This chapter contains sections titled: What Dating Is The Elevator Image Strategies Elevator Ethics Concluding Remarks.

A number of philosophers have argued in favour of extended simples on the grounds that they are needed by fundamental physics. The arguments typically appeal to theories of quantum gravity. To date, the argument in favour of extended simples has ignored the fact that the very existence of spacetime is put under pressure by quantum gravity. We thus consider the case for extended simples in the context of different views on the existence of spacetime. We show that the case for (...) extended simples based on physics is far more complex than has been previously thought. We present and then map this complexity, in order to present a much more textured picture of the argument for extended simples. (shrink)

Analogue Gravity Phenomenology is a collection of contributions that cover a vast range of areas in physics, ranging from surface wave propagation in fluids to nonlinear optics. The underlying common aspect of all these topics, and hence the main focus and perspective from which they are explained here, is the attempt to develop analogue models for gravitational systems. The original and main motivation of the field is the verification and study of Hawking radiation from a horizon: the enabling feature is (...) the possibility to generate horizons in the laboratory with a wide range of physical systems that involve a flow of one kind or another. The years around 2010 and onwards witnessed a sudden surge of experimental activity in this expanding field of research. However, building an expertise in analogue gravity requires the researcher to be equipped with a rather broad range of knowledge and interests. The aim of this book is to bring the reader up to date with the latest developments and provide the basic background required in order to appreciate the goals, difficulties and success stories in the field of analogue gravity. Each chapter of the book treats a different topic explained in detail by the major experts for each specific discipline. The first chapters give an overview of black hole spacetimes and Hawking radiation before moving on to describe the large variety of analogue spacetimes that have been proposed and are currently under investigation. This introductory part is then followed by an in-depth description of what are currently the three most promising analogue spacetime settings, namely surface waves in flowing fluids, acoustic oscillations in Bose-Einstein condensates and electromagnetic waves in nonlinear optics. Both theory and experimental endeavours are explained in detail. The final chapters refer to other aspects of analogue gravity beyond the study of Hawking radiation, such as Lorentz invariance violations and Brownian motion in curved spacetimes, before concluding with a return to the origins of the field and a description of the available observational evidence for horizons in astrophysical black holes. (shrink)

This paper elaborates on an intrinsically quantum approach to gravity, which begins with a general framework for quantum mechanics and then seeks to identify additional mathematical structure on Hilbert space that is responsible for gravity and other phenomena. A key principle in this approach is that of correspondence: this structure should reproduce spacetime, general relativity, and quantum field theory in a limit of weak gravitational fields. A central question is that of “Einstein separability,” and asks how to define mutually independent (...) subsystems, e.g. through localization. Familiar definitions involving tensor products or operator subalgebras do not clearly accomplish this in gravity, as is seen in the correspondence limit. Instead, gravitational behavior, particularly gauge invariance, suggests a network of Hilbert subspaces related via inclusion maps, contrasting with other approaches based on tensor-factorized Hilbert spaces. Any such localization structure is also expected to place strong constraints on evolution, which are also supplemented by the constraint of unitarity. (shrink)

The human species’ adaptive advantage is driven by its ability to build new material structures and artefacts. Engineering is the modern manifestation of this building instinct, and its advent has made the construction and use of technologies the central pattern of human life. In parallel, efficiency, the overarching narrative driving technology and related life practices, has pervaded most occupations as a value, forming a cultural backdrop that implicitly guides decisions and behaviour. We examine the process through which this backdrop has (...) developed, and argue that it emerged through the constant presence and use of built artefacts and structures, which function as manifestations of the engineering value of efficiency. The constant presence and use of built structures leads to the slow percolation of their building values into society, forming a cultural narrative that emphasises efficiency. This narrative then feeds back, to further reinforce efficiency-driven engineering processes. This loop creates a runaway building system that is highly resistant to change, even when faced with the prospect of the species going extinct. Any effort towards sustainability can be successful only when this all-pervading – and hence invisible – building loop is made explicit, and compensated for, through a counter-loop where building manifests sustainable engineering values. As a first step in revealing this structure, we characterise the emergence of the efficiency value as a cultural narrative, and analyse its wide-ranging environmental effects. We then present the design principle of ‘Solving for Pattern’ (SfP) as an illustrative contrast case. SfP, first articulated by Wendell Berry, focuses on interconnectedness and flourishing of all species as central design principles. We argue that these ecological principles can be extended to engineering, and can thus support the development of a robust operational-level building movement that manifests value systems oriented towards sustainability. To ground this proposal in actual practice, we outline two case studies of technology design that illustrates SfP. We also discuss three cases that illustrate SfP at a larger scale, and examine how these extend existing design approaches such as systems engineering. We conclude with a proposal to include SfP in engineering education curricula, to facilitate a faster cultural shift towards flourishing, which is required given the limited time window available to move to sustainable building practices. (shrink)

