**John Baez (UC Riverside), “Getting to the bottom of Noether’s theorem”**

In her paper of 1918, Noether’s theorem relating symmetries and conserved quantities was formulated in term of Lagrangian mechanics. But if we want to make the essence of this relation seem as self-evident as possible, we can turn to a formulation in term of Poisson brackets, which generalizes easily to quantum mechanics using commutators. The key question then becomes: when, and why, do observables generate one-parameter groups of transformations? This question sheds light on why complex numbers show up in quantum mechanics.

19 January 2019, 3pm, LPS seminar room

**Tomasz Placek (Jagiellonian University), “Interpreting non-Hausdorff (generalized) manifolds in General Relativity”**

The paper investigates the relations between Hausdorff and non-Hausdorff manifolds, as objects of General Relativity. We show that every non-Hausdorff manifold can be seen as a result of gluing together of some Hausdorff manifolds. In the light of this result we investigate a modal interpretation of a non-Hausdorff differential manifold according to which it represents a bundle of alternative spacetimes, all of which compatible with a given initial data set.

This talk is based on joint work with Joanna Luc. Please read their manuscript before the meeting.

17 November 2018, 3pm, LPS seminar room

**David Wallace (USC), “The Necessity of Statistical Mechanics”**

In discussions of the foundations of statistical mechanics, it is widely held that (a) the Gibbsian and Boltzmannian approaches are incompatible but empirically equivalent; (b) the Gibbsian approach may be calculationally preferable but only the Boltzmannian approach is conceptually satisfactory. I argue against both assumptions. Gibbsian statistical mechanics is applicable to a wide variety of problems and systems, such as the calculation of transport coefficients and the statistical mechanics and thermodynamics of mesoscopic systems, in which the Boltzmannian approach is inapplicable. And the supposed conceptual problems with the Gibbsian approach are either misconceived, or apply only to certain versions of the Gibbsian approach, or apply with equal force to both approaches. I conclude that Boltzmannian statistical mechanics is best seen as a special case of, and not an alternative to, Gibbsian statistical mechanics.

Please read David’s pre-print before the meeting.

6 October 2018, 3pm, LPS seminar room

**Chip Sebens (Caltech), “The Mass of the Gravitational Field”**

By mass-energy equivalence, the gravitational field has a relativistic mass density proportional to its energy density. I seek to better understand this mass of the gravitational field by asking whether it plays three traditional roles of mass: the role in conservation of mass, the inertial role, and the role as source for gravitation. The difficult case of general relativity is compared to the more straightforward cases of Newtonian gravity and electromagnetism by way of gravitoelectromagnetism, a special relativistic theory of gravity which resembles electromagnetism.

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**A Mini-Workshop on the Problem of Motion and Geodesic Theorems in GR**

10am: James Weatherall (Irvine), “The Motion of Small Bodies in Spacetime, or, Conservation, Inertia, and Spacetime Geometry”

11:30am: Coffee Break

11:45am: Dennis Lehmkuhl (Caltech), “The problem of motion: Einstein/Grommer and Thorne/Hartle compared”

1:15pm: Catered Lunch

2:30pm: Sam Fletcher (Minnesota), “When 2 Become 1: Approaches to the Problem of Motion”

4pm: Coffee Break

**Practical Information**

Location: The Einstein Papers Project, 363 S. Hill Ave, Pasadena, CA 91125

Local Organizer: Dennis Lehmkuhl

Parking: There is free street parking on Hill Avenue (during the weekend) and there is also a parking structure directly behind the EPP on Holliston Ave on S Holliston Ave.

5 May 2018, 3pm, LPS seminar room

**Joshua Norton (American University of Beirut), “The Hole Argument Against Everything”**

The Hole Argument was originally formulated by Einstein and it haunted him as he struggled to understand the meaning of spacetime coordinates in the context of the diffeomorphism invariance of general relativity. This argument has since been put to philosophical use by Earman and Norton (1987) to argue against a substantival conception of spacetime. In the present work I demonstrate how Earman and Norton’s Hole Argument can be extended to exclude everything and not merely substantival manifolds. These casualties of the hole demonstrate that the Hole Argument hinges essentially on our notion of determinism and not on the diffeomorphic freedom of general relativity.

Just as Earman and Norton argue that we should not let our metaphysics run roughshod over the structure of our physical theories, so I will argue that, in particular, we should not uncritically allow our metaphysics to dictate what our physical theories must determine. The central conviction which drives the arguments of this paper is that deterministic theories are not required to determine for future moments what they cannot determine for any present or past moments. I provide two arguments to the effect that a physically informed notion of determinism does not require general relativity to determine substantival facts. Consequently the Hole Argument cannot be used against substantival spacetime. The position that I advocate is an instance of “sophisticated determinism.”

A draft of Joshua’s paper can be found here.

24 February 2018, 3pm, LPS seminar room

**Lev Vaidman (Tel Aviv), “Defending the many-worlds interpretation of quantum mechanics”**

Starting from the premise that physics is deterministic and has no action at a distance, I will argue that the many-worlds interpretation is by far better than all existing alternatives. It keeps the physics part of the theory, the ontology of the universal wave function which incorporates all the worlds, very elegant. It is confirmed by experimental data with unprecedented precision. It provides a consistent connection with our experience. I will propose solutions for its alleged difficulties that the wave function in a high dimensional Hilbert space cannot correspond to our own experience of three spatial dimensions and that an experimentalist, who might have no ignorance of any detail of a quantum experiment, seems to have probabilities for different outcomes. The first difficulty is resolved by the observation that in every world the wave functions of all macroscopic objects are not entangled and thus defined in three dimension. The second is resolved by introducing the idea of probability of self-location of an observer in a particular world.

