Events Bulletin Board

Abstracts, Philosophy of Physics Research Seminar, HT 2013

The Philosophy of Physics seminar at Oxford will take place this Hilary term at the usual time of 4.30pm, Thursdays, in the Lecture Room at the Philosophy Centre. Please note the Centre's NEW ADDRESS: Radcliffe Humanities, Radcliffe Observatory Quarter, Woodstock Road, Oxford OX2 6GG. (This is the old Radcliffe Infirmary building.) The Lecture Room is on the second floor.

Week 1 (17 January):  Dr David Wallace, Philosophy Faculty, Oxford.

Title:   The non-question of Gibbs vs Boltzmann entropy

Abstract:  Contemporary philosophy of statistical mechanics is often set up as a battle royale between Gibbsian and Boltzmannian conceptions of entropy, with the Gibbsian approach generally regarded as philosophically suspect. I argue that, although much is indeed conceptually wrong  with Gibbsian statistical mechanics as it is conventionally presented, the framework itself is perfectly coherent. Furthermore, if the foundational assumptions required by BoltzmannÕs approach are granted, they suffice to underpin the Gibbsian approach equally well, and indeed the Boltzmannian approach can be understood as a special case of the Gibbsian approach. In particular, the question of which definition of entropy is right becomes essentially a matter of terminology, of no great conceptual significance.

Week 2 (24 January): Dr Brian Pitts, University of Cambridge

Title: Energy and Change in Lagrangian and Hamiltonian General Relativity

Abstract: The supposed lack of localized gravitational energy-momentum in General Relativity (GR) has inspired both absurdities and objections to GR.  The Noether pseudotensor has components in every coordinate system, but no transformation law relating them as equivalent faces of one thing (not a geometric object). Bergmann noted that formally there are infinitely many conserved gravitational energy-momenta; any vector field (or basis) gives a set.  One should expect inequivalent symmetries to yield inequivalent conserved quantities, so why not simply believe the mathematicsÕ indication of an infinite-component localized entity?

Hamiltonian GR supposedly defines change only asymptotically (if at all).  But the completed Dirac-Bergmann constrained dynamics analysis of Castellani, Salisbury, Pons, and Shepley implements Hamiltonian-Lagrangian equivalence and distinguishes the 4-dimensional gauge transformation generator ("t)G(t) from the Hamiltonian H.  4-dimensional Lagrangian change is the lack of a time-like Killing vector field.  Thus Hamiltonian change must be the Hamiltonian equivalent, vindicating the change-affirming common sense of Maudlin and Kuchař from the technicalities of Earman et al.  DiracÕs book notwithstanding, first-class primary constraints in GR do not always generate gauge transformations.   First-class primaries appear both in H to help to generate time evolution (the lapse and shift vector values at later times) and in ("t)G(t) to help to generate coordinate transformations.  Hence the conceptual side of the Dirac conjecture also fails.  Gauge equivalence in GR must be understood in terms of histories, not instantaneous states as Dirac envisaged---thereby feeding in the idea that different stages of history are physically equivalent by not adequately testing the formalism on its chief example.  More confusion is avoided by not introducing primitive point identities into mathematical physics.  Demanding that the Lie derivative vanish for ÒobservablesÓ is unmotivated by comparison with 4-dimensional tensor calculus, at least if observables have something to do with observations (as Bergmann held).  He developed the notion of observables in GR by analogy to Hamiltonian electromagnetism, thus tacitly inclining toward invariance over covariance and neglecting equivalence with Lagrangian GR.

Week 3 (Thu 31 January): Prof Dennis Dieks, University of Utrecht

Title: Indistinguishability and Individuality: Classical and Quantum

Abstract: In classical physics the concept of a particle seems clear enough: we are dealing with individuals, distinguished by individuating state-dependent properties (position, trajectory, etc.). However, even in classical physics there have been arguments that particles of the same kind are indistinguishable. The situation becomes more confusing in quantum mechanics. Here we have the famous symmetrization and anti-symmetrization postulates for bosons and fermions, respectively, which seem to entail  that all Òidentical particlesÓ of the same kind are in literally the same state and must therefore be completely indistinguishable. Still, in the classical limit they seem miraculously to emerge as individuals with different states.

We shall attempt to bring some order here, going from the Gibbs paradox to quantum theory.

Week 4 (Thursday 7 February): Dr Terry Rudolph, Imperial College, London

Title: Realism and the epistemic view of quantum states

The idea that quantum states reflect only an observers knowledge/beliefs/information about the world has a long history. The challenge for an advocate of this position, however, is to identify what we can deduce is really going on'' out there. There seem to three main paths proponents of the epistemic view have followed in trying to extract such a narrative from quantum theory. I will explain how the most na•ve such path--that quantum states can be associated with standard (probabilistic) uncertainty about some (arbitrary) real states of the world--is not tenable under some extremely mild assumptions about how any theory of reality must treat independent experiments. I will then overview the other two paths and what I see as the challenges they face.

Week 5 (Thursday 14 February):  Dr Jeffrey Ketland, Oxford

Title: Leibniz Equivalence

Abstract: In this talk I discuss two topics.

First, I will argue that the notion of a diffeomorphism is something of a red herring in the usual debates about the hole argument and Leibniz equivalence. It seems clear that, given a spacetime model, (M, g_{ab}, É), the application of an arbitrary permutation of the base set of M generates a new isomorphic model which represents the same physical possibility. There seems no genuine requirement that such a permutation must also be a diffeomorphism (i.e., automorphism) of M. For if one is allowed to shift around the tensor fields, why is one not allowed to shift around the open sets of the topology in M, so long as the overall result is isomorphic? I believe that this suggestion is in accord with R.M. WaldÕs formulation of the corresponding principle in his standard textbook on General Relativity.

Second, I will make some more tentative suggestions about how to think of possible worlds as not having any domain at all: namely, as certain kinds of categorical existentially quantified propositions (possibly infinitary), so that it is automatically true that isomorphic models represent the same world. This may also be of relevance to those are sympathetic to a version of structuralism, whether scientific or mathematical, in which one has Òstructures without relataÓ---no distinguished domain or base set.

Week 6 (Thursday 21 February): Dr Berry Groisman, D.A.M.T.P., Cambridge

Title: Sleeping Beauty in Quantumland

Abstract: I will discuss the treatment of the Sleeping Beauty Problem within the framework of the Many-Worlds Interpretation of Quantum Theory. I will take the view that the MWI is a fundamentally deterministic theory with full information being available to observers before experiments are carried out. The absence of objective uncertainty in this version of the MWI does not contradict the fact that observers might experience an 'illusion of probability'. I will argue, therefore, that the Sleeping Beauty Problem fits naturally into this interpretation of probability in Many Worlds and will demonstrate how this approach leads to the 'thirder' solution. I will comment on alternative views on the probability in Many Worlds and on alternative treatments of quantum Sleeping Beauty.

Week 7 (28 February):  Dr Martin Sahlen, Astrophysics, Oxford.

Title:   Questions in Philosophy of Cosmology

Abstract: Within modern physical cosmology, a series of new discoveries over the last 100 years have paved the way for a new conception of the Universe. The image has changed from a single, static galactic universe to a dynamically forming universe arisen from quantum mechanical fluctuations, expanding in size, and dominated by an unknown "dark" set of constituents.

But even as theoretical and observational discoveries have proceeded apace, a number of philosophical questions have come increasingly to the fore. Cosmology concerns a single time-situated system,  vast parts of which, even at the present epoch, are in principle unobservable: how is this limitation to be managed? Is cosmology a science, properly speaking, at all?

I will present the main current results in physical cosmology, future planned observations, and some of the key recent theoretical developments, with an eye to some of the inherent problems in the field: that the object of cosmology comprises a single, unrepeatable system, studied from a single, situated standpoint,  observations of which may be subject to selection effects consequent on our  existence as observers, that may be vastly larger than its visible part.

Abstracts, Philosophy of Physics Research Seminar, MT 2012

The Philosophy of Physics seminar at Oxford will take place this Michaelmas term at the usual time of 4.30pm, Thursdays, in the Lecture Room at the Philosophy Centre. Please note the Centre's NEW ADDRESS: Radcliffe Humanities, Radcliffe Observatory Quarter, Woodstock Road, Oxford OX2 6GG. (This is the old Radcliffe Infirmary building.) The Lecture Room is on the second floor.

Week 1 (11 October):  Dr Owen Maroney, Philosophy Faculty, Oxford.

Title: No go theorems and statistical states.

Abstract:  There has recently been a flurry of activity, proving limitations on whether it is possible to understand the quantum wavefunction as just a statistical (rather than physical) state.  I will review the three most recent no-go theorems, all focussed on the idea of psi-epistemic' hidden variable theories. I will try to clarify the assumptions involved and what possibilities they leave for a statistical interpretation of the quantum state.

Week 2 (18 October): Dr Olivier Darrigol, CNRS/UniversitŽ Paris VII (Denis Diderot); University of California, Berkeley.

Title: Necessity or contingency of the laws of classical mechanics.

Abstract: Nowadays, the laws of ordinary mechanics are usually regarded as contingent: the motion of macroscopic bodies could have obeyed other laws; it is only from experiment that we could learn the true laws. There was no such consensus in the early mechanical philosophy of the seventeenth century. Famously, Descartes and Newton held opposite views on this matter. The two most important writers on mechanics in the eighteenth century, d'Alembert and Euler, believed in the rational necessity of the laws of mechanics. So did too the two most influential philosophers of that century, Leibniz and Kant. Nineteenth-century physicists and critiques of science often held an intermediate position, in which some mechanical laws were rational and others empirical. They nonetheless approved mechanical reductionism. The purpose of this talk is to summarize these debates, to investigate the nature and quality of the arguments, and to question today's reigning anti-rationalism.

Week 3 (25 October): Dr. Adam Caulton, Department of Philosophy, Logic and Scientific Method, LSE

Title: Hume's dictum as a guide to physical ontology

Abstract: Quine's dictum that to be is to be the value of a variable has become an enormously popular mantra for ontologists of a regimenting disposition, but it is apt only on the assumption of other Quinean doctrines that are, for good reason, more controversial.  In this talk, I will outline an alternative that takes its inspiration from Hume's dictum that there are no necessary connections between distinct existents.  I will trace a brief history of the dictum within 20th Century analytic philosophy, and argue that Hume's dictum provides a better guide than Quine's for interpretative projects in the philosophy of physics.  Finally (and if there's time), I will attempt to use this application of Hume's dictum to reconcile a Kuhnian notion of conceptual relativity with Davidson's apparent scepticism about the possibility of rival conceptual schemes.

Week 4 (1 November): Dr. Gabor Hofer-Szabo, Institute of Philosophy, Research Center for the Humanities, Hungarian Academy of Sciences

Title: Bell Inequality and Common Causal Explanation in Algebraic Quantum Field Theory

Abstract: In the talk it will be argued that the violation of the Bell inequality in

algebraic quantum field theory does NOT exclude a common causal

explanation of a set of quantum correlations if we abandon commutativity

between the common cause and the correlating events. Moreover, it will

turn out that the common cause is local, i.e. localizable in the common

past of the correlating events. It will be argued furthermore that giving

up commutativity helps to maintain the validity of Reichenbach's Common

Cause Principle in algebraic quantum field theory.

Week 5 (8 November): Dr. Eric Cavalcanti, Department of Computer Science, Oxford University; School of Physics, University of Sydney

Title: What Bohr could have told Einstein at Solvay had he known about Bell

Abstract: The 1964 theorem of John Bell shows that no model that reproduces the predictions of quantum mechanics can simultaneously satisfy the assumptions of locality and determinism. On the other hand, the assumptions of signal locality plus predictability are also sufficient to derive Bell inequalities. This simple theorem, previously noted but published only relatively recently by Masanes, Acin and Gisin, has fundamental implications not entirely appreciated. Firstly, nothing can be concluded about the ontological assumptions of locality or determinism independently of each other—it is possible to reproduce quantum mechanics with deterministic models that violate locality as well as indeterministic models that satisfy locality. On the other hand, the operational assumption of signal locality is an empirically testable (and well-tested) consequence of relativity. Thus Bell inequality violations imply that we can trust that some events are fundamentally unpredictable, even if we cannot trust that they are indeterministic. This result grounds the quantum-mechanical prohibition of arbitrarily accurate predictions on the assumption of no superluminal signalling, regardless of any postulates of quantum mechanics, and underlies recent proposals for randomness generation certified by Bell inequality violations. It also sheds a new light on an early stage of the historical debate between Einstein and Bohr.

Week 7 (22 November): Dr. Tracy Lupher, Department of Philosophy and Religion, James Madison University.

Title: The Limitations of Physical Equivalence

Abstract: Some physicists and philosophers argue that unitarily inequivalent representations in quantum field theory are not physically significant because they are physically equivalent.  The heart of the argument relies on FellÕs theorem and its deployment in the algebraic approach to quantum field theory.  That argument and its use as a criterion for physical equivalence is examined in detail and it is proven that FellÕs theorem does not apply to the vast number of representations used in the algebraic approach.  Unitarily inequivalent representations are not another case of theoretical underdetermination, because they make different predictions about ÒclassicalÓ operators.  These results are applied to the Unruh effect where there is a continuum of UIRs to which FellÕs theorem does not apply.

Week 8 (29 November): Dr. Juha Saatsi, Department of Philosophy, University of Leeds.

"What is theoretical progress of science?"

