A possible way out of the conundrum of quantum gravity is the proposal that general relativity (GR) emerges from an underlying microscopic description. Despite recent interest in the emergent gravity program within the physics as well as the philosophy community, an assessment of the general motivation for this idea is lacking at the moment. We intend to fill this gap in the literature by discussing the main arguments in favour of the hypothesis that the metric field and its dynamics are (...) emergent. First, we distinguish between microstructure inspired from GR, such as through quantization or discretization, and microstructure that is not directly motivated from GR, such as strings, quantum bits or condensed matter fields. The emergent gravity approach can then be defined as the view that the metric field and its dynamics are derivable from the latter type of microstructure. Subsequently, we assess in how far the following properties of (semi-classical) GR are suggestive of underlying microstructure: (1) the metric's universal coupling to matter fields, (2) perturbative non-renormalizability, (3) black hole thermodynamics, and (4) the holographic principle. In the conclusion we formalize the general structure of the plausibility arguments put forward. (shrink)

Analogue experiments have attracted interest for their potential to shed light on inaccessible domains. For instance, ‘dumb holes’ in fluids and Bose–Einstein condensates, as analogues of black holes, have been promoted as means of confirming the existence of Hawking radiation in real black holes. We compare analogue experiments with other cases of experiment and simulation in physics. We argue—contra recent claims in the philosophical literature—that analogue experiments are not capable of confirming the existence of particular phenomena in inaccessible target systems. (...) As they must assume the physical adequacy of the modelling framework used to describe the inaccessible target system, arguments to the conclusion that analogue experiments can yield confirmation for phenomena in those target systems, such as Hawking radiation in black holes, beg the question. (shrink)

It has long been thought that observing distinctive traces of quantum gravity in a laboratory setting is effectively impossible, since gravity is so much weaker than all the other familiar forces in particle physics. But the quantum gravity phenomenology community today seeks to do the (effectively) impossible, using a challenging novel class of `tabletop' Gravitationally Induced Entanglement (GIE) experiments, surveyed here. The hypothesized outcomes of the GIE experiments are claimed by some (but disputed by others) to provide a `witness' of (...) the underlying quantum nature of gravity in the non-relativistic limit, using superpositions of Planck-mass bodies. We inspect what sort of achievement it would possibly be to perform GIE experiments, as proposed, ultimately arguing that the positive claim of witness is equivocal. Despite various sweeping arguments to the contrary in the vicinity of quantum information theory or given low-energy quantum gravity, whether or not one can claim to witness the quantum nature of the gravitational field in these experiments decisively depends on which out of two legitimate modelling paradigms one finds oneself in. However, by situating GIE experiments in a tradition of existing experiments aimed at making gravity interestingly quantum in the laboratory, we argue that, independently of witnessing or paradigms, there are powerful reasons to perform the experiments, and that their successful undertaking would indeed be a major advance in physics. (shrink)

We show by means of the AdS/CFT correspondence in the context of quantum gravity how inter-representational relations—loosely speaking relations among different equivalent representations of one and the same physics—can play out as a tool for intra-theoretical developments and thus boost theory development in the context of discovery. More precisely, we first show that, as a duality, the AdS/CFT correspondence cannot in itself testify to the quantum origin of gravity (though it may be utilized for this purpose). We then establish through (...) two case studies from emergent gravity (Jacobson (2016); Verlinde (2017)) that the holographic AdS/CFT correspondence can, however, still excel as a guiding principle towards the quantum origin of gravity (similar in nature to quantisation). (shrink)

Introduction for the Synthese Special Issue on Spacetime Functionalism.

We discuss the status of gravitational radiation in Newtonian theories. In order to do so, we consider various options for interpreting the Poisson equation as encoding propagating solutions, reflect on the extent to which limit considerations from general relativity can shed light on the Poisson equation’s conceptual status, and discuss various senses in which the Poisson equation counts as a dynamical equation.