Please read Lev’s article before the meeting.

9 December 2017, 3pm, LPS seminar room

**David Wallace (USC), “Why Black Hole Information Loss is Paradoxical”**

I distinguish between two versions of the black hole information-loss paradox. The first arises from apparent failure of unitarity on the spacetime of a completely evaporating black hole, which appears to be non-globally-hyperbolic; this is the most commonly discussed version of the paradox in the foundational and semipopular literature, and the case for calling it `paradoxical’ is less than compelling. But the second arises from a clash between a fully-statistical-mechanical interpretation of black hole evaporation and the quantum-field-theoretic description used in derivations of the Hawking effect. This version of the paradox arises long before a black hole completely evaporates, seems to be the version that has played a central role in quantum gravity, and is genuinely paradoxical. After explicating the paradox, I discuss the implications of more recent work on AdS/CFT duality and on the `Firewall paradox’, and conclude that the paradox is if anything now sharper. The article is written at a (relatively) introductory level and does not assume advanced knowledge of quantum gravity.

Please read David’s preprint before the meeting.

4 November 2017, 3pm, LPS seminar room

**Marian Gilton (UCI), “Could Charge and Mass be Universal Properties?”**

There is a tradition in contemporary analytic metaphysics of looking to fundamental particle physics for an accurate list of universal properties. The central candidates for such properties are electric charge, color charge, and mass. Tim Maudlin has recently argued against a number of metaphysical theories within this tradition (Aristotelian and Platonic theories of universal properties, trope theory, the theory of natural sets, etc.) on the grounds that the general formalism of our current best fundamental physics–i.e., fiber bundles–precludes the notion of universal property used in these metaphysical theories. Consequently, Maudlin calls for a “wholesale revision” of the theory of universals. This paper argues, contra Maudlin, that the fiber bundle formalism does allow for the possibility of some universal properties, and thus a wholesale revision of this metaphysical theory is not yet warranted.

Please read Marian’s draft manuscript in preparation for the meeting.

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**Jeff Russell (USC), “Space-Time Categories”**

Suppose we take seriously this lesson from the hole argument: there is no genuine difference between possible worlds related by a space-time diffeomorphism. In that case, what should we think the world’s genuine space-time structure is like? It won’t include facts about field-values at particular points in a manifold. Instead what we would like is a precise account of “structural roles” for things like fields in space-time. Ideas from categorical logic give us the resources to spell out such an account.

There are no readings for this meeting.

8 April 2017, 3pm, LPS seminar room

**Sean Carroll (Caltech), “Spacetime and Cosmology in Locally-Finite Hilbert Space”**

I will discuss some ideas stemming from two basic assumptions: (1) Quantum mechanics is Everettian, and there is no preferred structure on Hilbert space, only what we can derive from dynamical considerations; and (2) Hilbert space is locally finite-dimensional, i.e. regions of space are described by finite-dimensional factors. We are faced with the question of how not only quantum fields, but even space itself, emerge from the wave function, and I’ll describe some ideas in that direction, as well as some cosmological consequences.

Sean’s talk is not based on a particular paper, but he recommends these three papers (in order of decreasing readability) as background.

11 March 2017, 3pm, LPS seminar room

**Márton Gömöri (Eötvös University), “On the relation of the relativity principle and covariance”**

In its most widespread formulation, the special principle of relativity is the following statement: “The laws of physics have the same form in all inertial frames of reference.” While there is a longstanding discussion about the interpretation of the extended, general principle of relativity and its relation to the notion of general covariance, there seems to be a consensus that the above quoted special principle of relativity is absolutely unproblematic, and it is synonymous with the Lorentz covariance of the fundamental equations of physics. The talk will challenge this view through an analysis of the precise meaning of the special relativity principle, based on a precise mathematical formulation of its statement. It will be seen however that the main difficulties are not of formal/mathematical nature, but conceptual.

Please read Márton’s paper before the meeting.

25 February 2017, 3pm, LPS seminar room

**Neil Dewar (MCMP), ” Interpretation and equivalence; or, equivalence and interpretation
“**

This paper is about what it means to interpret a scientific theory (especially, a physical theory). My main contention is that a certain picture of interpretation is widespread (though implicit) in contemporary philosophy of science: a picture according to which interpretation of theories is relevantly analogous to the interpretation of foreign literature. On this “external” account of interpretation, meaning is to be imported into the equations by putting them in correspondence with some discourse whose signs and symbols are already endowed with significance. I contend that there is an alternative way of thinking about interpretation—what we can call the “internal” account of interpretation—which instead takes interpretation to be a matter of delineating a theory’s internal semantic architecture. At a minimum, I hope to show that the internal picture highlights an aspect of interpretation that we are otherwise at risk of neglecting. But I also aim to show that the internal picture offers a richer and more satisfying account of interpretation than the external picture does.