It is here argued that Halley's comet had a more pivotal role than has hitherto been believed in triggering Newton's acceptance of the law of gravity, dispelling his belief in Descartes' theory of vortices. It is found that historians have been unduly prone to credit Newton with dynamical insights at an earlier date than is warranted by the historical documents. A more convincing account of the transition from the period of Newton's alchemical researches of the 1670s to that of his (...) dynamical insights in the 1680s thereby becomes feasible. Acceptance of a principle of rectilinear inertia was a precondition for formulating the law. (shrink)

This work is intended to illustrate how gravity is a major factor in shaping life as we know it. It will be argued here that gravity has an influence at all levels, from particles to planets. Moreover, that any change in gravitational acceleration will have a direct and inevitable impact upon the form of any organism. From a fresh perspective some of the mysteries of evolution will be examined in light of gravity and its ubiquity. The creatures of the (...) Earth, past and present, have taken on many forms but why is it that all the terrestrial mega fauna have become extinct? Why is it that reptiles today are only a fraction of the size of their ancestors? Why is it that an insect never reaches the size of a large mammal? What is Tensegrity and how does it influence the structure of the cell, the protein and the larger body of an organism? Many of the considerations here are taken from novel scientific thinkers; these will be outlined and discussed. Many of the ideas may seem controversial and provocative but the author makes no apology for their inclusion. Indeed the purpose here is to stimulate a debate that hopefully leads to a better understanding of life and its evolution. (shrink)

How does the physics community deal with the subsequent work of a scientist whose earlier work has been regarded as incorrect? An interesting case of this involves Joseph Weber whose claim to have observed gravitational waves was rejected by virtually all of the physics community, although Weber himself continued to defend his work until his death in 2000. In the course of this defense Weber made a startling suggestion regarding the scattering of neutrinos. I will summarize the history of gravity (...) waves including the rejection of Weber's claim around 1975, his later work on gravity waves, and examine the reaction of the physics community to his neutrino hypothesis.----------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------- ---------------------------------------------------. (shrink)

The central thesis of this paper is that contemporary theoretical physics is grounded in philosophical presuppositions that make it difficult to effectively address the problems of subject-object interaction and discontinuity inherent to quantum gravity. The core objectivist assumption implicit in relativity theory and quantum mechanics is uncovered and we see that, in string theory, this assumption leads into contradiction. To address this challenge, a new philosophical foundation is proposed based on the phenomenology of Maurice Merleau-Ponty and Martin Heidegger. Then, through (...) the application of qualitative topology and hypernumbers, phenomenological ideas about space, time, and dimension are brought into focus so as to provide specific solutions to the problems of force-field generation and unification. The phenomenological string theory that results speaks to the inconclusiveness of conventional string theory and resolves its core contradiction. (shrink)

What it would take to vindicate folk temporal error theory? This question is significant against a backdrop of new views in quantum gravity—so-called timeless physical theories—that claim to eliminate time by eliminating a one-dimensional substructure of ordered temporal instants. Ought we to conclude that if these views are correct, nothing satisfies the folk concept of time and hence that folk temporal error theory is true? In light of evidence we gathered, we argue that physical theories that entirely eliminate an ordered (...) substructure vindicate folk temporal error theory. (shrink)

Why is gravity so weak? Why are the color forces between quarks so strong? In the standard model of particle physics, why are there so many different energies at which distinct fundamental forces are supposed to "unify", and what determines these widely separated energies? The answers to these questions may be provided by extra dimensions curled into loops a millimeter around. In other words, our universe may be only a millimeter across, in directions we are not yet able to perceive. (...) In this column we'll consider millimeter-size extra-dimensional loops and their implications. (shrink)

One of the great challenges for 21st century physics is to quantize gravity and generate a theory that will unify gravity with the other three fundamental forces of nature. This paper takes the (heretical) point of view that gravity may be an inherently classical, i.e., nonquantum, phenomenon and investigates the experimental consequences of such a conjecture. At present there is no experimental evidence of the quantum nature of gravity and the likelihood of definitive tests in the future is not at (...) all certain. If gravity is, indeed, a nonquantum phenomenon, then it is suggested that evidence will most likely appear at mesoscopic scales. (shrink)

Quantum gravity poses the problem of merging quantum mechanics and general relativity, the two great conceptual revolutions in the physics of the twentieth century. The loop and spinfoam approach, presented in this book, is one of the leading research programs in the field. The first part of the book discusses the reformulation of the basis of classical and quantum Hamiltonian physics required by general relativity. The second part covers the basic technical research directions. Appendices include a detailed history of the (...) subject of quantum gravity, hard-to-find mathematical material, and a discussion of some philosophical issues raised by the subject. This fascinating text is ideal for graduate students entering the field, as well as researchers already working in quantum gravity. It will also appeal to philosophers and other scholars interested in the nature of space and time. (shrink)

