Quantum Mechanics

Edited by Michael Cuffaro (University of Western Ontario, Ludwig Maximilians Universität, München)
Assistant editor: Radin Dardashti (Ludwig Maximilians Universität, München)
About this topic
Summary Issues in the philosophy of quantum mechanics include first and foremost, its interpretation. Probably the most well-known of these is the 'orthodox' Copenhagen interpretation associated with Neils Bohr, Werner Heisenberg, Wolfgang Pauli, John von Neumann, and others. Beginning roughly at the midway point of the previous century, philosophers' attention began to be drawn towards alternative interpretations of the theory, including Bohmian mechanics, the relative state formulation of quantum mechanics and its variants (i.e., DeWit's "many worlds" variant, Albert and Loewer's "many minds" variant, etc.), and the dynamical collapse family of theories. One particular interpretational issue that has attracted very much attention since the seminal work of John Bell, is the issue of the extent to which quantum mechanical systems do or do not admit of a local realistic description. Bell's investigation of the properties of entangled quantum systems, inspired by the famous thought experiment of Einstein, Podolsky, and Rosen, seems to lead one to the conclusion that the only realistic "hidden variables" interpretation compatible with the quantum mechanical formalism is a nonlocal one. In recent years, some of the attention has focused on applications of quantum mechanics and their potential for illuminating quantum foundations. These include the sciences of quantum information and quantum computation. Additional areas of research include philosophical investigation into the extensions of nonrelativistic quantum mechanics (such as quantum electrodynamics and quantum field theory more generally), as well as more formal logico-mathematical investigations into the structure of quantum states, state spaces, and their dynamics.
Key works Bohr 1928 and Heisenberg 1930 expound upon what has since become known as the 'Copenhagen interpretation' of quantum mechanics. The famous 'EPR' thought experiment of Einstein et al 1935 aims to show that quantum mechanics is an incomplete theory which should be supplemented by additional ('hidden') parameters. Bohr 1935 replies. More on Bohr's views can be found in Faye 1991, Folse 1985. Inspired by the EPR thought experiment, Bell 2004 [1964] proves what has since become known as "Bell's theorem." This, and a related result due to Kochen & Specker 1967 serve to revive the discussion of hidden variables and alternative interpretations of quantum mechanics. Jarrett 1984 analyses the key "factorisability" assumption Bell uses to derive his theorem into two distinct sub-assumptions, which Jarrett refers to as "locality" and "completeness". Two important volumes dedicated to the topics of entanglement and nonlocality are Cushing & McMullin 1989 and Maudlin 2002. Among the more discussed alternative interpretations of quantum mechanics are: Bohmian mechanics (Bohm 1952, and see also Cushing et al 1996), and Everett's relative state formulation (Everett Iii 1973). The latter gives rise to many variants, including the many worlds, many minds, and decoherence-based approaches (see Saunders et al 2010). Other notable interpretations and alternative theories include dynamical collapse theories (Ghirardi et al 1986), as well as the Copenhagen-inspired QBist view (Fuchs 2003, Fuchs manuscript). An attempt to axiomatize quantum mechanics in terms of information theoretic constraints, and a discussion of the relevance of this for the interpretation of quantum mechanics is given in Clifton et al 2002. Discussion of this and other issues in quantum information theory can be found in: Timpson 2004. Key works in the philosophy of quantum field theory include: Redhead 1995, Redhead 1994, Ruetsche 2011, Teller 1995.
Introductions Hughes 1989 is an excellent introduction to the formalism and interpretation of quantum mechanics. Albert 1992 is another, which focuses particularly on the problem of measurement in quantum mechanics.
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  1. Science and Irrationalism or the Generalized Complementarity Principle of Bohr.Alexander Klimets - 2004 - Physics of Consciousness and Life, Cosmology and Astrophysics (Kiev) 4 (2):49-63.
    The article formulates and substantiates the philosophical epistemological principle, which generalizes the principle of complementarity of Bohr to all phenomena of reality. The general complementarity principle is formulated as follows: the rational side of reality and its cognition and its associated irrational side of reality and its cognition are complementary to each other. The general principle of complementarity allows one to search for phenomena of duality in various fields, grouping them according to rational and irrational signs.