21 January 2017, 3pm, LPS seminar room

**David Wallace (USC), “Who’s afraid of coordinate systems? An essay in the representation of spacetime structure”**

Coordinate-based approaches to physical theories remain standard in mainstream physics but are largely eschewed in foundational discussion in favour of coordinate-free differential-geometric approaches. I defend the conceptual and mathematical legitimacy of the coordinate-based approach for foundational work. In doing so, I provide an account of the Kleinian conception of geometry as a theory of invariance under symmetry groups; I argue that this conception continues to play a very substantial role in contemporary mathematical physics and indeed that supposedly “coordinate-free” differential geometry relies centrally on this conception of geometry. I discuss some foundational and pedagogical advantages of the coordinate-based formulation and briefly connect it to some remarks of Norton on the historical development of geometry in physics during the establishment of the general theory of relativity.

Please read David’s manuscript before the meeting.

3 December 2016, 3pm, LPS seminar room

**Mike Schneider (UCI), on the cosmology constant problem**

This paper contends that the “Cosmological Constant Problem” (CCP) is not strictly a problem for our current theories, and so the proposed “solutions” to it cannot be solutions as such. Nonetheless, the CCP is consistently entertained as if it were a problem with a landscape of possible solutions. Given this state of affairs, I discuss how one ought to make sense of the role of the CCP in contemporary theoretical physics and generalize some lessons from it.

Please read Mike’s draft manuscript before the meeting.

15 October 2016, 3pm, LPS seminar room

**John Dougherty and Craig Callender (UCSD), on black hole thermodynamics**

Black hole thermodynamics (BHT) understands many relationships amongst black hole variables as manifestations of deep thermodynamic principles operating in the universe. BHT is widely accepted as being more than a formal analogy with thermodynamics; indeed, its identity with thermodynamics is commonly used as justification for many speculations in quantum gravity. Playing the role of philosophical gadfly, we want to pour a little cold water on the claim that BHT is more than a formal analogy. To do so, we show that BHT is often based on a kind of caricature of thermodynamics. Then we point to an important ambiguity in what systems the analogy is supposed to be between. Finally, and perhaps worst, we point out that one of the primary motivations for the theory arises from a terribly controversial understanding of entropy. BHT may be a useful guide to future physics. Only time will tell. But the analogy is not nearly as good as is commonly supposed.

Please read John and Craig’s manuscript before the meeting.

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**Dennis Lehmkuhl (Caltech), on the Problem of Motion**

The problem of motion of general relativity is about how exactly the gravitational field equations, the Einstein equations, are related to the equations of motion of material bodies subject to gravitational fields. This paper compares two approaches to derive the geodesic motion of (test) matter from the field equations: `the T approach’ and `the vacuum approach’. The latter approach has been dismissed by philosophers of physics because of it apparently representing material bodies by singularities. I shall argue that a careful interpretation of the approach shows that it does not depend on introducing singularities at all, and that it holds at least as much promise as the T approach. I finish with some general lessons about careful vs. literal interpretations of scientific theories.

Please read Dennis’s manuscript before the meeting.

7 May 2016, 3pm, LPS seminar room

**Bihui Li (USC), “Solutions in Constructive Field Theory”**

Constructive field theory aims to rigorously construct concrete solutions to Lagrangians used in particle physics, where the solutions satisfy some relevant set of axioms. I examine the nature of solutions in constructive field theory and their relationship to both axiomatic and Lagrangian quantum field theory (QFT). I argue that Lagrangian QFT provides conditions for what counts as a successful constructive solution, and that it provides other important information that guides constructive field theorists to solutions. Solutions matter because they describe the behavior of systems in QFT, and thus what QFT says the world is like. Constructive field theory, in incorporating ingredients from both axiomatic and Lagrangian QFT, clarifies existing disputes about which parts of QFT are relevant to philosophers and the role of rigor in these disputes.

Please read Bihui’s manuscript before the meeting.

16 April 2016, 3pm, LPS seminar room

**Julia Bursten (SFSU) on Multiscale Modeling**

Winsberg’s “handshaking” account of inter-model relations is a well-known theory of multiscale modeling in physical systems. Winsberg argues that relations among the component models in a multiscale modeling system are not related mereologically, but rather by empirically determined algorithms. I argue that while the handshaking account does demonstrate the existence of non-mereological relationships among component models, Winsberg does not attend to the different ways in which handshaking algorithms are developed. By overlooking the distinct strategies employed in different handshake models, Winsberg’s account fails to capture the central feature of effective multiscale modeling practices, namely, how the dominant behaviors of the modeled systems vary across the dierent scales, and how this variation constrains the ways modelers can combine component models. Using Winsberg’s example of nanoscale crack propagation, I distinguish two modes of handshaking and show how the different modes arise from the scale-dependent physics involved in each component model.

Please read Julia’s draft manuscript before the talk.

5 March 2016, 3pm, LPS seminar room

**Matt Leifer (Chapman), “Does time-symmetry in quantum theory imply retrocausality?”**

In [1], Huw Price argued that, under certain assumptions about the underlying ontology, an interpretation of quantum theory that is both realist and time-symmetric must be retrocausal, i.e. it must involve influences that travel backwards in time. Price’s argument is based on an analysis of a photon travelling between two polarizing beam-splitters. One of his assumptions is that the usual forward-evolving polarization vector of the photon is a beable, i.e. part of the ontology. He argues, on the basis of this and his other assumptions,

that a backward-evolving polarization vector must also be a beable.