Eternalism, the view that what we regard locally as being located in the past, the present and the future equally exists, is the best ontological account of temporal existence in line with special and general relativity. However, special and general relativity are not fundamental theories and several research programs aim at finding a more fundamental theory of quantum gravity weaving together all we know from relativistic physics and quantum physics. Interestingly, some of these approaches assert that time is not fundamental. (...) If time is not fundamental, what does it entail for eternalism and the standard debate over existence in time? First, I will argue that the non-fundamentality of time to be found in string theory entails standard eternalism. Second, I will argue that the non-fundamentality of time to be found in loop quantum gravity entails atemporal eternalism, namely a novel position in the spirit of standard eternalism. (shrink)

The theory of unconstrained membranes of arbitrary dimension is presented. Their relativistic dynamics is described by an action which is a generalization of the Stueckelberg point-particle action. In the quantum version of the theory, the evolution of a membrane's state is governed by the relativistic Schrödinger equation. Particular stationary solutions correspond to the conventional, constrained membranes. Contrary to the usual practice, our spacetime is identified, not with the embedding space (which brings the problem of compactification), but with a membrane of (...) dimension 4 or higher. A 4-membrane is thus assumed to represent spacetime. The Einstein-Hilbert action emerges as an effective action after functionally integrating out the membrane's embedding functions. (shrink)

Philosophers of physics and physicists have long been intrigued by the analogies and disanalogies between gravitational theories and gauge theories. Indeed, repeated attempts to collapse these disanalogies have made us acutely aware that there are fairly general obstacles to doing so. Nonetheless, there is a special case space-time dimensions) in which gravity is often claimed to be identical to a gauge theory. I subject this claim to philosophical scrutiny in this article. In particular, I analyse how the standard disanalogies can (...) be overcome in dimensions, and consider whether really licenses the interpretation of gravity as a gauge theory. Our conceptual analysis reveals more subtle disanalogies between gravity and gauge, and connects these to interpretive issues in classical and quantum gravity. 1 Introduction1.1 Motivation1.2 Prospectus2 Disanalogies3 Three-dimensional gravity and gauge3.1 gravity3.2 Chern–Simons3.2.1 Cartan geometry3.2.2 Overcoming obst-gauge via Cartan connections3.3 Disanalogies collapsed4 Two More Disanalogies4.1 What about the symmetries?4.2 The phase spaces of the two theories5 Summary and Conclusion. (shrink)

The search for a quantum theory of the gravitational field is one of the great open problems in theoretical physics. This book presents a self-contained discussion of the concepts, methods and applications that can be expected in such a theory. The two main approaches to its construction - the direct quantisation of Einstein's general theory of relativity and string theory - are covered. Whereas the first attempts to construct a viable theory for the gravitational field alone, string theory assumes that (...) a quantum theory of gravity will be achieved only through a unification of all the interactions. However, both employ the general method of quantisation of constrained systems, which is described together with illustrative examples relevant for quantum gravity. There is a detailed presentation of the main approaches employed in quantum general relativity: path-integral quantisation, the background-field method and canonical quantum gravity in the metric, connection and loop formulations. The discussion of string theory centres around its quantum-gravitational aspects and the comparison with quantum general relativity. Physical applications discussed at length include the quantisation of black holes, quantum cosmology, the indications of a discrete structure of spacetime, and the origin of irreversibility. This book will be of interest to researchers and students working in relativity and gravitation, cosmology, quantum field theory and related topics. It will also be of interest to mathematicians and philosophers of science. (shrink)

The Past Hypothesis is the claim that the Boltzmann entropy of the universe was extremely low when the universe began. Can we make sense of this claim when *classical* gravitation is included in the system? I first show that the standard rationale for not worrying about gravity is too quick. If the paper does nothing else, my hope is that it gets the problems induced by gravity the attention they deserve in the foundations of physics. I then try to make (...) plausible a very weak claim: that there is a well-defined Boltzmann entropy that *can* increase in *some* interesting self-gravitating systems. More work is needed before we can say whether this claim answers the threat to the standard explanation of entropy increase. (shrink)

