Bohmian Mechanics and Quantum Theory: an Appraisal Boston Studies in the Philosophy of Science
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Lecture Notes in Physics
Lecture Notes in Physics Editorial Board R. Beig, Wien, Austria J. Ehlers, Potsdam, Germany U. Frisch, Nice, France K. Hepp, Zurich,¨ Switzerland W. Hillebrandt, Garching, Germany D. Imboden, Zurich,¨ Switzerland R. L. Jaffe, Cambridge, MA, USA R. Kippenhahn, Gottingen,¨ Germany R. Lipowsky, Golm, Germany H. v. Lohneysen,¨ Karlsruhe, Germany I. Ojima, Kyoto, Japan H. A. Weidenmuller,¨ Heidelberg, Germany J. Wess, Munchen,¨ Germany J. Zittartz, Koln,¨ Germany 3 Berlin Heidelberg New York Barcelona Hong Kong London Milan Paris Singapore Tokyo Editorial Policy The series Lecture Notes in Physics (LNP), founded in 1969, reports new developments in physics research and teaching -- quickly, informally but with a high quality. Manuscripts to be considered for publication are topical volumes consisting of a limited number of contributions, carefully edited and closely related to each other. Each contribution should contain at least partly original and previously unpublished material, be written in a clear, pedagogical style and aimed at a broader readership, especially graduate students and nonspecialist researchers wishing to familiarize themselves with the topic concerned. For this reason, traditional proceedings cannot be considered for this series though volumes to appear in this series are often based on material presented at conferences, workshops and schools (in exceptional cases the original papers and/or those not included in the printed book may be added on an accompanying CD ROM, together with the abstracts of posters and other material suitable for publication, e.g. large tables, colour pictures, program codes, etc.). Acceptance Aprojectcanonlybeacceptedtentativelyforpublication,byboththeeditorialboardandthe publisher, following thorough examination of the material submitted. The book proposal sent to the publisher should consist at least of a preliminary table of contents outlining the structureofthebooktogetherwithabstractsofallcontributionstobeincluded. -
The Theory of (Exclusively) Local Beables
The Theory of (Exclusively) Local Beables Travis Norsen Marlboro College Marlboro, VT 05344 (Dated: June 17, 2010) Abstract It is shown how, starting with the de Broglie - Bohm pilot-wave theory, one can construct a new theory of the sort envisioned by several of QM’s founders: a Theory of Exclusively Local Beables (TELB). In particular, the usual quantum mechanical wave function (a function on a high-dimensional configuration space) is not among the beables posited by the new theory. Instead, each particle has an associated “pilot- wave” field (living in physical space). A number of additional fields (also fields on physical space) maintain what is described, in ordinary quantum theory, as “entanglement.” The theory allows some interesting new perspective on the kind of causation involved in pilot-wave theories in general. And it provides also a concrete example of an empirically viable quantum theory in whose formulation the wave function (on configuration space) does not appear – i.e., it is a theory according to which nothing corresponding to the configuration space wave function need actually exist. That is the theory’s raison d’etre and perhaps its only virtue. Its vices include the fact that it only reproduces the empirical predictions of the ordinary pilot-wave theory (equivalent, of course, to the predictions of ordinary quantum theory) for spinless non-relativistic particles, and only then for wave functions that are everywhere analytic. The goal is thus not to recommend the TELB proposed here as a replacement for ordinary pilot-wave theory (or ordinary quantum theory), but is rather to illustrate (with a crude first stab) that it might be possible to construct a plausible, empirically arXiv:0909.4553v3 [quant-ph] 17 Jun 2010 viable TELB, and to recommend this as an interesting and perhaps-fruitful program for future research. -
Dynamical Relaxation to Quantum Equilibrium