The assumption that the forward evolving polarization vector is a beable is an assumption of the reality of the quantum state. But one of the reasons for exploring retrocausal interpretations of quantum theory is that they offer the potential for evading the unpleasant conclusions of no-go theorems, such as Bell’s theorem and, in particular, recent proofs of the reality of the quantum state [2]. In this talk, I will show how Price’s argument can, in fact, be generalized so that it does not assume the reality of the quantum state. The relationship between Price’s argument and ours bears a strong parallel to the relationship between the EPR argument and Bell’s theorem. I also reformulate the common assumptions of Price’s and our arguments to make them more generally applicable and to pin down the notion of time-symmetry involved more precisely. The notion of time-symmetry used in the argument is stronger than the notion of time-symmetry usually used in physics, but bears a family resemblance to conditions used in other no-go theorems, such as parameter independence in Bell’s theorem, and Spekkens’ notion of contextuality. All of these can be derived from the assumption that, if a theory has a symmetry in its operational predictions, then that symmetry ought to hold at the ontological level as well.

This talk is based on joint work with Matt Pusey.

[1] H. Price. Does time-symmetry imply retrocausality? How the quantum world says “maybe”. Stud. Hist. Phil. Mod. Phys., 43(2):75–83, 2012. arXiv:1002.0906

[2] For a review see M. Leifer. Is the quantum state real? An extended review of psi-ontology theorems. Quanta, 3:67-155, 2014. arXiv:1409.1570

13 February 2016, 3pm, LPS seminar room

**Richard Dawid (Stockholm) on String Dualities and Empirical Equivalence**

String dualities constitute a specific form of empirical equivalence in physics. One may argue that, after a century when empirical equivalence was primarily of interest to philosophy of science, the rise of duality in string physics marks the first time that empirical equivalence takes centre stage in physics itself. The paper will make the case, however, that the philosophical repercussions of string dualities are in fact directly opposed to the way the significance of empirical equivalence was understood throughout most of the 20th century in philosophy of science as well as physics. Comparing the canonical perspective on empirical equivalence with the role played by duality today provides an interesting indicator of the way string physics has altered the physicists’ perspective on physical theory building.

Richard expects to distribute a paper a few days before the meeting.

16 January 2016, 3pm, LPS seminar room

**Patricia Palacios (Munich) on the role of approximation in a reductive model for phase transitions**

Abstract: Phase transitions, roughly understood as sudden changes in the phenomenological properties of a system, have recently motivated a debate about reduction and emergence in the physical sciences. In this debate there are two main positions: i) Phase transitions are paradigmatic cases of emergent or irreducible behavior (Lebowitz 1999, Batterman 2000, 2002, Bangu 2011); ii) phase transitions represent a successful case of Nagelian reduction (Butterfield 2011, Menon and Callender 2011, Norton 2012). This leads one to conceive of the discussion in the following terms: Phase transitions are either non-reductive phenomena or reductive phenomena satisfying the Nagelian model of reduction. In this paper I will suggest that this dichotomy is misleading. In fact, there are good reasons for considering phase transitions as a case of reduction that does not satisfy the Nagelian model of reduction, either in its strict or more liberal versions.

21 November 2015, 3pm, LPS seminar room

**John Byron Manchak (UCI) on Epistemic Holes in Spacetime**

Abstract: A number of models of general relativity seem to contain “holes” which are thought to be “physically unreasonable”. One seeks a condition to rule out these models. We examine a number of possibilities already in use. We then introduce a new condition: epistemic hole-freeness. Epistemic hole-freeness is not just a new condition — it is new in kind. In particular, it does not presuppose a distinction between spacetimes which are “physically reasonable” and those which are not.

Please read JB’s manuscript before the meeting.

24 October 2015, 3pm, LPS seminar room

**Chip Sebens (CalTech & UCSD) on Constructing and Constraining Wave Functions for Identical Quantum Particles**

Abstract: I address the problem of explaining the symmetry dichotomy within two interpretations of quantum mechanics which clarify the connection between particles and the wave function by including particles following definite trajectories in addition to, or in lieu of, the wave function: Bohmian mechanics and Newtonian quantum mechanics. I present and examine what I take to be the most illuminating explanation of the symmetry dichotomy given in the context of Bohmian mechanics (Bacciagaluppi, 2003). If the Bohmian guidance equation is formulated as to not rely on a correspondence between particles and arguments of the wave function, then the symmetry dichotomy must be postulated for the particle velocities to be well-defined. Still, the symmetry dichotomy remains an additional postulate. I propose an explanation of the symmetry dichotomy in Newtonian quantum mechanics which parallels Bacciagaluppi’s, but is simpler and stronger. In Newtonian quantum mechanics the wave function is not part of the fundamental ontology, but simply a convenient way of describing the positions and velocities of particles. Because a world in Newtonian quantum mechanics is equally well represented by multiple points in configuration space, it turns out that any wave function constructed to describe these worlds will be either symmetric or antisymmetric. The symmetry dichotomy need not be postulated. I show that both of these explanations can be given in reduced configuration space, though doing so is only necessary if one wants to defend exotic approaches to these interpretations which take configuration space as fundamental.

The talk will be based on Chip’s draft manuscript. This project further examines the theory proposed in Quantum Mechanics as Classical Physics (arXiv) (blog post).

