Perimeter Institute will host an international conference from July 18-21, 2006, in honour of Abner Shimony, one of the most eminent physicist-philosophers of our time. Professor Shimony is renowned for his contribution to the famous Bell-CHSH inequality and for many other contributions in the foundations of physics and philosophy. Talks and discussions will cover a wide range of subjects within physics and philosophy, including theoretical and experimental aspects of quantum entanglement and non-locality, relativistic causality, quantum measurement problem, probability theory, temporal transience, the mind-body problem, and scientific realism. http://pirsa.org/podcast/C06009 Science 2009 http://blogs.law.harvard.edu/tech/rss en-ca Thu, 08 Jan 2009 12:35:19 -0500 sbradwell@perimeterinstitute.ca Thu, 08 Jan 2009 12:35:19 -0500 G 180 pirsa-admin@perimeterinstitute.ca Steve Bradwell's - Podcast Generator Howard Burton,Lucien Hardy http://streamer.perimeterinstitute.ca/mp3/e33b1d79-2f63-4a3a-9a30-9e8b05ea1592.mp3 Science http://streamer.perimeterinstitute.ca/mp3/e33b1d79-2f63-4a3a-9a30-9e8b05ea1592.mp3 Tue, 18 Jul 2006 09:00:33 -0400 I will show Abner how to construct Minkowski's space-time diagrams directly from Einstein's two postulates and some very elementary plane geometry. This geometric route into special relativity was developed while teaching the subject to nonscientists, but some of its features may be unfamiliar to physicists and philosophers. N. David Mermin http://streamer.perimeterinstitute.ca/mp3/3351672a-d2b7-4d40-be3a-bedd2298a196.mp3 Science http://streamer.perimeterinstitute.ca/mp3/3351672a-d2b7-4d40-be3a-bedd2298a196.mp3 Tue, 18 Jul 2006 09:15:32 -0400 In the context of Bell-type experiments, two related notions of "separability" are offered, one of which is logically stronger than the other. It is shown that the weaker of these is logically equivalent to the statistical independence condition widely taken to have been refuted by the results of experiments testing the Bell inequalities. Some consequences of the analysis are discussed. Jon Jarrett http://streamer.perimeterinstitute.ca/mp3/3c7df6fa-ef13-49c1-801b-92d99d4b2014.mp3 Science http://streamer.perimeterinstitute.ca/mp3/3c7df6fa-ef13-49c1-801b-92d99d4b2014.mp3 Tue, 18 Jul 2006 10:15:14 -0400 Sandu Popescu http://streamer.perimeterinstitute.ca/mp3/ff9b7ba6-e873-4dd8-a7e7-1022b441fd8d.mp3 Science http://streamer.perimeterinstitute.ca/mp3/ff9b7ba6-e873-4dd8-a7e7-1022b441fd8d.mp3 Tue, 18 Jul 2006 11:45:17 -0400 Abner Shimony mentions that his undergraduate years at Yale in the forties provided an introduction to three profound philosophers that influenced his thought – Alfred North Whitehead, Charles Sanders Peirce and Kurt Gödel. For all three, mathematics played a central role in the unfolding of their lives and thought. This paper will focus on the earliest of this trio, and focus on Peirce’s complex and rich views on the nature and practice of mathematics, attending first to the necessary and foundational nature Peirce ascribes to mathematics and to the place of hypothesis, diagrams, and observation in its development. For Peirce the foundational nature of mathematics arises from the absence of a need to ground it in any further discipline, even a discipline such as logic. The contextualization of a number of these issues in the work of the British mathematicians George Boole and J.J. Sylvester will be explored as well as the powerful yet complex influence of his mathematician father, Benjamin Peirce. Then the role of mathematics in the empirical sciences will be considered, and the meeting point traced in Peirce between the abstract, general and necessary, qualities that figure in mathematics, and the particular and empirical that constitute the description of nature. As various commentators have noted, in the epistemological concerns that dominate Peirce's thinking, intriguing and interesting tensions appear between, on the one hand, his understanding of mathematics and, on the other, his view of an evolving nature which is governed by chance and our knowledge of which is always fallible and thus open to revision. The meeting place, the theme of Wigner’s famous essay reflecting on the effectiveness of mathematics in the natural sciences, is at the heart of the enterprise of mathematical physics. And