How does metaphysical necessity relate to the modal force often associated with natural laws? Fine argues that natural necessity can neither be obtained from metaphysical necessity via forms of restriction nor of relativization — and therefore pleads for modal pluralism concerning natural and metaphysical necessity. Wolff, 898–906, 2013) aims at providing illustrative examples in support of applying Fine’s view to the laws of nature with specific recourse to the laws of physics: On the one hand, Wolff takes it that equations (...) of motion can count as examples of physical laws that are only naturally but not metaphysically necessary. On the other hand, Wolff argues that a certain conservation law obtainable via Noether’s second theorem is an instance of a metaphysically necessary physical law. I show how Wolff’s example for a putatively metaphysically necessary conservation law fails but argue that so-called topological currents can nevertheless count as metaphysically necessary conservation laws carrying physical content. I conclude with a remark on employing physics to answer questions in metaphysics. (shrink)

Prominently, Norton argues against constructivism about spacetime theories, the doctrine that spatiotemporal structure in the dynamics only has derivative status. Among other things, he accuses Brown and Pooley's dynamical approach to special relativity of being merely half-way constructivist: setting up relativistic fields as presupposed in the dynamical approach to special relativity already requires spatiotemporal background structure. We first assess a recent solution proposal by Menon and then provide our very own defense of constructivism along two independent lines.

Recent work in the physics literature demonstrates that, in particular classes of rotating spacetimes, physical light rays in general do not traverse null geodesics. Having presented this result, we discuss its philosophical significance, both for the clock hypothesis (and, in particular, a recent purported proof thereof for light clocks), and for the operational meaning of the metric field. 1Introduction 2Fletcher's Theorem 2.1Maudlin on the clock hypothesis in special relativity 2.2Fletcher’s result in special relativity 2.3Fletcher’s theorem in general relativity 3Electromagnetism and (...) the Geometrical-Optical Limit 3.1Maxwell’s equations in curved spacetime 3.2The geometrical-optical limit 3.3Rotating spacetimes 3.4Aren’t Gödel spacetimes unphysical? 4The Clock Hypothesis and Chronogeometry 4.1Natural and mathematical observations 4.2Clock registry discord 4.3Chronogeometry 5Conclusion. (shrink)

In a recent paper, Tuomas Tahko has argued for a hybrid view of the laws of nature, according to which some physical laws are metaphysically necessary, while others are metaphysically contingent. In this paper, we show that his criterion for distinguishing between these two kinds of laws — which crucially relies on the essences of natural kinds — is on its own unsatisfactory. We then propose an alternative way of drawing the metaphysically necessary/contingent distinction for laws of physics based on (...) the central kinematical/dynamical distinction used in physical theorising, and argue that the criterion can be used to amend Tahko’s own account, but also that it can be combined with different metaphysical views about the source of necessity. (shrink)

Two approaches to elevating certain laws of nature over others have come to prominence recently. On the one hand, according to the meta-laws approach, there are meta-laws, laws which relate to laws as those laws relate to particular facts. On the other hand, according to the modal, or non-absolutist, approach, some laws are necessary in a stricter sense than others. Both approaches play an important role in current research, questioning the ‘orthodoxy’ represented by the leading philosophical theories of natural laws—Humeanism, (...) the DTA view, dispositional essentialism and primitivism. This paper clarifies the relations between these two emerging approaches, as well as their applicability to physical laws and the status of the challenges they pose for standard theories of laws of nature. We first argue that, despite some significant similarities between the two approaches (especially in the context of Lange’s counterfactual account of laws), they are in general distinct and largely independent of each other. Then, we argue that the support for meta-laws from physical theory and practice is more questionable than usually presented. (shrink)

The empirical coherence problem of quantum gravity is the worry that a theory which does not fundamentally contain local beables located in space and time—such as is arguably the case for certain approaches to quantum gravity—cannot be connected to measurements and thus has its prospects of being empirically adequate undermined. Spacetime functionalism à la Lam and Wüthrich is said to solve this empirical coherence problem as well as bridging a severe conceptual gap between spatiotemporal structures of classical spacetime theories on (...) the one hand, and the non-spatiotemporal structures in quantum gravity approaches on the other hand. The aim of this essay is to offer a deflationary account of both the empirical coherence problem and the spatiotemporal gap problem as they are claimed to arise at least prima facie for current theories of quantum gravity by Huggett and Wüthrich :276–285, 2013), Lam and Wüthrich and Le Bihan. I defend the view that spacetime functionalism is set up to address a problem which can usually be solved without it; and that it is wrongly claimed to solve another problem which for any actual account of quantum gravity is in fact currently non-existent anyway. (shrink)