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**Nora Boyd (Pittsburgh), “Are Astrophysical Models Permanently Underdetermined?”**

Abstract: Transient underdetermination is germane to scientific practice; modelers often elaborate multiple plausible alternatives to a scientific problem and then seek empirical constraints on these models. In contrast, permanent underdetermination undercuts the aim of increasing the representational fidelity of models. Renewing pessimism that Ian Hacking raised specifically regarding modeling in astrophysics, Stéphanie Ruphy has recently argued that the field is destined to produce nothing more than permanently underdetermined models. The present paper defends astrophysics against this charge. I argue that modelers can anticipate that underdetermination will be transient when distinguishing features can be extracted from the competing alternatives, differential empirical evidence can likely be collected, and model features can be evaluated in light of such evidence. The prospects for breaking instances of purported underdetermination should be individually appraised according to this framework and considered in their appropriate scientific contexts. Applying this approach I evaluate Ruphy’s case study, challenging her claim that the features she attributes to alternative models of our galaxy are characteristic of the field. I present a further example involving two currently underdetermined models of the instability driving explosions in core-collapse supernovae. Here, astrophysicists have good reason to think that forthcoming data will discriminate between the models. This case, I argue, is similar to other prominent examples of underdetermination in representation-driven astrophysical modeling. There is good reason to expect that in many cases the underdetermination of astrophysical models is only temporary.

Please read Nora’s paper before the meeting.

25 April 2015, 3pm, SST 777

**Christian Wüthrich (UCSD), “Spacetime from Causal Sets”**

Abstract: I will illustrate how space and time vanish in causal set theory and address the central question of this research program, viz. how relativistic spacetimes re-emerge from the fundamental causal sets. Part of what I plan to talk about is covered in Section 3 of the attendant paper, which is a draft of Chapter 3 of my forthcoming book with Nick Huggett; the rest will be treated in what will be Chapter 4. Sections 1 and 2 of the paper can be read as a preparation for those who are not familiar with causal set theory, but I do not plan to discuss them in the meeting.

Please read Chris’ paper before the meeting.

11 April 2015, 3pm, SST 777

**Sybil de Clark (Arizona), “Fluctuations of the Electromagnetic Vacuum Field or radiation reaction?”**

Abstract: The fact that various physical effects usually ascribed to vacuum fluctuations can also be accounted for by the radiation reaction field suggests that perhaps, there is little evidence for vacuum field fluctuations. But is that so? Where does the underdetermination between vacuum field and radiation reaction field come from, and what can be proposed to lift it? What other evidence do we have that the vacuum field is at least partly responsible for these effects? Furthermore, vacuum fluctuations have been ascribed to the Uncertainty Relations (UR). To what extent are such claims justified, and what interpretation of the UR do vacuum fluctuations suggest?

Please read Sybil’s paper before the meeting. If the length is a concern, she suggests focusing on sections 3, 4, 5.1, and 5.2

28 February 2015, 3pm, SBSG 1321

**Ben Feintzeig (UCI) on Parochial Observables in Classical and Quantum Field Theory**

Abstract: Ruetsche (2011) argues that there is a problem of unitarily inequivalent representations in quantum theories with infinitely many degrees of freedom that leads one to choose between the following interpretive options. Either one can be a Hilbert Space Conservative and maintain that possible worlds correspond to density operators on a particular privileged Hilbert space containing a concrete irreducible representation of the algebra of observables. Or one can be an Algebraic Imperialist and hold that possible worlds are represented by the states on the abstract C*-algebra of observables, which captures the structure all representations have in common.

I will argue for a position along the lines of Algebraic Imperialism (but differing somewhat from Ruetsche’s description of that position). First, I show that unitarily inequivalent representations arise already in classical theories. It is obvious in the classical case that a Hilbert Space Conservative fails to represent all physically significant states, and this argument extends in a natural way to the quantum case. Second, I show that Ruetsche’s argument against Algebraic Imperialism, which claims that the Imperialist cannot represent all physically significant observables, fails. I show that the Imperialist can account for all of the missing observables as idealizations (in a certain precise sense) from the original abstract algebra of observables.

Please read Ben’s papers “Unitary Inequivalence, Classical Systems, and the Interpretation of Quantum Theories” and “Toward an Understanding of Parochial Observables” before the meeting.

10 January 2015, 3pm, LPS seminar room

**Casey McCoy (UCSD), “What is the Horizon Problem?”**

Abstract: Cosmological inflation is widely considered an integral and empirically successful component of contemporary cosmology. It was originally motivated by its solution of certain fine-tuning problems of the hot big bang model, particularly what are known as the horizon problem and the flatness problem. Although the physics behind these problems is clear enough, it is unclear precisely what about them is problematic, and therefore precisely which problems inflationary theory is solving. I analyze the structure of these problems, showing how they depend on explicating the sense in which flatness and uniformity are special in the hot big bang model, and the sense in which such special conditions are problematic (in cosmology). I claim that there is no un-problematic interpretation of either problem available whose solution could explain the putative empirical success of inflationary theory. Thus either a new interpretation of such fine-tuning problems is needed, or else an alternate explanation of the theory’s success that does not depend on solving these problems.

Please read Casey’s preprint before the meeting. (Casey apologizes for the length!)

