Jeremy Butterfield | University of Cambridge (original) (raw)

Papers by Jeremy Butterfield

Research paper thumbnail of The Hole Argument and Beyond: Part I: The Story so Far

Journal of physics, Jun 1, 2023

In this two-part paper, we review, and then develop, the assessment of the hole argument for gene... more In this two-part paper, we review, and then develop, the assessment of the hole argument for general relativity. This first Part reviews the literature hitherto, focussing on the philosophical aspects. It also introduces two main ideas we will need in Part II: which will propose a framework for making comparisons of non-isomorphic spacetimes. In Section 1 of this paper, we recall Einstein’s original argument. Section 2 recalls the argument’s revival by philosophers in the 1980s and 1990s. This includes the first main idea we will need in Part II: namely, that two spacetime points in different possible situations are never strictly identical—they are merely counterparts. In Section 3, we report—and rebut—more recent claims to “dissolve” the argument. Our rebuttal is based on the fact that in differential geometry, and its applications in physics such as general relativity, points are in some cases identified, or correspond with each other, between one context and another, by means other than isometry (or isomorphism). We call such a correspondence a threading of points. This is the second main idea we shall use in Part II.

Research paper thumbnail of The Hole Argument and Beyond: Part II: Treating Non-isomorphic Spacetimes

Journal of physics, Jun 1, 2023

In this two-part paper we review, and then develop, the assessment of the hole argument for gener... more In this two-part paper we review, and then develop, the assessment of the hole argument for general relativity. The review (in Part I) discussed how to compare points in isomorphic spacetimes, i.e. models of the theory. This second Part proposes a framework for making comparisons of non-isomorphic spacetimes. It combines two ideas we discussed in Part I—the philosophical idea of counterparts, and the idea of threading points between spacetimes other than by isomorphism—with the mathematics of fibre bundles. We first recall the ideas from Part I (Section 1). Then in Section 2 and an Appendix, we define a fibre bundle whose fibres are isomorphic copies of a given spacetime or model, and discuss connections on this fibre bundle. This material proceeds on analogy with field-space formulations of gauge theories. Finally, in Section 3, we show how this fibre bundle gives natural expressions of the philosophical ideas of counterparts, and of threading.

Research paper thumbnail of On emergence in gauge theories at the 't Hooft limit

arXiv (Cornell University), Aug 24, 2012

Quantum field theories are notoriously difficult to understand, physically as well as philosophic... more Quantum field theories are notoriously difficult to understand, physically as well as philosophically. The aim of this paper is to contribute to a better conceptual understanding of gauge quantum field theories, such as quantum chromodynamics, by discussing a famous physical limit, the 't Hooft limit, in which the theory concerned often simplifies. The idea of the limit is that the number N of colours (or charges) goes to infinity. The simplifications that can happen in this limit, and that we will consider, are: (i) the theory's Feynman diagrams can be drawn on a plane without lines intersecting (called 'planarity'); and (ii) the theory, or a sector of it, becomes integrable, and indeed corresponds to a well-studied system, viz. a spin chain. Planarity is important because it shows how a quantum field theory can exhibit extended, in particular string-like, structures; in some cases, this gives a connection with string theory, and thus with gravity. Previous philosophical literature about how one theory (or a sector, or regime, of a theory) might be emergent from, and-or reduced to, another one has tended to emphasize cases, such as occur in statistical mechanics, where the system before the limit has finitely many degrees of freedom. But here, our quantum field theories, including those on the way to the 't Hooft limit, will have infinitely many degrees of freedom. Nevertheless, we will show how a recent schema by Butterfield and taxonomy by Norton apply to the quantum field theories we consider; and we will classify three physical properties of our theories in these terms. These properties are planarity and integrability, as in (i) and (ii) above; and the behaviour of the beta-function reflecting, for example, asymptotic freedom. Our discussion of these properties, especially the beta-function, will also relate to recent philosophical debate about the propriety of assessing quantum field theories, whose rigorous existence is not yet proven.

Research paper thumbnail of Peaceful Coexistence: Examining Kent's Relativistic Solution to the Quantum Measurement Problem

arXiv (Cornell University), Oct 21, 2017

Can there be 'peaceful coexistence' between quantum theory and special relativity? Thirty years a... more Can there be 'peaceful coexistence' between quantum theory and special relativity? Thirty years ago, Shimony hoped that isolating the culprit (i.e. the false assumption) in proofs of Bell inequalities as Outcome Independence would secure such peaceful coexistence: or, if not secure it, at least show a way-maybe the best or only way-to secure it. In this paper, I begin by being sceptical of Shimony's approach, urging that we need a relativistic solution to the quantum measurement problem (Section 2). Then I analyse Outcome Independence in Kent's realist one-world Lorentzinvariant interpretation of quantum theory (Section 3 and 4). Then I consider Shimony's other condition, Parameter Independence, both in Kent's proposal and more generally, in the light of recent remarkable theorems by Colbeck, Renner and Leegwater (Section 5). For both Outcome Independence and Parameter Independence, there is a striking analogy with the situation in pilot-wave theory. Finally, I will suggest that these recent theorems make some kind of peaceful coexistence mandatory for someone who, like Shimony, endorses Parameter Independence.

Research paper thumbnail of Reality and measurement in algebraic quantum theory : NWW 2015, Nagoya, Japan, March 9-13

Springer eBooks, 2018

Physics explains the laws of motion that govern the time evolution of observable properties and t... more Physics explains the laws of motion that govern the time evolution of observable properties and the dynamical response of systems to various interactions. However, quantum theory separates the observable part of physics from the unobservable time evolution by introducing mathematical objects that are only loosely connected to the actual physics by statistical concepts and cannot be explained by any conventional sets of events. Here, I examine the relation between statistics and dynamics in quantum theory and point out that the Hilbert space formalism can be understood as a theory of ergodic randomization, where the deterministic laws of motion define probabilities according to a randomization of the dynamics that occurs in the processes of state preparation and measurement.

Research paper thumbnail of Halvorson on Bell on ‘Subject and Object’

Hans Halvorson has recently criticised Bell's (1973) paper 'Subject and Object'. I maintain that ... more Hans Halvorson has recently criticised Bell's (1973) paper 'Subject and Object'. I maintain that his criticism is unfair.