arguably Peirce’s writings here serve to bring out a number of deep and persistent issues that attend exploring this topic. Ronald Anderson http://streamer.perimeterinstitute.ca/mp3/bfbe6db4-43a8-4eae-90c6-7d09e3b81fd7.mp3 Science http://streamer.perimeterinstitute.ca/mp3/bfbe6db4-43a8-4eae-90c6-7d09e3b81fd7.mp3 Tue, 18 Jul 2006 14:45:02 -0400 After having been a Whiteheadian for decades, Abner, under the influence of Lovejoy’s book, "The Revolt against Dualism,” no longer accepts Whitehead’s philosophy. In this paper I try to challenge this change of heart, as well as suggest a modification of Whitehead’s philosophy that allows for an elegant interpretation of the EPR/Bell correlations. Shimon Malin http://streamer.perimeterinstitute.ca/mp3/bafd33d6-637a-458e-ba24-d157dd7123f2.mp3 Science http://streamer.perimeterinstitute.ca/mp3/bafd33d6-637a-458e-ba24-d157dd7123f2.mp3 Tue, 18 Jul 2006 15:45:54 -0400 It is often suggested that the special theory of relativity is incompatible with any notion of the passage of time. I shall try to show, following in the footsteps of Abner Shimony, that there is transience to be found in Minkowski spacetime, but this transience is local rather than global. Steven Savitt http://streamer.perimeterinstitute.ca/mp3/3407ab21-fa40-4677-adf2-8bb37cfce4ad.mp3 Science http://streamer.perimeterinstitute.ca/mp3/3407ab21-fa40-4677-adf2-8bb37cfce4ad.mp3 Tue, 18 Jul 2006 17:15:27 -0400 Taking for granted that the mathematical apparatus for describing probabilities in quantum mechanics is well-understood via work of von Neumann, Lüders, Mackey, and Gleason, we present an overview of different interpretations of “probability” in quantum mechanics bearing on physics and experiment, with the aim of clarifying the meaning and place of so-called “objective” interpretations of quantum probability. The dichotomy “objective/subjective” is unfortunate, we argue, as we should distinguish two different dimensions integral to the concept of probability. The first concerns the values of probability functions, viz. what the real numbers measure, e.g. relative frequencies of experimental outcomes, or strengths of physical dispositions (objective-1), vs. degrees of belief of idealized agents (subjective-1), etc. But a second dimension is also important, concerning the domain of definition, the “events” or “bearers” of probability, what the probabilities are probabilities of. Relative frequencies of what, described how, or strengths of dispositions to do what, described how, degrees of belief in what, etc. Reminding ourselves of the quantum mechanical phenomenon of incompatible observables, we recall that contradictions are standardly avoided by describing probabilities as pertaining to “measurement outcomes” rather than “possessed properties”: thereby, subjective elements are introduced into the very description of the “events”. (Interpretations qualify as objective-2 if they avoid “bad words” like “measurement” as primitive, in favor of possessed properties or physical interactions; as subjective-2 if such terms are employed in an essential way.) This leads to a two-by-two matrix of interpretative possibilities. The remainder of our talk consists in filling in the blanks (which the reader is invited to try for him/herself) and providing commentary on the relative advantages and disadvantages, which go to the heart of the problem of interpreting quantum theory. Given our scheme, it turns out that “objective version of Copenhagen” makes good sense; this is one locus of “propensities”, which can be made sense of, we claim, along the lines of pre-hidden-variables Bohm (his 1951 text), not to be confused with Popper. We close by noting a serious deficiency in recent Bayesian approaches to quantum probability (lying in the subj-1, subj.