6 December 2014, 3pm, LPS seminar room

**Tom Pashby (USC), “On Meyer’s The Nature of Time: Tense Primitivism, Relationism, and Physics”**

Abstract: In Ulrich Meyer’s recent monograph The Nature of Time (OUP, 2013) he proposes a novel metaphysics of time based on his work in tense logic, which he calls a ‘modal’ theory of time (due to close analogies with modal logic). Meyer claims that we should be tense primitivists, who claim that truths about the world come irreducibly tensed. I motivate this view by situating it in a tradition that includes Kant and van Fraassen (1970) and contend that Meyer’s modal theory of time can be seen as an attempt to avoid the relativized (or contingent) a priori status accorded to time by van Fraassen. To reconcile his view with special relativity Meyer argues that Minkowski’s union of space and time still leaves room to combine alternative metaphysical theories of time and space—hybrid views. According to Meyer, it is perfectly consistent to be a substantivalist about spatial points while being a relationist about instants of time. This conflicts, I claim, with a recent minority consensus in the philosophy of physics which regards temporally related events in special relativity as having an invariant partial order rather than multiple conflicting total orderings into instants. I also complain that general relativity provides further reasons to be skeptical of Meyer’s project, which accords to temporal instants a primary role. As well as positive arguments for his own view of time, Meyer also provides a novel argument against temporal relationism, a direct competitor. I point out that this argument fails to apply to its intended target, Bertrand Russell, and show how Russell’s attempted relationist account of relativistic space-times can be completed, which, I claim, leaves temporal relationism in a better position with respect to modern physics than tense primitivism.

Tom will post a pre-print closer to the meeting date.

1 November 2014, 3pm, LPS seminar room

**Sarita Rosenstock (UC Irvine) and James Weatherall (UC Irvine) on Interpretations of Yang-Mills Theory (part 1)**

Abstract: We will discuss some topics related to the interpretation of classical Yang-Mills theory. First we will describe a way of thinking about Yang-Mills theory that is motivated by a geometrical understanding of general relativity. This will count as a, broadly speaking, “fiber bundle” interpretation of the theory.

Please read Jim’s paper “Fiber Bundles, Yang-Mills Theory, and General Relativity” before the meeting.

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**Tomasz Bigaj (Warsaw) on “Weak discernibility for quanta: why settle for less?”**

Abstract: My talk will consist of two (connected) parts. In the first part I will share with the audience the frustrations resulting from my struggle to understand the multitude of weakly discerning quantum-mechanical relations that have recently been proposed in the literature (Muller & Saunders 2008, Muller & Seevinck 2009, Caulton 2013, Huggett & Norton 2014). On the basis of my understanding of the philosophical motivations behind the whole weak discernibility program, I will attempt to argue that virtually all the proposed methods of discerning quantum particles are fatally flawed. In the face of this setback I will subsequently try to reverse the fortunes of discernibility by arguing that even absolute discernibility of fermions and bosons of the same type is sometimes attainable if we do it right, i.e. using properly symmetrized projection operators.

Previous acquaintance with the papers cited in the abstract can be helpful but is not necessary. The second part of the talk will be loosely based on the unpublished manuscript “Quantum particles, individual properties, and discernibility”.

13 April 2014, 3pm, LPS seminar room

**Eleanor Knox (Kings College, London) on “Spacetime Structuralism or Spacetime Functionalism?”**

Abstract: I examine some currently popular articulations of ontic structural realism with respect to spacetime points, and find them lacking. Instead, I propose functionalism about spacetime itself (with at most derivative consequences for its points). This has much in common with structuralist positions, but has the virtue of usefully applying to emergent spacetimes.

Please read Eleanor’s preprint in advance of the meeting.

22 February 2014, 3pm, LPS seminar room

**Holger Lyre (Magdeburg) on “Berry phase and quantum structural realism”**

Abstract: The purpose of the talk is to analyze the phenomenon of the Berry phase, to spell out its relevance for the quantum state space structure, and to argue for a realist position about this structure. While common wisdom tells us that the quantum state space is the projective Hilbert space, the appropriate structure rich enough to account for the Berry phase turns out to be a U(1) principal bundle over that projective space. Call this the quantum bundle. The Berry phase is the only known instance of a geometric quantum holonomy that, in the absence of any further causal mechanism to bring about this phenomenon, is directly rooted in the curvature of the quantum bundle. This motivates the claim that Berry’s geometric quantum holonomy supports ontic structural realism.

Please read Holger’s preprint in advance of the meeting.

11 January 2014, 3pm, LPS seminar room

**David Wallace (Oxford) on “Thoughts on the Gauge Principle”**

Abstract: Gauge symmetry occupies a paradoxical position in contemporary physics. How can one and the same thing be (a) the third pillar of relativistic quantum field theory, alongside special relativity and quantum mechanics, and (b) a mere descriptive redundancy, indicating that we have overdescribed the theory’s degrees of freedom? Working mostly in classical field theory but motivated by its application in quantum field theory, I will attempt to get some clarity on what we are really saying about a theory conceptually and metaphysically when we say that it has gauge symmetry. Along the way I hope to shed some light on the vexed question of in what sense general relativity is also a gauge theory.

There is no reading for this meeting.

7 December 2013, 3pm, LPS seminar room

** Foad Dizadji-Bahmani (CSU Los Angeles) on “A New Model of Intertheoretic Reduction”**

Preamble/Motivation: Intertheoretic reduction is a perennial theme in philosophy of science; it is a topic that has been present since the very beginning of analytic philosophy of science. There is a striking variety of reductive claims. Some claim that the very modus operandum of science is reductive, others that the history of science is replete with reductions, others still that the putative exemplars of reduction in science are not reductions after all, and yet others that intertheoretic reduction is not possible. Tied up with intertheoretic reduction are the notions of ontological reduction and reductionism. Yet, before one can consider whether or not reductions are ubiquitous, numerous, few, or impossible; whether science aims at reduction; whether all of science does reduce to physics; and so forth, one must first settle what it is for one theory to reduce to another.