Research paper thumbnail of Philosophy of Physics (Handbook of the Philosophy of Science) 2 volume set

North-Holland Publishing Co. eBooks, Nov 1, 2006

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Research paper thumbnail of Scientific Realism and Primordial Cosmology

Routledge eBooks, Nov 22, 2017

We discuss scientific realism from the perspective of modern cosmology, especially primordial cos... more We discuss scientific realism from the perspective of modern cosmology, especially primordial cosmology: i.e. the cosmological investigation of the very early universe. We first (Section 2) state our allegiance to scientific realism, and discuss what insights about it cosmology might yield, as against "just" supplying scientific claims that philosophers can then evaluate. In particular, we discuss: the idea of laws of cosmology, and limitations on ascertaining the global structure of spacetime. Then we review some of what is now known about the early universe (Section 3): meaning, roughly, from a thousandth of a second after the Big Bang onwards(!). The rest of the paper takes up two issues about primordial cosmology, i.e. the very early universe, where "very early" means, roughly, much earlier (logarithmically) than one second after the Big Bang: say, less than 10 −11 seconds. Both issues illustrate that familiar philosophical threat to scientific realism, the under-determination of theory by data-on a cosmic scale. The first issue (Section 4) concerns the difficulty of observationally probing the very early universe. More specifically, the difficulty is to ascertain details of the putative inflationary epoch. The second issue (Section 5) concerns difficulties about confirming a cosmological theory that postulates a multiverse, i.e. a set of domains (universes) each of whose inhabitants (if any) cannot directly observe, or otherwise causally interact with, other domains. This again concerns inflation, since many inflationary models postulate a multiverse.

Research paper thumbnail of Non-locality and quasiclassical reality in Kent’s formulation of relativistic quantum theory

Journal of physics, Sep 1, 2019

We report Adrian Kent's proposed framework for a realist, one-world, Lorentzinvariant formulation... more We report Adrian Kent's proposed framework for a realist, one-world, Lorentzinvariant formulation of quantum theory. The idea is to postulate a final boundary condition: in effect, a late-time distribution of mass-energy recording how photons scattered off macroscopic objects. Nature selects this final boundary condition with the orthodox late-time Born probability; and this defines the probability space of events, to give a realist quantum theory. We emphasize two topics. First, we consider this formulation's verdicts about traditional locality conditions, such as Outcome Independence and Parameter Independence. Second, we discuss a possible amendment to Kent's proposal that, roughly speaking, allows for the emergence of a quasiclassical history even when mass-energy is shielded or delayed from appearing in the final boundary condition.

Research paper thumbnail of On Dualities and Equivalences between Physical Theories

Oxford University Press eBooks, Aug 26, 2021

Dedicated to Graeme Segal. Forthcoming (abridged) in Philosophy Beyond Spacetime (OUP), ed.s N. H... more Dedicated to Graeme Segal. Forthcoming (abridged) in Philosophy Beyond Spacetime (OUP), ed.s N. Huggett, B. Le Bihan and C. Wüthrich. Motto: 'I defy anyone to avoid getting confused by active vs. passive transformations' (Graeme Segal, in conversation about Einstein's hole argument, 2006).

Research paper thumbnail of Determinism and indeterminism

Routledge eBooks, Sep 11, 2018

<jats:p>Over the centuries, the doctrine of determinism has been understood, and assessed, ... more <jats:p>Over the centuries, the doctrine of determinism has been understood, and assessed, in different ways. Since the seventeenth century, it has been commonly understood as the doctrine that every event has a cause; or as the predictability, in principle, of the entire future. To assess the truth of determinism, so understood, philosophers have often looked to physical science; they have assumed that their current best physical theory is their best guide to the truth of determinism. Most have believed that classical physics, especially Newton's physics, is deterministic. And in this century, most have believed that quantum theory is indeterministic. Since quantum theory has superseded classical physics, philosophers have typically come to the tentative conclusion that determinism is false.</jats:p> <jats:p>In fact, these impressions are badly misleading, on three counts. First of all, formulations of determinism in terms of causation or predictability are unsatisfactory, since 'event', 'causation' and 'prediction' are vague and controversial notions, and are not used (at least not univocally) in most physical theories. So if we propose to assess determinism by considering physical theories, our formulation of determinism should be more closely tied to such theories. To do this, the key idea is that determinism is a property of a theory. Imagine a theory that ascribes properties to objects of a certain kind, and claims that the sequence through time of any such object's properties satisfies certain regularities. Then we say that the theory is deterministic if and only if for any two such objects: if their properties match exactly at a given time, then according to the theory, they will match exactly at all future times.</jats:p> <jats:p>Second, this improved formulation reveals that there is a large gap between the determinism of a given physical theory, and the bolder, vague idea that motivated the traditional formulations: the idea that the world as a whole, independent of any single theory, is deterministic. Admittedly, one can make sense of this idea by adopting a sufficiently bold metaphysics: namely, a metaphysics that accepts the idea of a theory of the world as a whole, so that its objects are possible worlds, and determinism becomes the requirement that any two possible worlds described by the theory that match exactly at a given time also match exactly at all future times. But this idea cannot be made sense of using the more cautious strategy of considering determinism as a feature of a given physical theory.</jats:p> <jats:p>Third, according to this more cautious strategy, the traditional consensus is again misleading. Which theories are deterministic turns out to be a subtle and complicated matter, with many questions still open. But broadly speaking, it turns out that much of classical physics, even much of Newton's physics, is indeterministic. Furthermore, the alleged indeterminism of quantum theory is very controversial: it enters, if at all, only in quantum theory's account of measurement processes, an account which remains the most controversial part of the theory. These subtleties and controversies mean that physics does not pass to philosophers any simple verdict about determinism. But more positively, they also mean that determinism remains an exciting topic in the philosophy of science.</jats:p>

