I argue that, under the glitz, dual theories are examples of theoretically equivalent descriptions of the same underlying physical content: I distinguish them from cases of genuine underdetermination on the grounds that there is no real incompatibility involved between the descriptions. The incompatibility is at the level of unphysical structure. I argue that dual pairs are in fact very strongly analogous to gauge- related solutions even for dual pairs that look the most radically distinct, such as AdS/CFT.

The AdS/CFT duality has been a source of several strong conceptual claims in the physics literature that have yet to be explored by philosophers. In this paper I focus on one of these: the extent to which spacetime geometry and locality can be said to emerge from this duality, so that neither is fundamental. I argue: that the kind of emergence in question is relatively weak, involving one kind of spacetime emerging from another kind of spacetime; inasmuch as there is (...) something conceptually interesting to say about the emergence of spacetime and locality , it is no different from that already well known to those within canonical quantum gravity; that at the core of AdS/CFT is an issue of representation and redundancy in representation. (shrink)

The dominance of string theory in the research landscape of quantum gravity physics (despite any direct experimental evidence) can, I think, be justified in a variety of ways. Here I focus on an argument from mathematical fertility, broadly similar to Hilary Putnam’s ‘no miracles argument’ that, I argue, many string theorists in fact espouse in some form or other. String theory has generated many surprising, useful, and well-confirmed mathematical ‘predictions’—here I focus on mirror symmetry and the mirror theorem. These predictions (...) were made on the basis of general physical principles entering into string theory. The success of the mathematical predictions are then seen as evidence for the framework that generated them. I shall attempt to defend this argument, but there are nonetheless some serious objections to be faced. These objections can only be evaded at a considerably high (philosophical) price. (shrink)

What is spacetime? General relativity and quantum field theory answer this question in very different ways. This collection of essays by physicists and philosophers looks at the problem of uniting these two most fundamental theories of our world, focusing on the nature of space and time within this new quantum framework, and the kind of metaphysical picture suggested by recent developments in physics and mathematics. This is a book that will inspire further philosophical reflection on recent advances in modern physics.

In this paper I wish to make some headway on understanding what \emph{kind} of problem the ``problem of time'' is, and offer a possible resolution---or, rather, a new way of understanding an old resolution. The response I give is a variation on a theme of Rovelli's \emph{evolving constants of motion} strategy. I argue that by giving correlation strategies a \emph{structuralist} basis, a number of objections to the standard account can be blunted. Moreover, I show that the account I offer provides (...) a suitable ontology for time in both classical and quantum canonical general relativity. (shrink)

‘Quantum Gravity’ does not denote any existing theory: the field of quantum gravity is very much a ‘work in progress’. As you will see in this chapter, there are multiple lines of attack each with the same core goal: to find a theory that unifies, in some sense, general relativity (Einstein’s classical field theory of gravitation) and quantum field theory (the theoretical framework through which we understand the behaviour of particles in non-gravitational fields). Quantum field theory and general relativity seem (...) to be like oil and water, they don’t like to mix—it is fair to say that combining them to produce a theory of quantum gravity constitutes the greatest unresolved puzzle in physics. Our goal in this chapter is to give the reader an impression of what the problem of quantum gravity is; why it is an important problem; the ways that have been suggested to resolve it; and what philosophical issues these approaches, and the problem itself, generate. This review is extremely selective, as it has to be to remain a manageable size: generally, rather than going into great detail in some area, we highlight the key features and the options, in the hope that readers may take up the problem for themselves—however, some of the basic formalism will be introduced so that the reader is able to enter the physics and (what little there is of) the philosophy of physics literature prepared. I have also supplied references for those cases where I have omitted some important facts. Hence, this chapter is intended primarily as a catalyst for future research projects by philosophers of physics, both budding and well-matured. (shrink)

This brief paper shows how an exact analogue of Einstein's original hole argument can be constructed in the loop representation of quantum gravity. The new argument is based on the embedding of spin-networks in a manifold and the action of the diffeomorphism constraint on them. The implications of this result are then discussed. I argue that the conclusions of many physicists working on loop quantum gravity---Rovelli and Smolin in particular---that the loop representation uniquely supports relationalism are unfounded.

In this introduction, we describe the rationale behind this special issue on Principles of Quantum Gravity. We explain what we mean by ‘principles’ and relate this to the various contributions. Finally, we draw out some general themes that can be found running throughout these contributions.

Background independence is generally considered to be ‘the mark of distinction’ of general relativity. However, there is still confusion over exactly what background independence is and how, if at all, it serves to distinguish general relativity from other theories. There is also some confusion over the philosophical implications of background independence, stemming in part from the definitional problems. In this paper I attempt to make some headway on both issues. In each case I argue that a proper account of the (...) observables of such theories goes a long way in clarifying matters. Further, I argue, against common claims to the contrary, that the fact that these observables are relational has no bearing on the debate between substantivalists and relationalists, though I do think it recommends a structuralist ontology, as I shall endeavour to explain. (shrink)

Where does the study of the flow of time belong: physics, the cognitive sciences, philosophy, or somewhere else? Physicists and philosophers have set themselves up into two camps: those who believe there is genuine flow or becoming in the world and those who believe there is just a block of events. What had not been considered is whether the subjective feeling of flow of time is the same the world over, whether it could be tampered with by brain injury, or (...) whether it is present at all developmental stages. We lay out the problem, explain terms, and provide synopses of relevant ideas. (shrink)

This is an essay review of two textbooks on quantum gravity by Carlo Rovelli and Claus Kiefer.