Abstract: In this paper I develop and defend a new model of intertheoretic reduction. First, I advocate a particular method for developing some such model, which is a constitutive approach in contradistinction to one based on reflective equilibrium. Second, using this method, I take the relation between the Boyles-Charles law of classical thermodynamics and the so-called kinetic theory of gases to be constitutive of reduction. Third, I discuss how this model compares to Nagel’s well-known model, and, in particular, how my model avoids many of the well-known problems with Nagel’s. Fourth, I apply the model to the relation between a) the classical 2nd Law of Thermodynamics and Boltzmannian statistical mechanics, and b) the classical 2nd Law of Thermodynamics and what in previous work I have called the Aharonov approach to quantum statistical mechanics.

This is no reading for this meeting.

2 November 2013, 4:15pm, LPS seminar room

**Kerry McKenzie (Western) on “Prescriptions on Priority”**

Abstract: In my recent work ‘Priority and Particle Physics’, I suggested that ontic structural realists could use resources gleaned from analytic metaphysics to sharpen up their fundamentality claims — most obviously that concerning the supposed priority of structures over objects. In this talk I want to reconsider that strategy, and investigate whether the fundamentality metaphysics needed for philosophy of physics can in fact be done ‘in house’. After walking us through some priority claims made by philosophers of physics, I will argue that our handling of priority could definitely use some conceptual clear-up. But I’ll also argue that the task of better articulating the concept will be largely continuous with other, antecedently familiar issues in the philosophy of science. While this seems to prise fundamentality questions a little way out of the armchair, what is noteworthy — and dare I say disappointing?! — is that the conception of ontological priority we thereby arrive at looks a lot like that defended in contemporary analytic metaphysics. The significance of this for the much-discussed antagonism between the two fields is a question I’ll leave on the table.

Readings: Although there isn’t a paper associated with the talk, Kerry suggests reading her earlier paper for background.

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**Topic: David Ellerman on the objective indefiniteness interpretation of quantum mechanics**

Readings: Please read David’s paper, if you have the stamina. You can also look at his slides. Only the first half or so are for the talk, the rest are ‘appendices’ designed for people who would like to go beyond the slides, but don’t the time for the paper. Here is a one-page precis of the the paper.

11 May 2013, 3:00pm, LPS seminar room

**Topic: Oliver Pooley on general covariance**

Readings: Please read Oliver’s published paper as preparation for the meeting. You may also want to read a paper by Domenico Giulini as background. I may also distribute a handout detailing Oliver’s recent work on this topic.

4-5 May 2013 (cross-listed event)

**Category-Theoretic Foundations of Mathematics Workshop**

For more information on this event hosted by LPS Irvine, visit the workshop website.

27 April 2013, 3:00pm, LPS seminar room

**Topic: Sam Fletcher: “Physicality and topological stability in relativity theory”**

Readings: Please read Sam’s paper in advance of the meeting.

2 March 2013, **2:00pm**, LPS seminar room

**Topic: Ken Wharton: “Realistic Lagrangian-only quantum theory”**

Readings: Please read Ken’s paper in advance of the meeting. Here is an abstract of the main ideas of the paper.

23 February 2013, 3:00pm, LPS seminar room

**Topic: Dean Rickles on Eddington’s physics**

Readings: Please read Dean’s paper that I sent around in advance of the meeting.

12 January 2013, 3:00pm, LPS seminar room

**Topic: Carolyn Brighouse on the dimension of space**

Readings: Please read Carolyn’s article in advance of the meeting.

8 December 2012, 3:00pm, LPS seminar room

**Topic: Bryan Roberts on Curie’s principle**

Readings: Please read Bryan’s article in advance of the meeting.

10 November 2012, 3:00pm, LPS seminar room

**Topic: Jeremy Butterfield: “Which quantum field theories really exist?” (Joint work with Nazim Bouatta)**

Readings: Please read Jeremy’s article (jointly written with Nazim Bouatta) in advance of the meeting, focusing on Section 2.2.1. Jeremy has also prepared a handout and some slides for the meeting.

20 October 2012, 3:00pm, LPS seminar room

**Topic: Benjamin Feintzeig on hidden variables and commutativity in quantum mechanics**

Readings: Please read Ben’s paper in advance of the meeting.

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**Topic: Chip Sebens: “A laws-first introduction to quantum field theory”**

Readings: Please read Chip’s paper beforehand.

26 May 2012, 3:00pm, LPS seminar room

**Topic: David Ellerman on delayed choice experiments and retrocausality**

Readings: Please read David’s paper on the topic. You can also read his slides in advance, although paper copies will be distributed at the meeting.

18-19 May 2012, UCSD (cross-listed event)

**Conference on time and physics**

More information can be found at Taking up Spacetime.

14 April 2012, 3:00pm, LPS seminar room

**Topic: Gábor Hofer-Szabó: “Bell inequality and common causal explanation in algebraic quantum field theory”**

Readings: Please read his recent paper in preparation for the meeting. If you have more time, you may want to read this paper or even that paper as background.

Abstract: In the talk it will be argued that the violation of the Bell inequality in algebraic quantum field theory do not exclude a commmon 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.

28 January 2012 , 3:00pm, LPS seminar room **(cancelled)**

**Topic: Adrian Wüthrich on locality, causality, and realism in the derivation of Bell’s inequality**

Readings: Please read Adrian’s new paper on the topic. As background, you may want to reread his older work which appeared in BJPS.

14 January 2012 , 3:00pm, LPS seminar room

**Topic: John Manchak on the relationship between spacetime singularities, holes, and extensions**

Readings: Please read John’s paper in advance of the meeting.