Research paper thumbnail of John Bell on 'Subject and Object': an Exchange

arXiv (Cornell University), Jun 2, 2021

This three-part paper comprises: (i) a critique by Halvorson of Bell's (1973) paper 'Subject and ... more This three-part paper comprises: (i) a critique by Halvorson of Bell's (1973) paper 'Subject and Object'; (ii) a comment by Butterfield; (iii) a reply by Halvorson. An Appendix gives the passage from Bell that is the focus of Halvorson's critique. Bell then says that (3) is a serious defect that makes quantum mechanics "vague" and "intrinsically ambiguous" and "only approximately self-consistent." (We have included the complete text of the relevant passage in an appendix.) Let me begin by saying that I simply deny (1), i.e. that quantum mechanics is fundamentally about the results of measurements. I'm afraid that Bell has himself made a logical leap from "the quantum mechanical formalism needs a user" to "quantum mechanics is fundamentally about the results of measurements." There is a wide range of possibilities between these two extremes-e.g. that the quantum-mechanical formalism provides a means for translating facts about subatomic reality into a language that human beings can understand. I will grant that Bell is correct about (2), that the subject-object distinction is needed for quantum mechanics, but unfortunately, Bell has misunderstood the sense in which it is needed. He seems to think that quantum mechanics must describe the world as bifurcated into two parts-subject and object. If that were correct, then I would completely understand Bell's unease with the distinction. If the theory describes a world with two parts, then the theory should offer some guidance about what belongs to each part. But if you think about the meaning the word "subject", it quickly becomes obvious that it's not supposed to play the role of a predicate in the theory (unlike, say, "electron"). Rather, the idea is that a subject uses the theory to describe objects-and in the case at hand, these objects fall under the laws of quantum mechanics. The theory sees no subjects, it sees only objects, and so it has no need for specifying where and when the subject-object split occurs. Such a split is a necessary prerequisite to physical theorizing, when a subject decides to use a theory to try to say something true about the world. Now what about the complaint that quantum mechanics does not specify who the subject is, or when and where and how she decides to use the theory? But wait a minute. Is there any theory that does that? What an amazing theory it would be! Indeed, such a theory would fulfill Hegel's aspiration of finally unifying the subject and object. In other words, such a theory would "theorize itself." Is Bell suggesting that quantum mechanics is defective because it doesn't yet achieve the Hegelian Aufhebung of the subject-object distinction? So, in short, Bell is correct that quantum mechanics, as it stands, needs a subject. But that is true of every theory that has ever appeared in physics-i.e. these theories need subjects to decide when and where and how to describe things. Bell's subsequent rhetoric in the article is effective only against the backdrop of his false assumption that the subject must appear in the quantum-mechanical description. For example, Bell raises a question for which quantum mechanics doesn't appear to have an answer. Now must this subject include a person? Or was there already some such subjectobject distinction before the appearance of life in the universe? (p 40) But quantum mechanics is simply not interested in the question of what counts as a subject. If you ask me what counts as a subject, then my answer is that anyone who can use a theory to describe things is a subject-no other qualifications are necessary! If your dog can theorize, then he is a subject, and if an artificial intelligence could theorize, then it would also be a subject. And to Bell's second question, I suspect that before the appearance of "life" in the universe, there were no things that could describe other things, and hence no

Research paper thumbnail of Erich Joos et al., Decoherence and the Appearance of a Classical World in Quantum Theory. Berlin: Springer (2003), 496 pp., <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>69.95</mn><mo stretchy="false">(</mo><mi>c</mi><mi>l</mi><mi>o</mi><mi>t</mi><mi>h</mi><mo stretchy="false">)</mo><mi mathvariant="normal">.</mi><mi>G</mi><mi>e</mi><mi>o</mi><mi>f</mi><mi>f</mi><mi>r</mi><mi>e</mi><mi>y</mi><mi>S</mi><mi>e</mi><mi>w</mi><mi>e</mi><mi>l</mi><mi>l</mi><mo separator="true">,</mo><mi>Q</mi><mi>u</mi><mi>a</mi><mi>n</mi><mi>t</mi><mi>u</mi><mi>m</mi><mi>M</mi><mi>e</mi><mi>c</mi><mi>h</mi><mi>a</mi><mi>n</mi><mi>i</mi><mi>c</mi><mi>s</mi><mi>a</mi><mi>n</mi><mi>d</mi><mi>I</mi><mi>t</mi><mi>s</mi><mi>E</mi><mi>m</mi><mi>e</mi><mi>r</mi><mi>g</mi><mi>e</mi><mi>n</mi><mi>t</mi><mi>M</mi><mi>a</mi><mi>c</mi><mi>r</mi><mi>o</mi><mi>p</mi><mi>h</mi><mi>y</mi><mi>s</mi><mi>i</mi><mi>c</mi><mi>s</mi><mi mathvariant="normal">.</mi><mi>P</mi><mi>r</mi><mi>i</mi><mi>n</mi><mi>c</mi><mi>e</mi><mi>t</mi><mi>o</mi><mi>n</mi><mo separator="true">,</mo><mi>N</mi><mi>J</mi><mo>:</mo><mi>P</mi><mi>r</mi><mi>i</mi><mi>n</mi><mi>c</mi><mi>e</mi><mi>t</mi><mi>o</mi><mi>n</mi><mi>U</mi><mi>n</mi><mi>i</mi><mi>v</mi><mi>e</mi><mi>r</mi><mi>s</mi><mi>i</mi><mi>t</mi><mi>y</mi><mi>P</mi><mi>r</mi><mi>e</mi><mi>s</mi><mi>s</mi><mo stretchy="false">(</mo><mn>2002</mn><mo stretchy="false">)</mo><mo separator="true">,</mo><mn>304</mn><mi>p</mi><mi>p</mi><mi mathvariant="normal">.</mi><mo separator="true">,</mo></mrow><annotation encoding="application/x-tex">69.95 (cloth).Geoffrey Sewell, Quantum Mechanics and Its Emergent Macrophysics. Princeton, NJ: Princeton University Press (2002), 304 pp., </annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord">69.95</span><span class="mopen">(</span><span class="mord mathnormal">c</span><span class="mord mathnormal" style="margin-right:0.01968em;">l</span><span class="mord mathnormal">o</span><span class="mord mathnormal">t</span><span class="mord mathnormal">h</span><span class="mclose">)</span><span class="mord">.</span><span class="mord mathnormal">G</span><span class="mord mathnormal">eo</span><span class="mord mathnormal" style="margin-right:0.10764em;">ff</span><span class="mord mathnormal" style="margin-right:0.03588em;">rey</span><span class="mord mathnormal" style="margin-right:0.05764em;">S</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.02691em;">w</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.01968em;">ll</span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mord mathnormal">Q</span><span class="mord mathnormal">u</span><span class="mord mathnormal">an</span><span class="mord mathnormal">t</span><span class="mord mathnormal">u</span><span class="mord mathnormal">m</span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mord mathnormal">ec</span><span class="mord mathnormal">hani</span><span class="mord mathnormal">cs</span><span class="mord mathnormal">an</span><span class="mord mathnormal">d</span><span class="mord mathnormal" style="margin-right:0.07847em;">I</span><span class="mord mathnormal">t</span><span class="mord mathnormal">s</span><span class="mord mathnormal" style="margin-right:0.05764em;">E</span><span class="mord mathnormal">m</span><span class="mord mathnormal" style="margin-right:0.02778em;">er</span><span class="mord mathnormal" style="margin-right:0.03588em;">g</span><span class="mord mathnormal">e</span><span class="mord mathnormal">n</span><span class="mord mathnormal" style="margin-right:0.10903em;">tM</span><span class="mord mathnormal">a</span><span class="mord mathnormal">cro</span><span class="mord mathnormal">p</span><span class="mord mathnormal">h</span><span class="mord mathnormal">ys</span><span class="mord mathnormal">i</span><span class="mord mathnormal">cs</span><span class="mord">.</span><span class="mord mathnormal" style="margin-right:0.13889em;">P</span><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="mord mathnormal">in</span><span class="mord mathnormal">ce</span><span class="mord mathnormal">t</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mord mathnormal" style="margin-right:0.09618em;">J</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">:</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.13889em;">P</span><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="mord mathnormal">in</span><span class="mord mathnormal">ce</span><span class="mord mathnormal">t</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mord mathnormal" style="margin-right:0.10903em;">U</span><span class="mord mathnormal">ni</span><span class="mord mathnormal" style="margin-right:0.03588em;">v</span><span class="mord mathnormal">ers</span><span class="mord mathnormal">i</span><span class="mord mathnormal">t</span><span class="mord mathnormal" style="margin-right:0.03588em;">y</span><span class="mord mathnormal" style="margin-right:0.13889em;">P</span><span class="mord mathnormal">ress</span><span class="mopen">(</span><span class="mord">2002</span><span class="mclose">)</span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mord">304</span><span class="mord mathnormal">pp</span><span class="mord">.</span><span class="mpunct">,</span></span></span></span>67.50 (cloth)