  2. How Has Quantum Physics Affected the Free Will Debate?Neer Singhal - manuscript
    This paper discusses the extent to which advances in quantum physics can affect ideas of free will and determinism. It questions whether arguments that conclude the existence of free will from quantum physics are as valid as they seem. -/- The paper discusses the validity of Searle’s philosophy of mind, Robert Kane’s parallel processing, and Ted Honderich’s near-determinism, as well as dealing with chaos theory, the relationship between ‘randomness’ and ‘unpredictability,’ and Bell’s theorem, discussing how they can be used to (...)
  3. Deep Indeterminacy in Physics and Fiction.George Darby, Martin Pickup & Jon Robson - 2017 - In Otávio Bueno, Steven French, George Darby & Dean Rickles (eds.), Thinking About Science, Reflecting on Art: Bringing Aesthetics and Philosophy of Science Together. Routledge.
    Indeterminacy in its various forms has been the focus of a great deal of philosophical attention in recent years. Much of this discussion has focused on the status of vague predicates such as ‘tall’, ‘bald’, and ‘heap’. It is determinately the case that a seven-foot person is tall and that a five-foot person is not tall. However, it seems difficult to pick out any determinate height at which someone becomes tall. How best to account for this phenomenon is, of course, (...)
  4. Emergent Quasiparticles. Or How to Get a Rich Physics From a Sober Metaphysics.Alexandre Guay & Olivier Sartenaer - 2018 - In Melinda Fagan, Otávio Bueno & Ruey-Lin Chen (eds.), Individuation, Process and Scientific Practices. New York, USA: Oxford University Press. pp. 214-235.
    Among the very architects of the recent re-emergence of emergentism in the physical sciences, Robert B. Laughlin certainly occupies a prominent place. Through a series of works beginning as early as his Nobel lecture in 1998, a lecture given after having been awarded, together with Störmer and Tsui, the Nobel prize in physics for its contribution in the elucidation of the fractional quantum Hall effect, Laughlin openly and relentlessly advocated a strongly anti-reductionistic view of physics – and, more particularly, of (...)
  5. The Legitimate Route to the Scientific Truth.Joseph Krecz - manuscript
    We leave in a beautiful and uniform world, a world where everything probable is possible. The human have became a dominant component of life form on earth for some time. We realized that intellectual inquiry can have practical outcome, and the humans list of achievements are enormous and impressive. The burning of organic matter for extracting energy has been a constant and ever increasing source of pollution, we are still doing it. The amazing human intellect has proved capable of amazing (...)
  6. The Tacit ‘Quantum’ of Meeting the Aesthetic Sign; Contextualize, Entangle, Superpose, Collapse or Decohere.Jan Broekaert - 2018 - Foundations of Science 23 (2):255-266.
    The semantically ambiguous nature of the sign and aspects of non-classicality of elementary matter as described by quantum theory show remarkable coherent analogy. We focus on how the ambiguous nature of the image, text and art work bears functional resemblance to the dynamics of contextuality, entanglement, superposition, collapse and decoherence as these phenomena are known in quantum theory. These quantumlike properties in linguistic signs have previously been identified in formal descritions of e.g. concept combinations and mental lexicon representations and have (...)
  7. Ψ-Epistemic Quantum Cosmology?Peter W. Evans, Sean Gryb & Karim P. Y. Thébault - 2016 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 56:1-12.
    This paper provides a prospectus for a new way of thinking about the wavefunction of the universe: a Ψ-epistemic quantum cosmology. We present a proposal that, if successfully implemented, would resolve the cosmological measurement problem and simultaneously allow us to think sensibly about probability and evolution in quantum cosmology. Our analysis draws upon recent work on the problem of time in quantum gravity and causally symmet- ric local hidden variable theories. Our conclusion weighs the strengths and weaknesses of the approach (...)
  8. Interaction-Free Effects Between Distant Atoms.Yakir Aharonov, Eliahu Cohen, Avshalom C. Elitzur & Lee Smolin - 2018 - Foundations of Physics 48 (1):1-16.
    A Gedanken experiment is presented where an excited and a ground-state atom are positioned such that, within the former’s half-life time, they exchange a photon with 50% probability. A measurement of their energy state will therefore indicate in 50% of the cases that no photon was exchanged. Yet other measurements would reveal that, by the mere possibility of exchange, the two atoms have become entangled. Consequently, the “no exchange” result, apparently precluding entanglement, is non-locally established between the atoms by this (...)