The online dating application has in recent years become a major avenue for meeting potential partners. But while the digital public sphere has gained the attention of political philosophers, a systematic normative evaluation of issues arising in the ‘digital sexual sphere’ is lacking. I provide a philosophical framework for assessing dating app corporation conduct, capturing why people use these apps and their experience so often is unsatisfactory. Identifying dating apps as agents intervening in a social institution necessary (...) for the reproduction of society, with immense power over people's lives, I ask if they exercise their power in line with individuals’ interests. Acknowledging that people have claims to non-interference, equal standing, and choice improvement relating to intimacy, I find that the traditional, non-digital, sexual sphere poses problems to their realisation, especially for sexual minorities. In this context, apps’ potential for justice in the sexual sphere is immense, but unfulfilled. (shrink)

Dispositionalism is the theory of modality according to which all (metaphysical and natural) modal truths are made true by some actual irreducibly dispositional property. The relationship between Dispositionalism and time is yet to be satisfactorily explored. In this paper we contribute to this task by examining how Dispositionalism deals with ‘dated truths’: propositions involving a specific time, e.g. “It might rain at 12.30”. We examine two possible accounts: the first, 'Dated Manifestations Strategy', is the idea that powers are very fine-grained, (...) and tend towards temporally very specific manifestations. We argue that such strategy should not be adopted, for it leads to unnecessary violations of ontological parsimony; it is unable to accommodate an ontology of platonic universals; and it is incapable of offering a principled explanation of the forward-looking nature of powers. We offer an alternative account, the "Duration Strategy", which relies on an independently determined arrow of time and the existence of some “duration facts” that specify how long a power takes to bring about its manifestation. We argue that the Duration Strategy is to be preferred. We then flesh out the account by exploring the connection between powers, duration facts, and processes. (shrink)

Curiously, in some ways gravity is also the strongest force in the universe. It always adds, never subtracts, and can build up until it overwhelms all other forces.. In normal stars gravity is balanced by heat energy from fusion reactions in the star's core. Eventually, however, the hydrogen and heavier elements fueling these reactions are used up, gravity takes over, and the star collapses in on itself. The result is a supernova explosion, which converts a sizable fraction of the star's (...) mass-energy to light, neutrinos, and gravity waves. (shrink)

Social epistemologists use the term hermeneutical injustice to refer to a form of epistemic injustice in which a structural prejudice in the economy of collective interpretive resources results in a person’s inability to understand his/her/their own social experience. This essay argues that the phenomenon of unacknowledged date rapes, that is, when a person experiences sexual assault yet does not conceptualize him/her/their self as a rape victim, should be regarded as a form of hermeneutical injustice. The fact that the concept of (...) date rape has been widely used for at least three decades indicates the intractability of hermeneutical injustices of this sort and the challenges with its overcoming. (shrink)

While it is well known that Plutarch’s De facie in orbe lunae was a major source of inspiration for Galileo’s Sidereus nuncius, its influence on his Dialogo sopra i due massimi sistemi del mondo, and especially on his views on gravity, has not been sufficiently explored. This essay offers the first systematic comparison of Plutarch’s and Galileo’s accounts of gravity by focusing on four themes: the thought experiment of a stone falling in a tunnel passing through the center of the (...) Earth; the account of gravity as a tendency to unite with the whole; the view that the Moon is a separate center of attraction; and the impossibility of attraction by an incorporeal point. The essay analyzes the role that these themes play in De facie and in the Dialogo, trying to understand how Galileo appropriated, reworked, and expanded on Plutarch’s views. (shrink)

It was recognized almost from the original formulation of general relativity that the theory was incomplete because it dealt only with classical, rather than quantum, matter. What must be done in order to complete the theory has been a subject of considerable debate over the last century, and here I just mention a few of the various options that have been suggested for a quantum theory of gravity. The aim of what follows is twofold. First, I address worries about the (...) consistency and physical plausibility of hybrid theories of gravity—theories involving a classical gravitational field and quantum matter fields. Such worries are shown to be unfounded. These hybrid theories—mongrel gravity—in fact comprise the only current, actual theories of gravity that incorporate quantum matter, and they also offer legitimate promise as tools for discovering the full theory of gravity. So my second aim is to highlight these theories as providing an interesting example of scientific revolution in action. I begin to try to draw some philosophical lessons from mongrel gravity theories, but more importantly I try to convince philosophers of physics that they should pay more attention to them. (shrink)

A generalized and unifying viewpoint to both general relativity and quantum mechanics and information is investigated. It may be described as a generaliztion of the concept of reference frame from mechanics to thermodynamics, or from a reference frame linked to an element of a system, and thus, within it, to another reference frame linked to the whole of the system or to any of other similar systems, and thus, out of it. Furthermore, the former is the viewpoint of general relativity, (...) the latter is that of quantum mechanics and information. Ciclicity in the manner of Nicolas Cusanus (Nicolas of Cusa) is complemented as a fundamental and definitive property of any totality, e.g. physically, that of the universe. It has to contain its externality within it somehow being namely the totality. This implies a seemingly paradoxical (in fact, only to common sense rather logically and mathematically) viewpoint for the universe to be repesented within it as each one quant of action according to the fundamental Planck constant. That approach implies the unification of gravity and entanglement correspondiing to the former or latter class of reference frames. An invariance, more general than Einstein's general covariance is to be involved as to both classes of reference frames unifying them. Its essence is the unification of the discrete and cotnitinuous (smooth). That idea underlies implicitly quantum mechanics for Bohr's principle that it study the system of quantum microscopic entities and the macroscopic apparatus desribed uniformly by the smmoth equations of classical physics. (shrink)

