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)

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)

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)

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)

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.

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.

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)

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)

We find that E. J. Lowe’s resolution to David Lewis’s problem of temporary intrinsics is wrong, but not quite for the reasons adduced by Lewis himself. Our discussion hinges on a connection between state-independent properties and intrinsic properties.

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)

During its forty year lifespan, string theory has always had the power to divide, being called both a 'theory of everything' and a 'theory of nothing'. Critics have even questioned whether it qualifies as a scientific theory at all. This book adopts an objective stance, standing back from the question of the truth or falsity of string theory and instead focusing on how it came to be and how it came to occupy its present position in physics. An unexpectedly rich (...) history is revealed, with deep connections to our most well-established physical theories. Fully self-contained and written in a lively fashion, the book will appeal to a wide variety of readers from novice to specialist. (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)

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.

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

‘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)

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.

This book investigates the metaphysical position of dual-aspect monism, with particular emphasis on the concept of meaning as a fundamental feature of the fabric of reality.

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.

Interpreting physical theories -- General concepts of physics -- Symmetries in physics -- Getting philosophy from symmetry -- Further adventures in space and time -- Linking micro to macro -- Quantum philosophy -- On the edge : a snapshot of advanced topics.

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

Stephen Wolfram has recently outlined an unorthodox, multicomputational approach to fundamental theory, encompassing not only physics but also mathematics in a structure he calls The Ruliad, understood to be the entangled limit of all possible computations. In this framework, physical laws arise from the the sampling of the Ruliad by observers (including us). This naturally leads to several conceptual issues, such as what kind of object is the Ruliad? What is the nature of the observers carrying out the sampling, and (...) how do they relate to the Ruliad itself? What is the precise nature of the sampling? This paper provides a philosophical examination of these questions, and other related foundational issues, including the identification of a limitation that must face any attempt to describe or model reality in such a way that the modeller-observers are included. (shrink)

Philosophy, science, and history -- Logic and philosophy of science -- Demarcation and the scientific method -- The nature of scientific theories.

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.

In their modern classic ``What Price Substantivalism? The Hole Story'' Earman and Norton argued that substantivalism about spacetime points implies that general relativity is indeterministic and, for that reason, must be rejected as a candidate ontology for the theory. More recently, Earman has cottoned on to a related argument (in fact, related to a \emph{response} to the hole argument) that arises in the context of canonical general relativity, according to which the enforcing of determinism along standard lines---using the machinery of (...) gauge theory---leads to a `frozen universe' picture (grounded in an absence of changes in values of general relativity's observables). \emph{Prima facie} this would seem to land the anti-substantivalist in waters at least as deep as those that Earman and Norton argued troubled substantivalism. In this paper I introduce the argument in what I think are clearer terms than Earman's, and assess his treatment of the problem. For the most part I agree with Earman about the nature of the problem, but I find aspects of his discussion wanting, especially as regards his proposed ontology. I argue that ontological sense can be made of the changelessness if a structuralist stance is adopted with respect to a natural class of observables. (shrink)

Why life’s shortness—more than anything else—is what makes it meaningful Death might seem to render pointless all our attempts to create a meaningful life. Doesn’t meaning require transcending death through an afterlife or in some other way? On the contrary, Dean Rickles argues, life without death would be like playing tennis without a net. Only constraints—and death is the ultimate constraint—make our actions meaningful. In Life Is Short, Rickles explains why the finiteness and shortness of life is (...) the essence of its meaning—and how this insight is the key to making the most of the time we do have. Life Is Short explores how death limits our options and forces us to make choices that forge a life and give the world meaning. But people often live in a state of indecision, in a misguided attempt to keep their options open. This provisional way of living—always looking elsewhere, to the future, to other people, to other ways of being, and never committing to what one has or, alternatively, putting in the time and energy to achieve what one wants—is a big mistake, and Life Is Short tells readers how to avoid this trap. By reminding us how extraordinary it is that we have any time to live at all, Life Is Short challenges us to rethink what gives life meaning and how to make the most of it. (shrink)

A deeper meaning for quantum theory is presented, integrating recent developments in participatory realist approaches to quantum mechanics with older ideas involving ineffability and nothingness. I argue that Schelling's notion of the Godhead serves as a useful way of interpreting a superposition which then grounds both our freedom and the indeterminacy of quantum phenomena that makes the theory function.

This book explores the many and diverse ways in which nothingness is weaved into the fabric of our existence. It can express the very ground of reality or a cessation of mind: a winking out, as well as being a guide for painting meditative states. It is inescapably linked with the divine in many traditions as a precondition of our existence. It is the Pleroma before consciousness and the gateway to enlightenment. While these essays are indeed wide ranging and eclectic, (...) they share one theme in common: nothingness is not nothing. (shrink)

In this article, we discuss a hypothesis to explain the preferential synthesis of the superoxide sensitive form of aconitase in mitochondria and the phenotype observed in manganese superoxide dismutase mutant mice, which show a gross over accumulation of stored fat in liver. The model proposes that intermediary metabolism is redox regulated by mitochondrial superoxide generated during mitochondrial respiration. This regulates the level of reducing equivalents (NADH) entering the electron transport chain (ETC) through the reversible inactivation of mitochondrial aconitase. This control (...) mechanism has a dual function; firstly, it regulates levels of superoxide generated by the ETC and, secondly, it fine‐tunes metabolism by channeling citrate either for the production of NADH for energy metabolism or diverting it for the synthesis of fats. In this setting, the mitochondrial redox state influences metabolic decisions via a superoxide–aconitase rheostat. BioEssays 26:894–900, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

We review some recent strands in the philosophy and physics of time. We explain the new orthodoxy denying time any fundamental status, and then turn to several proposals that deny this. There is a standard procedure to square the opposing views by looking at the way agents are embedded in the universe. This has also been questioned by some recent work. We focus on Lee Smolin’s recent work in this vein and on his view that novelty and freedom pose problems (...) for anti-fundamentalist views. We ultimately defend this component. (shrink)

This (somewhat polemical) paper focuses on the ontological nature of money and draws comparisons to the ontological status of gauge freedom in physics. The parallels allow us to move beyond the social constructivist theories of Searle et al., and thereby avoid some pitfalls with such views. Since we have a reasonably good grasp of the ontological features in the physics context, we can pull back lessons from there onto the economic domain. In general, we find that this approach offers a (...) nice lens through which to view the ontological peculiarities of money. (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’.