Philosophy of Science, Apr 1, 2005

Research paper thumbnail of Against <i>Pointillisme</i> about Mechanics

The British Journal for the Philosophy of Science, Dec 1, 2006

This paper forms part of a wider campaign: to deny pointillisme. That is the doctrine that a phys... more This paper forms part of a wider campaign: to deny pointillisme. That is the doctrine that a physical theory's fundamental quantities are defined at points of space or of spacetime, and represent intrinsic properties of such points or point-sized objects located there; so that properties of spatial or spatiotemporal regions and their material contents are determined by the point-by-point facts. More specifically, this paper argues against pointillisme about the concept of velocity in classical mechanics; especially against proposals by Tooley, Robinson and Lewis. A companion paper argues against pointillisme about (chrono)geometry, as proposed by Bricker. To avoid technicalities, I conduct the argument almost entirely in the context of "Newtonian" ideas about space and time, and the classical mechanics of pointparticles, i.e. extensionless particles moving in a void. But both the debate and my arguments carry over to relativistic physics.

Research paper thumbnail of Handbook of the Philosophy of Science

Research paper thumbnail of Vacuum Correlations and Outcome Dependence in Algebraic Quantum Field Theory

Annals of the New York Academy of Sciences, Apr 1, 1995

Research paper thumbnail of Peaceful Coexistence: Examining Kent’s Relativistic Solution to the Quantum Measurement Problem

Springer proceedings in mathematics & statistics, 2018

Can there be 'peaceful coexistence' between quantum theory and special relativity? Thirty years a... more Can there be 'peaceful coexistence' between quantum theory and special relativity? Thirty years ago, Shimony hoped that isolating the culprit (i.e. the false assumption) in proofs of Bell inequalities as Outcome Independence would secure such peaceful coexistence: or, if not secure it, at least show a way-maybe the best or only way-to secure it. In this paper, I begin by being sceptical of Shimony's approach, urging that we need a relativistic solution to the quantum measurement problem (Section 2). Then I analyse Outcome Independence in Kent's realist one-world Lorentzinvariant interpretation of quantum theory (Section 3 and 4). Then I consider Shimony's other condition, Parameter Independence, both in Kent's proposal and more generally, in the light of recent remarkable theorems by Colbeck, Renner and Leegwater (Section 5). For both Outcome Independence and Parameter Independence, there is a striking analogy with the situation in pilot-wave theory. Finally, I will suggest that these recent theorems make some kind of peaceful coexistence mandatory for someone who, like Shimony, endorses Parameter Independence.

Research paper thumbnail of Scientific Realism and Primordial Cosmology

arXiv (Cornell University), Jun 13, 2016

We discuss scientific realism from the perspective of modern cosmology, especially primordial cos... more We discuss scientific realism from the perspective of modern cosmology, especially primordial cosmology: i.e. the cosmological investigation of the very early universe. We first (Section 2) state our allegiance to scientific realism, and discuss what insights about it cosmology might yield, as against "just" supplying scientific claims that philosophers can then evaluate. In particular, we discuss: the idea of laws of cosmology, and limitations on ascertaining the global structure of spacetime. Then we review some of what is now known about the early universe (Section 3): meaning, roughly, from a thousandth of a second after the Big Bang onwards(!). The rest of the paper takes up two issues about primordial cosmology, i.e. the very early universe, where "very early" means, roughly, much earlier (logarithmically) than one second after the Big Bang: say, less than 10 −11 seconds. Both issues illustrate that familiar philosophical threat to scientific realism, the under-determination of theory by data-on a cosmic scale. The first issue (Section 4) concerns the difficulty of observationally probing the very early universe. More specifically, the difficulty is to ascertain details of the putative inflationary epoch. The second issue (Section 5) concerns difficulties about confirming a cosmological theory that postulates a multiverse, i.e. a set of domains (universes) each of whose inhabitants (if any) cannot directly observe, or otherwise causally interact with, other domains. This again concerns inflation, since many inflationary models postulate a multiverse.

Research paper thumbnail of Physics, philosophy of

Routledge eBooks, Sep 11, 2018

Research paper thumbnail of Determinism and indeterminism

Routledge eBooks, Sep 11, 2018

Research paper thumbnail of The Hole Argument and Beyond: Part I: The Story so Far

Journal of physics, Jun 1, 2023

In this two-part paper, we review, and then develop, the assessment of the hole argument for gene... more In this two-part paper, we review, and then develop, the assessment of the hole argument for general relativity. This first Part reviews the literature hitherto, focussing on the philosophical aspects. It also introduces two main ideas we will need in Part II: which will propose a framework for making comparisons of non-isomorphic spacetimes. In Section 1 of this paper, we recall Einstein’s original argument. Section 2 recalls the argument’s revival by philosophers in the 1980s and 1990s. This includes the first main idea we will need in Part II: namely, that two spacetime points in different possible situations are never strictly identical—they are merely counterparts. In Section 3, we report—and rebut—more recent claims to “dissolve” the argument. Our rebuttal is based on the fact that in differential geometry, and its applications in physics such as general relativity, points are in some cases identified, or correspond with each other, between one context and another, by means other than isometry (or isomorphism). We call such a correspondence a threading of points. This is the second main idea we shall use in Part II.