The mutual conceptual incompatibility between General Relativity and Quantum Mechanics / Quantum Field Theory is generally seen as the most essential motivation for the development of a theory of Quantum Gravity. It leads to the insight that, if gravity is a fundamental interaction and Quantum Mechanics is universally valid, the gravitational field will have to be quantized, not at least because of the inconsistency of semi-classical theories of gravity. The objective of a theory of Quantum Gravity would then be to (...) identify the quantum properties and the quantum dynamics of the gravitational field. If this means to quantize General Relativity, the general-relativistic identification of the gravitational field with the spacetime metric has to be taken into account. The quantization has to be conceptually adequate, which means in particular that the resulting quantum theory has to be background-independent. This can not be achieved by means of quantum field theoretical procedures. More sophisticated strategies, like those of Loop Quantum Gravity, have to be applied. One of the basic requirements for such a quantization strategy is that the resulting quantum theory has a classical limit that is (at least approximately, and up to the known phenomenology) identical to General Relativity. However, should gravity not be a fundamental, but an induced, residual, emergent interaction, it could very well be an intrinsically classical phenomenon. Should Quantum Mechanics be nonetheless universally valid, we had to assume a quantum substrate from which gravity would result as an emergent classical phenomenon. And there would be no conflict with the arguments against semi-classical theories, because there would be no gravity at all on the substrate level. The gravitational field would not have any quantum properties to be captured by a theory of Quantum Gravity, and a quantization of General Relativity would not lead to any fundamental theory. The objective of a theory of 'Quantum Gravity' would instead be the identification of the quantum substrate from which gravity results. The requirement that the substrate theory has General Relativity as a classical limit – that it reproduces at least the known phenomenology – would remain. The paper tries to give an overview over the main options for theory construction in the field of Quantum Gravity. Because of the still unclear status of gravity and spacetime, it pleads for the necessity of a plurality of conceptually different approaches to Quantum Gravity. (shrink)

Just about every odd year in the early fifth century B.C. has been proposed as the date of the Nemean victory of Pytheas from Aegina, celebrated in Pindar's Fifth Nemean and Bacchylides' thirteenth ode. Scholars have attempted to date both odes with the help of Isthmian 6 and 5, which celebrate victories of a member of the same family and the latter of which at 48ff. refers to Salamis as a recent event. Various interpretations of the victory catalogues in I. (...) 6 and 5 have led to various dates for N. 5 and B. 13. The fullest analysis of the material is that by Severyns, who argues that N. 5 and B. 13 must be at least seven years earlier than I. 5. In his conclusion , however, he still suggests three possible dates for N. 5 and B. 13: 487, 489, and 485 B.C., in what he considers to be the order of likelihood. (shrink)

Physics seems to tell us that there are four fundamental force-fields in nature: the gravitational, the electromagnetic, the weak, and the strong (or interactions). But it also seems to tell us that gravity cannot possibly be a force-field, in the same sense as the other three are. And yet the search for a grand unification of all four force-fields is today one of the hottest pursuits. Is this the result of a simple confusion? This article aims at clarifying this situation (...) by (i) reviewing the gauge-field programme and its conception of unification of force-fields, (ii) examining the various attempts at a gauge theory of gravity, and (iii) articulating the nature of "gauging" and using it to explain the difference between gravity and the other force-fields. (shrink)

This paper considers Newton’s position on gravity’s cause, both conceptually and historically. With respect to the historical question, I argue that while Newton entertained various hypotheses about gravity’s cause, he never endorsed any of them, and in particular, his lack of confidence in the hypothesis of robust and unmediated distant action by matter is explained by an inclination toward certain metaphysical principles. The conceptual problem about gravity’s cause, which I identified earlier along with a deeper problem about individuating substances, is (...) that a decisive conclusion is impossible unless certain speculative aspects of his empiricism are abandoned. In this paper, I situate those conceptual problems in Newton’s natural philosophy. They arise from ideas that push empiricism to potentially self-defeating limits, revealing the danger of allowing immaterial spirits any place in natural philosophy, especially spatially extended spirits supposed capable of co-occupying place with material bodies. Yet because their source ideas are speculative, Newton’s method ensures that these problems pose no threat to his rational mechanics or the profitable core of his empiricism. They are easily avoided by avoiding their source ideas, and when science emerges from natural philosophy, it does so with an ontology unencumbered by immaterial spirits. (shrink)