Dynamical relaxation to quantum equilibrium Or, an account of Mike's attempt to write an entirely new computer code that doesn't do quantum Monte Carlo for the first time in years. ESDG, 10th February 2010 Mike Towler TCM Group, Cavendish Laboratory, University of Cambridge www.tcm.phy.cam.ac.uk/∼mdt26 and www.vallico.net/tti/tti.html [email protected] { Typeset by FoilTEX { 1 What I talked about a month ago (`Exchange, antisymmetry and Pauli repulsion', ESDG Jan 13th 2010) I showed that (1) the assumption that fermions are point particles with a continuous objective existence, and (2) the equations of non-relativistic QM, allow us to deduce: • ..that a mathematically well-defined ‘fifth force', non-local in character, appears to act on the particles and causes their trajectories to differ from the classical ones. • ..that this force appears to have its origin in an objectively-existing `wave field’ mathematically represented by the usual QM wave function. • ..that indistinguishability arguments are invalid under these assumptions; rather antisymmetrization implies the introduction of forces between particles. • ..the nature of spin. • ..that the action of the force prevents two fermions from coming into close proximity when `their spins are the same', and that in general, this mechanism prevents fermions from occupying the same quantum state. This is a readily understandable causal explanation for the Exclusion principle and for its otherwise inexplicable consequences such as `degeneracy pressure' in a white dwarf star. Furthermore, if assume antisymmetry of wave field not fundamental but develops naturally over the course of time, then can see character of reason for fermionic wave functions having symmetry behaviour they do. -
Cvi, 1999: 5-24
Nicholas Huggett OFFICE: HOME: Department of Philosophy, M/C 267, 3730 N. Lake Shore Drive, #3B University of Illinois at Chicago, Chicago, IL 60613 601 South Morgan St, Chicago, IL 60607-7114 Telephone: 312-996-3022 773-818-5495/773-281-5728 Fax: 312-413-2093 Email: [email protected] EMPLOYMENT: 2015- : LAS Distinguished Professor, University of Illinois at Chicago. Spring 2018: Visiting Associate Dean, College of Liberal Arts and Sciences, University of Illinois at Chicago. 2009-15: Full Professor, University of Illinois at Chicago. 2001-9: Associate Professor, University of Illinois at Chicago. 1996-2001: Assistant Professor, University of Illinois at Chicago. 1995-6: Visiting Assistant Professor, Brown University. 1994-5: Visiting Assistant Professor, University of Kentucky. EDUCATION: Rutgers University: PhD, 1995. (Dissertation: The Philosophy of Fields and Particles in Classical and Quantum Mechanics, including The Problem of Renormalization. Supervised by Robert Weingard.) Oxford University: BA Hons in Physics and Philosophy, 1988. AWARDS AND FELLOWSHIPS: Foundational Questions Institute Member, 2017-. Outstanding Graduate Mentor Award, Graduate College, University of Illinois at Chicago, 2015. Professorial Fellow, Institute of Philosophy, School of Advanced Studies, University of London, April-May 2011. American Council of Learned Societies Collaborative Fellowship, 2010-13. Grant for full-time research. University of Illinois at Chicago Humanities Institute Fellow, 2005-6. Grant for full-time research. University of Illinois at Chicago, University Scholar, 2002-5. National Science Foundation Science and Technology Studies Scholars Award, 2001-2002. Grant for full-time research. !1/!13 Nicholas Huggett University of Illinois at Chicago Humanities Institute Fellow, 1999 -2000. Grant for full-time research. -
Beyond the Quantum
Beyond the Quantum Antony Valentini Theoretical Physics Group, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom. email: [email protected] At the 1927 Solvay conference, three different theories of quantum mechanics were presented; however, the physicists present failed to reach a consensus. To- day, many fundamental questions about quantum physics remain unanswered. One of the theories presented at the conference was Louis de Broglie's pilot- wave dynamics. This work was subsequently neglected in historical accounts; however, recent studies of de Broglie's original idea have rediscovered a power- ful and original theory. In de Broglie's theory, quantum theory emerges as a special subset of a wider physics, which allows non-local signals and violation of the uncertainty principle. Experimental evidence for this new physics might be found in the cosmological-microwave-background anisotropies and with the detection of relic particles with exotic new properties predicted by the theory. 