Important features of space and time are taken to be missing in quantum gravity, allegedly requiring an explanation of the emergence of spacetime from non-spatio-temporal theories. In this paper, we argue that the explanatory gap between general relativity and non-spatio- temporal quantum gravity theories might significantly be reduced with two moves. First, we point out that spacetime is already partially missing in the context of general relativity when understood from a dynamical perspective. Second, we argue that most approaches to quantum (...) gravity already start with an in-built distinction between structures to which the asymmetry between space and time can be traced back. (shrink)

The empirical coherence problem of quantum gravity is the worry that a theory which does not fundamentally contain local beables located in space and time—such as is arguably the case for certain approaches to quantum gravity—cannot be connected to measurements and thus has its prospects of being empirically adequate undermined. Spacetime functionalism à la Lam and Wüthrich is said to solve this empirical coherence problem as well as bridging a severe conceptual gap between spatiotemporal structures of classical spacetime theories on (...) the one hand, and the non-spatiotemporal structures in quantum gravity approaches on the other hand. The aim of this essay is to offer a deflationary account of both the empirical coherence problem and the spatiotemporal gap problem as they are claimed to arise at least prima facie for current theories of quantum gravity by Huggett and Wüthrich :276–285, 2013), Lam and Wüthrich and Le Bihan. I defend the view that spacetime functionalism is set up to address a problem which can usually be solved without it; and that it is wrongly claimed to solve another problem which for any actual account of quantum gravity is in fact currently non-existent anyway. (shrink)

Recent work in the physics literature demonstrates that, in particular classes of rotating spacetimes, physical light rays in general do not traverse null geodesics. Having presented this result, we discuss its philosophical significance, both for the clock hypothesis, and for the operational meaning of the metric field.

Philosophy Compass, Volume 17, Issue 4, April 2022.

The self-interaction spin-2 approach to GR has been extremely influential in the particle physics community. Leaving no doubt regarding its heuristic value, we argue that any view of the metric field of GR as nothing but a stand-in for a self-coupling field in at spacetime runs into a dilemma: either the view is physically incomplete in so far as it requires recourse to GR after all, or it leads to an absurd multiplication of alternative viewpoints on GR rendering any understanding (...) of the metric field as nothing but a spin-2 field in at spacetime unjustified. (shrink)

Principles are central to physical reasoning, particularly in the search for a theory of quantum gravity (QG), where novel empirical data is lacking. One principle widely adopted in the search for QG is UV completion: the idea that a theory should (formally) hold up to all possible high energies. We argue---/contra/ standard scientific practice---that UV-completion is poorly-motivated as a guiding principle in theory-construction, and cannot be used as a criterion of theory-justification in the search for QG. For this, we explore (...) the reasons for expecting, or desiring, a UV-complete theory, as well as analyse how UV completion is used, and how it should be used, in various specific approaches to QG. (shrink)

Principles are central to physical reasoning, particularly in the search for a theory of quantum gravity, where novel empirical data are lacking. One principle widely adopted in the search for QG is ultraviolet completion: the idea that a theory should hold up to all possible high energies. We argue— contra standard scientific practice—that UV-completion is poorly motivated as a guiding principle in theory-construction, and cannot be used as a criterion of theory-justification in the search for QG. For this, we explore (...) the reasons for expecting, or desiring, a UV-complete theory, as well as analyse how UV-completion is used, and how it should be used, in various specific approaches to QG. 1Introduction 1.1Principles in theory development and evaluation 2Primer on UV-Completion, Renormalizability, and All That 2.1Renormalizability and UV-completion 2.2Other forms of UV-completion 3Why Should QG Be UV-Complete? 3.1UV-completion and fundamentality 3.2UV-completion and minimal length 4UV-Completion in Different Approaches to QG 4.1String theory 4.2Asymptotic safety 4.3Causal dynamical triangulation 4.4Higher derivative approaches 4.5Supergravity 4.6Causal set theory 4.7Canonical QG 4.8Loop quantum gravity 4.9Approaches based on alternative gravitational theories 4.10Emergent gravity approaches 5UV-Completion as a Guiding Principle in QG 6Conclusion. (shrink)