An axiomatization of the so-called Teleparallel Equivalent to General Relativity is presented. A set of formal and semantic postulates are elaborated from where the physical meaning of various key concepts of the theory are clarified. These concepts include those of inertia, Lorentz and diffeomorphism invariance, and reference frame. It is shown that Teleparallel Gravity admits a wider representation of space-time than General Relativity, allowing to define properties of the gravitational field such as energy and momentum that are usually considered problematic. (...) In this sense, although the dynamical equations of both theories are equivalent, their inequivalence from a physical point of view is demonstrated. Finally, the axiomatic formulation is used to compare Teleparallel Gravity with other theories of gravity based on absolute parallelism such as non-local and f(T) gravity. (shrink)

In the author’s previous contribution to this journal (Rosen 2015), a phenomenological string theory was proposed based on qualitative topology and hypercomplex numbers. The current paper takes this further by delving into the ancient Chinese origin of phenomenological string theory. First, we discover a connection between the Klein bottle, which is crucial to the theory, and the Ho-t’u, a Chinese number archetype central to Taoist cosmology. The two structures are seen to mirror each other in expressing the psychophysical (phenomenological) action (...) pattern at the heart of microphysics. But tackling the question of quantum gravity requires that a whole family of topological dimensions be brought into play. What we find in engaging with these structures is a closely related family of Taoist forebears that, in concert with their successors, provide a blueprint for cosmic evolution. Whereas conventional string theory accounts for the generation of nature’s fundamental forces via a notion of symmetry breaking that is essentially static and thus unable to explain cosmogony successfully, phenomenological/Taoist string theory entails the dialectical interplay of symmetry and asymmetry inherent in the principle of synsymmetry. This dynamic concept of cosmic change is elaborated on in the three concluding sections of the paper. Here, a detailed analysis of cosmogony is offered, first in terms of the theory of dimensional development and its Taoist (yin-yang) counterpart, then in terms of the evolution of the elemental force particles through cycles of expansion and contraction in a spiraling universe. The paper closes by considering the role of the analyst per se in the further evolution of the cosmos. (shrink)

This study analyses the predictions of the General Theory of Relativity (GTR) against a slightly modified version of the standard central mass solution (Schwarzschild solution). It is applied to central gravity in the solar system, the Pioneer spacecraft anomalies (which GTR fails to predict correctly), and planetary orbit distances and times, etc (where GTR is thought consistent.) -/- The modified gravity equation was motivated by a theory originally called ‘TFP’ (Time Flow Physics, 2004). This is now replaced by the ‘Geometric (...) Model’, 2014 [20], which retains the same theory of gravity. This analysis is offered partially as supporting detail for the claim in [20] that the theory is realistic in the solar system and explains the Pioneer anomalies. The overall conclusion is that the model can claim to explain the Pioneer anomalies, contingent on the analysis being independently verified and duplicated of course. -/- However the interest lies beyond testing this theory. To start with, it gives us a realistic scale on which gravity might vary from the accepted theory, remain consistent with most solar-scale astronomical observations. It is found here that the modified gravity equation would appear consistent with GTR for most phenomena, but it would retard the Pioneer spacecraft by about the observed amount (15 seconds or so at time). Hence it is a possible explanation of this anomaly, which as far as I know remains unexplained now for 20 years. -/- It also shows what many philosophers of science have emphasized: the pivotal role of counterfactual reasoning. By putting forward an exact alternative solution, and working through the full explanation, we discover a surprising ‘counterfactual paradox’: the modified theory slightly weakens GTR gravity – and yet the effect is to slow down the Pioneer trajectory, making it appear as if gravity is stronger than GTR. The inference that “there must be some tiny extra force…” (Musser, 1998 [1]) is wrong: there is a second option: “…or there may be a slightly weaker form of gravity than GTR.” . (shrink)

This self-contained letter shows how ψ-epistemic quantum gravity (QG), that is, QG with a ψ-epistemic interpretation of quantum theory, in principle obtains from a deterministic model of the Elementary Process Theory (EPT) that describes an individual process at supersmall (Planck) scale by which a predominantly gravitational interaction takes place. While both ψ-epistemic QG and the model of the EPT remain to be formulated rigorously, this shows how the probabilistic nature of our knowledge of the physical world emerges in a strictly (...) deterministic universe--God does not play dice, it is our knowledge of the outcome of a process that is fundamentally probabilistic. -/- Edit: a completely worked-out and majorly revised version of this letter-type preprint has been published as a book chapter. (shrink)