I explore, with examples from physics, the idea that science makes theoretical progress if a better confirmed theory Ôlatches better onto realityÕ than its predecessor. I compare this conception of theoretical progress with the 'epistemic conception' advocated (inter alia) by Bird.  According to Bird science makes progress Ôprecisely when it shows accumulation of knowledgeÕ. I argue that BirdÕs conception fails of accommodate some theoretical progress in science, and that it leads to an impoverished conception of scientific realism.

Abstracts, Philosophy of Physics Research Seminar, MT 2011

October 13. William Harper, Department of Philosophy, University of Western Ontario

ÒIsaac Newton's Scientific MethodÓ

Abstract:

On the basic hypothetico-deductive model hypothesized principles are tested by experimental verification of observable consequences drawn from them. Empirical success is limited to accurate prediction of observable phenomena.

NewtonÕs inferences from phenomena realize an ideal of empirical success that is richer than prediction. To realize NewtonÕs richer conception of empirical success a theory needs to do more than to accurately predict the phenomena it purports to explain; in addition, it needs to have the phenomena accurately measure parameters of the theory.  NewtonÕs method aims to turn theoretical questions into ones which can be empirically answered by measurement from phenomena. Propositions inferred from phenomena are provisionally accepted as guides to further research. Newton employs theory-mediated measurements to turn data into far more informative evidence than can be achieved by hypothetico-deductive confirmation alone. On his method deviations from the model developed so far count as new theory-mediated phenomena to be exploited as carrying information to aid in developing a more accurate successor.

All of these enrichments are exemplified in the classical response to MercuryÕs perihelion problem. Contrary to Kuhn, NewtonÕs method endorses the radical transition from his theory to EinsteinÕs.  These richer themes of NewtonÕs method are, also, strikingly realized in the response to a challenge to general relativity from a later problem posed by MercuryÕs perihelion.

We can also see NewtonÕs method at work in cosmology today in the support afforded to the (dark energy) cosmic expansion from the agreeing measurements from supernovae and cosmic microwave background radiation.

Oct 20. Matt Leifer,  Quantum Information Group, Physics and Astronomy Department, UCL, and Perimeter Institute for Theoretical Physics, Ontario, Canada.

"Quantum Theory as a Causally Neutral Theory of Bayesian Inference"

Abstract:

Quantum theory can be viewed as a noncommutative generalization of classical probability theory, but, as it stands, the analogy is not complete.  The basic rules of classical probabilistic inference are independent of causal structure whereas the conventional quantum formalism requires causal structure to be specified in advance.

In this talk, I outline an alternative formalism for finite-dimensional quantum theory, based on the idea of a quantum conditional state, that unifies the quantum rules of inference in different causal scenarios. In particular, quantum dynamics, the Born rule, ensemble averaging, and the rules for inferences across space-like separation can all be viewed as special cases of a quantum generalization of the belief propagation rule P(Y) = \sum_X P(Y|X)P(X).  The formalism gives rise to a quantum generalization of Bayes' theorem, and an associated notion of Bayesian conditioning.  These can be used to derive and generalize the retrodicitive formalism for quantum theory of Pegg et. al. and provide an intuitive derivation of ensemble steering in EPR-type experiments.

Our notion of quantum Bayesian conditioning differs from the projection postulate, which several authors (e.g. Bub) have argued is a quantum generalization of conditioning.  I will explain why projection cannot be viewed as a type of conditioning in our formalism and show that it should instead be thought of as an instance of quantum belief propagation followed by conditioning.

This talk is based on joint work with Rob Spekkens arXiv:1107.5849

Oct 27. Simon Saunders, Faculty of Philosophy, Oxford University

ÒNewton's theory of gravity in the light of cosmologyÓ.

Abstract:

Newton famously thought his theory of gravity required the existence of absolute space and time. It was subsequently realized that neo-Newtonian or Galilean space-time is sufficient, based on the concept of a class of intertial frames rather than absolute space. But if we lived in a 'large enough' Newtonian universe, no such inertial frames could ever be discovered by any operational method.

The privileged frames that can be operationally defined in accordance with Newton's theory are rather non-rotating freely-falling frames. This raises the suspicion that the space-time structure implicit in Principia is weaker than Galilean space-time, to be grounded on Corollary VI to the Laws, whereas Galilean space-time is grounded on Corollary V (the relativity principle). Unlike the latter, this structure, for a theory of particles, admits of a purely relational interpretation, in the sense of Huygens, based only on the comparison of directions in space (as given by particle pairs) at different times.

Nov 3. Matthew Pusey, Controlled Quantum Dynamics Centre for Doctoral Training, Imperial College.

"Local realism for product states needs the quantum state"

Abstract:

If the quantum state is a real thing then the existence of entangled states shows that physical reality is not local. Before Bell's theorem it was reasonable to hope that local realism could be saved by adopting the view that quantum states are not real, but rather a representation of knowledge. Based on joint work with Jonathan Barrett and Terry Rudolph, I will argue that the failure of local realism is in fact qualitatively more dramatic under this latter perspective. I will do this by describing a class of experiments, involving unentangled states, for which the only local explanation is that the quantum state is real.

Nov 10. Fotini Markopoulou, Perimeter Institute for Theoretical Physics, Ontario.

ÔSpin systems as toy models for emergent gravityÕ

Abstract:

A number of recent proposals for a quantum theory of gravity are based on the idea that spacetime geometry and gravity are derivative concepts and only apply at an approximate level.  Two fundamental challenges to any such approach are, at the conceptual level, the role of time in the emergent context and, technically, the fact that the lack of a fundamental spacetime makes difficult the straightforward application of well-known methods of statistical physics and quantum field theory to the problem.  We initiate a study of such problems using spin systems as toy models for emergent geometry and gravity.  These are models of quantum networks with no a priori geometric notions.

In this talk we present two models.  The first is a model of emergent (flat) space and matter and we show how to use methods from quantum information theory to derive features such as speed of light from a non-geometric quantum system.  The second model exhibits interacting matter and geometry, with the geometry defined by the behavior of matter.  This is essentially a Hubbard model on a dynamical lattice.  We will see that regions of high connectivity behave like analogue black holes.  Particles in their vicinity behave as if they are in a Schwarzchild geometry.  Time permitting, I will show our study of the entanglement entropy of the system, which suggests particle localization near these traps.

Nov 17. Owen Maroney, Faculty of Philosophy, Oxford University

"What does violating the Leggett Garg Inequality actually tell us?  (Two ways to be a macrorealist, and one way not to be.)"

Abstract:

The Leggett Garg Inequalities were introduced with the intention of providing a Bell Inequality-like test of whether macroscopic objects
like cats are always in one or another macroscopically distinct state, and never in superpositions of such states.  Leggett and Garg dubbed
this idea "macrorealism".  Critics immediately argued that it was an additional condition - non-invasive measureability - that was really at
stake.  Leggett, however, maintained that the non-invasiveness of the relevant measurements was simply a natural consequence of macrorealism
and the issue remained stalled.

Advances in quantum technology have led to a number of experiments recently testing violations of the Leggett Garg Inequality, albeit in
microscopic systems.  It seemed a good idea, therefore, to revisit the basis of the Inequality and ask what, if anything, these experiments
might be revealing.

Surprisingly, perhaps, it turns out that a violation does do more that just refute non-invasive measureability.  Although "macrorealist"  theories can, and should, deny non-invasive measureability,  there remain additional non-trivial constraints they must fulfil to account for a Leggett Garg Inequality violation.

Nov 24. Hasok Chang, Department of History and Philosophy of Science, University of Cambridge

ÒOperationalism and Realism in 19th-century Atomic ChemistryÓ

Abstract:

In this paper I offer a new philosophical interpretation of the development of atomic chemistry in the 19th century.  I argue that success in this field owed much to a particular kind of operationalism, a key component in an epistemic attitude which I call active realism (though it is not so consonant with scientific realism as normally conceived).  We lose sight of crucial aspects of this history if we approach it through a preoccupation with the question of whether atoms really exist, or whether statements we make about the unobservable atoms and molecules are Òreally trueÓ. As Alan Rocke has argued, chemical atomism was unhampered by the persisting doubts about the real existence of physical atoms.  Chemists devised various ways of operationalizing the atom by incorporating it into clear and stable epistemic activities, such as the tracking of combining weights, and decomposition by electrolysis.  Particularly striking is the mid-century success of atomic chemistry based on operational methods of atom-counting, using combining volumes and specific heat.  On the other hand, different operationalizations of the atom did often diverge, as manifested in the fact that at least 4 different sets of atomic weights were in widespread use until the 1860s.  This is a reminder of a fundamental dilemma faced by Percy Bridgman: when there are multiple methods purporting to measure the same quantity, does each method really define a separate concept as his operationalist philosophy dictated, or are we somehow justified in regarding the different methods as different ways of getting at the same thing?  Ultimately Bridgman left this issue unresolved.  Interestingly, the same philosophical indecision was at the heart of the successful development of 19th-century atomic chemistry. In the absence of unification, each operationalization provided an independent window on reality.

Dec 1. Wayne Struyve, Institute for Theoretical Physics, Catholic University of Leuven

ÒSpontaneous symmetry breaking and the Higgs mechanismÓ

Abstract:

The Higgs mechanism gives mass to Yang-Mills gauge bosons. According to  the conventional wisdom, this happens through the spontaneous breaking  of gauge symmetry. But if gauge symmetries merely reflect a redundancy  in the state description, what exactly does it mean to break it? I want to address this question in the context of classical field theory.

Abstracts, Philosophy of Physics Research Seminar, TT 2011

All talks are Thursdays 4:30-6:30, Lecture Room, 10 Merton Street, followed by dinner for those who are interested.

May 5th (Week 1): Frank Arntzenius and Cian Dorr (Faculty of Philosophy, Oxford University) "The ontology of gauge theories and differential geometry"

Abstract:

The first half of this talk will argue that gauge field theories should be interpreted as talking about an ontology of 'fibre bunde substantivalism': one in which every point of spacetime is associated with a real, concrete space (the fibre over that point).  The second half will attempt to extend the programme of nominalising physical theories initiated by Hartry Field in _Science Without Numbers_.  We will show how an ontology of fibre bundle substantivalism can provide us with a nominalistically acceptable account of spacetime _qua_ differentiable manifold, thereby opening up a straightforward route towards the nominalisation of any physical theory formulable in differential-geometric terms.

Abstracts, Philosophy of Physics Research Seminar, HT 2011

All talks are Thursdays 4:30-6:30, Lecture Room, 10 Merton Street, followed by dinner for those who are interested.

Jan 27th (Week 2): Roman Frigg (LSE): ÒExplaining Thermodynamic-Like Behaviour In Terms of Epsilon-ErgodicityÓ

Abstract: Macroscopic systems such as gases reach equilibrium when left to themselves. Why do they behave in this way? The canonical answer to this question, originally proffered by Boltzmann, is that the systems have to be ergodic. This answer has been criticised on different grounds and is now widely regarded as flawed. In this paper we argue that some of the main arguments against BoltzmannÕs answer, in particular, arguments based on the KAM-theorem and the Markus-Meyer theorem, are beside the point or inconclusive. We then argue that something close to BoltzmannÕs original proposal is true: systems approach equilibrium if they are epsilon-ergodic, i.e. ergodic on the entire accessible phase space except for a small region of measure epsilon. This answer is promising because there are good reasons to believe that relevant systems in statistical mechanics are epsilon-ergodic.

Feb 3 (Week 3): Carl Hoefer (Barcelona): TBC

Feb 10 (Week 4): David Wallace (Oxford): ÒSymmetry, locality, and spaceÓ

Abstract: I attempt to square the circle between (a) the view that two situations, related by a symmetry, are the same situation differently described (so that symmetry can seem like an inessential consequence of our choosing an excessive mathematical formalism), and (b) the manifest fact that symmetries - local and global - seem to play an absolutely essential role in physical theories (so that they seem like features of the theory itself, not just of our formulation of it). In doing so, I hope to cast some light on the relationship between symmetries and the spaces of which they are symmetries, and also on the gauge principle.

Feb 17 (Week 5): Jon Barrett (Royal Holloway): TBC

Feb24 (Week 6): Steven French (Leeds):  ÒDoing Away with Dispositions: Towards a Law-Based View of ModalityÓ

Abstract: Most metaphysicians accept a form of possibility in actuality, articulated through dispositional accounts of properties. Advocates of the dispositional essentialist variant of such accounts have drawn on modern physics in support of their programme. However I shall suggest that such support is equivocal at best and that the recent development of this programme has led to the denial of an appropriate role for laws and symmetries in physics. As an alternative I shall defend the view that laws and symmetries themselves should be regarded as part of the 'fundamental base' of reality, drawing on recent work in metaphysics. This raises a number of issues to do with the relationship between laws and properties, the modal nature of laws and the relationship between determinable and determinate aspects of the fundamental base, which I hope to explore.

Abstracts, Philosophy of Physics Research Seminar, MT 2010

All talks are Thursdays 4:30-6:30, Lecture Room, 10 Merton Street, followed by dinner for those who are interested.

October 14th (week 1):

Prof Doreen Fraser, Department of Philosophy, University of Waterloo, Canada.

"Emergence and Explanation in Quantum Field Theory and Statistical Mechanics"

The insight that a formal, mathematical identification can be made between the theory of critical phenomena in statistical mechanics (SM) and renormalization methods in quantum field theory (QFT) has led to significant advances in both fields in the decades since Kenneth Wilson and his collaborators first published their results.  An important question about these developments has been raised and debated by structural realists:   What is the physical basis for this mathematical analogy?  As a way of exploring this issue, I will consider whether analogues of BattermanÕs arguments that modern thermodynamics is an emergent theory apply to effective QFTs.  This investigation will illuminate some important differences between the physical interpretations of the similar mathematical formalisms employed in QFT and SM.