1 Introduction 2 A tower of Babel 3 Pilot-wave dynamics 4 The renaissance of de Broglie's theory 5 What if pilot-wave theory is right? 6 The new physics of quantum non-equilibrium 7 The quantum conspiracy Published in: Physics World, November 2009, pp. 32{37. arXiv:1001.2758v1 [quant-ph] 15 Jan 2010 1 1 Introduction After some 80 years, the meaning of quantum theory remains as controversial as ever. The theory, as presented in textbooks, involves a human observer performing experiments with microscopic quantum systems using macroscopic classical apparatus. The quantum system is described by a wavefunction { a mathematical object that is used to calculate probabilities but which gives no clear description of the state of reality of a single system. -
Signal-Locality in Hidden-Variables Theories
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server Signal-Locality in Hidden-Variables Theories Antony Valentini1 Theoretical Physics Group, Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2BZ, England.2 Center for Gravitational Physics and Geometry, Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA. Augustus College, 14 Augustus Road, London SW19 6LN, England.3 We prove that all deterministic hidden-variables theories, that reproduce quantum theory for an ‘equilibrium’ distribution of hidden variables, give in- stantaneous signals at the statistical level for hypothetical ‘nonequilibrium en- sembles’. This generalises another property of de Broglie-Bohm theory. Assum- ing a certain symmetry, we derive a lower bound on the (equilibrium) fraction of outcomes at one wing of an EPR-experiment that change in response to a shift in the distant angular setting. We argue that the universe is in a special state of statistical equilibrium that hides nonlocality. PACS: 03.65.Ud; 03.65.Ta 1email: [email protected] 2Corresponding address. 3Permanent address. 1 Introduction: Bell’s theorem shows that, with reasonable assumptions, any deterministic hidden-variables theory behind quantum mechanics has to be non- local [1]. Specifically, for pairs of spin-1/2 particles in the singlet state, the outcomes of spin measurements at each wing must depend instantaneously on the axis of measurement at the other, distant wing. In this paper we show that the underlying nonlocality becomes visible at the statistical level for hypothet- ical ensembles whose distribution differs from that of quantum theory. -
Interpreting Supersymmetry
Interpreting Supersymmetry David John Baker Department of Philosophy, University of Michigan [email protected] October 7, 2018 Abstract Supersymmetry in quantum physics is a mathematically simple phenomenon that raises deep foundational questions. To motivate these questions, I present a toy model, the supersymmetric harmonic oscillator, and its superspace representation, which adds extra anticommuting dimensions to spacetime. I then explain and comment on three foundational questions about this superspace formalism: whether superspace is a sub- stance, whether it should count as spatiotemporal, and whether it is a necessary pos- tulate if one wants to use the theory to unify bosons and fermions. 1 Introduction Supersymmetry{the hypothesis that the laws of physics exhibit a symmetry that transforms bosons into fermions and vice versa{is a long-standing staple of many popular (but uncon- firmed) theories in particle physics. This includes several attempts to extend the standard model as well as many research programs in quantum gravity, such as the failed supergravity program and the still-ascendant string theory program. Its popularity aside, supersymmetry (SUSY for short) is also a foundationally interesting hypothesis on face. The fundamental equivalence it posits between bosons and fermions is prima facie puzzling, given the very different physical behavior of these two types of particle. And supersymmetry is most naturally represented in a formalism (called superspace) that modifies ordinary spacetime by adding Grassmann-valued anticommuting coordinates. It 1 isn't obvious how literally we should interpret these extra \spatial" dimensions.1 So super- symmetry presents us with at least two highly novel interpretive puzzles. Only two philosophers of science have taken up these questions thus far. -
Quantum Computing in the De Broglie-Bohm Pilot-Wave Picture