One prominent criticism of Newtonianism held that gravitational attraction is an occult quality. The charge, pressed most forcefully by Leibniz, claims that Newton had abandoned the intelligibility of mechanism and allowed for an unexplained and inexplicable force in nature. This paper focuses on one of Newton’s replies to this accusation: his claim that gravitation is no more mysterious than phenomena like inertia and impenetrability. I argue that we can understand and motivate this Newtonian position by looking at the account of (...) material substance developed in Newton’s early manuscript essay De gravitatione. This account makes clear Newton’s sensitivity to the explanatory limits of mechanism. Newton was perceptive in noting that while the mechanical philosophy sought to provide explanations in terms of matter and motion, it failed to explain matter and motion themselves. This sheds light on the motivations behind the theory of bodies in De gravitatione. And it helps to explain why he was so unmoved by what many saw as a serious challenge to his theory of gravity. (shrink)

This is a nontechnical overview of how various approaches to quantum gravity suggest modifications to the way we conceptualize space and time. A theory of quantum gravity is needed to reconcile quantum physics with general relativity, our best theory for gravity. The most popular approaches to quantum gravity are string theory and loop quantum gravity. So far, no approach has been empirically successful, and there is no commonly accepted theory. Thus, the conclusions presented here are tentative. Many approaches suggest that (...) space and time—or perhaps, it is better to talk about spacetime—might not be fundamental. Various views on how to think about time in quantum gravity are briefly presented. (shrink)

This paper discusses the physical effect of gravity on space, a rather treacherous topic that has not gained much attention in the literature, unlike the effect of gravity on time which has been clearly established from the beginning as a consequence of the Equivalence Principle and also experimentally tested. The difficulties encountered in analysing the effect of gravity on space can be represented by the need to compare vectors associated with different spatial points in a curved manifold, where the parallel-transport (...) of vectors depends on the chosen path. This same problem can also be seen from another perspective: the effect of gravity on space is embodied in the components of the metric tensor, which however are not uniquely determined as a consequence of the degrees of freedom due to the Bianchi identities. We here show that, however, there are circumstances under which these difficulties can be overcome, resulting in a clear representation of the effect of gravity on space. This effect is perfectly dual to the corresponding effect on time: while gravity slows down time, it expands space. This can clarify topics like the effects of gravity at the centre of a spherically symmetric system, where the literature does not provide clear answers. A final confirmation of the gravitational expansion of space is provided by the Equivalence Principle. The conclusions help fill a conceptual gap that has so far prevented gravitational effects on time and space from being viewed on an equal footing. (shrink)

A number of recent theories of quantum gravity lack a one-dimensional structure of ordered temporal instants. Instead, according to many of these views, our world is either best represented as a single three-dimensional object, or as a configuration space composed of such three-dimensional objects, none of which bear temporal relations to one another. Such theories will be empirically self-refuting unless they can accommodate the existence of conscious beings capable of representation. For if representation itself is impossible in a timeless world, (...) then no being in such a world could entertain the thought that a timeless theory is true, let alone believe such a theory or rationally believe it. This paper investigates the options for understanding representation in a three-dimensional, timeless, world. Ultimately it concludes that the only viable option is one according to which representation is taken to be deeply non-naturalistic. Ironically then we are left with two seemingly very unattractive options. Either a very naturalistic motivation—taking seriously a live view in fundamental physics—leads us to a very non-naturalistic view of the mental, or else views in the philosophy of mind partly dictate what is an acceptable theory in physics. (shrink)

One of the great and persistent technological dreams of science fiction has been the invention which would nullify or reverse the force of gravity. H. G. Wells in The First Men in the Moon did it in 1901 with Cavorite, a substance which shields objects behind it from gravitational lines of force. James Blish in the Cities in Flight series used the Spindizzy, a device which converts rotation and magnetism into gravity fields and forces. And, of course, "floaters", "null-g speeders" (...) and "grav sleds" have abounded as techno-props in science fiction stories for many years. (shrink)

The correspondence principle made of unitarity, locality and renormalizability has been very successful in quantum field theory. Among the other things, it helped us build the standard model. However, it also showed important limitations. For example, it failed to restrict the gauge group and the matter sector in a powerful way. After discussing its effectiveness, we upgrade it to make room for quantum gravity. The unitarity assumption is better understood, since it allows for the presence of physical particles as well (...) as fake particles (fakeons). The locality assumption is applied to an interim classical action, since the true classical action is nonlocal and emerges from the quantization and a later process of classicization. The renormalizability assumption is refined to single out the special role of the gauge couplings. We show that the upgraded principle leads to an essentially unique theory of quantum gravity. In particular, in four dimensions, a fakeon of spin 2, together with a scalar field, is able to make the theory renormalizable while preserving unitarity. We offer an overview of quantum field theories of particles and fakeons in various dimensions, with and without gravity. (shrink)

Gravity and Grace was the first ever publication by the remarkable thinker and activist, Simone Weil. In it Gustave Thibon, the priest to whom she had entrusted her notebooks before her untimely death, compiled in one remarkable volume a compendium of her writings that have become a source of spiritual guidance and wisdom for countless individuals.