October 21st (week 2):

Steve Simon, Department of Physics, Oxford University.

"Knots, World-Lines, and Quantum Computation"

The talk will be an introduction to topological quantum computing, an active field of research which aims to exploit the existence of 'topological phases' of matter to achieve coherent manipulation of quantum information.

Sigma Club at LSE --- Programme for Michaelmas Term 2010/11

Monday October 25. 5:15-7:00pm

Jeremy Butterfield, Trinity College, University of Cambridge

Particles as Properties (joint work with Adam Caulton, University of London)

Abstract:

In this paper, we have two main aims: the first negative, the second positive.

First, we show that what are usually called particle labels' (labelling a factor Hilbert space) do not correspond to the physical idea of a particle. This point is widely recognized, especially in the practice of physics. But it is worth developing in detail since almost all authors in the interpretive literature take particles to correspond to labels (whatever their other disagreements, e.g. about particles being indiscernible, or being individuals).

Our second aim is to develop a positive account of the physical idea of a particle (in non-relativistic quantum mechanics). Our main idea is that it is a (higher-order) property of what is traditionally called the assembly of particles', and is an emergent or approximate feature of certain states. This conception of particle is familiar from quantum field theory, where it is usually motivated by the existence of superpositions of particle-number. But we argue that it is also well motivated for non-relativistic quantum mechanics.

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Monday November 1. 5:15-7:00pm

Bob Coecke, Oxford University

In the beginning God created tensor

Abstract

It is now exactly 75 years ago that John von Neumann denounced his own Hilbert space formalism: I would like to make a confession which may seem immoral: I do not believe absolutely in Hilbert space no more.''(sic) [1] His reason was that Hilbert space does not elucidate in any direct manner the key quantum behaviors.  So what are these key quantum behaviors then? [2,3]

For Schrodinger this is the behavior of compound quantum systems, described by the tensor product [4, again 75 years ago].  While the quantum information endeavor is to a great extend the result of exploiting this important insight, the language of the field is still very much that of strings of complex numbers, which is akin to the strings of 0's and 1's in the early days of computer programming.  If the manner in which we describe compound quantum systems captures so much of the essence of quantum theory, then it should be at the forefront of the presentation of the theory, and not preceded by continuum structure, field of complex numbers, vector space over the latter, etc, to only then pop up as some secondary construct.

Over the past couple of years we have played the following game: how much quantum phenomena can be derived from compoundness + epsilon'.

It turned out that epsilon can be taken to be very little', surely not involving anything like continuum, fields, vector spaces, but merely a two-dimensional space' of temporal composition (cf and then') and compoundness (cf while'), together with some very natural purely operational assertion, including one which in a constructive manner asserts entanglement; among many other things, trace structure (cf von Neumann above) then follow [5, survey].  In a very short time, this radically different approach has produced a universal graphical language for quantum theory which helped to resolve some open problems. It also paved the way to automate quantum reasoning [6] and has even helped to solve problems outside physics, most notably in modeling meaning for natural languages [7].  Meanwhile several researchers aiming beyond quantum theory' have taken up several of our ideas eg [8].

All of this gives a totally new conception about what's logical' about quantum theory.

[1] M Redei (1997) Why John von Neumann did not like the Hilbert space formalism of quantum mechanics (and what he liked instead).  Stud Hist Phil Mod Phys 27, 493-510.

[2] For von Neumann, initially these were the propositions that one could measure with certainty, an idea that he later abandoned in favor of the trace structure, which generates probability [1].

[3] Still, today for most physicists quantum' is synonym for Hilbert space', which of course is not unrelated to the dominant shut up and calculate''-conception of quantum theory.

[4] E Schroedinger, (1935) Discussion of probability relations between separated systems.  Proc Camb Phil Soc 31, 555-563; (1936) 32, 446-451.

[5] B Coecke (2010) Quantum picturalism. Cont Phys 51, 59-83.

arXiv:0908.1787

[6] L Dixon, R Duncan & A Kissinger.

dream.inf.ed.ac.uk/projects/quantomatic/

[7] B Coecke, S Clark & M Sadrzadeh (2010) Ling Anal 36. Mathematical foundations for a compositional distributional model of meaning.

arXiv:1003.4394

[8] L Hardy (2010) A formalism-local framework for general probabilistic theories including quantum theory. arXiv:1005.5164

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Monday November 15. 5:15-7:00pm

Chris L. Farmer, University of Oxford

Inverse Problems: Formulation, Computation and Interpretation.

Abstract:

Mathematical theories are used for making predictions in, for example, weather forecasting, climate prediction and oil recovery from geological formations.

Prediction involves setting well-posed problems using a state space and equations evolving the system state through time. Some elements of the state, the 'parameters', do not change in time. Other elements of the state, the 'variables', do change in time. To make predictions then requires knowing the state at the initial time. This is 'forward modelling'. In practical problems the initial values of the variables or the values of the parameters are usually unknown. However, a few measurements of the state can be made, and so the 'inverse problem' is to infer the parameters and the variables from the measurements and the forward model. With limited information a unique answer is not possible, and thus inverse problems are generally ill-posed problems.

One framework for studying such problems is provided by Bayesian statistics. The first part of the talk outlines how this is used. The second part of the talk summarises our current ability to actually perform Bayesian inference for realistic forward models. When carefully designed, a Bayesian framework leads to a well-posed inverse problem and a solution in the form of a probability measure.

When forward models are accurate, the Bayesian framework is satisfactory; when models are inaccurate there are severe problems of interpretation. One practical difficulty is to ascertain how accurate a theory is from the sparse observations when they are needed to infer the parameters. This is, possibly, the situation in climate prediction. A further difficulty is that we usually know anyway, that the forward model is very far from accurate. So how can forward and inverse problem solving be used in a defensible way as a basis for decision-making and control? The third part of the talk will thus discuss how inverse problems are involved in practical decision-making and control. In control theory it is sometimes observed that by making sufficient use of feedback one can be robust to model error. Perhaps then, we should concentrate more on problems of decision and control and less upon problems of prediction.

On Symmetry in Physics
A One-Day Conference

Saturday 30 October 2010
The Deighton Room,  Blue Boar Court,  Trinity College, Cambridge

This room is on the first floor at the intersection of Trinity Street and
Green Street, but is hard to find from within the College's Court (accessed
via Whewell's Court). Therefore, at 09.50, 10.25 and at 13.50, there will
be a guide whom you can ask, who will be stationed on the cobblestones at
the front of Trinity College's main entrance, i.e. opposite Heffer's
bookshop, on Trinity Street.

10.00 Hilary Greaves, Oxford University
On the empirical significance of ("global" and "local")  symmetries

11.00 Coffee

11.30 David Wallace, Oxford University
Symmetry, locality, and space

12.30 Lunch

2.00 pm Adam Caulton,  London University
Two ways to permute particles in quantum mechanics

3.00 pm Tea

3.45     pm Nazim.Bouatta, Cambridge University
Symmetries, Infinities and Wilsonian Quantum Field Theory

4.45 Close

£2 registration: to be paid at the door. To help organize seating. please
email the organizers to say if you are coming.

Organized by:
J Butterfield (

ABSTRACTS

Hilary Greaves: On the empirical significance of ("global" and "local") symmetries

There is something of a tension between two aspects of symmetry in physics. On the one hand, there is a widespread consensus that 'two states of affairs related by a symmetry transformation are really just the same state of affairs differently described': that is, that if two mathematical models
of a physical theory are related by a symmetry transformation, then those models represent one and the same physical state of affairs. This seems to give symmetry a purely formal role in physics: symmetries are not features of the world, but merely features of our method of describing the world.

On the other hand, it seems to be a matter of plain historical fact that the observable consequences of symmetries have guided physicists
in their construction of theories ever since Galileo's ship thought experiment. It is prima facie mysterious how this fact is compatible with
the account of symmetries given above.

The usual story about how to reconcile the idea of symmetry as surplus structure with the idea of symmetry as an empirical feature of the
world gives a key role to the distinction between 'global' and 'local' symmetries: it is supposed to be the case that global symmetries (e.g. the Lorentz invariance of special relativity) correspond to Galileo-ship type experiments, while local symmetries (e.g. the diffeomorphism invariance of general relativity, or the gauge invariance of electromagnetism) do not. (This 'usual story' has recently been defended by, among others, Katherine Brading, Harvey Brown and Richard Healey.) In my talk, I will raise several puzzles that I don't think the usual account can deal with.

I will then go on to sketch an alternative account, carefully drawing out the precise consequences of the (well-known) idea that, to realise a symmetry empirically, one must be symmetry-transforming only a subsystem of the universe, and not the universe as a whole. According to this alternative account, both global and local symmetries can correspond to Galileo-ship type phenomena; in particular, there are such phenomena corresponding to both the (local) gauge invariance of classical electromagnetism and the (local) diffeomorphism invariance of general relativity. The key distinction, which I will draw in the talk, is rather between 'interior' and 'non-interior' symmetries.

This talk is based on a forthcoming joint paper with David Wallace.

David Wallace: Symmetry, locality, and space

I attempt to square the circle between (a) the view that two situations, related by a symmetry, are the same situation differently described (so
that symmetry can seem like an inessential consequence of our choosing an excessive mathematical formalism), and (b) the manifest fact that
symmetries - local and global - seem to play an absolutely essential role in physical theories (so that they seem like features of the theory itself,
not just of our formulation of it). In doing so, I hope to cast some light on the relationship between symmetries and the spaces of which they are
symmetries, and also on the gauge principle.

Adam Caulton:  Two ways to permute particles in quantum mechanics

Broadly speaking, particle statistics in elementary quantum mechanics have been given two origins, which are apparently in tension. According to one account, one quantizes using the usual classical configuration space, and the resulting Hilbert space is broken into superselection "symmetry
sectors" corresponding to inequivalent representations of the symmetric group, owing to the Indistinguishability Postulate. Fermions and bosons arise alongside paraparticles as possible particle statistics. According to another account, a reduced configuration space is first obtained by
quotienting the classical configuration space by the symmetric group, and then one quantizes. But non-trivial topological features of the reduced
configuration space allow for multi-valued wave-functions. In three spatial dimensions, fermions and bosons arise (but not paraparticles); in two
spatial dimensions, particles with statistics somewhere between fermions and bosons arise---the anyons. The two accounts are in tension because
anyonic states apparently do not lie within symmetry sectors.

In response to this situation, I will first argue that there is no real conflict between anyonic "statistics" and the Indistinguishability Postulate. Rather, confusion arises from the fact that unitary representations of the symmetric group ambiguously represent both synchronic permutations of labels within a state and diachronic transpositions of particles. Further, the diachronic transpositions admit a different group of representations (namely, the braid group) when the transpositions are governed by path-dependent dynamics---which is exactly what to expect in two but no more spatial dimensions.

Finally, I will argue that two issues remain for philosophical anti-haecceitists about quantum particles. First, the formal resources necessary to mark the synchronic/diachronic difference appears to mean trouble for anti-haecceitists who also wish time to be an emergent feature of dynamics, in the sense advocated by Barbour. Second, given that the two procedures---quotienting under the symmetric group and quantization---do not commute, it is indeterminate which order an anti-haecceitist ought to favour.

Nazim Bouatta: Symmetries, Infinities and Wilsonian Quantum Field Theory

Wilson's renormalization group (RG) approach gives a new point of view about the meaning of quantum field theory. In this context, I will
conceptually analyze the status of "non-renormalizable" gauge theories, viz. non-renormalizable theories in the Dyson power counting sense. I will
examine the nature of the "infinities" in these gauge theories by means of the BRST symmetry and the Batalin-Vilkovisky (BV) formalism. Finally, I
will discuss the idea of emergent "accidental" symmetries in the framework of effective field theories. I will illustrate our discussion by an example
in particle physics: baryon number conservation.

Abstracts, Philosophy of Physics Research Seminar, TT 2010

1st Week (29 April) Alastair Wilson ÒMetaphysics in light of Everettian Quantum MechanicsÓ

Abstract:  If an Everett-style interpretation of quantum theory is correct, what are the metaphysical implications? In this talk I argue that Everettian quantum mechanics (EQM), taken seriously, licenses a variety of arguments for distinctively metaphysical conclusions. After explaining the nature of my project, and defending the propriety and feasibility of appealing to evidence from physics in metaphysics, I outline my preferred version of EQM, which includes a postulate connecting variation amongst Everett branches with objective modality in nature. I argue that this postulate is required if Everettians are to make sense of objective probability; and I use it to provide support for a number of metaphysical doctrines in the context of EQM, including the reducibility of the modal to the non-modal, the necessity of existence, the indexicality of actuality, and the necessity of laws of nature.

2nd Week (6 May) Andreas Doering ÒSome basics of the topos approach to the formulation of physical theoriesÓ

Abstract: The topos approach, which is motivated by the still-open question of finding a theory of quantum gravity, aims to provide a framework for the formulation of physical theories in general, and a new mathematical formulation of quantum theory in particular. The latter includes a novel geometric underpinning by suitable pointless spaces and a new form of quantum logic. A procedure called ÒdaseinisationÓ is the bridge between the usual Hilbert space formalism and the topos form of quantum theory. I will present the basics of the topos approach, with some emphasis on conceptual aspects.