A common feature of all standard theories of the laws of nature is that they are "absolutist": They take laws to be either all metaphysically necessary or all contingent. Science, however, gives us reason to think that there are laws of both kinds, suggesting that standard theories should make way for "non-absolutist" alternatives: theories which accommodate laws of both modal statuses. In this paper, we set out three explanatory challenges for any candidate non-absolutist theory and discuss the prospects of the (...) two extant candidates in light of these challenges. We then develop our own non-absolutist theory, the essentialist DTA account, which combines the nomic-necessitation or DTA account with an essentialist approach to metaphysical modality in order to meet the three explanatory challenges. Finally, we argue that the distinction between kinematical and dynamical laws found in physical theories supports both non-absolutism in general and our proposed essentialist DTA view in particular. (shrink)

In a recent article in this journal, Sus purports to account for what have been identified as the ‘two miracles’ of general relativity—that (1) the local symmetries of all dynamical equations for matter fields coincide, and (2) the symmetries of the dynamical equations governing matter fields coincide locally with the symmetries of the metric field—by application of the familiar result that every symmetry of the action is also a symmetry of the resulting equations of motion. In this reply, we argue (...) that, while otherwise exemplary in its clarity, Sus’ paper fails in this regard, for it rests upon a illegitimate application of the aforementioned result. Thus, we conclude, pace Sus, that these two miracles persist in general relativity. (shrink)

Philosophy Compass, Volume 17, Issue 10, October 2022.

Die Suche nach historischen Quellen für die Leibniz’sche Philosophie scheint zunächst unerschöpflich. Durch alle in diesem Band versammelten Arbeiten wird der Einfluss der Philosophie des Aristoteles auf das Leibniz’sche Denken näher umrissen. Ein wesentliches Ziel ist es hierbei, einen Beitrag zur Analyse dieser philosophischen Beziehung zu leisten und zu zeigen, dass auch Aristoteles’ Philosophie nach Ansicht unserer Autoren entscheidend zum Verständnis des Leibniz’schen Denkens beiträgt. Die Texte befassen sich mit wesentlichen Themen der Leibniz’schen Logik und Metaphysik, z. B. mit den (...) Grundbegriffen „Monade“ (und deren „Körperhaftigkeit“), „Entelechie“, „Nous“, mit dem Problem der Individuation (Individuum, Atomismus, Einheit), mit den substanziellen Formen, mit der Wissenschaft im Allgemeinen und der Technik, mit der Transformation der Logik, mit den Prinzipien (nämlich denjenigen des zureichenden Grundes, der Individuation und der Notwendigkeit), mit Zukunft und Kontingenz sowie Vergänglichkeit, mit der Theorie der syllogistischen Folgerung, usw. Diese Themen werden stets in der Gegenüberstellung von Leibniz und Aristoteles behandelt – sie zeigen daher, wie Leibniz aristotelische Thesen übernahm, veränderte oder kritisierte. The search for the historical sources of Leibniz’s philosphy initially seems to be unending. All the essays in this volume outline more clearly the influence of Aristotle’s philosophy on Leibniz’s thought. In this context a fundamental aim is to contribute to the analysis of this philosophical relationship and to demonstrate that Aristotle’s philosophy, in the opinion of our authors, plays a decisive role in the understanding of Leibniz’s thought. The texts address fundamental themes of Leibniz’s logic and metaphysics, e.g. the basic concepts of ‘monads’ (and their ‘corporality’), ‘entelechy’ and ‘nous; the problem of individuation (individual, atomism, unity); substantial forms; knowledge in general, and technology; the transformation of logic; principles (namely those of sufficient grounds, of individuation and of necesssity); future and contingency and transientness; the theory of syllogistic deduction, etc. These themes are regularly considered in the comparison between Leibniz and Aristotle – they demonstrate how Leibniz took over, treated or criticised Aristotelian theses. (shrink)