3 December 2011, 3:00pm, LPS seminar room

**Topic: Jim Weatherall on theoretical equivalence**

Readings: Please read his draft in preparation for the meeting.

19 November 2011, 3:00pm, LPS seminar room

**Topic: Erik Curiel on connecting surface gravity and temperature for classical black holes**

Readings: Please read his draft in preparation for the meeting.

12 November 2011, 3:00pm, LPS seminar room

**Topic: Alexei Grinbaum on quantum observers and Kolmogorov complexity**

Readings: Please read Alexei’s paper in preparation for the meeting.

17 September 2011, 3:00pm, LPS seminar room

**Topic: Yakir Aharonov and Jeff Tollaksen: “Can the future affect the present without violating causality?”**

Readings: Please read their recent *Physics Today* paper in preparation for the meeting.

Abstract: We will discuss properties of pre- and post-selected ensembles in quantum mechanics and the way to observe these properties through the use of a new type of non-disturbing measurement called ‘weak measurement’. A number of these new experiments have already been successfully performed.

We will also discuss another type of measurements which does not disturb the observed quantum system, called ‘measurement of the set of deterministic operators’. The main result of this new approach is the realization that the basic difference between classical and quantum mechanics is the non-local aspects of quantum dynamics.

Theoretical analysis of the outcomes of these experiments have produced several very rich results. First, it has shed new light on the most puzzling features of quantum mechanics, such as interference, entanglement, etc. Secondly, it has uncovered a host of new quantum phenomena, which were previously hidden.

]]>**Topic: Jim Weatherall**

Readings: Please read Jim’s paper in preparation for the meeting. This paper by Joy Christian, where he outlines his model for EPR-Bohm correlations, served as a source of inspiration for Jim’s project.

7 May 2011, 3:00pm, LPS seminar room

**Topic: Tarun Menon on Landauer’s Principle**

Readings: Please read Tarun’s paper in preparation for the meeting. As background reading, Tarun recommends Norton’s paper on the eaters of the lotus and Owen Maroney’s SEP entry.

**Cross-listed event: one-day workshop at UC Irvine**, 9 April 2011

Speakers: Bob Geroch, Hans Halvorson, Miklos Redei, Jos Uffink

For more information, please visit the workshop’s website.

19 February 2011, 3:00pm, LPS seminar room

**Topic: Bryan Roberts on time-reversing a quantum system**

Readings: Please read Bryan’s paper in preparation for the meeting.

29 January 2011, 3:00pm, LPS seminar room

**Topic: David Rideout on causal sets**

Readings: David will present recent research related to his article with Maqbool Ahmed which serves as primary reading. To put this in context of the search for a dynamical law, use his joint article with Rafael Sorkin as background. For a classic reference to causal sets, see the paper by Bombelli, Lee, Meyer, and Sorkin.

20 November 2010, 3:00pm, LPS seminar room

**Topic: Dennis Lehmkuhl on unification in field theories**

Readings: Please read Dennis’s paper in preparation for the meeting.

30 October 2010, 3:00pm, LPS seminar room

**Topic: Vincent Lam on the notions of energy, mass, and their conservation and localization in GR**

Readings: Please read Vincent’s paper in preparation for the meeting.

26 September 2010, 3:00pm (Sunday), LPS seminar room

**Topic: Sam Fletcher on Norton’s dome**

Readings: Please read Sam’s paper in preparation for the meeting.

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**Topic: Sam Fletcher and Jason Hoelscher-Obermaier on physical computation**

Readings: Please read a short paper by Michael Nielsen and the discussion notes by Sam and Jason in preparation for the meeting.

23 May 2010, 3:00pm (Sunday), LPS seminar room

**Topic: Jim Weatherall on explanations in physics**

Readings: Please read his manuscript in preparation for the meeting.

1 May 2010, 3:00pm, LPS seminar room

**Topic: Jeff Barrett on Everett, constructive empiricism, and empirical faithfulness**

Readings: Please read the following documents in advance of the meeting: (1) a copy of Everett’s short thesis with Jeff’s commentary as adobe post-its, (2) a short review of Bas van Fraassen’s recent book, and (3) a short draft paper on Everett’s notion of empirical faithfulness, (4) the second appendix of Everett’s long version of the thesis, which contains Everett’s most careful description of what a satisfactory physical theory should do.

27 February 2010, 3:00pm, LPS seminar room

**Topic: Sheldon Smith on Batterman on causation in classical physics**

Readings: The paper is sent out individually.

23 January 2010, 3:00pm, LPS seminar room

**Topic: John Baez on the spin foam approach to quantum gravity**

Readings: We will start the session by talking about John’s misgivings about quantum gravity, on which more can be found here. John will then present his work on the spin foam approach to QG, the ideas behind it, and the problems with it. In preparation, please read this article. As background, you may also want to look at this more technical article.

5 December 2009, 3:00pm, LPS seminar room

**Topic: Elias Okon: “Quantum challenges to the equivalence principle”**

Readings: Elias has written a handout that can be downloaded here. You may also want to read Elias’s project proposal for his postdoc, which can be found here. Please do not distribute either document.

3 October 2009, 3:00pm, LPS seminar room

**Topic: Tarun Menon: “The Conway-Kochen free will theorem”**

Readings: An electronic copy of the paper can be found here. The paper is a draft and not fit for distribution. Please read also the recent paper by Conway and Kochen.

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