  9. Time Reversal Invariance in Quantum Mechanics.Reza Moulavi Ardakani - 2017 - Dissertation, Texas Tech University
    Symmetries have a crucial role in today’s physics. In this thesis, we are mostly concerned with time reversal invariance (T-symmetry). A physical system is time reversal invariant if its underlying laws are not sensitive to the direction of time. There are various accounts of time reversal transformation resulting in different views on whether or not a given theory in physics is time reversal invariant. With a focus on quantum mechanics, I describe the standard account of time reversal and compare it (...)
  10. Review of The Quantum Revolution in Philosophy. [REVIEW]David Glick - 2018 - British Journal for the Philosophy of Science.
  11. Haag’s Theorem, Apparent Inconsistency, and the Empirical Adequacy of Quantum Field Theory.Michael E. Miller - 2015 - British Journal for the Philosophy of Science:axw029.
    Haag’s theorem has been interpreted as establishing that quantum field theory cannot consistently represent interacting fields. Earman and Fraser have clarified how it is possible to give mathematically consistent calculations in scattering theory despite the theorem. However, their analysis does not fully address the worry raised by the result. In particular, I argue that their approach fails to be a complete explanation of why Haag’s theorem does not undermine claims about the empirical adequacy of particular quantum field theories. I then (...)
  12. The Limits of Physical Equivalence in Algebraic Quantum Field Theory.Tracy Lupher - 2016 - British Journal for the Philosophy of Science:axw017.
    Some physicists and philosophers argue that unitarily inequivalent representations in quantum field theory are mathematical surplus structure. Support for that view, sometimes called ‘algebraic imperialism’, relies on Fell’s theorem and its deployment in the algebraic approach to QFT. The algebraic imperialist uses Fell’s theorem to argue that UIRs are ‘physically equivalent’ to each other. The mathematical, conceptual, and dynamical aspects of Fell’s theorem will be examined. Its use as a criterion for physical equivalence is examined in detail and it is (...)
  13. Toward an Understanding of Parochial Observables.Benjamin Feintzeig - 2016 - British Journal for the Philosophy of Science:axw010.
    Ruetsche claims that an abstract C*-algebra of observables will not contain all of the physically significant observables for a quantum system with infinitely many degrees of freedom. This would signal that in addition to the abstract algebra, one must use Hilbert space representations for some purposes. I argue to the contrary that there is a way to recover all of the physically significant observables by purely algebraic methods. 1 Introduction2 Preliminaries3 Three Extremist Interpretations3.1 Algebraic imperialism3.2 Hilbert space conservatism3.3 Universalism4 Parochial (...)
  14. An Intrinsic Theory of Quantum Mechanics: Progress in Field's Nominalistic Program, Part I.Eddy Keming Chen - manuscript
    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 (...)
  15. Time’s Arrow in a Quantum Universe I: On the Simplicity and Uniqueness of the Initial Quantum State.Eddy Keming Chen - manuscript
    In a quantum universe with a strong arrow of time, we postulate a low-entropy boundary condition (the Past Hypothesis) to account for the temporal asymmetry. In this paper, I show that the Past Hypothesis also contains enough information to significantly simplify the quantum ontology and clearly define a unique initial condition in such a world. First, I introduce Density Matrix Realism, the thesis that the quantum universe is described by a fundamental density matrix (a mixed state) that corresponds to some (...)
  16. Ontological Aspects of Quantum Field Theory.Meinard Kuhlmann, Holger Lyre & Andrew Wayne (eds.) - 2002 - World Scientific.
  17. A Century of Quantum Theory: Time for a Change in Thinking.Thomas Görnitz - 2017 - Foundations of Science 22 (4):749-762.
    The aim of science is the explanation of complicated systems by reducing it to simple subsystems. According to a millennia-old imagination this will be attained by dividing matter into smaller and smaller pieces of it. The popular superstition that smallness implies simplicity seems to be ineradicable. However, since the beginning of quantum theory it would be possible to realize that the circumstances in nature are exactly the other way round. The idea “smaller becomes simpler” is useful only down to the (...)
  18. From Cubist Simultaneity to Quantum Complementarity.Christophe Schinckus - 2017 - Foundations of Science 22 (4):709-716.