Quantum Computing in the de Broglie-Bohm Pilot-Wave Picture Philipp Roser September 2010 Blackett Laboratory Imperial College London Submitted in partial fulfilment of the requirements for the degree of Master of Science of Imperial College London Supervisor: Dr. Antony Valentini Internal Supervisor: Prof. Jonathan Halliwell Abstract Much attention has been drawn to quantum computing and the expo- nential speed-up in computation the technology would be able to provide. Various claims have been made about what aspect of quantum mechan- ics causes this speed-up. Formulations of quantum computing have tradi- tionally been made in orthodox (Copenhagen) and sometimes many-worlds quantum mechanics. We will aim to understand quantum computing in terms of de Broglie-Bohm Pilot-Wave Theory by considering different sim- ple systems that may function as a basic quantum computer. We will provide a careful discussion of Pilot-Wave Theory and evaluate criticisms of the theory. We will assess claims regarding what causes the exponential speed-up in the light of our analysis and the fact that Pilot-Wave The- ory is perfectly able to account for the phenomena involved in quantum computing. I, Philipp Roser, hereby confirm that this dissertation is entirely my own work. Where other sources have been used, these have been clearly referenced. 1 Contents 1 Introduction 3 2 De Broglie-Bohm Pilot-Wave Theory 8 2.1 Motivation . 8 2.2 Two theories of pilot-waves . 9 2.3 The ensemble distribution and probability . 18 2.4 Measurement . 22 2.5 Spin . 26 2.6 Objections and open questions . 33 2.7 Pilot-Wave Theory, Many-Worlds and Many-Worlds in denial . -
The Spirit and the Intellect: Lessons in Humility
BYU Studies Quarterly Volume 50 Issue 4 Article 6 12-1-2011 The Spirit and the Intellect: Lessons in Humility Duane Boyce Follow this and additional works at: https://scholarsarchive.byu.edu/byusq Recommended Citation Boyce, Duane (2011) "The Spirit and the Intellect: Lessons in Humility," BYU Studies Quarterly: Vol. 50 : Iss. 4 , Article 6. Available at: https://scholarsarchive.byu.edu/byusq/vol50/iss4/6 This Article is brought to you for free and open access by the Journals at BYU ScholarsArchive. It has been accepted for inclusion in BYU Studies Quarterly by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Boyce: The Spirit and the Intellect: Lessons in Humility The Spirit and the Intellect Lessons in Humility Duane Boyce “The only wisdom we can hope to acquire is the wisdom of humility: humility is endless.” —T. S. Eliot1 Whence Such Confidence? I have friends who see themselves as having intellectual problems with the gospel—with some spiritual matter or other. Interestingly, these friends all share the same twofold characteristic: they are confident they know a lot about spiritual topics, and they are confident they know a lot about various intellectual matters. This always interests me, because my experience is very different. I am quite struck by how much I don’t know about spiritual things and by how much I don’t know about anything else. The overwhelming feeling I get, both from thoroughly examining a scriptural subject (say, faith2) and from carefully studying an academic topic (for example, John Bell’s inequality theorem in physics), is the same—a profound recognition of how little I really know, and how significantly, on many topics, scholars who are more knowledgeable than I am disagree among themselves: in other words, I am surprised by how little they really know, too. -
1 Inequivalent Vacuum States and Rindler Particles Robert Weingard
1 Inequivalent Vacuum States and Rindler Particles Robert Weingard Barry Ward Rutgers University (Published as: “Etats du vide non equivalents et particules de Rindler” in Le Vide: Univers du Tout et du Rien, eds. E. Gunzig and S. Diner (Revue de l'Université de Bruxelles: Éditions Complexes: 1998), 241-255.) 