slightly off the mass shell. This off-shell behavior would be followed by subsequent diffusion of momentum throughout the crystal to bring the nucleus back onto the mass shell and the crystal to a final relaxed state in which it moves rigidly with the appropriate recoil velocity. This mechanism explains the Mössbauer effect at the microscopic level and reconciles it with relativity. Because off-mass-shell quantum mechanics is required, the on-mass-shell theories developed originally for the Mössbauer effect are inadequate. Another possibility is that that the recoil response involves a non-perturbative effect in the standard model which could allow for a non-local instantaneous momentum transfer between the crystal and the decay, as proposed for example by Preparata and others in super-radiance theory. The recoil time of the crystal is probably not instantaneous, and if it could be measured, one could distinguish between various theories. An experiment is proposed in this paper to measure this time. The idea is to measure the total energy radiated due to bremsstrahlung from a charged Mössbauer crystal which has experienced a recoil. Using Larmor’s formula, along with corrections to it, allows one to design an experiment. The favored idea is to use many small nano-spheres of Mössbauer-active metals, whose outer surfaces are charged. The energy radiated then varies as the charge squared divided by the recoil time. This can then be measured with the extreme sensitivity available in Mössbauer experiments. If it turns out that experiments prove the need for off-mass-shell theory, then this would have profound implications for all of condensed matter physics. It would mean that an off-mass-shell theory like those considered by Stueckelberg, Horwitz, Piron, Greenberger, and many others are required to describe nature. The inclusion of these would be a major shift in the foundations. It would mean that there are new dynamic variables—the rest masses of particles. The ability to measure the diffusion relaxation time should prove useful also in chemical analysis, and provide a new class of analytical methods for material science. This problem is also interesting because the Mössbauer effect is a phenomenon where the solid-state environment dramatically and indisputably influences the probability of a nuclear process. (shrink)

In the new physics and in the new field of cosmometry, 1 it is the fundamental pattern that results in the motion from which all is created. Everything starts with the point of infinite potential. The tetrahedron at the point gives birth to the cuboctahedron ; its motion and structure result in the creation of the torus structure. The torus structure is self-referencing on a moment by moment basis since all must pass through the center. But isn't self-referencing the basis (...) for consciousness? It is said that all of creation has awareness, but at different levels. We know plants are aware of threats and of death to other living creatures by the work of Cleve Backster. We know we influence random number generators from the PEAR studies at Princeton. We know baby chicks will influence the movement of robots programed to do a random walk from the work of Rene Peoc'h. Quantum physics has embraced geometry with the work in the equations which explain the Feynman diagrams where particles come in and out of existence; those equations form a structure called the Amplituhedron - which is a quarter of a star tetrahedron. We also know that the tetrahedron can form the star tetrahedron and that each point of the star tetrahedron can form its own star tetrahedron, which can go on infinitely. That is, there is infinity in the finite. As in the fractal and holographic universe, each point or tetrahedron is connected to every other point. If each point has awareness due to formation of the torus, then Hermes teaching of "As above, as below" has meaning in the torus structure. If the torus is the fundamental unit of self-reference, is that the fundamental unit from which consciousness arises? The torus or double torus appears to be fundamental to all of creation - from galaxies to planets to atoms to photons. (shrink)

Aberrations -- Absorption -- Accuracy and precision -- Alpha radiation -- Amplitude -- Angular forces -- Angular momentum -- Antenna -- Arago dot -- Aperture -- Archimedes's principle -- Band theory of solids -- Bernoulli's principle -- Beta radiation -- Blackbody radiation -- Bohr atom -- Bose condensation -- Bra-ket notation -- British thermal unit (BTU) -- Calculating system efficiency -- Circular motion -- Closed systems and isolated systems -- Concave and convex -- Conservation of charge -- Conservation of energy (...) -- Convection and conduction -- Cosmic radiation -- Crest and trough -- Density and specific gravity -- Diode -- Distance and area -- Distortion -- Doppler effect -- Dynamic systems theory -- Edison effect -- Eigenvectors -- Elastic and inelastic collisions -- Electric circuits: Parallel vs series, diagrams and components -- Electric potential -- Energy and power -- Enthalpy -- Entropy -- Euler's laws of motion -- Falling bodies and physics -- Faraday's law -- Feynman diagrams -- Flywheel -- Focal point -- Free body diagram -- Frequency -- Gamma radiation -- Gauss's law -- Gluon -- Gravitational potential energy -- Harmonic oscillator -- Harmonics -- Heisenberg uncertainty principle -- Higgs boson -- Horsepower -- Ideal gas law -- Joule --. (shrink)