3rd Week (13 May) Keith Hannabuss ÒSome recent developments in Quantum ElectrodynamicsÓ

Abstract: This talk will review the history of electrodynamics and the problem of divergences, together with some of the more recent ideas on how those can be tamed. It will not assume any detailed knowledge of QED.

4th Week (20 May) Harvey Brown ÒBoltzmannÕs H-theorem and its discontentsÓ

Abstract: A comparison is made of the traditional Loschmidt (reversibility) and Zermelo (recurrence) objections to Boltzmann's H-theorem, and its simplified variant in the Ehrenfests' 1912 wind-tree model. The little-cited 1896 (measure-theoretic) objection of Zermelo (similar to an 1889 argument due to PoincarŽ) is also analysed. Significant differences between the objections are highlighted, and several old and modern misconceptions concerning both them and the H-theorem are clarified. Particular emphasis is given to the radical nature of PoincarŽ's and Zermelo's attack, and the importance of the shift in Boltzmann's thinking in response to the objections taken together.

5th Week (27 May) Nancy Cartwright (LSE) ÒWhoÕs afraid of external validity?Ó

6th Week (3 June) Darrell Rowbottom ÒConfirmation and the intersubjective interpretation of probabilityÓ

7th Week (10 June) David Wallace ÒThe logic of the Past HypothesisÓ

Abstract: I attempt to get as clear as possible on the chain of reasoning by which irreversible macrodynamics is derivable from time-reversible microdynamics, and in particular, to clarify just what kinds of assumptions about the initial state of the Universe, and about the nature of the microdynamics, are needed in those derivations. I conclude that while a ÒPast HypothesisÓ about the early Universe does seem necessary to carry out such derivations, that Hypothesis is not correctly understood as a constraint on the early UniverseÕs entropy.

8th Week (17 June) Adam Caulton (Cambridge) ÒInterpreting physical theories with symmetriesÓ

Abstracts, Philosophy of Physics Research Seminar, TT 2008

All talks are thursdays 4:30-6:30, Lecture Room, 10 Merton Street, followed by dinner for those who are interested.

30 April: Luke Glynn (Philosophy, Oxford)

ÒProbability-Lowering Causes and Probability-Raising Non-CausesÓ

Abstract:

The starting point in the development of probabilistic analyses of token causation has usually been the naive intuition that, in some relevant sense, a cause raises the probability of its effect. But there are well-known examples both of non-probability-raising causation and of probability-raising non-causation. Sophisticated extant probabilistic analyses treat some such cases correctly, but only at the cost of excluding the possibilities of direct non-probability-raising causation, failures of causal transitivity, action-at-a-distance, prevention, and causation by absence and omission. I show that an examination of the structure of these problem cases – facilitated by the use of causal graphs – suggests a different treatment, one which avoids the costs of extant analyses.

7 May: Guido Bacciagaluppi

Title: Heisenberg on hidden variables

14 May

No talk.

21 May: Peter Byrne

Title: The Devil's Pitchfork: Multiple Universes, Mutually Assured Destruction, and the Meltdown of a Nuclear Family -- The Life of Hugh Everett III

28 May: Jos Uffink

Title: Entanglement,  entropy and utility:  the analogy between axiomatic approaches to quantitative measures thereof.

4 June: Cian Dorr

11 June: Oliver Pooley

Title: Relativity, Branching Spacetimes and the Passage of Time

18 June: Tien Cao

Title: TBA

Abstracts, Philosophy of Physics Research Seminar, MT 2008

22 January (1 Week) – Jonathan Barrett (Physics, Bristol): Processing Information: Is Quantum Theory Special?

29 January (2nd week) – David Wallace (Philosophy, Oxford):

ÒThe irrelevance of gravitational entropy in cosmological thermodynamicsÓ

Abstract:

There is a widespread view that (i) in the presence of gravity, highly concentrated systems are actually higher-entropy than more dispersed systems, and (ii) that – because it makes the early universe low- rather than high-entropy – this is the ultimate explanation of the second law of thermodynamics. This view has recently been sharply criticised by Earman, who argues that (iii) gravitational entropy is too ill-defined to play a foundational role of this kind. I will review this discussion and argue that (i)-(iii) are all either flat wrong or at any rate often understood in a confused fashion. I will argue that (a) we have a perfectly satisfactory understanding of the consequences of gravity for entropy at the energy scales relevant to classical cosmology; (b) that understanding does lead to the conclusion that uniform dispersed systems are relatively low-entropy, but this is not really because squeezing those systems into smaller spaces increases their entropy; (c) that spatial uniformity is not, as far as thermodynamics is concerned, the real explanation for the lowness of the entropy of the early universe and hence for the 2nd law in our present epoch.

5 February (3rd Week) – Jonathan Tallant (Philosophy, Nottingham):

ÒExistence PresentismÓ.

Abstract:

Grant the presentist that everything exists now: what is it about the world that makes a moment ÔnowÕ?  It turns out that this is a difficult question to answer and a number of concerns arise in discussion of the various options. To deal with these concerns, IÕll put forward and defend  a new version of presentism: Existence Presentism.

Existence presentism, I argue, turns out to have particular modal consequences. Namely, that it is necessarily true if true at all. Although the conclusion isnÕt novel, it is (I think) a conclusion for which we donÕt typically see an argument. However, the modal result itself then turns out to be problematic since we have the appearance of the genuine possibility of eternalism. To square the circle I spend the latter portions  of the paper arguing that eternalism has the mere appearance of possibility.

The result is this: we have a new variety of presentism on our hands, one that is able to solve certain problems that afflict traditional strains of presentism. We can also explain away the seeming possibility of eternalism. This, it seems to me, is to put presentism on a stronger (if not yet strong) footing.

12 February (4th Week) – Bob Coecke (Comlab, Oxford):

ÒHigh-level reasoning about the low-level scaleÓ

Abstract:

We report on progress in an approach which aims to provide quantum theory with a purely diagrammatic calculus, a logical foundation, and increased degrees of axiomatic freedom, while still retaining full expressiveness.

Key to this approach is the fact that monoidal categories provide a natural framework to reason about systems, processes and their interactions of any kind.  We provide two applications of this framework.

An axiomatization of the notion of complementary observables exposes the flows of information in sophisticated quantum informatic protocols involving complex entanglements, and an axiomatization of relative phases provides new insights in the origin and peculiarity of quantum non-locality.

The applications are drawn from the following papers:

[1] Bob Coecke & Ross Duncan. "Interacting quantum observables". ICALP'08.

[2] Bob Coecke, Bill Edwards and Rob Spekkens. "The group-theoretic origin of non-locality".  Hopefully available by the date of the talk.

19 February (5th Week) – Dennis Lehmkuhl (Philosophy, Oxford): Is matter an aspect of spacetime structure? On Classical Unified Field Theories

26 February (6th Week) – Katherine Brading (Philosophy, Notre Dame), title TBC

5 March (7th Week) – Mark Sprevak (History and Philosophy of Science, Cambridge): Are computations objective features of the world?

12 March (8th Week) – Dennis Dieks (Institute for History and Foundations of Science, Utrecht), title TBC

Abstracts, Philosophy of Physics Research Seminar, MT 2008

October 23. Prof Michel Janssen, Program in the History of Science, Technology, and Medicine, University of Minnesota/Max Planck Institute for the History of Science (MPIWG), Berlin

Title: Pascual JordanÕs Resolution of the Conundrum of the Wave-Particle Duality of Light

Abstract: In a key contribution to the 1926 Dreimaennerarbeit with Born and Heisenberg, Jordan showed for a simple model of quantized waves how one recovers both the wave and the particle term of Einstein's famous 1909 formula for the mean-square-energy-fluctuation in black-body radiation. So the two terms do not require separate mechanisms, as Einstein thought, but arise from a unified dynamical framework (which can be expressed in terms of particles or waves). I give a detailed reconstruction of JordanÕs derivation of this result and tell the curious story of its reception. I defend Jordan's argument against various criticisms in the literature, but I also argue that the argument is incomplete. In modern terms, Jordan calculated the quantum uncertainty in the energy of a subsystem in an energy eigenstate of the system as a whole, whereas the thermal fluctuation is the average of this quantity over an ensemble of such states. This talk is based on a recent paper I wrote together with Tony Duncan (SHPMP 39 (2008): 634-666) in the context of a larger history of quantum project led by Juergen Renn and his group in Berlin (
http://quantum-history.mpiwg-berlin.mpg.de/main).

October 30. Prof DŽcio Krause, Department of Philosophy, Federal University of Santa Catarina, Brazil.

Title: Quantum (Non-) Individuality -- Logical aspects

Abstract: In this talk I discuss in a general way some reasons which would sustain a metaphysics of non-individuals, based on a possible interpretation of quantum objects. I emphasize some of the involved foundational problems that appear when we consider the underlying logic (mathematics included) used to approach the subject.

November 6. Dr Alexei Grinbaum, LARSIM laboratory, CEA (French Atomic Energy Commission)-Saclay, France

Title: Which fine-tuning arguments are fine?

Abstract. Arguments from naturalness are much used in quantum field theory in the last 25 years. Still naturalness can be understood in several non-equivalent ways. We review the role of fine tuning/naturalness in the purported solution of QFT problems and we oppose 'can this be true' evaluations of models solving the hierarchy problem to the unsound use of fine tuning for preferring one model over another.

November 13.  Prof Lane Hughston, Department of Mathematics, Imperial College

Title: Do we really need dynamical models for quantum state reduction ?

Abstract: This talk will present an overview of dynamical models for the "collapse of the wave function", and will discuss some of the foundational issues arising in connection with such models.

In non-relativistic quantum mechanics the expectation value of the energy is a conserved quantity. It is possible to extend the dynamical law associated with the evolution of a quantum state to include a nonlinear stochastic component, while respecting the conservation law. In accordance with the dynamics thus obtained, referred to as the energy-based stochastic Schrodinger equation, it can be shown that an arbitrary initial state collapses spontaneously to one of the energy eigenstates, with the Born-rule probabilities. Two such models will be analyzed in this talk: one that achieves state reduction in infinite time, and the other in finite time. Closed-form solutions can be obtained for both of these models. With these solutions at hand it is possible in principle to simulate explicitly the dynamics of the quantum states of even complicated physical systems. An interesting byproduct of the investigation is the resolution of an important issue concerning the "tail problem" in the collapse of the wave function.

Do we really need dynamic reduction models? I shall argue that such models do not really "solve" the problem of the collapse of the wave function, at least perhaps not in the original sense envisaged two decades ago by Diosi, Ghirardi, Gisin, Pearle, Percival and others --- but may nevertheless be valid as dynamical models for the evolution of a quantum state.

(Based in part on work carried out in collaboration with D. C. Brody.)

November 20. Prof Simon Saunders, Faculty of Philosophy, Oxford University.

Title: Chance in the Everett Interpretation

Abstract: In the Everett interpretation of quantum mechanics, the wave function of the universe has the macroscopic structure of innumerable branches, in each of which quasiclassical equations hold to high accuracy. I argue that ratios in the squared norms of branch amplitudes fulfil the three key roles of objective chance: (i) the statistical inference role (chance is manifested in statistics); (ii) the decision theory role (chance as a guide to credence); and (iii) the link with uncertainty (chance events are uncertain). (i) is easily demonstrated, whilst (ii), granted the structure to the wave-function, is established by the Born-rule theorem due to Deutsch and Wallace. This talk is concerned with (iii), considered by many the 'Achilles heel' of the Everett interpretation. It can be relegated to a semantic problem, but it can also be given a more substantive basis given the atemporal representation of the wave-function in terms of quantum histories. Vaidman's recent proposal, that uncertainty in the Everett interpretation be anchored to Aharonov's 2-vector formalism, is also considered. On either count, Everettian worlds have a natural representation as divergent worlds, rather than overlapping worlds (in Lewis' sense), whereupon quantum mechanical uncertainty reflects self-locating ignorance.

November 27.  Dr David Frame, Department of Physics, Oxford University

Title, Abstract TBA

December 4.  Prof Nick E. Mavromatos, Department of Physics, King's College London

Title: Quantum Gravity, Microscopic Time Irreversibility and EPR Correlations

Abstract: I discuss the concept of time in some (stringy) versions of space time-foam models of quantum gravity, and discuss the conditions under which  the induced decoherence of matter in such models may imply a microscopic time irreversibility, due to the fact that the CPT operator is ill-defined (intrinsic CPT symmetry violation). I discuss perturbative'' situations, i.e. situations in which the concept of antiparticle is still in place, but its properties in connection with the particle are affected by the above-mentioned breakdown of CPT. I will explain how space-time foam may affect (modify) Einstein-Podolsky-Rosen (EPR) correlations in entangled particle states of mesons, yielding effects that, depsite being attributed to quantum gravity, may have a chance of being falsified in upcoming experimental facilities. The key point, which leads to an enhancment of the magnitude of such effects in low-energy experiments (as compared to Planck scale), is the near-degeneracy of the mass states of the involved mesons.

Abstracts, Philosophy of Physics Research Seminar, TT 2008

Th 24th April:

Title: ÒIn what sense does Ònothing make sense except in the light of evolutionÓ

Speaker: Paul Griffiths (philosophy department, University of Sydney; and ESRC Centre for Genomics in Society, University of Exeter):

Abstract: Dobzhansky argued that biology only makes sense if life on earth has a shared history. But his dictum is often reinterpreted to mean that biology only makes sense in the light of adaptation. Some philosophers of science have argued in this spirit that all work in ÔproximalÕ biosciences such as anatomy, physiology and molecular biology must be framed, at least implicitly, by the selection histories of the organisms under study. Others have denied this and have proposed non-evolutionary ways in which biologists can frame these investigations. This paper argues that an evolutionary perspective is indeed necessary, but that it must be a forward-looking perspective informed by a general understanding of the evolutionary process, not a backward-looking perspective informed by the specific evolutionary history of the species being studied. Interestingly, it turns out that there are aspects of proximal biology that even a creationist cannot study except in the light of a theory of their effect on future evolution.