-2 quadrant), viz. its explanatory impoverishment. But I’ve already given too many hints. Geoffrey Hellman http://streamer.perimeterinstitute.ca/mp3/18423b6c-65a2-4f73-be5d-eee47cc48d76.mp3 Science http://streamer.perimeterinstitute.ca/mp3/18423b6c-65a2-4f73-be5d-eee47cc48d76.mp3 Wed, 19 Jul 2006 09:15:32 -0400 Once again the problem of indistinguishability has been recently tackled. The question is why indistinguishability, in quantum mechanics but not in classical one, forces a changes in statistics. Or, what is able to explain the difference between classical and quantum statistics? The answer given regards the structure of their state spaces: in the quantum case the measure is discrete whilst in the classical case it is continuous. Thus the equilibrium measure on classical phase space is continuous, whilst on Hilbert space it is discrete. Put in other words, this difference goes along the way followed for a long time, it refers to the different nature of elementary particles. Answer of this type completely obscure the probabilistic side of the question. We are able to give in fully probability terms a deduction of the equilibrium probability distribution for the elements of a finite abstract system. Specializing this distribution we reach equilibrium distributions for classical particles, bosons and fermions. Moreover we are able to deduce Gentile's parastatistics too. Domenico Constantini http://streamer.perimeterinstitute.ca/mp3/2b079759-4397-4ebf-8acf-27a1e7bcf43c.mp3 Science http://streamer.perimeterinstitute.ca/mp3/2b079759-4397-4ebf-8acf-27a1e7bcf43c.mp3 Wed, 19 Jul 2006 10:15:57 -0400 The way we combine operators in quantum theory depends on the causal relationship involved. For spacelike separated spacetime regions we use the tensor product. For immediately sequential regions of spacetime we use the direct product. In the latter case we lose information – that is we cannot go from the direct product of two operators to the two original operators. This is a kind of compression. We will see that such compression is associated with causal adjacency. We will situate this in the context of a much broader framework potentially suitable for developing a theory of quantum gravity. Lucien Hardy http://streamer.perimeterinstitute.ca/mp3/4724fcd3-24b5-46d3-974a-50ab8144ed53.mp3 Science http://streamer.perimeterinstitute.ca/mp3/4724fcd3-24b5-46d3-974a-50ab8144ed53.mp3 Wed, 19 Jul 2006 11:45:10 -0400 If one is worried by the quantum measurement problem,a natural question to ask is: Does the quantum-mechanical description of the world retain its validity when its application leads to superpositions of states which by some reasonable criterion are _macroscopically distinct_? Or rather, does any such superposition automatically get "collapsed", even in the absence of "measurement" by a human observer, into one or other of its branches? Scenarios which predict the latter (for example the GRWP theory) may be denoted generically by the term "macrorealistic". Even if one believes that QM remains the whole truth at the macrolevel, it is clear that to the extent that environmental decoherence destroys the delicate phase relations characterizing the superposition, the predictions of QM will be indistinguishable experimentally from those of the class of macrorealistic theories (a remark which is often taken, in my opinion quite erroneously, as "solving" the measurement problem). Thus, to distinguish experimentally between QM and macrorealism one needs a system in which decoherence is low enough that (given that QM is correct) one has a realistic chance of observing _quantum interference of macroscopically distinct states_ ("QIMDS"). Over the last few years, a surprising variety of candidate systems has emerged; however, while all experiments to date have been consistent with the continued validity of QM, none has so far refuted macrorealism outright. In this talk I review the systems in question and discuss the prospects for a truly definitive experiment. Anthony Leggett http://streamer.perimeterinstitute.ca/mp3/8b48b23a-69a2-4e30-9670-28615cafebe6.mp3 Science http://streamer.perimeterinstitute.ca/mp3/8b48b23a-69a2-4e30-9670-28615cafebe6.mp3 Wed, 19 Jul 2006 14:45:28 -0400 After giving an introduction to the Continuous Spontaneous Localization (CSL) theory of dynamical wave function collapse, I shall discuss 10 problems of dynamical collapse models, 5 of which were resolved by CSL's advent, and 5 of which have been subsequently attacked with varying success. Philip Pearle http://streamer.perimeterinstitute.ca/mp3/15fac4da-33c7-4d4b-99c6-09f0db6434a2.mp3 Science http://streamer.perimeterinstitute.ca/mp3/15fac4da-33c7-4d4b-99c6-09f0db6434a2.mp3 Wed, 19 Jul 2006 15:45:45 -0400 According to a widely accepted view, the emergence of macroscopic behavior is related to the loss of quantum mechanical coherence. Opinions on the possible cause