We show that in the presence of the torsion tensor \, the quantum commutation relation for the four-momentum, traced over spinor indices, is given by \. In the Einstein–Cartan theory of gravity, in which torsion is coupled to spin of fermions, this relation in a coordinate frame reduces to a commutation relation of noncommutative momentum space, \, where U is a constant on the order of the squared inverse of the Planck mass. We propose that this relation replaces the integration (...) in the momentum space in Feynman diagrams with the summation over the discrete momentum eigenvalues. We derive a prescription for this summation that agrees with convergent integrals: \^s}\rightarrow 4\pi U^{s-2}\sum _{l=1}^\infty \int _0^{\pi /2} d\phi \frac{\sin ^4\phi \,n^{s-3}}{[\sin \phi +U\varDelta n]^s}\), where \}\) and \ does not depend on p. We show that this prescription regularizes ultraviolet-divergent integrals in loop diagrams. We extend this prescription to tensor integrals. We derive a finite, gauge-invariant vacuum polarization tensor and a finite running coupling. Including loops from all charged fermions, we find a finite value for the bare electric charge of an electron: \. This torsional regularization may therefore provide a realistic, physical mechanism for eliminating infinities in quantum field theory and making renormalization finite. (shrink)

This paper is concerned with tracing the implications of two ideas as they affect quantum theory. One, which descends from Leibniz and Mach, is that there is no space-time continuum, but that which are involved are spacial and temporal relations involving the distant matter of the universe. The other is that our universe is finite. The picture of the world to which we are led is that of an enormous space-time Feynman diagram whose vertices are events. A consequence of (...) finiteness is that between each pair of events, along a world line, there can be only finitely many intermediate events. A further change is that we are no longer required to believe that particles need be anywhere between events. The paper takes up nonrelativistic quantum theory in a way that is consistent with these ideas. By considering analogies between the Wiener and the Feynman integrals, and between the Wiener process and related discrete processes, there is obtained a straightforward theory for the Feynman integral. Propagators are worked out for many of the cases relevant to the nonrelativistic theory.The paper shows that, even when there are, along each world-line, no more than one event per Compton wavelength, agreement is good with the usual Schrödinger theory. (shrink)

In QED, an external electromagnetic field can be accounted for non-perturbatively by replacing the causal propagators used in Feynman diagram calculations with Green’s functions for the Dirac equation under the external field. If the external field destabilises the vacuum, then it is a difficult problem to determine which Green’s function is appropriate, and multiple approaches have been developed in the literature whose equivalence, in many cases, is not clear. In this paper, we demonstrate for a broad class of external (...) fields that includes all that act for a finite time, that four Green’s functions used in the literature are equivalent: Schwinger’s “proper-time” propagator; the “causal propagator” used in the “Bogoliubov transformation” method based on the canonical quantization of the field operator; and two defined using analytic continuation from complexified parameters. To do so, we formulate Schwinger’s “proper-time quantum mechanics" as a Schrödinger wave mechanics, and use this to re-derive Schwinger’s expression for the propagator as a statement relating solutions of the inhomogeneous Dirac equation to those of the inhomogeneous “proper-time Dirac equation”. This is done by constructing direct integral spectral decompositions of the Hamiltonians of both equations, and deriving a form for solutions of the inhomogeneous Dirac equation in terms of these decompositions. We then show that all four propagators return solutions of the inhomogeneous Dirac equation that satisfy the same boundary condition, which under a physically reasonable assumption is sufficient to specify the solution uniquely. (shrink)