****************************************************************************************************************************************************

Th 1st May

Title: Geometrizing gravity and vice versa: the force of a formulation

Speaker: Eleanor Knox (philosophy department, Oxford University)

Abstract: It is well-known that NewtonÕs theory of gravity, commonly held to describe a gravitational force, can be recast in a geometrical form: Newton-Cartan theory. It is less well-known that general relativity, an apparently geometrical theory, can be reformulated in such a way that it resembles a force theory; teleparallel gravity does just this. This raises questions. One of these concerns theoretical underdetermination. I argue that we should see Newton-Cartan and teleparallel theory as reformulations of Newtonian gravity and general relativity and not independent theories. However, if the same gravitational theory may be formulated in geometrical and non-geometrical terms, this raises conceptual problems of its own. I argue that these formulations do not wear their interpretations on their sleeves. The geometrical nature of a gravitational theory is not a straightforward consequence of anything internal to that theory as a theory of gravity. Rather, it essentially relies on the rest of nature (the non-gravitational interactions) conspiring to choose the appropriate set of inertial frames.

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Everett@50: The Everett interpretation of quantum mechanics, 50 years on.

Oxford University, July 19-July 21, 2007

Organisers:

Simon Saunders

David Wallace

Peter Taylor

Full schedule: http://users.ox.ac.uk/~everett/schedule.htm

Website: http://users.ox.ac.uk/~everett/

Schedule

 Thursday 19th July 2007 10.30 - 11.00 Coffee 11.00 - 1.00 The Everett interpretation: 50 years on. Simon Saunders Decoherence and ontology. David Wallace Commentator: Robert Geroch Chair: Jeremy Butterfield 1.00 - 2.00 Sandwich lunch, Ryle Room, 10 Merton St. 2.00 - 3.30 Can the world be only wave-function? Tim Maudlin Commentator: Adrian Kent Chair: Michel Janssen 3.30 - 4.00 Tea 4.00 - 5.30 Two Dogmas About Quantum Mechanics. Jeffrey Bub and Itamar Pitowsky Commentator: Christopher Timpson Chair: Barry Loewer 6.30 - 10.00 Evening drinks and dinner, Cherwell Boathouse

 Friday 20th July 2007 9.30 - 11.00 Probability in the Everett picture. David Z. Albert Commentator: David Papineau Chair: Christopher Timpson 11.00 - 11.30 Coffee 11.30 - 1.00 Everett and Evidence. Wayne Myrvold and Hilary Greaves Commentator: Barry Loewer Chair: James Ladyman 1.00 - 3.00 Lunch at the Head of the River 3.00 - 4.30 Apart from universes. David Deutsch The time symmetric QM and the MWI. Lev Vaidman Chair: Oliver Pooley 4.30 - 5.00 Tea 5.00 - 6.30 Quantum cosmology. James B. Hartle Some remarkable implications of probabilities without time. Andreas J. Albrecht Chair: Peter Lewis 7.00 - 10.00 Conference dinner, Oriel College

 Saturday 21st July 2007 9.30 - 11.00 A metaphysician looks at the Everett interpretation. John Hawthorne Commentator: James Ladyman Chair: Tony Sudbery 11.00 - 11.30 Coffee 11.30 - 1.00 Explaining probability. Simon Saunders Commentator: Oliver Pooley Chair: Alastair Rae 1.00 - 2.30 Lunch, local restaurants 2.30 - 4.00 Pilot-wave theory: Everett in denial? Antony Valentini Commentator: Harvey Brown Chair: Adrian Kent 4.00 - 4.30 Tea 4.30 - 6.00 Round table discussion: David Wallace, Jeremy Butterfield, David Z. Albert 7.00 Drinks, Old Cloisters, New College 8.30 Farewell dinner, The Undercroft, New College

Abstracts, Philosophy of Physics Research Seminar, TT 2007

PROF RICHARD HEALEY, Arizona

26 April:  ÔGauge Symmetry and the Theta-vacuumÕ

Abstract. According to conventional wisdom, local gauge symmetry is not a symmetry of nature, but an artifact of how our theories represent nature. But a study of the so-called theta-vacuum appears to refute this view. The ground state of a quantized non-Abelian Yang-Mills gauge theory is characterized by a real-valued parameter ө (theta)—a fundamental new constant of nature. The structure of this vacuum state is often said to arise from a degeneracy of the vacuum of the corresponding classical theory: this degeneracy allegedly arises from the fact that ÒlargeÓ (but not ÒsmallÓ) local gauge transformations connect physically distinct states of zero field energy. If that is right, then some local gauge transformations do generate empirical symmetries. In defending conventional wisdom against this challenge I hope to clarify the meaning of empirical symmetry while deepening our understanding of gauge transformations.

DR SIMON BENJAMIN, Oxford

10 May: "Measurement as the fundamental mechanism in a quantum computer."

Abstract: The paradigm of measurement based quantum computing (MBQC)
has proven to be very rich. It is both simple to apply and very
flexible, allowing it to be employed for many different physical
implementation schemes. Yet at the same time it offers deep insights
into the structure of quantum computational tasks. I'll give a basic
review of the essential ideas in the paradigm, including graph states
and cluster states: these are the many-qubit entangled states which
MBQC consumes as a kind of resource. I will then go on to discuss a
set of schemes for large scale QIP which I consider to be the most
promising and exciting proposals to-date; they use measurements both
to _create_ and to _consume_ the graph state resource, so that
measurements alone form the essential mechanism of the device. The
measurements required to create entanglement are interesting in their
own right: the key is not to learn too much about the system being
measured, so that one is tempted to apply slogans like, "Ignorance is
power"!

DR SIMON SAUNDERS, Oxford

17 May: Probability and semantics for branching worlds

Abstract: According to Everettian quantum mechanics, we live in an emergent
branching multiverse. This is a structure that has been partially
anticipated by contemporary metaphysicians, save for two crucial features:
(i) branches come with quantities (squared amplitudes) whose sum is constant
under branching (ii) branches are emergent structures, defined in a suitable
approximation. Both features matter when it comes to the semantics of
branching - to truth-conditions for ordinary utterances, including talk of
probability. Here I shall deal (almost) exclusively with the latter, and
with the explanation, more broadly, of why physical probability has the
characteristics it does - why it cannot be directly measured, and why it is
manifested in statistics.

PROF SANDU POPESCU, Bristol

24 May.: 'Entanglement and the Foundations of Statistical Mechanics'

Abstract: Statistical mechanics is one of the most successful areas of physics. Yet, almost 150 years since its inception, its foundations and basic postulates are still the subject of debate. Here we suggest that the main postulate of statistical mechanics, the equal a priori probability postulate, should be abandoned as misleading and unnecessary. We argue that it should be replaced by a general canonical principle, whose physical content is fundamentally different from the postulate it replaces: it refers to individual states, rather than to ensemble or time averages. Furthermore, whereas the original postulate is an unprovable assumption, the principle we propose is mathematically proven. The key element in this proof is the quantum entanglement between the system and its environment. Our approach separates the issue of finding the canonical state from finding out how close a system is to it, allowing us to go even beyond the usual boltzmannian situation.

Abstracts, Philosophy of Physics Research Seminar, HT 2007

PROF SANDU POPESCU, Bristol

18 Jan.: 'Entanglement and the Foundations of Statistical Mechanics'

Abstract: Statistical mechanics is one of the most successful areas of physics. Yet, almost 150 years since its inception, its foundations and basic postulates are still the subject of debate. Here we suggest that the main postulate of statistical mechanics, the equal a priori probability postulate, should be abandoned as misleading and unnecessary. We argue that it should be replaced by a general canonical principle, whose physical content is fundamentally different from the postulate it replaces: it refers to individual states, rather than to ensemble or time averages. Furthermore, whereas the original postulate is an unprovable assumption, the principle we propose is mathematically proven. The key element in this proof is the quantum entanglement between the system and its environment. Our approach separates the issue of finding the canonical state from finding out how close a system is to it, allowing us to go even beyond the usual boltzmannian situation.

DR DAVID WALLACE, Oxford

25th Jan.: 'The Ontology of the Quantum State'

Abstract: What ontology does realism about the quantum state suggest? The main extant view is \textit{wave-function realism}. I elaborate the sense in which wave-function realism does provide an ontological picture; and defend it from certain objections that have been raised against it. However, there are good reasons to be dissatisfied with wave-function realism, as I go on to elaborate. This motivates the development of an opposing picture: what I call \textit{spacetime state realism}; a view which takes the states associated to spacetime regions as fundamental. This approach enjoys a number of beneficial features, although, unlike wave-function realism, it involves non-separability at the level of fundamental ontology. I will investigate the pros and cons of this non-separability, arguing that it is a quite acceptable feature; even one that proves fruitful in the context of relativistic covariance.

PROF DAVID DEUTSCH, Oxford

1 Feb.: 'Physics as Quantum Constructor Theory'

Abstract:: Constructor theory is the (as yet largely non-existent) general theory of what can be constructed from what. It can be regarded as the ultimate generalisation of the theory of computation (the theory of what *information* can be constructed from what other information, and using what resources). But, more fundamentally, it can -- and for various reasons should -- also be regarded as a way of expressing the whole of physics (and the whole of science).

DR JAN BROEKAERT, Vrije Universiteit, Brussels

8 Feb.: 'Towards a Lorentz-PoincarŽ type interpretation of General Relativity Theory.'

Abstract: The geometric interpretation of General Relativity Theory  reduces gravitation to a mass and energy induced  curvature of the metric of the spacetime continuum. This geometrical approach to gravitation is seamlessly adjusted to the Einstein-Minkowski interpretation of Special Relativity and inherits the Parmenidian ontology of the Minkowskian block universe.

In  the  physical  interpretation of Special Relativity Theory;  Lorentz and PoincarŽ -inter alia- conceived consistent electromagnetic processes as rod contractions, clock slowing and  light synchronization to conjure the Lorentz transformations,  proper to a classical  space and time ontology with a  less exotic temporal becoming. There is no completed correspondence with a similar ''physical" interpretation in General Relativity Theory; however some elements are present in various alternative developments of relativistic gravitation (Wilson 1921, Dicke 1957, Dehnen et. al. 1960, Thirring 1961). Another recurrent argument for the possibility of  a  ''Lorentz-PoincarŽ"-type development of gravitation is found in geometric conventionalism  (e.g. Sexl 1970, Dieks 1987); leaving underdetermined the intrinsic nature of space and time at the expense of modifications of the physical laws that go with it.   We have shown, at the hand of  a relativistic gravitation model with Euclidean coordinate space and coinciding till first Post-Newtonian order  with General Relativity Theory, that it is indeed possible to maintain an explicit Lorentz-PoincarŽ type interpretation to this extent (Broekaert 2005).  While in principle this description allows a cosmological time and a prior-geometric space, the latter remains fundamentally  non observable because of the implemented PoincarŽ Principle of Relativity, prohibiting the perception of a preferred frame  (e.g. PoincarŽ 1904). We will discuss some of the conceptual advantages of this type of interpretation in terms of the physics of gravitation, other than attraction.

PROF STEPHAN HARTMANN, LSE and Tilburg

15 Feb.: 'Probability and decoherence'

PROF IAN PERCIVAL, Queen Mary, London

22 Feb.: 'Newton, Berkeley and quantum theory'

DR PIETER KOK, Oxford and Sheffield

1 Mar.: 'Cluster states: a new class of entanglement'

PROF JEFFREY BUB, Maryland

8 Mar.: 'Two dogmas about quantum mechanics'

Abstract: I discuss what Pitowsky (2007) has called two 'dogmas' about quantum mechanics. The first dogma is Bell's assertion that measurement should never be introduced as a primitive in a fundamental mechanical theory like classical or quantum mechanics, but should always be open to a dynamical analysis in principle. The second dogma is the view that the quantum state has an ontological significance analogous to the ontological significance of the classical state (which specifies a complete catalogue of a system's properties), i.e., that the quantum state is a (perhaps incomplete) representation of physical reality. I argue that both dogmas are called into question by a 'no cloning' principle that distinguishes quantum information from classical information. I distinguish two measurement problems: a problem about individual events, which I argue is a pseudo-problem, and a tractable problem about probabilities, which finds a solution in the phenomenon of decoherence.

Structuralism about Physics and Mathematics Conference

Department of Philosophy, University of Bristol

Saturday 2nd and Sunday 3rd December 2006

Organisers: James Ladyman and ¯ystein Linnebo

Programme

Saturday

12.00pm – registration

12.30pm – 2.10pm

James Ladyman (Bristol) ÔOn the Identity and Diversity of Objects in a StructureÕ

2.30pm Tea and Coffee

2.30pm – 4.10pm

¯ystein Linnebo (Bristol)

4.20pm – 6.00pm

Stewart Shapiro (Ohio State and St. Andrews)

Sunday

9.00am – 10.40am

Oliver Pooley (Oxford)

10.40am – 11.00am Tea and Coffee

11.00am – 12.40 pm

Simon Saunders (Oxford) ÔIndistinguishabilityÕ

12.40pm – 1.20pm

1.20pm –2.40pm

Steven French (Leeds)

2.40pm – 3.00pm Tea and Coffee

3.00pm – 4.20pm

Fred MŸller (Utrecht)

4.20pm – Concluding Discussion

***************************

One-Day Conference on Foundations of Physics

in Memory of Jeeva Anandan

Convenor: Harvey Brown

The meeting will take place on Saturday, 25 November 2006, in the Lecture Room of the Philosophy Centre, 10 Merton Street, Oxford OX1 4JJ.