Research paper thumbnail of The Hole Argument and Beyond: Part II: Treating Non-isomorphic Spacetimes

Journal of physics, Jun 1, 2023

In this two-part paper we review, and then develop, the assessment of the hole argument for gener... more In this two-part paper we review, and then develop, the assessment of the hole argument for general relativity. The review (in Part I) discussed how to compare points in isomorphic spacetimes, i.e. models of the theory. This second Part proposes a framework for making comparisons of non-isomorphic spacetimes. It combines two ideas we discussed in Part I—the philosophical idea of counterparts, and the idea of threading points between spacetimes other than by isomorphism—with the mathematics of fibre bundles. We first recall the ideas from Part I (Section 1). Then in Section 2 and an Appendix, we define a fibre bundle whose fibres are isomorphic copies of a given spacetime or model, and discuss connections on this fibre bundle. This material proceeds on analogy with field-space formulations of gauge theories. Finally, in Section 3, we show how this fibre bundle gives natural expressions of the philosophical ideas of counterparts, and of threading.

Research paper thumbnail of On emergence in gauge theories at the 't Hooft limit

arXiv (Cornell University), Aug 24, 2012

Quantum field theories are notoriously difficult to understand, physically as well as philosophic... more Quantum field theories are notoriously difficult to understand, physically as well as philosophically. The aim of this paper is to contribute to a better conceptual understanding of gauge quantum field theories, such as quantum chromodynamics, by discussing a famous physical limit, the 't Hooft limit, in which the theory concerned often simplifies. The idea of the limit is that the number N of colours (or charges) goes to infinity. The simplifications that can happen in this limit, and that we will consider, are: (i) the theory's Feynman diagrams can be drawn on a plane without lines intersecting (called 'planarity'); and (ii) the theory, or a sector of it, becomes integrable, and indeed corresponds to a well-studied system, viz. a spin chain. Planarity is important because it shows how a quantum field theory can exhibit extended, in particular string-like, structures; in some cases, this gives a connection with string theory, and thus with gravity. Previous philosophical literature about how one theory (or a sector, or regime, of a theory) might be emergent from, and-or reduced to, another one has tended to emphasize cases, such as occur in statistical mechanics, where the system before the limit has finitely many degrees of freedom. But here, our quantum field theories, including those on the way to the 't Hooft limit, will have infinitely many degrees of freedom. Nevertheless, we will show how a recent schema by Butterfield and taxonomy by Norton apply to the quantum field theories we consider; and we will classify three physical properties of our theories in these terms. These properties are planarity and integrability, as in (i) and (ii) above; and the behaviour of the beta-function reflecting, for example, asymptotic freedom. Our discussion of these properties, especially the beta-function, will also relate to recent philosophical debate about the propriety of assessing quantum field theories, whose rigorous existence is not yet proven.

Research paper thumbnail of Peaceful Coexistence: Examining Kent's Relativistic Solution to the Quantum Measurement Problem

arXiv (Cornell University), Oct 21, 2017

Can there be 'peaceful coexistence' between quantum theory and special relativity? Thirty years a... more Can there be 'peaceful coexistence' between quantum theory and special relativity? Thirty years ago, Shimony hoped that isolating the culprit (i.e. the false assumption) in proofs of Bell inequalities as Outcome Independence would secure such peaceful coexistence: or, if not secure it, at least show a way-maybe the best or only way-to secure it. In this paper, I begin by being sceptical of Shimony's approach, urging that we need a relativistic solution to the quantum measurement problem (Section 2). Then I analyse Outcome Independence in Kent's realist one-world Lorentzinvariant interpretation of quantum theory (Section 3 and 4). Then I consider Shimony's other condition, Parameter Independence, both in Kent's proposal and more generally, in the light of recent remarkable theorems by Colbeck, Renner and Leegwater (Section 5). For both Outcome Independence and Parameter Independence, there is a striking analogy with the situation in pilot-wave theory. Finally, I will suggest that these recent theorems make some kind of peaceful coexistence mandatory for someone who, like Shimony, endorses Parameter Independence.

Research paper thumbnail of Reality and measurement in algebraic quantum theory : NWW 2015, Nagoya, Japan, March 9-13

Springer eBooks, 2018

Physics explains the laws of motion that govern the time evolution of observable properties and t... more Physics explains the laws of motion that govern the time evolution of observable properties and the dynamical response of systems to various interactions. However, quantum theory separates the observable part of physics from the unobservable time evolution by introducing mathematical objects that are only loosely connected to the actual physics by statistical concepts and cannot be explained by any conventional sets of events. Here, I examine the relation between statistics and dynamics in quantum theory and point out that the Hilbert space formalism can be understood as a theory of ergodic randomization, where the deterministic laws of motion define probabilities according to a randomization of the dynamics that occurs in the processes of state preparation and measurement.

Research paper thumbnail of Halvorson on Bell on ‘Subject and Object’

Hans Halvorson has recently criticised Bell's (1973) paper 'Subject and Object'. I maintain that ... more Hans Halvorson has recently criticised Bell's (1973) paper 'Subject and Object'. I maintain that his criticism is unfair.

Research paper thumbnail of Philosophy of Physics (Handbook of the Philosophy of Science) 2 volume set

North-Holland Publishing Co. eBooks, Nov 1, 2006

Google, Inc. (search). ...

Research paper thumbnail of Scientific Realism and Primordial Cosmology

Routledge eBooks, Nov 22, 2017

We discuss scientific realism from the perspective of modern cosmology, especially primordial cos... more We discuss scientific realism from the perspective of modern cosmology, especially primordial cosmology: i.e. the cosmological investigation of the very early universe. We first (Section 2) state our allegiance to scientific realism, and discuss what insights about it cosmology might yield, as against "just" supplying scientific claims that philosophers can then evaluate. In particular, we discuss: the idea of laws of cosmology, and limitations on ascertaining the global structure of spacetime. Then we review some of what is now known about the early universe (Section 3): meaning, roughly, from a thousandth of a second after the Big Bang onwards(!). The rest of the paper takes up two issues about primordial cosmology, i.e. the very early universe, where "very early" means, roughly, much earlier (logarithmically) than one second after the Big Bang: say, less than 10 −11 seconds. Both issues illustrate that familiar philosophical threat to scientific realism, the under-determination of theory by data-on a cosmic scale. The first issue (Section 4) concerns the difficulty of observationally probing the very early universe. More specifically, the difficulty is to ascertain details of the putative inflationary epoch. The second issue (Section 5) concerns difficulties about confirming a cosmological theory that postulates a multiverse, i.e. a set of domains (universes) each of whose inhabitants (if any) cannot directly observe, or otherwise causally interact with, other domains. This again concerns inflation, since many inflationary models postulate a multiverse.