of this loss diverge. In the present talk it will be shown how a small, assessable amount of indeterminacy in the structure of space-time may lead to the emergence of macroscopic behavior, in agreement with empirical evidence. Andor Frenkel http://streamer.perimeterinstitute.ca/mp3/b429f9ac-92d4-489f-a2d6-19cf99155916.mp3 Science http://streamer.perimeterinstitute.ca/mp3/b429f9ac-92d4-489f-a2d6-19cf99155916.mp3 Wed, 19 Jul 2006 17:15:58 -0400 Lee Smolin,Abner Shimony http://streamer.perimeterinstitute.ca/mp3/6369063a-a835-4758-a9d7-eb00de8ed7c3.mp3 Science http://streamer.perimeterinstitute.ca/mp3/6369063a-a835-4758-a9d7-eb00de8ed7c3.mp3 Wed, 19 Jul 2006 19:30:01 -0400 Alain Aspect http://streamer.perimeterinstitute.ca/mp3/b735baca-bc4a-460a-8fd7-febea3a9a96c.mp3 Science http://streamer.perimeterinstitute.ca/mp3/b735baca-bc4a-460a-8fd7-febea3a9a96c.mp3 Thu, 20 Jul 2006 09:15:49 -0400 Feynman was probably correct to say that the only mystery of quantum mechanics is the principle of superposition. Although we may never know which slit a photon has been passing in a Young’s double-slit experiment, we do have a corresponding classical concept in classical electromagnetic theory: the superposition of electromagnetic fields at a local space-time point is a solution of the Maxwell equations. In the case of joint photo-detection measurement of two photons, however, the superposition involves the addition of two-photon amplitudes, different yet indistinguishable alternatives resulting in a click-click joint photo-detection event. There is no counterpart of such concept in classical electromagnetic theory and the superposition may happen at distance. It is the two-photon superposition responsible for the mysteries of EPR by means of reality and causality. This talk will analyze the physics of based on several recent experiments. Yanhau Shih http://streamer.perimeterinstitute.ca/mp3/6b09e5de-27a4-4fa8-a930-383f94df5bd6.mp3 Science http://streamer.perimeterinstitute.ca/mp3/6b09e5de-27a4-4fa8-a930-383f94df5bd6.mp3 Thu, 20 Jul 2006 10:15:37 -0400 An experimental realization of our spin-1/2 particle version of the Einstein-Podolsky-Rosen (EPR) experiment will be briefly reviewed. In the proposed experiment, two 199Hg atoms in the ground 1S0 electronic state, each with nuclear spin I=1/2, are generated in an entangled state with total nuclear spin zero. Such a state can be obtained by dissociation of a 199Hg2 molecule (dimer) using a spectroscopically selective stimulated Raman process. From symmetry considerations, the nuclear spin singlet state is guaranteed if the initial 199Hg2 molecule is in a rotational state with an even quantum number. Consequently, a thorough investigation and analysis of the rotational structure of the 199Hg2 molecule is required; results of this analysis will be presented. Edward Fry http://streamer.perimeterinstitute.ca/mp3/a48128bf-b52f-4108-ae98-389a495fd5c9.mp3 Science http://streamer.perimeterinstitute.ca/mp3/a48128bf-b52f-4108-ae98-389a495fd5c9.mp3 Thu, 20 Jul 2006 11:45:51 -0400 Entanglement swapping is such a powerful technique for dealing with EPR problems, that it can handle inefficient counters and Bell Theorems without inequalities, even for two particles. We will examine some of the results and pitfalls. Daniel Greenberger http://streamer.perimeterinstitute.ca/mp3/ad7984e5-ebcb-49dc-b663-d85acfedda29.mp3 Science http://streamer.perimeterinstitute.ca/mp3/ad7984e5-ebcb-49dc-b663-d85acfedda29.mp3 Thu, 20 Jul 2006 14:45:53 -0400 I will report my efforts to describe elementary Quantum behaviours, specifically single-particle interference and two-particle entanglement, in an accelerating frame. Mike Horne http://streamer.perimeterinstitute.ca/mp3/d6032612-59e6-4e9f-97f8-f3f834aed47b.mp3 Science http://streamer.perimeterinstitute.ca/mp3/d6032612-59e6-4e9f-97f8-f3f834aed47b.mp3 Thu, 20 Jul 2006 15:45:01 -0400 Anton Zeilinger http://streamer.perimeterinstitute.ca/mp3/a5617ad6-5a7f-415b-a78f-cb8a45e300fe.mp3 Science http://streamer.perimeterinstitute.ca/mp3/a5617ad6-5a7f-415b-a78f-cb8a45e300fe.mp3 Thu, 20 Jul 2006 17:15:24 -0400 Abner Shimony is well-known for, among other contributions, his seminal work on Bell inequalities, turning a philosophical question into an experimental one. In my presentation I like to remind us how this experimental field is nowadays