10.00–10.15 Opening remarks by Harvey Brown

10.15–11.30 Dr Dharamvir Ahluwalia-Khalilova (Department of Physics and Astronomy, University of Canterbury, New Zealand)

A new fermionic quantum field for dark matter

11.30–12.45 Dr Jos Uffink (Institute for History and Foundations of Mathematics and Natural Sciences, Utrecht University)

Protective measurement revisited

2.15–3.30 Prof Erik Sjšqvist (Department of Quantum Chemistry, Uppsala University)

Quantum Holonomies

3.30–4.45 Prof Leo Stodolsky (Max Planck institute for Physics, Munich)

Why the best wavefunction is no wavefunction

4.45–5.15 Tea/Coffee

5.15–6.30 Prof Sir Roger Penrose (Mathematical Institute, Oxford University)

TBA

Abstracts, Philosophy of Physics Research Seminar, MT 2006

12 October: Dr. Pedro Ferreira, Oxford University:

Modifying gravity: an alternative to dark matter.

19 October: Dr Guido Bacciagaluppi, Institut d'Histoire et de Philosophie des Sciences et des Techniques, CNRS, Paris.

Non-equilibrium, Non-locality and Non-linearity

Abstract: Non-equilibrium solutions are investigated in a Nelson-like framework of
diffusion processes on configuration space (more precisely, solutions
with initial or final constraints). Even if the framework is restricted,
to local theories, imposing initial (or final) constraints on particle
distributions can mimic non-local behaviour at the level of the
probability distribution and probability current. Specifically, one can
show that a non-linear Schršdinger equation for non-interacting (but
generally entangled) particles can be derived from such a local theory
with constraints.

26 October: Dr. Rob Spekkens, Department of Applied Mathematics and Theoretical Physics, Cambridge University

Quantum coherence: fact or fiction?

Abstract:  A controversy that has arisen many times over in disparate contexts is whether quantum coherences between eigenstates of additively conserved quantities are fact or fiction. I present a pedagogical introduction to the debate in the form of a hypothetical dialogue between proponents from each of the two camps: a factist and a fictionist. A resolution of the debate can be achieved, I argue, by recognizing that quantum states do not only contain information about the intrinsic properties of a system but about its extrinsic properties as well, that is, about its relation to other systems external to it. Specifically, the coherent quantum state of the factist is the appropriate description of the relation of the system to one reference frame, while the incoherent quantum state of the fictionist is the appropriate description of the relation of the system to another, uncorrelated, reference frame. The two views, I conclude, are alternative but equally valid paradigms of description.  This conclusion has implications for a variety of conceptual puzzles including whether it is possible to lift superselection rules, whether synchronized clocks and aligned Cartesian frames are a source of entanglement, and whether a single particle can exhibit Bell correlations.

2 November: Professor John Mayberry, University of Bristol.

Extensional structuralism and the problem of indiscernibles

Abstract: Extensional structuralism is the standard method that
mathematicians use in expounding mathematics. The simplest kind of
extensional structure is a set equipped with a morphology, which consists
of various functions and relations taken in extension (i.e., as sets of
ordered pairs). Such familiar mathematical structures as groups, rings, and
ordered fields are extensional structures of this sort.
In this talk I shall define the notion of indiscernibility in extensional
structures and discuss its relation to the traditional Kantian problem of
enantiomorphs.

9 November: Dr. Ioannis Votsis, Philosophisches Institut Heinrich-Heine-UniversitŠt DŸsseldorf

Structural realism 2.0

Abstract: In this talk, I focus on the epistemic variety of structural realism. The aim is to explore new sources of support, tackle certain threats, suggest various adjustments, discuss neglected issues, and, finally, try to put things in perspective. In more detail, I will look at: (1) the argument from transmission (found in PoincarŽ, Russell, Carnap and Quine), (2) the argument from the increased mathematisation of science, (3) the tenability of the structure vs. nature distinction, (4) a particular version of the non-isomorphic models problem, (5) the relationship between the foundations of science and the foundations of mathematics and (6) a round-up of the main challenges. By discussing these issues, I hope that a clearer picture will emerge of the merits, desiderata and limits of epistemic structural realism.

16 November: Professor Samir Okasha

Where Rational Choice and Evolution Part Ways

Abstract: Abstract: The paper has two parts. Firstly, I examine the phenomenon of risk-averse behaviour, a long standing puzzle for the theory of rational choice. I argue that interesting light can be shed on the phenomenon by considering it from the viewpoint of evolutionary, rather than rational
choice, theory. Secondly, I examine Brian Skyrms' recent ideas on the general relationship between evolution and rational choice. Skyrms argues that in certain contexts, evolution and rational choice 'part ways', i.e. strategies that are ruled out by considerations of rational self-interest
may nonetheless be favoured by natural selection. I show that the phenomenon of risk-aversion demonstrates a more radical 'parting of ways' than those discussed by Skyrms.

23 November: Dr. Antony Valentini, Perimeter Institute for Theoretical Physics, Waterloo

Inflationary cosmology as a probe of primordial quantum mechanics

Abstract: We show that inflationary cosmology may be used to test the statistical predictions of quantum theory at short distances and early times. Hidden-variables theories, such as de Broglie-Bohm pilot-wave theory, allow the existence of vacuum states with non-standard field fluctuations (Òquantum nonequilibriumÓ). We show that inflationary expansion will transfer any primordial nonequilibrium to cosmological scales, resulting in anomalous power spectra, non-random phases, and non-Gaussianity in the cosmic microwave background. The conclusions depend only weakly on the details of the de Broglie-Bohm dynamics. Here we discuss, in particular, nonequilibrium breaking of scale invariance for the primordial power spectrum, as well as nonequilibrium violation of the scalar-tensor consistency relation. Recent observations are used to set limits on violations of quantum theory in the early universe.

30 November: Dr. Simon Saunders, University of Oxford

NewtonÕs Corollary VI, and all that: why absolute rotation is relational

Abstract: Corollary VI of Principia, Book I, Axioms, anticipated – or was identical to - EinsteinÕs equivalence principle, yet its role in NTG, historically and conceptually, has received very little attention. It implies that gravitational acceleration (and hence the gravitational force) is purely relational, a point about NTG stated as a paradox (or an inconsistency) by Norton in 1992. I shall review the relevant history and show how to answer NortonÕs paradox without the more elaborate apparatus of Newton-Cartan theory, used by Malament in his 1995 reply to Norton. I shall also consider how, in the light of it, absolute rotation should have been analysed as relative motion (and nearly was, by Huygens, Euler, and Maxwell), and how MachÕs principle should have been framed in consequence.

***********************************************************************************

History and Philosophy of Mathematics Day

Tuesday 23 May 2006

University of Bristol, 9 Woodland Road, Bristol  BS8 1TB

PROGRAMME

10.30 - 12.30 Dr Hannes Leitgeb (University of Bristol) "Formal and
Informal Provability"

2.00 - 4.00 Professor Hartry Field (New York University) "Truth and
the Unprovability of Consistency"

4.00 - 5.00 tea

5.00 - 7.00 Dr Eleanor Robson (HPS, Cambridge) "A Short History of
Numbers in the Middle East"

7.00 dinner

for further information contact Hannes Leitgeb or Alexander Bird:
<
http://www.bris.ac.uk/philosophy/department/staff/>

<
http://www.bris.ac.uk/philosophy/department/events/
history_phil_maths.html>

********************
Professor Alexander Bird

University of Bristol
Bristol  BS8 1TB, United Kingdom
Tel: +44 (0)117 928 7826
Fax: +44 (0)117 928 7825
Web:
http://eis.bris.ac.uk/~plajb/

Oxford, Michaelmas Term 2004

Interdisciplinary seminar "The Oxford Advanced Seminar on Informatic
Structures" - nine lectures on "CONCEPTS OF SPACE"

Mathematical foundations of physics talks in it are:

Friday 15 October (week 1) Jonathan Gratus (University of Wales at
Bangor) title TBA (discrete space-time, quantum groups, fractafolds)

Friday 29 October (week 3) Basil Hiley (Birkbeck College) - coauthor of
David Bohm of the The Undivided Universe: Ontological Interpretation of
Quantum Theory.  TITLE:  The role of non-commutative geometry in algebraic
quantum mechanics: a physicist's perspective.

week 7 and 8 yet unconfirmed

Friday 17 December (week 10) Frank Valckenborgh (Macquarie University,
Sydney) title TBA (Hilbert space representation theorems from projective
geometry)

All seminars are at:

http://se10.comlab.ox.ac.uk:8080/InformaticPhenomena/index.html

Trinity Term 2004

LSE

Unless otherwise noted, all seminars and events are held in T206 and are open to the public.

Monday, 26 April 2:00-4:00 pm

SIGMA CLUB

PUBLIC LECTURE

Margaret Brown

Professor of Mathematics Education, King's College London

Chair: Anthony O'Hear

CPNSS, LSE

Mathematics for the Millions

Thursday, 29 April 5.30-7:30 pm

LAKATOS AWARD LECTURE

Patrick Suppes

Winner of the 2003 award

Why are the Concepts of Representation and Invariance Important in Science

Venue: Old Theatre

Friday, 30 April 11:00-1:00pm

LAKATOS AWARD SPECIALIST LECTURE

Patrick Suppes

Winner of the 2003 Award

Where do Bayesian Priors Come From?

Wednesday, 12 May 4:00-6:00 pm

SPECIAL LECTURE (organised by Roman Frigg and Stephan Hartmann)

Paul Hoyningen-Huene

Hanover

On the Nature of Science

Monday, 24 May 5:30-7:00 pm

POPPER DEBATE

Science and Religion - Conflict or Peaceful Coexistence?

Peter Atkins

Professor of Chemistry

University of Oxford

Peter Lipton

Hans Rausing Professor of History and Philosophy of Science

University of Cambridge

Keith Ward

Emeritus Regius Professor of Divinity

University of Oxford

Co-Director, CPNSS, LSE

Venue: Old Theatre, Old Building

TUESDAY, 1 June 2:00-4:00 pm

POPPER SEMINAR

Harvey Brown

Oxford

The Arrow of Time in Thermodynamics

Monday, 7 June 5:15-7:00 pm (Tea at 4:45 in T116)

BRITISH SOCIETY FOR THE PHILOSOPHY OF SCIENCE

Helen Billinge

LSE

Constructive Mathematics and Pragmatism

Wednesday, 9 June  2:00-4:00 pm

RESEARCH SEMINARS IN THE PHILOSOPHY OF NATURAL SCIENCES (PHYSICS, PH 551)

Roman Frigg and Stephan Hartmann

Guest Speaker  TBA

Information in Biology

Wednesdays, 16 June 11:00-1:00 pm

RESEARCH METHODS IN PHILOSOPHY (PH500)

Elliott Sober

Probability in the Philosophy of Biology

Wednesday, 23 June 2:00-4:00 pm

RESEARCH SEMINARS IN THE PHILOSOPHY OF NATURAL SCIENCES (PHYSICS, PH 551)

Imperial College London

Quantum Information

Friday-Saturday, 25-26 June

'RISK, UNCERTAINTY AND DISSENT' CONFERENCE

Seville, Spain

Organisers: CPNSS jointly with GOPA (Group of Policy Advisers, European

Commission) and IPTS (Institute for Prospective and Technological Studies,

Seville)

Programme Under Construction

TUESDAY, 29 June 2:00-4:00 pm

POPPER SEMINAR

Branden Fitelson

UC Berkeley

Ravens, Emeralds, and Bayesianism Revisited

The University of Bristol Philosophy of Physics Seminar

11th May        Dr Peter Morgan (Oxford)

"An understanding of QFT"

18th May        Dr Patrick Enfield (Bristol)

"Tributaries, rivers, and Chinese boxes: physicists and

philosophers on realism and the progress of science"

1st June        Professor Peter Landsberg (Southampton)

"Pauli and an ergodic theorem"

8th June        Professor Basil Hiley (Birkbeck)

"TBA"

The seminars will take place at 5.00 p.m. in room 3.27, physics department, University of Bristol, Tyndall Avenue, Bristol. All Welcome

University of Bristol, 9 Woodland Road, Bristol BS8 1TB, 0117 928 7609

Louvain-la-Neuve, Belgium

The Arrow of Time: Physics and Philosophy, 7-8 May 2004

supported by the European Science Foundation (Network on Philosophical and Foundational Problems of Modern Physics),

Institut SupŽrieur de Philosophie, Place du cardinal Mercier 14, Auditorium Socrate -240.

See http://www.lofs.ucl.ac.be/recherche/colloques/time.html, and  www.philphys.nl

Instructions on how to get there can be found at: http://www.adcp.ucl.ac.be/cartes.html

If you wish to spend some nights in Louvain-la-Neuve, I suggest that you directly contact the Hotel Le Relais, where most speakers will stay during the Workshop. http://www.relais.ucl.ac.be/eng/accueil.htm

Attendance and coffee breaks are free. If you wish to attend, please confirm your participation with Ms. Virginie Haulotte. haulotte@sisp.ucl.ac.be

Talks will begin at 9:30 on Friday 7th and will be over on Saturday 8th at 5:00 pm Speakers are by invitation only. The following speakers have confirmed

their participation (some titles are provisional). You will receive the final program and schedule shortly.