Research paper thumbnail of Non-locality and quasiclassical reality in Kent’s formulation of relativistic quantum theory

Journal of physics, Sep 1, 2019

We report Adrian Kent's proposed framework for a realist, one-world, Lorentzinvariant formulation... more We report Adrian Kent's proposed framework for a realist, one-world, Lorentzinvariant formulation of quantum theory. The idea is to postulate a final boundary condition: in effect, a late-time distribution of mass-energy recording how photons scattered off macroscopic objects. Nature selects this final boundary condition with the orthodox late-time Born probability; and this defines the probability space of events, to give a realist quantum theory. We emphasize two topics. First, we consider this formulation's verdicts about traditional locality conditions, such as Outcome Independence and Parameter Independence. Second, we discuss a possible amendment to Kent's proposal that, roughly speaking, allows for the emergence of a quasiclassical history even when mass-energy is shielded or delayed from appearing in the final boundary condition.

Research paper thumbnail of On Dualities and Equivalences between Physical Theories

Oxford University Press eBooks, Aug 26, 2021

Dedicated to Graeme Segal. Forthcoming (abridged) in Philosophy Beyond Spacetime (OUP), ed.s N. H... more Dedicated to Graeme Segal. Forthcoming (abridged) in Philosophy Beyond Spacetime (OUP), ed.s N. Huggett, B. Le Bihan and C. Wüthrich. Motto: 'I defy anyone to avoid getting confused by active vs. passive transformations' (Graeme Segal, in conversation about Einstein's hole argument, 2006).

Research paper thumbnail of Determinism and indeterminism

Routledge eBooks, Sep 11, 2018

<jats:p>Over the centuries, the doctrine of determinism has been understood, and assessed, ... more <jats:p>Over the centuries, the doctrine of determinism has been understood, and assessed, in different ways. Since the seventeenth century, it has been commonly understood as the doctrine that every event has a cause; or as the predictability, in principle, of the entire future. To assess the truth of determinism, so understood, philosophers have often looked to physical science; they have assumed that their current best physical theory is their best guide to the truth of determinism. Most have believed that classical physics, especially Newton's physics, is deterministic. And in this century, most have believed that quantum theory is indeterministic. Since quantum theory has superseded classical physics, philosophers have typically come to the tentative conclusion that determinism is false.</jats:p> <jats:p>In fact, these impressions are badly misleading, on three counts. First of all, formulations of determinism in terms of causation or predictability are unsatisfactory, since 'event', 'causation' and 'prediction' are vague and controversial notions, and are not used (at least not univocally) in most physical theories. So if we propose to assess determinism by considering physical theories, our formulation of determinism should be more closely tied to such theories. To do this, the key idea is that determinism is a property of a theory. Imagine a theory that ascribes properties to objects of a certain kind, and claims that the sequence through time of any such object's properties satisfies certain regularities. Then we say that the theory is deterministic if and only if for any two such objects: if their properties match exactly at a given time, then according to the theory, they will match exactly at all future times.</jats:p> <jats:p>Second, this improved formulation reveals that there is a large gap between the determinism of a given physical theory, and the bolder, vague idea that motivated the traditional formulations: the idea that the world as a whole, independent of any single theory, is deterministic. Admittedly, one can make sense of this idea by adopting a sufficiently bold metaphysics: namely, a metaphysics that accepts the idea of a theory of the world as a whole, so that its objects are possible worlds, and determinism becomes the requirement that any two possible worlds described by the theory that match exactly at a given time also match exactly at all future times. But this idea cannot be made sense of using the more cautious strategy of considering determinism as a feature of a given physical theory.</jats:p> <jats:p>Third, according to this more cautious strategy, the traditional consensus is again misleading. Which theories are deterministic turns out to be a subtle and complicated matter, with many questions still open. But broadly speaking, it turns out that much of classical physics, even much of Newton's physics, is indeterministic. Furthermore, the alleged indeterminism of quantum theory is very controversial: it enters, if at all, only in quantum theory's account of measurement processes, an account which remains the most controversial part of the theory. These subtleties and controversies mean that physics does not pass to philosophers any simple verdict about determinism. But more positively, they also mean that determinism remains an exciting topic in the philosophy of science.</jats:p>

Research paper thumbnail of John Bell on 'Subject and Object': an Exchange

arXiv (Cornell University), Jun 2, 2021

This three-part paper comprises: (i) a critique by Halvorson of Bell's (1973) paper 'Subject and ... more This three-part paper comprises: (i) a critique by Halvorson of Bell's (1973) paper 'Subject and Object'; (ii) a comment by Butterfield; (iii) a reply by Halvorson. An Appendix gives the passage from Bell that is the focus of Halvorson's critique. Bell then says that (3) is a serious defect that makes quantum mechanics "vague" and "intrinsically ambiguous" and "only approximately self-consistent." (We have included the complete text of the relevant passage in an appendix.) Let me begin by saying that I simply deny (1), i.e. that quantum mechanics is fundamentally about the results of measurements. I'm afraid that Bell has himself made a logical leap from "the quantum mechanical formalism needs a user" to "quantum mechanics is fundamentally about the results of measurements." There is a wide range of possibilities between these two extremes-e.g. that the quantum-mechanical formalism provides a means for translating facts about subatomic reality into a language that human beings can understand. I will grant that Bell is correct about (2), that the subject-object distinction is needed for quantum mechanics, but unfortunately, Bell has misunderstood the sense in which it is needed. He seems to think that quantum mechanics must describe the world as bifurcated into two parts-subject and object. If that were correct, then I would completely understand Bell's unease with the distinction. If the theory describes a world with two parts, then the theory should offer some guidance about what belongs to each part. But if you think about the meaning the word "subject", it quickly becomes obvious that it's not supposed to play the role of a predicate in the theory (unlike, say, "electron"). Rather, the idea is that a subject uses the theory to describe objects-and in the case at hand, these objects fall under the laws of quantum mechanics. The theory sees no subjects, it sees only objects, and so it has no need for specifying where and when the subject-object split occurs. Such a split is a necessary prerequisite to physical theorizing, when a subject decides to use a theory to try to say something true about the world. Now what about the complaint that quantum mechanics does not specify who the subject is, or when and where and how she decides to use the theory? But wait a minute. Is there any theory that does that? What an amazing theory it would be! Indeed, such a theory would fulfill Hegel's aspiration of finally unifying the subject and object. In other words, such a theory would "theorize itself." Is Bell suggesting that quantum mechanics is defective because it doesn't yet achieve the Hegelian Aufhebung of the subject-object distinction? So, in short, Bell is correct that quantum mechanics, as it stands, needs a subject. But that is true of every theory that has ever appeared in physics-i.e. these theories need subjects to decide when and where and how to describe things. Bell's subsequent rhetoric in the article is effective only against the backdrop of his false assumption that the subject must appear in the quantum-mechanical description. For example, Bell raises a question for which quantum mechanics doesn't appear to have an answer. Now must this subject include a person? Or was there already some such subjectobject distinction before the appearance of life in the universe? (p 40) But quantum mechanics is simply not interested in the question of what counts as a subject. If you ask me what counts as a subject, then my answer is that anyone who can use a theory to describe things is a subject-no other qualifications are necessary! If your dog can theorize, then he is a subject, and if an artificial intelligence could theorize, then it would also be a subject. And to Bell's second question, I suspect that before the appearance of "life" in the universe, there were no things that could describe other things, and hence no