The metaphysics of quantum gravity explores metaphysical issues related to research programs in theoretical physics clustered under the term quantum gravity. These research programs aim at the formulation of a theory that reconciles the theory of general relativity with quantum theory. The goal is not necessarily to come up with a unified single theory but, more pragmatically, to describe phenomena with a dual nature, embodying both quantum and relativistic features—such as black holes and the early universe. -/- Approaches to quantum (...) gravity are not yet fully worked-out theories. Nevertheless, they already provide a certain partial understanding of physical reality in different ways. Remarkably, they do so with a striking similarity: they virtually all deny the existence of some features usually regarded as essential to the existence of spacetime (or space and/or time) such as its four-dimensionality, the existence of distances and durations between events, or even the very partial ordering of events. -/- This observation is particularly noteworthy, considering the pervasive influence of spatial and temporal organisation on the human mind across various facets of daily life and theoretical thinking, ranging from most ancient religions to contemporary scientific worldviews. The metaphysics of quantum gravity takes as its starting point the puzzling observation that physics could teach us that space and time are not fundamental. It draws on resources from traditional metaphysics to tackle a set of issues related to the possible non-fundamentality of spacetime, and it investigates its potential implications for venerable traditional issues in metaphysics. -/- The metaphysics of quantum gravity is a relatively small and new research field, and thus as of now, its focus has been on explaining how spacetime could emerge from a more fundamental and non-spatiotemporal ontology. Consequently, this article is equally focused on questions regarding the status of spacetime and the emergence of spacetime. Section 1 situates the field within metaphysics of science more broadly. Sections 2 and 3 investigate, respectively, the status of spacetime in different approaches to quantum gravity and a number of potential issues with its lack of fundamentality. The article then covers the nature of the emerging spatiotemporal ontology (Section 4) and the building relation that relates it to the underlying non-spatiotemporal ontology (Section 5). Section 6 surveys various potential applications of spacetime emergence to a number of debates in metaphysics. (shrink)

Observational indications combined with analyses of analogue and emergent gravity in condensed matter systems support the possibility that there might be two distinct energy scales related to quantum gravity: the scale that sets the onset of quantum gravitational effects $E_{\rm B}$ (related to the Planck scale) and the much higher scale $E_{\rm L}$ signalling the breaking of Lorentz symmetry. We suggest a natural interpretation for these two scales: $E_{\rm L}$ is the energy scale below which a special relativistic spacetime emerges, (...) $E_{\rm B}$ is the scale below which this spacetime geometry becomes curved. This implies that the first ‘quantum’ gravitational effect around $E_{\rm B}$ could simply be that gravity is progressively switched off, leaving an effective Minkowski quantum field theory up to much higher energies of the order of $E_{\rm L}$ . This scenario may have important consequences for gravitational collapse, inasmuch as it opens up new possibilities for the final state of stellar collapse other than an evaporating black hole. (shrink)

This book provides a compilation of in-depth articles and reviews on key topics within gravitation, cosmology and related issues. It is a celebratory volume dedicated to Prof. Thanu Padmanabhan ("Paddy"), the renowned relativist and cosmologist from IUCAA, India, on the occasion of his 60th birthday. The authors, many of them leaders of their fields, are all colleagues, collaborators and former students of Paddy, who have worked with him over a research career spanning more than four decades. Paddy is a scientist (...) of diverse interests, who attaches great importance to teaching. With this in mind, the aim of this compilation is to provide an accessible pedagogic introduction to, and overview of, various important topics in cosmology, gravitation and astrophysics. As such it will be an invaluable resource for scientists, graduate students and also advanced undergraduates seeking to broaden their horizons. (shrink)

The gravity-related model of spontaneous wave function collapse, a longtime hypothesis, damps the massive Schrödinger Cat states in quantum theory. We extend the hypothesis and assume that spontaneous wave function collapses are responsible for the emergence of Newton interaction. Superfluid helium would then show significant and testable gravitational anomalies.

The article is devoted to the identification of factors influencing the export trade flows of the Russian Federation to the EAEU member states. Gravity modeling (H. Linnemann's model) was used as a research tool. The introduction of dummy variables is justified. A comparative analysis of the identified factors is presented. A forecast of export trade flows of the Russian Federation to the EAEU countries for 2020-2022 has been made.