List of speakers:

David Atkinson  (UniversitŽ de Groningen)

Does Quantum Electrodynamics have an Arrow of Time?

Gennaro Auletta (UniversitŽ GrŽgorienne, Rome)

Reversibility and Irreversibility in Quantum Mechanics

Jean Bricmont (UniversitŽ Catholique de Louvain)

Boltzmann's explanation of the arrow of time

Harvey Brown (UniversitŽ d'Oxford)

Time and relativity

Marisa Dalla Chiara (UniversitŽ de Florence)

Quantum histories and quantum computations

Dennis Dieks (UniversitŽ d'Utrecht)

Becoming, relativity and locality

Mauro Dorato (UniversitŽ de Rome III)

Is becoming accessible to physical theories

Vincenzo Fano (UniversitŽ d'Urbino)

The direction of time: Why is it a problem?

Mathias Frisch (UniversitŽ du Maryland)

Pierre Gaspard (UniversitŽ Libre de Bruxelles)

Statistical-mechanical explanations of the thermodynamic arrow of time

Michel Paty (UniversitŽ de Paris VII)

The flow of time: physical time and cosmological time

Huw Price (UniversitŽ de Sidney)

Sommerfeld's Puzzling Prescription: New Thoughts on the Arrow of Radiation

Jos Uffink (UniversitŽ d'Utrecht)

Irreversibility in thermodynamics

ESF Conference on Philosophical and Foundational Issues in Spacetime Theories,

Oxford, 24–27 March 2004

PROGRAMME (as of March 22th 2004)

 Wednesday 24 March 9.00 Dr Harvey Brown (Oxford) Relativity as a "constructive" theory: a defence of the Pauli-Eddington-Bell interpretation 10.15 Dr Henrik Zinkernagel (Grenada) Cosmology and the Meaning of Time 11.15 Coffee 11.45 Dr Edward Anderson (London) Plausible first principles for geometrodynamics? General relativity can be formulated in a number of ways.  One such is geometrodynamics: the dynamics of 3-geometries.  Whereas Arnowitt--Deser--Misner and Dirac obtained this by laborious rearrangement of the Einstein field equations, Wheeler asked whether it could be made to rest instead on plausible first principles".  Hojman--Kuchar--Teitelboim derived geometrodynamics from spacetime first principles.  More recently Barbour, Foster, Kelleher, O Murchadha and I have been working on the derivation from 3-space principles.  In this talk I explain the 3-space approach (TSA).  I briefly mention how general relativity is not uniquely picked out by the TSA.  I relate the TSA to Kuchar's scheme which presupposes spacetime.  I show that the TSA is plausible" in that the usual full set of fundamental matter fields can be included.  I investigate how the relativity principles, the principle of equivalence and the gauge principle may arise in the TSA. References: S.A. Hojman, K.V. Kuchar and C. Teitelboim, Ann. Phys. 96 p 88 (1976). J.B. Barbour, B.Z. Foster and N. O Murchadha, Class. Quantum Grav 19 p 3217 (2002), gr-qc/0012089. E. Anderson and J.B. Barbour, Class. Quantum Grav. 19 p 3249 (2002), gr-qc/0201092. E. Anderson, Phys. Rev. D68 p 104001 (2003), gr-qc/0302035. E. Anderson, PhD Thesis, University of London (2004). E. Anderson, J.B. Barbour, B.Z. Foster, N. O' Murchadha, Class. Quantum Grav. 20 p 157 (2003), gr-qc/0211022. E. Anderson, J.B. Barbour, B.Z. Foster, B. Kelleher and N. O' Murchadha,  forthcoming. K.V. Kuchar, J. Math Phys 17 p 777; p 792; p 801 (1976). 14.00 Dr Simon Saunders (Oxford) Frame-dependence: pros and cons 15.15 Prof Andreas Bartels and Prof Holger Lyre (Bonn) Structural realism and the generality of the hole argument 16.15 Tea 16.45 Dr Oliver Pooley (Oxford) What is Observable in Special and General Relativity? Thursday 25 March 9.00 Prof Gerard Emch (Florida and Oxford) Symmetry and the Symplectic Geometry of Gravitational Wave Causality 10.15 Prof Dennis Dieks (Utrecht) Another look at general covariance and the equivalence of frames of reference In his general theory of relativity Einstein sought to generalize his special relativistic principle of relativity to a principle according to which all frames of reference, regardless of their motion, are equivalent. He thought to have achieved this aim through the general covariance of the equations of GRT: because the equations take the same form in every frame of reference, all frames are physically equivalent. There seems to be a consensus among philosophers of relativity that Einstein was mistaken here: form invariance of the equations does not imply physical equivalence of frames. We will argue, however, that Einstein's position is not unreasonable at all. Although there are certainly physical differences between reference frames in general relativity, these differences should be seen as fact-like rather than law-like. By contrast, in classical mechanics and in special relativity the differences between inertial systems and accelerated systems have a law-like status. The fact-like character of the differences between frames in general relativity justifies regarding them as equivalent in the same sense as inertial frames in special relativity are equivalent. 11.15 Coffee 11.45 Prof Massimo Pauri (Parma) and Dr Luca Lusanna (Florence) General Covariance and the Objectivity of Spacetime Point-events We show the unique capabilities of the ADM Hamiltonian approach to metric gravity to get new insights into a series of foundational issues of GR. Our results - valid for the Christodoulou-Klainermann class of models of the theory - include: a) finding the "last remnant of physical objectivity of space-time" by means of a physical individuation of point-events in terms of the intrinsic degrees of freedom of the gravitational field; b) a counter-example to the frozen-evolution picture; c) the definition of extended, non-inertial, space-time laboratories in which tidal-like and generalized inertial effects can be separated (though not invariantly); d) a main conjecture (which would entail invariance of the above separation) about the relation of the Dirac and the Bergmann definitions of observable; e) a disclosure of the dynamical nature that the traditional "conventions" about distant simultaneity assume in canonical metric gravity: different "conventions" within the same Ÿniverse" are simply gauge-related options; f) an implementation of the physical individuation of point-events through a well-defined empirical procedure leading to an operational definition of space-time. At the end, a peculiar holistic and structuralist view of space-time emerges. References: * L.Lusanna and M.Pauri, The Physical Role of Gravitational and Gauge Degrees of Freedom in General Relativity - I: Dynamical Synchronization and Generalized Inertial Effects, pre-print. * L.Lusanna and M.Pauri, The Physical Role of Gravitational and Gauge Degrees of Freedom in General Relativity - II : Dirac versus Bergmann Observables and the Objectivity of Space-Time, pre-print. * M.Pauri and M.Vallisneri, Ephemeral Point-Events: is there a Last Remnant of Physical Objectivity?, essay for the 70th birthday of R.Torretti, Dialogos 79, 263 (2002) (gr-qc/0203014). * L.Lusanna and M.Pauri, General Covariance and the Objectivity of Space-Time Point-Events: The Physical Role of Gravitational and Gauge Degrees of Freedom in General Relativity (gr-qc/0301040). * M.Dorato and M.Pauri, Holism and Structuralism in Classical and Quantum General Relativity, Pittsburgh-Archive, ID code 1606, February 10, 2004. * L.Lusanna, The Rest-Frame Instant Form of Metric Gravity, Gen.Rel.Grav. 33, 1579 (2001) (gr-qc/0101048). * L.Lusanna and S.Russo, A New Parametrization for Tetrad Gravity, Gen.Rel.Grav. 34, 189 (2002)(gr-qc/0102074). * R.De Pietri, L.Lusanna, L.Martucci and S.Russo, Dirac's Observables for the Rest-Frame Instant Form of Tetrad Gravity in a Completely Fixed 3-Orthogonal Gauge, Gen.Rel.Grav. 34, 877 (2002) (gr-qc/0105084). * D.Alba and L.Lusanna, Simultaneity, Radar 4-Coordinates and the 3+1 Point of View about Accelerated Observers in Special Relativity (gr-qc/0311058). * J.Agresti, R.DePietri, L.Lusanna and L.Martucci, Hamiltonian Linearization of the Rest-Frame Instant Form of Tetrad Gravity in a Completely Fixed 3-Orthogonal Gauge: a Radiation Gauge for Background-Independent Gravitational Waves in a Post-Minkowskian Einstein Space-Time, to appear in Gen.Rel.Grav. (gr-qc/0302084). * L.Lusanna, Towards a Unified Description of the Four Interactions in Terms of Dirac-Bergmann Observables, invited contribution to the book Quantum Field Theory: a 20th Century Profile, of the Indian National Science Academy, ed.A.N.Mitra, forewards by F.J.Dyson (Hindustan Book Agency, New Delhi, 2000) (hep-th/9907081). 14.00 Prof Istvan Nemeti and Prof Hajnal Andreka (Budapest) On the logical foundation of spacetime theories We will discuss two kinds of connections between logic and relativity. (1) Logical foundation of relativity. Foundation of Mathematics (FOM) bulletinboard (http://www.cs.nyu.edu/pipermail/fom/, December 2003 - February 2004) contains several postings by leading logician Harvey Friedman in which he proposes to export the methodology, spirit, and machinery of Foundational Thinking from the area of Foundations of Mathematics to a similar foundation of relativity which eventually would provide logic-based axiomatic foundation for both special relativity and general relativity. Of course, one begins with special relativity (but keeping an eye open for the direction of general relativity). The above aims coincide with the ones our group has been pursuing (leading to a broader cooperation). A precise conceptual analysis of relativity emerges on these foundations elaborated purely in first-order logic (FOL). E.g. we formalize (in FOL) Einstein's SPR (Special Principle of Relativity) and we calibrate its deductive role/power in the hierarchy of axioms/postulates/principles of relativity theory. As an example illustrating the uses of this precise logic-based framework we do the following. Although it is customary to derive NoFTL (No Faster Than Light travel) from SPR, we show that SPR does not entail this conclusion logically. On the other hand, making some of the usual tacit assumptions explicit, we prove NoFTL from these tacit assumptions without using SPR. Then we discuss what extra power SPR adds to these tacit assumptions. Material on the above can be found in the web-site http://www.math-inst.hu/pub/algebraic-logic/Contents.html, e.g. [1]-[4] below. (2) In the other direction, relativity theory can influence FOM, too! The Relativity |--> Logic  connection is discussed in [5]-[7]. Besides Malament-Hogarth-Tipler (beyond Turing) computability, we will also connect these ideas to CTC's in spacetimes popularly named "time-travel". E.g. mathematical logic can be applied to discussing how much of the consistency constraints imposed by the possiblility of time-travel are dictated by purely logical considerations and how much are generated by the resources of physical theories. Cf. Christian Wuthrich [W], [ESW]. References: [1] Andreka-Madarasz-Nemeti: Logical axiomatizAtions of spacetime. http://www.math-inst.hu/pub/algebraic-logic/lstsamples.pdf [2] Madarasz-Nemeti-Toke: Generalizing the logic-approach to spacetime towards general relativity. http://www.math-inst.hu/pub/algebraic-logic/loc-mnt04.pdf [3] Andreka-Madarasz-Nemeti: Introduction to logical analysis of relativity theories. http://www.math-inst.hu/pub/algebraic-logic/PartI.ps.gz . [4] Madarasz: Logic and relativity (in the light of definability theory). http://www.math-inst.hu/pub/algebraic-logic/diszi0226.ps.gz (big file) [5] Etesi-Nemeti: Non-Turing computations via Malament-Hogarth spacetimes. http://www.math-inst.hu/pub/algebraic-logic/turing.pdf [6] Hogarth: Predictability, Computability, and spacetime. http://www.math-inst.hu/pub/algebraic-logic/Hogarththesis.ps.gz [7] Andreka-Nemeti: Questions on Kerr spacetime. http://www.math-inst.hu/pub/algebraic-logic/kerr.ps [W] Wuthrich: Does modern phyusics permit the operation of time machines? http://aardvark.ucsd.edu/grad_conference/wuthrich.pdf [ESW] Earman-Smeenk-Wuthrich: Take a ride on a time machine. http://philsci-archive.pitt.edu/documents/disk0/00/00/09/65/index.html 15.15 Prof Sir Roger Penrose (Oxford) Quantum Superpositions of Spacetimes: do they Reduce Because of a Clash of Principles? 16.15 Tea 16.45 Dr Nick Bostrom (Oxford) Self-Locating Belief in an Infinite Spacetime Background papers: 1.  "Self-Locating Belief in Big Worlds: CosmologyÕs Missing Link to Observation" Journal of Philosophy, Vol. 99, No. 12 (2002). Abstract. Current cosmological theories say that the world is so big that all possible observations are in fact made. But then, how can such theories be tested? What could count as negative evidence? To answer that, we need to consider observation selection effects. A preprint of this paper is available here: http://www.anthropic-principle.com/preprints/cos/big2.pdf 2.  Anthropic Bias: Observation Selection Effects in Science and Philosophy (Routledge: New York, 2002). Abstract. This book presents the first mathematical theory of observation selection effects - an important kind of bias that infests many branches of science and philosophy. We can tame these biases! There are implications for cosmology, evolutionary biology, game theory, the interpretation of quantum mechanics, the Doomsday argument, the Sleeping Beauty problem, the search for extraterrestrial life, the question of whether God exists, and traffic planning. Five sample chapters are available online at: http://www.anthropic-principle.com/book/ 3.  I maintain a general preprint achieve of online papers on related topics at: http://www.anthropic-principle.com/preprints.html Friday 26 March 9.00 Dr Fay Dowker (London and Perimeter Institute, Waterloo) The Causal Set as the Deep Structure of Spacetime One approach to solving the problem of quantum gravity is based on the causal set hypothesis, which states that the deep, quantum structure of spacetime is discrete and is what is known in mathematics as a partial order'' or poset'', a kind of extended family tree. Causal set theory has now reached a stage of maturity in which both foundational issues and phenomenological questions can be addressed concretely. An example of the former is the question of what the observables of quantum gravity are (in other words, what is the solution of the problem of time'' in the causal set context). An example of phenomenology is the Lucretius effect'' of causal set discreteness on the propagation of massive particles. Relevant papers: 1)Background Causal Set material, all by Rafael Sorkin and available from his website http://www.physics.syr.edu/~sorkin/some.papers/ (i) A Specimen of Theory Construction from Quantum Gravity (ii) First Steps with Causal Sets (iii) Spacetime and Causal Sets 2) Observables'' in Causal Set Cosmology http://arxiv.org/abs/gr-qc/0210061 3) The Lucretius effect (swerves'') Quantum Gravity Phenomenology, Lorentz Invariance and Discreteness http://arxiv.org/abs/gr-qc/0311055 10.15 Dr Carl Dolby (Oxford) Life in an Energy Eigenstate: The Problem of Time in Quantum Gravity 11.15 Coffee 11.45 Dr Joy Christian (Oxford) Passage of Time in a Planck Scale Rooted Local Inertial Structure http://arxiv.org/abs/gr-qc/0308028 It is argued that the problem of time' in quantum gravity necessitates a refinement of the local inertial structure of the world, demanding a replacement of the usual Minkowski line element by a 4+2n dimensional pseudo-Euclidean line element, with the extra 2n being the number of internal phase space dimensions of the observed system. In the refined structure, the inverse of the Planck time takes over the role of observer-independent conversion factor usually played by the speed of light, which now emerges as an invariant but derivative quantity. In the relativistic theory based on the refined structure, energies and momenta turn out to be invariantly bounded from above, and lengths and durations similarly bounded from below, by their respective Planck scale values. Along the external timelike world-lines, the theory naturally captures the flow of time' as a genuinely structural attribute of the world. The theory also predicts expected deviations--suppressed quadratically by the Planck energy--from the dispersion relations for free fields in the vacuum. The deviations from the special relativistic Doppler shifts predicted by the theory are also suppressed quadratically by the Planck energy. Nonetheless, in order to estimate the precision required to distinguish the theory from special relativity, an experiment with a binary pulsar emitting TeV range gamma-rays is considered in the context of the predicted deviations from the second-order shifts. AFTERNOON FREE Saturday 27 March 9.00 Prof Don Howard (Notre Dame USA) Spin, Space, Symmetries, and Statistics: Some Questions about Covariance, Nonseparability, and Particle Identity in the 1920s 10.15 Prof Michel Ghins (Louvain) Revisiting the Equivalence Principle in General Relativity Relevant paper: Studies In History and Philosophy of Modern Physics 32, March 2001, 33--51 doi:10.1016/S1355-2198(00)00038-1 11.15 Coffee 11.45 Dr Julian Barbour (Oxford) Absolute and Relative Motion: A Review