    This article offers a contribution to the history of scientific ideas by proposing an epistemological argument supporting the assumption made by Miller whereby Niels Bohr has been influenced by cubism when he developed his non-intuitive complementarity principle. More specifically, this essay will identify the Bergsonian durée as the conceptual bridge between Metzinger and Bohr. Beyond this conceptual link between the painter and the physicist, this paper aims to emphasize the key role played by art in the development of human knowledge.
  19. Formal and Physical Equivalence in Two Cases in Contemporary Quantum Physics.Doreen Fraser - 2017 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 59:30-43.
  20. Dualities and Emergent Gravity: Gauge/Gravity Duality.Sebastian de Haro - 2017 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 59:109-125.
    In this paper I develop a framework for relating dualities and emergence: two notions that are close to each other but also exclude one another. I adopt the conception of duality as 'isomorphism', from the physics literature, cashing it out in terms of three conditions. These three conditions prompt two conceptually different ways in which a duality can be modified to make room for emergence; and I argue that this exhausts the possibilities for combining dualities and emergence. I apply this (...)
  21. Yes, More Decoherence: A Reply to Critics.Elise Crull - 2017 - Foundations of Physics 47 (11):1428-1463.
    Recently I published an article in this journal entitled “Less interpretation and more decoherence in quantum gravity and inflationary cosmology” :1019–1045, 2015). This article generated responses from three pairs of authors: Vassallo and Esfeld :1533–1536, 2015), Okon and Sudarsky :852–879, 2016) and Fortin and Lombardi. In what follows, I reply to the criticisms raised by these authors.
  22. Interpretation and Decoherence: A Contribution to the Debate Vassallo & Esfeld Versus Crull.Sebastian Fortin & Olimpia Lombardi - 2017 - Foundations of Physics 47 (11):1423-1427.
    Two recent papers appeared in FOOP disagree regarding the role played by decoherence in quantum physics. On the one hand, Elise Crull considers that decoherence, by itself, solves many conceptual problems in quantum physics, with no need of interpretative considerations. On the other hand, Antonio Vassallo and Michael Esfeld reply by correctly claiming that, although decoherence is a powerful tool to deal with conceptual problems, it does not dispense us from interpreting the formalism. In this brief note we want to (...)
  23. The Invisibility of Diffeomorphisms.Sebastian De Haro - 2017 - Foundations of Physics 47 (11):1464-1497.
    I examine the relationship between \\)-dimensional Poincaré metrics and d-dimensional conformal manifolds, from both mathematical and physical perspectives. The results have a bearing on several conceptual issues relating to asymptotic symmetries in general relativity and in gauge–gravity duality, as follows: I draw from the remarkable work by Fefferman and Graham on conformal geometry, in order to prove two propositions and a theorem that characterise which classes of diffeomorphisms qualify as gravity-invisible. I define natural notions of gravity-invisibility that apply to the (...)
  24. Why is the Transference Theory of Causation Insuffcient? The Challenge of the Aharonov-Bohm Effect.Vincent Ardourel & Alexandre Guay - forthcoming - Studies in History and Philosophy of Modern Physics.
    The transference theory reduces causation to the transmission of physical conserved quantities, like energy or momenta. Although this theory aims at applying to all felds of physics, we claim that it fails to account for a quantum electrodynamic effect, viz. the Aharonov-Bohm effect. After having argued that the Aharonov-Bohm effect is a genuine counter-example for the transference theory, we offer a new physicalist approach of causation, ontic and modal, in which this effect is embedded.
  25. What Weak Measurements and Weak Values Really Mean: Reply to Kastner.Eliahu Cohen - 2017 - Foundations of Physics 47 (10):1261-1266.
    Despite their important applications in metrology and in spite of numerous experimental demonstrations, weak measurements are still confusing for part of the community. This sometimes leads to unjustified criticism. Recent papers have experimentally clarified the meaning and practical significance of weak measurements, yet in Kastner, Kastner seems to take us many years backwards in the the debate, casting doubt on the very term “weak value” and the meaning of weak measurements. Kastner appears to ignore both the basics and frontiers of (...)
  26. Theoretical and Conceptual Analysis of the Celebrated 4π-Symmetry Neutron Interferometry Experiments.Massimiliano Sassoli de Bianchi - 2017 - Foundations of Science 22 (3):627-653.