General relativity cannot be formulated as a perturbatively renormalizable quantum field theory. An argument relying on the validity of the Bekenstein–Hawking entropy formula aims at dismissing gravity as non-renormalizable per se, against hopes that d-dimensional GR could turn out to have a non-perturbatively renormalizable d–dimensional quantum field theoretic formulation. In this note we discuss various forms of highly problematic semi-classical extrapolations assumed by both sides of the debate concerning what we call The Entropy Argument, and show that a large class (...) of dimensional reduction scenarios leads to the blow-up of Bekenstein–Hawking entropy. (shrink)

In many countries, science is challenged by science-related populism, which deems the common sense of “ordinary people” superior to the knowledge of “academic elites”. Individual support for science-related populism can be associated with people’s communication behavior: On the one hand, people who hold science-related populist attitudes may inform themselves differently about science; they may even be disconnected from societal discourse around science. On the other hand, they may communicate more actively on social media and in interpersonal conversations. We test this (...) using nationally representative survey data from Switzerland. Results show that science-related populists use TV and social networking sites more often to get information about science. They are also more likely to communicate about science in social media comments. However, science-related populist attitudes are not associated with a general preference for social media over journalistic media. Science-related populism has thus not (yet) fueled a “science-related public disconnection”. We also run multiverse analyses, which show further nuances of our results, and discuss implications for science communication. (shrink)

For over a century, the Danish thinker Søren Kierkegaard has been at the center of a number of important discussions, concerning not only philosophy and theology, but also, more recently, fields such as social thought, psychology, and contemporary aesthetics, especially literary theory. Despite his relatively short life, Kierkegaard was an extraordinarily prolific writer, as attested to by the 26-volume Princeton University Press edition of all of his published writings. But Kierkegaard left behind nearly as much unpublished writing, most of which (...) consists of what are called his "journals and notebooks." Kierkegaard has long been recognized as one of history's great journal keepers, but only rather small portions of his journals and notebooks are what we usually understand by the term “diaries.” By far the greater part of Kierkegaard’s journals and notebooks consists of reflections on a myriad of subjects—philosophical, religious, political, personal. Studying his journals and notebooks takes us into his workshop, where we can see his entire universe of thought. We can witness the genesis of his published works, to be sure—but we can also see whole galaxies of concepts, new insights, and fragments, large and small, of partially completed but unpublished works. Kierkegaard’s Journals and Notebooks enables us to see the thinker in dialogue with his times and with himself. Kierkegaard wrote his journals in a two-column format, one for his initial entries and the second for the extensive marginal comments that he added later. This edition of the journals reproduces this format, includes several photographs of original manuscript pages, and contains extensive scholarly commentary on the various entries and on the history of the manuscripts being reproduced. Volume 9 of this 11-volume series includes five of Kierkegaard’s important “NB” journals, which span from June 1852 to August 1854. This period was marked by Kierkegaard’s increasing preoccupation with what he saw as an unbridgeable gulf in Christianity—between the absolute ideal of the religion of the New Testament and the official, state-sanctioned culture of “Christendom,” which, embodied by the Danish People’s Church, Kierkegaard rejected with increasing vehemence. Crucially, Kierkegaard’s nemesis, Bishop Jakob Peter Mynster, died during this period and, in the months following, Kierkegaard can be seen moving inexorably toward the famous “attack on Christendom” with which he ended his life. (shrink)