Research paper thumbnail of Erich Joos et al., Decoherence and the Appearance of a Classical World in Quantum Theory. Berlin: Springer (2003), 496 pp., <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>69.95</mn><mo stretchy="false">(</mo><mi>c</mi><mi>l</mi><mi>o</mi><mi>t</mi><mi>h</mi><mo stretchy="false">)</mo><mi mathvariant="normal">.</mi><mi>G</mi><mi>e</mi><mi>o</mi><mi>f</mi><mi>f</mi><mi>r</mi><mi>e</mi><mi>y</mi><mi>S</mi><mi>e</mi><mi>w</mi><mi>e</mi><mi>l</mi><mi>l</mi><mo separator="true">,</mo><mi>Q</mi><mi>u</mi><mi>a</mi><mi>n</mi><mi>t</mi><mi>u</mi><mi>m</mi><mi>M</mi><mi>e</mi><mi>c</mi><mi>h</mi><mi>a</mi><mi>n</mi><mi>i</mi><mi>c</mi><mi>s</mi><mi>a</mi><mi>n</mi><mi>d</mi><mi>I</mi><mi>t</mi><mi>s</mi><mi>E</mi><mi>m</mi><mi>e</mi><mi>r</mi><mi>g</mi><mi>e</mi><mi>n</mi><mi>t</mi><mi>M</mi><mi>a</mi><mi>c</mi><mi>r</mi><mi>o</mi><mi>p</mi><mi>h</mi><mi>y</mi><mi>s</mi><mi>i</mi><mi>c</mi><mi>s</mi><mi mathvariant="normal">.</mi><mi>P</mi><mi>r</mi><mi>i</mi><mi>n</mi><mi>c</mi><mi>e</mi><mi>t</mi><mi>o</mi><mi>n</mi><mo separator="true">,</mo><mi>N</mi><mi>J</mi><mo>:</mo><mi>P</mi><mi>r</mi><mi>i</mi><mi>n</mi><mi>c</mi><mi>e</mi><mi>t</mi><mi>o</mi><mi>n</mi><mi>U</mi><mi>n</mi><mi>i</mi><mi>v</mi><mi>e</mi><mi>r</mi><mi>s</mi><mi>i</mi><mi>t</mi><mi>y</mi><mi>P</mi><mi>r</mi><mi>e</mi><mi>s</mi><mi>s</mi><mo stretchy="false">(</mo><mn>2002</mn><mo stretchy="false">)</mo><mo separator="true">,</mo><mn>304</mn><mi>p</mi><mi>p</mi><mi mathvariant="normal">.</mi><mo separator="true">,</mo></mrow><annotation encoding="application/x-tex">69.95 (cloth).Geoffrey Sewell, Quantum Mechanics and Its Emergent Macrophysics. Princeton, NJ: Princeton University Press (2002), 304 pp., </annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord">69.95</span><span class="mopen">(</span><span class="mord mathnormal">c</span><span class="mord mathnormal" style="margin-right:0.01968em;">l</span><span class="mord mathnormal">o</span><span class="mord mathnormal">t</span><span class="mord mathnormal">h</span><span class="mclose">)</span><span class="mord">.</span><span class="mord mathnormal">G</span><span class="mord mathnormal">eo</span><span class="mord mathnormal" style="margin-right:0.10764em;">ff</span><span class="mord mathnormal" style="margin-right:0.03588em;">rey</span><span class="mord mathnormal" style="margin-right:0.05764em;">S</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.02691em;">w</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.01968em;">ll</span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mord mathnormal">Q</span><span class="mord mathnormal">u</span><span class="mord mathnormal">an</span><span class="mord mathnormal">t</span><span class="mord mathnormal">u</span><span class="mord mathnormal">m</span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mord mathnormal">ec</span><span class="mord mathnormal">hani</span><span class="mord mathnormal">cs</span><span class="mord mathnormal">an</span><span class="mord mathnormal">d</span><span class="mord mathnormal" style="margin-right:0.07847em;">I</span><span class="mord mathnormal">t</span><span class="mord mathnormal">s</span><span class="mord mathnormal" style="margin-right:0.05764em;">E</span><span class="mord mathnormal">m</span><span class="mord mathnormal" style="margin-right:0.02778em;">er</span><span class="mord mathnormal" style="margin-right:0.03588em;">g</span><span class="mord mathnormal">e</span><span class="mord mathnormal">n</span><span class="mord mathnormal" style="margin-right:0.10903em;">tM</span><span class="mord mathnormal">a</span><span class="mord mathnormal">cro</span><span class="mord mathnormal">p</span><span class="mord mathnormal">h</span><span class="mord mathnormal">ys</span><span class="mord mathnormal">i</span><span class="mord mathnormal">cs</span><span class="mord">.</span><span class="mord mathnormal" style="margin-right:0.13889em;">P</span><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="mord mathnormal">in</span><span class="mord mathnormal">ce</span><span class="mord mathnormal">t</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mord mathnormal" style="margin-right:0.09618em;">J</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">:</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.13889em;">P</span><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="mord mathnormal">in</span><span class="mord mathnormal">ce</span><span class="mord mathnormal">t</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mord mathnormal" style="margin-right:0.10903em;">U</span><span class="mord mathnormal">ni</span><span class="mord mathnormal" style="margin-right:0.03588em;">v</span><span class="mord mathnormal">ers</span><span class="mord mathnormal">i</span><span class="mord mathnormal">t</span><span class="mord mathnormal" style="margin-right:0.03588em;">y</span><span class="mord mathnormal" style="margin-right:0.13889em;">P</span><span class="mord mathnormal">ress</span><span class="mopen">(</span><span class="mord">2002</span><span class="mclose">)</span><span class="mpunct">,</span><span class="mspace" style="margin-right:0.1667em;"></span><span class="mord">304</span><span class="mord mathnormal">pp</span><span class="mord">.</span><span class="mpunct">,</span></span></span></span>67.50 (cloth)