    In 1975, two experimental groups have independently observed the \-symmetry of neutrons’ spin, when passing through a static magnetic field, using a three-blade interferometer made from a single perfect Si-crystal. In this article, we provide a complete analysis of the experiment, both from a theoretical and conceptual point of view. Firstly, we solve the Schrödinger equation in the weak potential approximation, to obtain the amplitude of the refracted and forward refracted beams, produced by the passage of neutrons through one of (...)
  27. Response to Comment on ‘Non-Representative Quantum Mechanical Weak Values’ by Ben-Israel and Vaidman.B. E. Y. Svensson - 2017 - Foundations of Physics 47 (9):1258-1260.
    Ben-Israel and Vaidman have raised objections to my arguments that there are cases where a quantum mechanical weak value can be said not to represent the system to which it pertains. They are correct in pointing out that some of my conclusions were too general. However, for weak values of projection operators my conclusions still stand.
  28. The Number Behind the Simplest SIC–POVM.Ingemar Bengtsson - 2017 - Foundations of Physics 47 (8):1031-1041.
    The simple concept of a SIC poses a very deep problem in algebraic number theory, as soon as the dimension of Hilbert space exceeds three. A detailed description of the simplest possible example is given.
  29. SICs and Algebraic Number Theory.Marcus Appleby, Steven Flammia, Gary McConnell & Jon Yard - 2017 - Foundations of Physics 47 (8):1042-1059.
    We give an overview of some remarkable connections between symmetric informationally complete measurements and algebraic number theory, in particular, a connection with Hilbert’s 12th problem. The paper is meant to be intelligible to a physicist who has no prior knowledge of either Galois theory or algebraic number theory.
  30. Quantum Walks, Weyl Equation and the Lorentz Group.Bisio Alessandro, D’Ariano Giacomo Mauro & Perinotti Paolo - 2017 - Foundations of Physics 47 (8):1065-1076.
    Quantum cellular automata and quantum walks provide a framework for the foundations of quantum field theory, since the equations of motion of free relativistic quantum fields can be derived as the small wave-vector limit of quantum automata and walks starting from very general principles. The intrinsic discreteness of this framework is reconciled with the continuous Lorentz symmetry by reformulating the notion of inertial reference frame in terms of the constants of motion of the quantum walk dynamics. In particular, among the (...)
  31. Negativity Bounds for Weyl–Heisenberg Quasiprobability Representations.John B. DeBrota & Christopher A. Fuchs - 2017 - Foundations of Physics 47 (8):1009-1030.
    The appearance of negative terms in quasiprobability representations of quantum theory is known to be inevitable, and, due to its equivalence with the onset of contextuality, of central interest in quantum computation and information. Until recently, however, nothing has been known about how much negativity is necessary in a quasiprobability representation. Zhu :120404, 2016) proved that the upper and lower bounds with respect to one type of negativity measure are saturated by quasiprobability representations which are in one-to-one correspondence with the (...)
  32. Deciding the Mind–Body Problem Experimentally.Pierre Uzan - 2017 - Axiomathes 27 (4):333-354.
    A Bell-type strategy of decision for the long-standing question of the nature of psychophysical correlations has been previously presented in a recent article published in Mind and Matter. This strategy of decision is here applied to experimental data on psychophysiological correlations, namely, correlations between cardiovascular and emotional variables that have been reported in several independent publications. This statistical analysis shows that a substantial majority of these correlations cannot be interpreted as an exchange of signals or a mere “interaction”, whatever its (...)
  33. Can We Do Without Realism?Desmond Sander - manuscript
    I am interested in understanding what happens. It goes without saying, at least for me, that physics — I mean 20th. Century physics — is our best account so far of what happens, very compelling and astonishingly successful. But physics, as is well-known has some deep problems. I have slowly come to realise that the source of those problems is a philosophical mistake, a mistake that is not restricted to physicists but shared by nearly everyone. To put it briefly, it (...)
  34. A Gleason-Type Theorem for Any Dimension Based on a Gambling Formulation of Quantum Mechanics.Alessio Benavoli, Alessandro Facchini & Marco Zaffalon - 2017 - Foundations of Physics 47 (7):991-1002.
    Based on a gambling formulation of quantum mechanics, we derive a Gleason-type theorem that holds for any dimension n of a quantum system, and in particular for \. The theorem states that the only logically consistent probability assignments are exactly the ones that are definable as the trace of the product of a projector and a density matrix operator. In addition, we detail the reason why dispersion-free probabilities are actually not valid, or rational, probabilities for quantum mechanics, and hence should (...)