"Introducing the reader to the very latest developments in the philosophical foundations of physics, this book covers advanced material at a level suitable for ...

In this paper I examine the connection between symmetry and modality from the perspective of `reduction' methods in geometric mechanics. I begin by setting the problem up as a choice between two opposing views: reduction and non-reduction. I then discern four views on the matter in the literature; they are distinguished by their advocation of distinct geometric spaces as representing `reality'. I come down in favour of non-reductive methods.

In this chapter I consider what recent work on background independent physics can do for structuralism, and what structuralism can do for background independent physics. I focus on the problems of time and observables in gravitational physics. The ‘frozen’ character of the observables of general relativity is usually considered to constitute a serious problem for the theory. I argue that by invoking correlations between physical quantities we can provide a natural explanation of the appear- ance of time and change in (...) timeless structures. I argue that this response can resolve a problem with Max Tegmark’s ‘extreme structuralist’ position. I then consider what bearing the mathematical representation used has on the debate over the nature of structure in discussions of structural realism. I argue that it has both the resources to ground the notion of structure in physics and to answer the ‘no relations without relata’ objection. (shrink)

In this chapter we consider economic systems, and in particular financial systems, from the perspective of the physics of complex systems (i.e. statistical physics, the theory of critical phenomena, and their cognates). This field of research is known as econophysics—alternative names are ‘financial physics’ and ‘statistical phynance.’ This title was coined in 1995 by Eugene Stanley, and since then its researchers have attempted to forge it as an independent and important field, one that stands in opposition to standard (‘Neo-Classical’) economic (...) theory. Econophysicists argue that the empirical data is best explained in terms flowing out of statistical physics, according to which the (stylized) facts of economics are best understood as emergent properties of a complex system. However, some economists argue that the methods used by econophysics are not sufficient to prove the existence of underlying complexity in economic systems. The complexity claim can nonetheless be defended as a good example of an inference to the best explanation rather than a definitive deduction. (shrink)

I examine the early history of quantum gravity and comment on its suitability as an episode that demands an integrated approach to history and philosophy of science.

Many of the advances in string theory have been generated by the discovery of new duality symmetries connecting what were once thought to be distinct theories, solu- tions, processes, backgrounds, and more. Indeed, duality has played an enormously important role in the creation and development of numerous theories in physics and numerous fields of mathematics. Dualities often lie at those fruitful intersections at which mathematics and physics are especially strongly intertwined. In this paper I describe some of these dualities and (...) unpack some of their philosophical conse- quences, focusing primarily on string-theoretic dualities. I argue that dualities fall uncomfortably between symmetries and gauge redundancies, but that they differ in that they point to genuinely new deeper structures. (shrink)

In this paper I look at causality in the context of intervention research, and discuss some problems faced in the evaluation of causal hypotheses via interventions. I draw attention to a simple problem for evaluations that employ randomized controlled trials. The common alternative to randomized trials, the observational study, is shown to face problems of a similar nature. I then argue that these problems become especially acute in cases where the intervention is complex (i.e. that involves intervening in a complex (...) system). Finally, I consider and reject a possible resolution of the problem involving the simulation of complex interventions. The conclusion I draw from this is that we need to radically reframe the way we think about causal inference in complex intervention research. (shrink)

_Thinking about Science, Reflecting on Art: Bringing Aesthetics and Philosophy of Science togethe_r is the first book to systematically examine the relationship between the philosophy of science and aesthetics. With contributions from leading figures from both fields this edited collection engages with such questions as: Does representation function in the same way in science and in art? What important characteristic do scientific models share with literary fictions? What is the difference between interpretation in the sciences and in the arts? Can (...) there be a science of aesthetics? In what ways can aesthetics and philosophy of science be integrated? Aiming to develop the interconnections between the philosophy of science and the philosophy of art more broadly and more deeply than ever before this volume not only explores scientific representation by comparison with fiction but extends the scope of interaction to include metaphysical and other questions around methodology in mainstream philosophy of science, including the aims of science, the characterisation of scientific understanding, and the nature of observation, as well as drawing detailed comparisons between specific examples in both art and the sciences. (shrink)

Symposium review of Richard Healey, Gauging What’s Real: The Conceptual Foundations of Contemporary Gauge Theories. Oxford: Oxford University Press, 2007. Pp. 297. $99.00 HB.

Just one damn thing after another Content Type Journal Article DOI 10.1007/s11016-010-9485-1 Authors Dean Rickles, Unit for History and Philosophy of Science, The University of Sydney, Sydney, NSW 2006, Australia Journal Metascience Online ISSN 1467-9981 Print ISSN 0815-0796.

Given that worlds are defined compositionally as maximally spatiotemporally interrelated sums of possible objects, or as recombinations of actual states of affairs: what of empty worlds? It seems that such theories cannot admit such worlds, for nothing cannot come from the fusion or recombination of something. This is generally supposed to rule out metaphysical nihilism, the claim that there might have been nothing. In this brief note, I argue that the two positions can be made compatible by modifying the relationship (...) between possibilities and possible worlds. (shrink)

‘Fundamental’ is a prime example of what philosopher John Post called an “accordion word”: highly flexible and capable of expanding or contracting depending on context. Physicists and many cosmologists will view their domain as fundamental, and one will often see the expression ‘fundamental physics’ to describe an actual subject area—the idea being that such practitioners are dealing in ‘compositional ultimates’.

Public health involves the application of a wide variety of scientific and non-scientific disciplines to the very practical problems of improving population health and preventing disease. Public health has received surprisingly little attention from philosophers of science. In this chapter we consider some neglected but important philosophical aspects of the science of public health.