Philosophy of Science, Apr 1, 2005

Research paper thumbnail of Against <i>Pointillisme</i> about Mechanics

The British Journal for the Philosophy of Science, Dec 1, 2006

This paper forms part of a wider campaign: to deny pointillisme. That is the doctrine that a phys... more This paper forms part of a wider campaign: to deny pointillisme. That is the doctrine that a physical theory's fundamental quantities are defined at points of space or of spacetime, and represent intrinsic properties of such points or point-sized objects located there; so that properties of spatial or spatiotemporal regions and their material contents are determined by the point-by-point facts. More specifically, this paper argues against pointillisme about the concept of velocity in classical mechanics; especially against proposals by Tooley, Robinson and Lewis. A companion paper argues against pointillisme about (chrono)geometry, as proposed by Bricker. To avoid technicalities, I conduct the argument almost entirely in the context of "Newtonian" ideas about space and time, and the classical mechanics of pointparticles, i.e. extensionless particles moving in a void. But both the debate and my arguments carry over to relativistic physics.

Research paper thumbnail of Handbook of the Philosophy of Science

Research paper thumbnail of Vacuum Correlations and Outcome Dependence in Algebraic Quantum Field Theory

Annals of the New York Academy of Sciences, Apr 1, 1995

Research paper thumbnail of Peaceful Coexistence: Examining Kent’s Relativistic Solution to the Quantum Measurement Problem

Springer proceedings in mathematics & statistics, 2018

Can there be 'peaceful coexistence' between quantum theory and special relativity? Thirty years a... more Can there be 'peaceful coexistence' between quantum theory and special relativity? Thirty years ago, Shimony hoped that isolating the culprit (i.e. the false assumption) in proofs of Bell inequalities as Outcome Independence would secure such peaceful coexistence: or, if not secure it, at least show a way-maybe the best or only way-to secure it. In this paper, I begin by being sceptical of Shimony's approach, urging that we need a relativistic solution to the quantum measurement problem (Section 2). Then I analyse Outcome Independence in Kent's realist one-world Lorentzinvariant interpretation of quantum theory (Section 3 and 4). Then I consider Shimony's other condition, Parameter Independence, both in Kent's proposal and more generally, in the light of recent remarkable theorems by Colbeck, Renner and Leegwater (Section 5). For both Outcome Independence and Parameter Independence, there is a striking analogy with the situation in pilot-wave theory. Finally, I will suggest that these recent theorems make some kind of peaceful coexistence mandatory for someone who, like Shimony, endorses Parameter Independence.

Research paper thumbnail of Scientific Realism and Primordial Cosmology

arXiv (Cornell University), Jun 13, 2016

We discuss scientific realism from the perspective of modern cosmology, especially primordial cos... more We discuss scientific realism from the perspective of modern cosmology, especially primordial cosmology: i.e. the cosmological investigation of the very early universe. We first (Section 2) state our allegiance to scientific realism, and discuss what insights about it cosmology might yield, as against "just" supplying scientific claims that philosophers can then evaluate. In particular, we discuss: the idea of laws of cosmology, and limitations on ascertaining the global structure of spacetime. Then we review some of what is now known about the early universe (Section 3): meaning, roughly, from a thousandth of a second after the Big Bang onwards(!). The rest of the paper takes up two issues about primordial cosmology, i.e. the very early universe, where "very early" means, roughly, much earlier (logarithmically) than one second after the Big Bang: say, less than 10 −11 seconds. Both issues illustrate that familiar philosophical threat to scientific realism, the under-determination of theory by data-on a cosmic scale. The first issue (Section 4) concerns the difficulty of observationally probing the very early universe. More specifically, the difficulty is to ascertain details of the putative inflationary epoch. The second issue (Section 5) concerns difficulties about confirming a cosmological theory that postulates a multiverse, i.e. a set of domains (universes) each of whose inhabitants (if any) cannot directly observe, or otherwise causally interact with, other domains. This again concerns inflation, since many inflationary models postulate a multiverse.

Research paper thumbnail of Physics, philosophy of

Routledge eBooks, Sep 11, 2018

Research paper thumbnail of Determinism and indeterminism

Routledge eBooks, Sep 11, 2018

Research paper thumbnail of Conceptual Analysis of Black Hole Entropy in String Theory

The microscopic state counting of the extremal Reissner-Nordström black hole performed by Andrew ... more The microscopic state counting of the extremal Reissner-Nordström black hole performed by Andrew Strominger and Cumrun Vafa in 1996 has proven to be a central result in string theory. Here, with a philosophical readership in mind, the argument is presented in its contemporary context and its rather complex conceptual structure is analysed. In particular, we will identify the various inter-theoretic relations, such as duality and linkage relations, on which it depends. We further aim to make clear why the argument was immediately recognised as a successful accounting for the entropy of this black hole and how it engendered subsequent work that intended to strengthen the string theoretic analysis of black holes. Its relation to the formulation of the AdS/CFT conjecture will be briefly discussed, and the familiar reinterpretation of the entropy calculation in the context of the AdS/CFT correspondence is given. Finally, we discuss the heuristic role that Strominger and Vafa's microscopic account of black hole entropy played for the black hole information paradox. A companion paper analyses the ontology of the Strominger-Vafa black hole states, the question of emergence of the black hole from a collection of D-branes, and the role of the correspondence principle in the context of string theory black holes.

Research paper thumbnail of Emergence and Correspondence for String Theory Black Holes

This is one of a pair of papers that give a historical-cum-philosophical analysis of the endeavou... more This is one of a pair of papers that give a historical-cum-philosophical analysis of the endeavour to understand black hole entropy as a statistical mechanical entropy obtained by counting string-theoretic microstates. Both papers focus on Andrew Strominger and Cumrun Vafa's groundbreaking 1996 calculation, which analysed the black hole in terms of D-branes. The first paper gives a conceptual analysis of the Strominger-Vafa argument, and of several research efforts that it engendered. In this paper, we assess whether the black hole should be considered as emergent from the D-brane system, particularly in light of the role that duality plays in the argument. We further identify uses of the quantum-to-classical correspondence principle in string theory discussions of black holes, and compare these to the heuristics of earlier efforts in theory construction, in particular those of the old quantum theory.