Trinity Term 2003

A One-Day Conference

In Memory of Jim Cushing

Faculty of Philosophy, 10 Merton St., Oxford

Thursday June 26th 2003, 10.15–17.30

10.15 – 10.45 Registration and Coffee

10.45 – 11.45: Michael Redhead (LSE)

Broken Bootstraps: the Rise and Fall of a Research Programme

11.45 – 12.45: Michael Dickson (Indiana, and Oxford)

Dirac on Mathematical Beauty and Scientific Progress

12.45 – 2.00 Sandwich Lunch

2.00 – 3.00: Antony Valentini (Perimeter Institute, Waterloo)

Quantum Theory as an Equilibrium Physics: Some New Results

3.00 – 4.00: Mara Beller (Hebrew University, Jerusalem)

Jim Cushing's Quest for Understanding--Physics, Philosophy, History

4.00 – 4.30 Tea

Registration (covering coffee, sandwich lunch, tea): £ 6, £ 3 for students;

to be paid on arrival on the day.

Contact details; To enable us to estimate numbers, please email Jeremy Butterfield, jb56@cus.cam.ac.uk, between Monday 23 and Wednesday 25 June, just to say you (and how many of you!) are coming.

The organizers gratefully acknowledge sponsorship by the British Society for the Philosophy of Science

A One-Day Conference:

Friday 25th April 2003

Faculty of Philosophy, 10 Merton St., Oxford

10.15-17.30

10.15 - 10.45 Registration and Coffee

10.45 - 11.45: Owen Maroney (Bristol): Measurement, Entropy and the Szilard Engine

11.45 -  12.45: Chris Isham (Imperial College London): Quantising on a Category: A new approach to quantum spacetime.

12.45 - 2.00 Sandwich Lunch

2.00 - 3.00: Julian Barbour (Oxford): Time and Relativity

3.00 - 4.00: Richard Healey (Arizona, and LSE): Change without Change, and How to Observe it in General Relativity

4.00 - 4.30 Tea

4.30 - 5.30: Steven French (Leeds): From Groups to Gestalt: Varieties of Structuralism as a Response to Quantum Physics

Registration (covering coffee, sandwich lunch, tea): £ 6, £ 3 for students; to be paid on arrival on the day.

Note: If you have not already registered, and plan to attend, please contact Harvey Brown (Ox.276930 and harvey.brown@philosophy.ox.ac.uk) (by Thursday April 24 at latest).

Hilary Term 2003

Philosophy of Mathematics Seminar

These lectures, followed by discussion, will take place on Mondays at 4.30 p.m. in the Ryle Room at the Philosophy Faculty, 10 Merton Street.

week 1  (20 January):  Daniel Isaacson (Oxford), ÒPhilosophical significance of complex conjugation.Ó

week 2  (27 January):  Marcus Giaquinto (University College London), ÒThe distinction between geometrical and algebraic thinking.Ó

week 3  (3 February):  John Mayberry (Bristol), ÒHow to think about natural numbers.Ó

week 4  (10 February):  Mary Leng (St JohnÕs College, Cambridge), ÒNaturalism and linguistic frameworks:  mathematical ontology in a post-Quinean setting.Ó

week 5  (17 February):  Michael Potter (Fitzwilliam College, Cambridge),  ÒHow far can you go?  Some reflections on limitation of size.Ó

week 6  (24 February):  John Lucas (Merton College, Oxford), ÒPrototopology: the fourth volume of Principia Mathematica that never was.Ó   (See J.R. Lucas, The Conceptual Roots of Mathematics, Routledge, London, 2000, Chapter 10, for background to this talk.)

week 7 (3 March):  Philip Scowcroft (Wesleyan University and Oxford), ÒBrouwerÕs creative subject and variants of KripkeÕs schema.Ó

week 8 (10 March):  No meeting, to avoid clashing with a lecture by Adam Rieger (Glasgow), ÒSet theory and second-order logicÓ, at a meeting of the British Society for the Philosophy of Science, LSE, 5.15-7.00 (tea at 4.45 in T16).

Convener:  Daniel Isaacson, Faculty of Philosophy, 10 Merton Street Oxford OX1 4JJ (01865) 276929

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SYMMETRY AND STRUCTURES IN PHYSICS

A One-Day Conference

Faculty of Philosophy, University of Oxford

Friday January 10th 2003, 11.00 – 17.00

Programme: (Coffee from 10.30)

11.00 - 11.45:

Harvey Brown, Oxford: Aspects of the Role of Symmetry in Physics

11.45 -12.30:

Katherine Brading, Oxford: Some Variations on a Noether Theme

12.30 -1.15:

David Wallace, Oxford: Quantum Probability and Decision Theory,

Revisited

1.15 - 2.15: Sandwich Lunch

2.15 – 3.00:

James Ladyman, Bristol: Symmetry and Modality

3.00 – 3.45:

Oliver Pooley, Oxford: Should we be Sophisticated Substantivalists?

3.45 – 4.15:  Tea

4.15 – 5.00:

Simon Saunders, Oxford: Global Descriptivism

Registration (covering coffee, sandwich lunch, tea): £ 6, £ 3 for students;

to be paid on arrival on the day.

Contact details; To enable us to estimate numbers, please email Jeremy Butterfield, jb56@cus.cam.ac.uk, between Monday 6 and Wednesday 8 January, just to say you (and how many of you!) are coming.

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Michaelmas Term 2002

Reverse Sokal Hoax

Anyone interested in following the trauma following the Bogdanov brothers 'reverse Sokal hoax might like to read along with the rest of the mathematical physics community on the website set up for it:  http://www.lns.cornell.edu/spr/2002-10/thrd10.html

There you will also find a denial by the Bogdanov brothers that it is in fact a hoax:.

Friday 5th Week Theoretical Physics Colloquium (2.15 Dennis Sciama Lecture Room, Nuclear Physics)

Our very own Simon Saunders is speaking on

ÒDerivation of the Born Rule from Operational AssumptionsÓ

Abstract:

Whence the Born rule? It is fundamental to quantum mechanics; it is the essential link between probability and a formalism which is otherwise deterministic; it encapsulates the measurement postulates. Gleason's theorem does of course throw light on it, but it is a purely mathematical theorem, and its premise is too strong to have any operational meaning. Here the Born rule  is derived much more simply, from purely operational assumptions.

The argument is related to Deutsch's derivation of the Born rule from decision theory. The latter was criticized by Barnum et al, but their objections have recently been countered by Wallace. The argument from decision theory that Wallace has presented is sound. However, it draws heavily on the Everett interpretation; this case is of particular interest, as the interpretation of probability has long been considered a weakness of Everett's approach, but the key ideas of the derivation are of more general application, and, in other contexts, his focus on a purely subjective notion of probability is unduly restrictive.

In contrast, the derivation of the Born rule that we shall present is independent of decision theory, and independent of any assumptions about the measuring process. As such it applies to all the major foundational approaches to quantum mechanics. We assume the conventional scheme for the description of experiments, in terms of an initial state, measured observable, and macroscopic outcomes. We assume there is a general algorithm, given a description of this form, for the probabilities of the observable outcomes. (The Born rule is such an algorithm.)  Our argument then takes the following form: for a certain class of experiments, there are definite rules for determining such descriptions, based on simple operational prescriptions and theoretical assumptions that concern only the state-preparation device, not the measurement device. In particular cases, these rules imply that the experiment can be described in two different ways. But the algorithm we are looking for concerns the probabilities of the observed outcomes, so in such cases it must yield the same probabilities, when applied to these different descriptions. Constraints of this form are in fact sufficient to force the Born rule.

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This term we are running our first weekly research seminar in Philosophy of Science, replacing our usual weekly philosophy of physics seminar (which will be back in Hilary and Trinity terms):

Thurs 17 Oct K Wilkes: Models and Realism; the animal model in the brain and behavioural sciences

Thurs 24 Oct N Jardine: Whigs and Stories: Herbert Butterfield and the historiography of the sciences

Thurs 31 Oct  D Papineau: Decisions and Many Minds

Thurs 7 Nov : J Campbell Causal vs Epiphenomenal Progressions

Thurs 14 Nov: Tim Williamson, Evidential Probability

Thurs 21 Nov: Frank Jackson The How and Why of Narrow Content

Thurs 28 Nov R Harre: Science as model making: two roles for iconic representations

Thurs 5 Dec N Cartwright:  Causes and Probabilities

All meetings will take place at 4.00 pm, The Old Library, All Souls College.

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This termÕs Philosophy of Mathematics research seminar series, convened by Dan Isaacson, features:

Week 1: Tuesday, 15 October.   Professor Elaine Landry (Calgary),

Category theory as a framework for an in re interpretation of mathematical structuralism

Week 2: Thursday, 24 October.  Dr David Corfield (Oxford),

Towards a philosophy of real mathematics

Week 3: Tuesday, 29 October.  Professor Brian Davies (King's College London),

Empiricism in arithmetic and analysis

Week 4: Thursday, 7 November.  Dr Gianluigi Oliveri (Oxford and Palermo),

Mathematics, a quasi-empirical science?

Week 6: Thursday, 21 November. Professor Robert Thomas (Manitoba and Oxford)

The Comparison of Mathematics with Narrative

Week 8: Thursday, 5 December. Dr. Daniel Isaacson (Oxford)

Philosophical Significance of Complex Conjugation.

All meetings, whether on Tuesday or on Thursday, will take place in the Lecture Room, 10 Merton Street.

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Bruno Latour will be giving this year's Clarendon Lectures in Oxford:

Professor Bruno Latour (Centre de Sociologie de l'Innovation, Ecole Nationale SupŽrieure des Mines de Paris) will give three lectures on INFORMATION AND ORGANIZATION

Lecture 1: Tuesday 22 October 2002

Four New Uncertainties in the Social Sciences

Lecture 2: Wednesday 23 October 2002

For a Critique of Pure Reason

Lecture 3: Thursday 24 October 2002

The Trouble with Organisation

All lectures take place at 5 pm at the Said Business School, Park End Street, Oxford, OX4 1HP (next to Oxford rail station).

All lectures are free and open to the public. The first lecture will be followed by a drinks reception.

For further information, contact Liz Buckle, Marketing Coordinator, liz.buckle@sbs.ox.ac.uk, 01865 288852 Said Business School