  35. Spacetime Fluctuations and a Stochastic Schrödinger–Newton Equation.Bera Sayantani, Giri Priyanka & P. Singh Tejinder - 2017 - Foundations of Physics 47 (7):897-910.
    We propose a stochastic modification of the Schrödinger–Newton equation which takes into account the effect of extrinsic spacetime fluctuations. We use this equation to demonstrate gravitationally induced decoherence of two gaussian wave-packets, and obtain a decoherence criterion similar to those obtained in the earlier literature in the context of effects of gravity on the Schrödinger equation.
  36. Equivalent Quantum Equations in a System Inspired by Bouncing Droplets Experiments.Christian Borghesi - 2017 - Foundations of Physics 47 (7):933-958.
    In this paper we study a classical and theoretical system which consists of an elastic medium carrying transverse waves and one point-like high elastic medium density, called concretion. We compute the equation of motion for the concretion as well as the wave equation of this system. Afterwards we always consider the case where the concretion is not the wave source any longer. Then the concretion obeys a general and covariant guidance formula, which leads in low-velocity approximation to an equivalent de (...)
  37. Bohr’s Complementarity Framework in Biosemiotics.Filip Grygar - 2017 - Biosemiotics 10 (1):33-55.
    This paper analyses Bohr’s complementarity framework and applies it to biosemiotic studies by illustrating its application to three existing models of living systems: mechanistic biology, Barbieri’s version of biosemiotics in terms of his code biology and Markoš’s phenomenological version of hermeneutic biosemiotics. The contribution summarizes both Bohr’s philosophy of science crowned by his idea of complementarity and his conception of the phenomenon of the living. Bohr’s approach to the biological questions evolved – among other things – from the consequences of (...)
  38. Demystifying Weak Measurements.R. E. Kastner - 2017 - Foundations of Physics 47 (5):697-707.
    A large literature has grown up around the proposed use of ‘weak measurements’ to allegedly provide information about hidden ontological features of quantum systems. This paper attempts to clarify the fact that ‘weak measurements’ involve strong measurements on one member of an entangled system. The only thing ‘weak’ about such measurements is that the correlation established via the entanglement does not correspond to eigenstates of the ‘weakly measured observable’ for the remaining component system subject to the weak measurement. All observed (...)
  39. Time Symmetric Quantum Mechanics and Causal Classical Physics?W. Bopp Fritz - 2017 - Foundations of Physics 47 (4):490-504.
    A two boundary quantum mechanics without time ordered causal structure is advocated as consistent theory. The apparent causal structure of usual “near future” macroscopic phenomena is attributed to a cosmological asymmetry and to rules governing the transition between microscopic to macroscopic observations. Our interest is a heuristic understanding of the resulting macroscopic physics.
  40. Comment on “Non-Representative Quantum Mechanical Weak Values”.Ben-Israel Alon & Vaidman Lev - 2017 - Foundations of Physics 47 (4):467-470.
    Svensson argued that the concept of the weak value of an observable of a pre- and post-selected quantum system cannot be applied when the expectation value of the observable in the initial state vanishes. Svensson’s argument is analyzed and shown to be inconsistent using several examples.
  41. Design for a Superluminal Signaling Device.Sarfatti Jack - 1991 - Physics Essays 4 (3):315-336.
    This paper is of historical interest cited by MIT Historian of Physics David Kaiser in his book "How the Hippies Saved Physics" - based on a patent disclosure.
  42. Finite-Time Flocking Problem of a Cucker-Smale-Type Self-Propelled Particle Model.Yuchen Han, Donghua Zhao & Yongzheng Sun - 2016 - Complexity 21 (S1):354-361.
  43. On the CHSH Form of Bell’s Inequalities.Lambare Justo Pastor - 2017 - Foundations of Physics 47 (3):321-326.
    A common mistake present in the derivation of the usually known as the CHSH form of Bell’s inequalities is pointed out. References and comments to the correct approach are given. This error does not alter the final result and only affects the logical consistency of the derivation, but since it seems to be a widespread misconception regarding the roll and interpretation of the of use of hidden variables in Bell’s theorem it is considered to be of general interest.