feeding into applied science. This is happening both in terms of the involved technologies and in the conceptual tools. Nicolas Gisin http://streamer.perimeterinstitute.ca/mp3/bb805ccb-4e33-418e-b785-5dd565ebbe68.mp3 Science http://streamer.perimeterinstitute.ca/mp3/bb805ccb-4e33-418e-b785-5dd565ebbe68.mp3 Fri, 21 Jul 2006 09:15:45 -0400 A theory governing the metric and matter fields in spacetime is {it locally causal} if the probability distribution for the fields in any region is determined solely by physical data in its past, i.e. it is independent of events at space-like separated points. This is the case according to general relativity, and it is natural to hypothesise that it should also hold true in any theory in which the fundamental description of space-time is classical and geometric --- for instance, some hypothetical theory which stochastically couples a classical spacetime geometry to a quantum field theory of matter. On the other hand, a quantum theory of gravity should allow the creation of spacetimes which macroscopically violate local causality. I describe a feasible experiment to test the local causality of spacetime, and hence to test whether gravity is better described, in this respect, by general relativity or by quantum theory. The experiment will either identify a definite limit to the domain of validity of quantum theory or else produce significant evidence for the hypothesis that gravity is described by a quantum theory. Adrian Kent http://streamer.perimeterinstitute.ca/mp3/8994d3ca-3399-4730-817e-53447489341c.mp3 Science http://streamer.perimeterinstitute.ca/mp3/8994d3ca-3399-4730-817e-53447489341c.mp3 Fri, 21 Jul 2006 10:15:43 -0400 Chris Fuchs http://streamer.perimeterinstitute.ca/mp3/4b3a82ca-1c1a-4e53-aca6-1900c2d21de9.mp3 Science http://streamer.perimeterinstitute.ca/mp3/4b3a82ca-1c1a-4e53-aca6-1900c2d21de9.mp3 Fri, 21 Jul 2006 11:45:48 -0400 Newton’s methodology is significantly richer than the hypothetico-deductive model. It is informed by a richer ideal of empirical success that requires not just accurate prediction but also accurate measurement of parameters by the predicted phenomena. It accepts theory mediated measurements and theoretical propositions as guides to research Kuhn has suggested that along with revolutionary changes in scientific theory come revolutionary changes in methodology. I will argue that, when Einstein found his theory could handle the Mercury perihelion problem, Einstein’s theory was doing better than Newton’s theory on Newton’s standard. The richer themes of Newton’s methodology continue to be strikingly realized in the testing frameworks for General Relativity. William Harper http://streamer.perimeterinstitute.ca/mp3/163f5a91-3e36-4b11-91ee-6178f4483ee4.mp3 Science http://streamer.perimeterinstitute.ca/mp3/163f5a91-3e36-4b11-91ee-6178f4483ee4.mp3 Fri, 21 Jul 2006 14:45:21 -0400 In this talk I will discuss the question of how to characterize, in an operationally meaningful way, the inevitable “disturbance” of a quantum system in a measurement. I will review some well-known limitations of quantum measurements (facts), and give precise formulations of trade-off relations between information gain and “disturbance”. Famous examples among these limitations are the uncertainty principle, the complementarity principle, and Wigner’s theorem on limitations on measurements imposed by conservation laws. The universal validity of each of these has been challenged repeatedly, and no conclusive resolution seems to have been reached. I will analyze some long-standing conflations and misconceptions (myths) concerning these quantum limitations, such as the reduction of the uncertainty principle to the idea of mechanical disturbance (momentum kicks), the claim that the uncertainty principle has nothing to do with (the impossibility of) simultaneous measurements of noncommuting quantities, and some alleged violations of the uncertainty and complementarity principles. Recent rigorous work has led to apparently contradictory conclusions on these issues. I will show that the contradictions dissolve if due attention is paid to the choice of operationally meaningful notions of measurement accuracy and disturbance. Paul Busch http://streamer.perimeterinstitute.ca/mp3/148c7aa4-10b8-4e01-8f15-b3d6b7a54358.mp3 Science http://streamer.perimeterinstitute.ca/mp3/148c7aa4-10b8-4e01-8f15-b3d6b7a54358.mp3 Fri, 21 Jul 2006 15:47:02 -0400 Here are some topics in physics and philosophy on which my work is incomplete. I invite my friends in this assembly, and their colleagues and students, to continue the work and inform me about their progress. 