Professor Sir Roger Penrose's work, spanning fifty years of science, with over five thousand pages and more than three hundred papers, has been collected together for the first time and arranged chronologically over six volumes, each with an introduction from the author. Where relevant, individual papers also come with specific introductions or notes. Developing ideas sketched in the first volume, twistor theory is now applied to genuine issues of physics, and there are the beginnings of twistor diagram theory (an analogue (...) of Feynman Diagrams). This collection includes joint papers with Stephen Hawking, and uncovers certain properties of black holes. The idea of cosmic censorship is also first proposed. Along completely different lines, the first methods of aperiodic tiling for the Euclidean plane that come to be known as Penrose tiles are described. This volume also contains Penrose's three prize-winning essays for the Gravity Foundation (two second places with both Ezra Newman and Steven Hawking, and a solo first place for 'The Non-linear graviton'). (shrink)

Variable particle masses have sometimes been invoked to explain observed anomalies in low energy nuclear reactions (LENR). Such behavior has never been observed directly, and is not considered possible in theoretical nuclear physics. Nevertheless, there are covariant off-mass-shell theories of relativistic particle dynamics, based on works by Fock, Stueckelberg, Feynman, Greenberger, Horwitz, and others. We review some of these and we also consider virtual particles that arise in conventional Feynman diagrams in relativistic field theories. Effective Lagrangian models (...) incorporating variable mass particle theories might be useful in describing anomalous nuclear reactions by combining mass shifts together with resonant tunneling and other effects. A detailed model for resonant fusion in a deuterium molecule with off-shell deuterons and electrons is presented as an example. Experimental means of observing such off-shell behavior directly, if it exists, is proposed and described. Brief explanations for elemental transmutation and formation of micro-craters are also given, and an alternative mechanism for the mass shift in the Widom–Larsen theory is presented. If variable mass theories were to find experimental support from LENR, then they would undoubtedly have important implications for the foundations of quantum mechanics, and practical applications may arise. (shrink)

A virtual particle is an elementary particle in a quantum field theory that serves to symbolise the interaction of its counterparts, the so called real particles. In the last 20 years, philosophers of physics have put forth several arguments for and against an interpretation of virtual particles as being like ordinary objects in space and time. In this article, I will attempt to systematise the major arguments and argue that no pro-argument is ultimately satisfactory, and that only one contra-argument—that of (...) superposition—is sufficient to deny the realistic interpretation of virtual particles. The secondary aim of this paper is to argue that even the philosophical considerations of virtual particles overestimate their role in that these entities are merely pictorial descriptions of a mathematical approximation method. This description, while helpful, is not necessary to understand particle interactions. In the end, quantum field theory is not the place to explain what actually happens in the very centre of an individual particle interaction. (shrink)

The first volume of the Brandeis University Summer Institute lecture series of 1970 on theories of interacting elementary particles, consisting of four sets of lectures. Every summer since 1959 Brandeis University has conducted a lecture series centered on various areas of theoretical physics. The areas are sufficiently broad to interest a large number of physicists and the lecturers are among the original explorers of these areas. The 1970 lectures, presented in two volumes, are on theories of interacting elementary particles. The (...) four lecturers of Volume 1, and the range of the topics they cover, are as follows: Stephen L. Adler on "Perturbation Theory Anomalies": introduction and review of perturbation theory; the VVA triangle anomaly; absence of radiative corrections; generalizations of our results; connection between Ward identity anomalies and commutator anomalies; applications of the Bjorken limit; and breakdown of the Bjorken limit in perturbation theory. Stanley Mandelstam on "Dynamical Applications of the Veneziano formula for the four-point scalar amplitude; factorization; the operator formalism; Veneziano-type quark models; and higher-order Feynman-like diagrams. Steven Weinberg on "Dynamic and Algebraic Symmetries": Introduction; hadron electrodynamics; local symmetries; and chirality. Wolfhart Zimmermann on "Local Operator Products and Renormalization in Quantum Field Theory": introduction; renormalization; operator product expansions; and local field equations. The second volume contains lectures by Rudolf Haag on observables and fields, by Maurice Jacob on duality, by Michael Reed on non-Fock representations, and by Bruno Zumino on effective Lagrangians and broken symmetries. (shrink)