  44. Simulations of Closed Timelike Curves.A. Brun Todd & M. Wilde Mark - 2017 - Foundations of Physics 47 (3):375-391.
    Proposed models of closed timelike curves have been shown to enable powerful information-processing protocols. We examine the simulation of models of CTCs both by other models of CTCs and by physical systems without access to CTCs. We prove that the recently proposed transition probability CTCs are physically equivalent to postselection CTCs, in the sense that one model can simulate the other with reasonable overhead. As a consequence, their information-processing capabilities are equivalent. We also describe a method for quantum computers to (...)
  45. Particles, Cutoffs and Inequivalent Representations. Fraser and Wallace on Quantum Field Theory.Matthias Egg, Vincent Lam & Andrea Oldofredi - 2017 - Foundations of Physics 47 (3):453-466.
    We critically review the recent debate between Doreen Fraser and David Wallace on the interpretation of quantum field theory, with the aim of identifying where the core of the disagreement lies. We show that, despite appearances, their conflict does not concern the existence of particles or the occurrence of unitarily inequivalent representations. Instead, the dispute ultimately turns on the very definition of what a quantum field theory is. We further illustrate the fundamental differences between the two approaches by comparing them (...)
  46. Quantum Weak Values and Logic: An Uneasy Couple.E. Y. Svensson Bengt - 2017 - Foundations of Physics 47 (3):430-452.
    Quantum mechanical weak values of projection operators have been used to answer which-way questions, e.g. to trace which arms in a multiple Mach–Zehnder setup a particle may have traversed from a given initial to a prescribed final state. I show that this procedure might lead to logical inconsistencies in the sense that different methods used to answer composite questions, like “Has the particle traversed the way X or the way Y?”, may result in different answers depending on which methods are (...)
  47. Action Quantization, Energy Quantization, and Time Parametrization.Edward R. Floyd - 2017 - Foundations of Physics 47 (3):392-429.
    The additional information within a Hamilton–Jacobi representation of quantum mechanics is extra, in general, to the Schrödinger representation. This additional information specifies the microstate of \ that is incorporated into the quantum reduced action, W. Non-physical solutions of the quantum stationary Hamilton–Jacobi equation for energies that are not Hamiltonian eigenvalues are examined to establish Lipschitz continuity of the quantum reduced action and conjugate momentum. Milne quantization renders the eigenvalue J. Eigenvalues J and E mutually imply each other. Jacobi’s theorem generates (...)
  48. Lagrangian Description for Particle Interpretations of Quantum Mechanics: Entangled Many-Particle Case.Roderick I. Sutherland - 2017 - Foundations of Physics 47 (2):174-207.
    A Lagrangian formulation is constructed for particle interpretations of quantum mechanics, a well-known example of such an interpretation being the Bohm model. The advantages of such a description are that the equations for particle motion, field evolution and conservation laws can all be deduced from a single Lagrangian density expression. The formalism presented is Lorentz invariant. This paper follows on from a previous one which was limited to the single-particle case. The present paper treats the more general case of many (...)
  49. Quantum Teleportation and Grover’s Algorithm Without the Wavefunction.Gerd Niestegge - 2017 - Foundations of Physics 47 (2):274-293.
    In the same way as the quantum no-cloning theorem and quantum key distribution in two preceding papers, entanglement-assisted quantum teleportation and Grover’s search algorithm are generalized by transferring them to an abstract setting, including usual quantum mechanics as a special case. This again shows that a much more general and abstract access to these quantum mechanical features is possible than commonly thought. A non-classical extension of conditional probability and, particularly, a very special type of state-independent conditional probability are used instead (...)
  50. The Contextuality Loophole is Fatal for the Derivation of Bell Inequalities: Reply to a Comment by I. Schmelzer.Theodorus M. Nieuwenhuizen & Marian Kupczynski - 2017 - Foundations of Physics 47 (2):316-319.
    Ilya Schmelzer wrote recently: Nieuwenhuizen argued that there exists some “contextuality loophole” in Bell’s theorem. This claim in unjustified. It is made clear that this arose from attaching a meaning to the title and the content of the paper different from the one intended by Nieuwenhuizen. “Contextual loophole” means only that if the supplementary parameters describing measuring instruments are correctly introduced, Bell and Bell-type inequalities may not be proven. It is also stressed that a hidden variable model suffers from a (...)
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