1. There is a well known theorem of Wigner that a necessary condition for a quantity M of a physical system O to be measured without distortion (i.e., if O is in an eigenstate u of M just prior to the measurement then it remains in u immediately afterwards) is the commutation of M with any additive conserved quantity. This theorem has been generalized by Stein and Shimony by relaxing the condition “without distortion”, but the natural full generalization has neither been proven nor refuted by a counter-example. 2. In two-particle interferometry, using an ensemble of pairs of particles in a pure entangled state ?, the fringe visibility V12 of pairs counted in coincidence may be defined analogously to the fringe visibility V1 of single particles, and a complementarity relation has been derived: V12 + V122 = 1. Generalizations of this complementarity relation to n-tuples (n ?2) of entangled particle are desired. 3. Relations have been explored among various reasonable definitions of “degree of entanglement”, but further systematization of these relations is desirable. 4. Bell’s Theorem shows that certain quantum mechanical predictions cannot be derived in any “local realistic” theory, and experiments have overwhelmingly favored quantum mechanics in situations of theoretical conflict. Is it plausible to maintain “peaceful coexistence” between the nonlocality of quantum mechanics and the locality of relativity theory by citing the impossibility of using the former to send superluminal messages? But if this strategy fails, what is the proper adjudication of the conflict between these fundamental physical theories? 5. Stochastic modification of quantum dynamics (proposed by Ghirardi-Rimini-Weber, Gisin, Pearle, Wigner, Penrose, Károlyházy, and others) has been proposed as a promising program for solving the quantum mechanical measurement problem. But theoretical refinements of the proposed modifications are desirable as well as definitive experimental tests. Two promising areas of relevant experimental research are quantum gravity and variants of the “quantum telegraph” (an ensemble of atoms undergoing transitions between the ground state and a metastable state when exposed to appropriate laser beams). 6. Corinaldesi conjectured that the boson statistics of integral spin particles and the fermion statistics of half-integral spin particles are consequences of their dynamics rather than of their kinematics (the latter usually accepted because of Pauli’s spin and statistics theorem), so that obedience to the Pauli Exclusion Principle in a freshly formed ensemble of electrons would become increasingly strict as the ensemble ages. To test Corinaldesi’s conjecture it was proposed to form fresh ensembles of electrons by allowing a high velocity beam of Ne+ ions in a linear accelerator to be intersected by electrons from an electron gun, thereby neutralizing a subset of the ions. Transitions of electrons to the doubly occupied 1S shell in the complete Ne atoms will be monitored by suitable x-ray detectors at varying distances from the region of intersection, in order to scrutinize the conjectured diminution with time of violations of the Exclusion Principle. Refinements of this design and actual performance of the experiment are requested. 7. A test of the speculative conjecture that wave packet reduction is a psycho-physical phenomenon, occurring only when a conscious observer reads a measuring device, was performed in 1977 by three of my undergraduate students. They used a slow gamma emitter (about one emission per minute) monitored by a detector connected to registration devices in two separated rooms. There was a short time delay between the two registrations. The observer in the first room read his registration device in randomly chosen intervals of time and the observer in... Abner Shimony http://streamer.perimeterinstitute.ca/mp3/14eff417-3ebd-4571-99df-6475295ad1d9.mp3 Science http://streamer.perimeterinstitute.ca/mp3/14eff417-3ebd-4571-99df-6475295ad1d9.mp3 Fri, 21 Jul 2006 17:15:32 -0400