For over a century, the Danish thinker Søren Kierkegaard has been at the center of a number of important discussions, concerning not only philosophy and theology, but also, more recently, fields such as social thought, psychology, and contemporary aesthetics, especially literary theory. Despite his relatively short life, Kierkegaard was an extraordinarily prolific writer, as attested to by the 26-volume Princeton University Press edition of all of his published writings. But Kierkegaard left behind nearly as much unpublished writing, most of which (...) consists of what are called his "journals and notebooks." Kierkegaard has long been recognized as one of history's great journal keepers, but only rather small portions of his journals and notebooks are what we usually understand by the term "diaries." By far the greater part of Kierkegaard's journals and notebooks consists of reflections on a myriad of subjects--philosophical, religious, political, personal. Studying his journals and notebooks takes us into his workshop, where we can see his entire universe of thought. We can witness the genesis of his published works, to be sure--but we can also see whole galaxies of concepts, new insights, and fragments, large and small, of partially completed but unpublished works. Kierkegaard's Journals and Notebooks enables us to see the thinker in dialogue with his times and with himself. Volume 5 of this 11-volume series includes five of Kierkegaard's important "NB" journals, covering the months from summer 1848 through early May 1849. This was a turbulent period both in the history of Denmark--which was experiencing the immediate aftermath of revolution and the fall of absolutism, a continuing war with the German states, and the replacement of the State Church with the Danish People's Church--and for Kierkegaard personally. The journals in the present volume include Kierkegaard's reactions to the political upheaval, a retrospective account of his audiences with King Christian VIII, deliberations about publishing an autobiographical explanation of his writings, and an increasingly harsh critique of the Danish Church. These journals also reflect Kierkegaard's deep concern over his collision with the satirical journal Corsair, an experience that helped radicalize his view of "essential Christianity" and caused him to ponder the meaning of martyrdom. Kierkegaard wrote his journals in a two-column format, one for his initial entries and the second for the extensive marginal comments that he added later. This edition of the journals reproduces this format, includes several photographs of original manuscript pages, and contains extensive scholarly commentary on the various entries and on the history of the manuscripts being reproduced. (shrink)

For over a century, the Danish thinker Søren Kierkegaard has been at the center of a number of important discussions, concerning not only philosophy and theology, but also, more recently, fields such as social thought, psychology, and contemporary aesthetics, especially literary theory. Despite his relatively short life, Kierkegaard was an extraordinarily prolific writer, as attested to by the 26-volume Princeton University Press edition of all of his published writings. But Kierkegaard left behind nearly as much unpublished writing, most of which (...) consists of what are called his "journals and notebooks." Kierkegaard has long been recognized as one of history's great journal keepers, but only rather small portions of his journals and notebooks are what we usually understand by the term "diaries." By far the greater part of Kierkegaard's journals and notebooks consists of reflections on a myriad of subjects--philosophical, religious, political, personal. Studying his journals and notebooks takes us into his workshop, where we can see his entire universe of thought. We can witness the genesis of his published works, to be sure--but we can also see whole galaxies of concepts, new insights, and fragments, large and small, of partially completed but unpublished works. Kierkegaard's Journals and Notebooks enables us to see the thinker in dialogue with his times and with himself. Volume 4 of this 11-volume series includes the first five of Kierkegaard's well-known "NB" journals, which contain, in addition to a great many reflections on his own life, a wealth of thoughts on theological matters, as well as on Kierkegaard's times, including political developments and the daily press. Kierkegaard wrote his journals in a two-column format, one for his initial entries and the second for the extensive marginal comments that he added later. This edition of the journals reproduces this format, includes several photographs of original manuscript pages, and contains extensive scholarly commentary on the various entries and on the history of the manuscripts being reproduced. (shrink)

This book undertakes an extensive study of the constellation of two eminent thinkers of post-idealism for the first time. The contributions in this volume analyze the relationship between Schopenhauer and Kierkegaard systematically and historically from a number of thematic perspectives: metaphysics and ethics, freedom and original sin, existential philosophy and the theory of suffering, art and aesthetics, religion and science. The book also goes into Kierkegaard s explicit disagreement with Schopenhauer and last but not least discusses the conflicting poles of (...) idealism and modernity. The volume is rounded off by a first complete and annotated German translation of the notes on Schopenhauer, which Kierkegaard wrote in his late journals.". (shrink)

A cursory observer of Cree Indians in the small Canadian community we will describe would conclude that they are an “ acculturated “ but “deviant” company of persons. They give the appearance of being acculturated in that there is little in evidence of the distinctive culture they once had. White members of the community see nothing in visible Indian behavior which evokes the image of Charles Russell's noble warrior savages. To the contrary, whites regard Indians as social outcasts and renegades, (...) and base this judgment on that Indian behavior they choose to see. Indians drink to excess, men and women alike; they get in fights and get arrested by the police; they panhandle; and they break all sorts of rules governing the conduct of respectable people in respectable public places. All of this whites abhor, and use to explain Indian authorship of Indians’ social and economic marginality. If they wished to, so the argument goes, Indians could easily better themselves— they merely and simply want in initiative. (shrink)