2 1. Introduction The fundamental theories of contemporary physics are quantum field theories. The lowest energy state of a quantum field is the vacuum state. While the vacuum state does not necessarily have zero energy, it is the zero particle state: more energetic states of the field are states that "contain" particles. Recent work has appeared to indicate that which state of a field we account the vacuum state is dependent on our reference frame. While all inertial frames determine one vacuum state, called the Minkowski vacuum, a reference frame that uniformly accelerates (a Rindler frame) will, it is claimed, determine a different vacuum state, and the inertial vacuum will be a superposition of Rindler frame particle states i.e., for the Rindler observer, the inertial vacuum "contains" some indeterminate number of particles. This is quite a surprising prediction. One would certainly expect observers in different states of motion to disagree about the momenta and energies of particles, but for one observer to claim that the field "contains" particles where another says there are none is, at least, counter to our naive intuitions. In this paper we will argue that the naive intuitions are, in fact, correct. The claim that, for a uniformly accelerating observer, the inertial vacuum state "contains" particles is mistaken. -
Extreme Quantum Nonequilibrium, Nodes, Vorticity, Drift, and Relaxation Retarding States
Extreme quantum nonequilibrium, nodes, vorticity, drift, and relaxation retarding states Nicolas G Underwood1;2 1Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario, Canada, N2L 2Y5 2Kinard Laboratory, Clemson University, Clemson, South Carolina, USA, 29634 E-mail: [email protected] Abstract. Consideration is given to the behaviour of de Broglie trajectories that are separated from the bulk of the Born distribution with a view to describing the quantum relaxation properties of more `extreme' forms of quantum nonequilibrium. For the 2-dimensional isotropic harmonic oscillator, through the construction of what is termed the `drift field’, a description is given of a general mechanism that causes the relaxation of `extreme' quantum nonequilibrium. Quantum states are found which do not feature this mechanism, so that relaxation may be severely delayed or possibly may not take place at all. A method by which these states may be identified, classified and calculated is given in terms of the properties of the nodes of the state. Properties of the nodes that enable this classification are described for the first time. 1. Introduction De Broglie-Bohm theory [1,2,3,4] is the archetypal member of a class [5,6,7,8] of interpretations of quantum mechanics that feature a mechanism by which quantum probabilities arise dynamically [5,9, 10, 11, 12, 13, 14] from standard ignorance-type probabilities. This mechanism, called `quantum relaxation', occurs spontaneously through a process that is directly analogous to the classical relaxation (from statistical nonequilibrium to statistical equilibrium) of a simple isolated mechanical system as described by the second thermodynamical law. -
Pilot Wave Theory, Bohmian Metaphysics, and the Foundations of Quantum Mechanics Lecture 7 Not Even Wrong
Pilot wave theory, Bohmian metaphysics, and the foundations of quantum mechanics Lecture 7 Not even wrong. Why does nobody like pilot-wave theory? Mike Towler TCM Group, Cavendish Laboratory, University of Cambridge www.tcm.phy.cam.ac.uk/∼mdt26 and www.vallico.net/tti/tti.html [email protected] – Typeset by FoilTEX – 1 Acknowledgements The material in this lecture is to a large extent a summary of publications by Peter Holland, Antony Valentini, Guido Bacciagaluppi, David Peat, David Bohm, Basil Hiley, Oliver Passon, James Cushing, David Peat, Christopher Norris, H. Nikolic, David Deutsch and the Daily Telegraph. Bacciagaluppi and Valentini’s book on the history of the Solvay conference was a particularly vauable resource. Other sources used and many other interesting papers are listed on the course web page: www.tcm.phy.cam.ac.uk/∼mdt26/pilot waves.html MDT – Typeset by FoilTEX – 2 Life on Mars Today we are apt to forget that - not so very long ago - disagreeing with Bohr on quantum foundational issues, or indeed just writing about the subject in general, was professionally equivalent to having a cuckoo surgically attached to the centre of one’s forehead via a small spring. Here, for example, we encounter the RMP Editor feeling the need to add a remark on editorial policy before publishing Prof. Ballentine’s (hardly very controversial) paper on the statistical interpretation, concluding with what seems very like a threat. One need hardly be surprised at Bohm’s reception seventeen years earlier.. – Typeset by FoilTEX – 3 An intimidating atmosphere.. “The idea of an objective real world whose smallest parts exist objectively in the same sense as stones or trees exist, independently of whether or not we observe them..