The LIGO-Virgo Collaboration achieved the first ‘direct detection’ of gravitational waves in 2015, opening a new “window” for observing the universe. Since this first detection (‘GW150914’), dozens of detections have followed, mostly produced by binary black hole mergers. However, the theory-ladenness of the LIGO-Virgo methods for observing these events leads to a potentially-vicious circularity, where general relativistic assumptions may serve to mask phenomena that are inconsistent with general relativity (GR). Under such circumstances, the fact that GR can ‘save the (...) phenomena’ may be an artifact of theory-laden methodology.This paper examines several ways that the LIGO-Virgo observations are used in theory and hypothesis testing, despite this circularity problem. First, despite the threat of vicious circularity, these experiments succeed in testing GR. Indeed, early tests of GR using GW150914 are best understood as a response to the threat of theory-ladenness and circularity. Each test searches for evidence that LIGO-Virgo’s theory-laden methods are biasing their overall conclusions. The failure to find evidence of this places constraints on deviations from the predictions of GR. Second, these observations provide a basis for studying astrophysical and cosmological processes, especially through analyses of populations of events. As gravitational-wave astrophysics transitions into mature science, constraints from early tests of GR provide a scaffolding for these population-based studies. I further characterize this transition in terms of its increasing connectedness to other parts of astrophysics and the prominence of reasoning about selection effects and other systematics in drawing inferences from observations.Overall, this paper analyses the ways that theory and hypothesis testing operate in gravitational-wave astrophysics as it gains maturity. In particular, I show how these tests build on one another in order to mitigate a circularity problem at the heart of the observations. (shrink)

This article seeks to provide a historically well-informed analysis of an important post-Newtonian area of research in experimental physics between 1798 and 1898, namely the determination of the mean density of the earth and, by the end of the nineteenth century, the gravitational constant. Traditionally, research on these matters is seen as a case of “puzzle solving.” In this article, the author shows that such focus does not do justice to the evidential significance of eighteenth- and nineteenth-century experimental research (...) on the mean density of the earth and the gravitational constant. As Newton’s theory of universal gravitation was mainly based on astronomical observation, it remained to be shown that Newton’s law of universal gravitation did not break down at terrestrial distances. In this context, Cavendish’ experiment and related nineteenth-century experiments played a decisive role, for they provided converging and increasingly stronger evidence for the universality of Newton’s theory of gravitation. More precisely, the author shall argue that, as the accuracy and precision of the experimental apparatuses and the procedures to eliminate external disturbances involved increasingly improved, the empirical support for the universality of Newton’s theory of gravitation improved correspondingly. (shrink)

The kinematic aspects of the rocket-borne clock experiment by Vessot and Levine are analyzed with the revised Robertson's test theory of special relativity (Found. Phys. 14, 625 (1984)). Besides the expected time-dilation, it is found that the intermediate steps of this experiment yield in principle Michelson-Morley type information (a relation between longitudinal and transverse length contractions) in the third order of the velocities involved, but no relativity-of-simultaneity related effects.The flat space-time test theory induces a family of “spherically symmetric” line elements (...) that become the Schwarzschild line element in the relativistic case and also in theabinito rest frame of the theory. These line elements represent the same space-time manifold, but pertain in a one-to-one correspondence to the different flat space-time coordinate transformations of the test theory. The conserved energy is related to the family of local energies in the tangent plane. No deviations from the orthodoxy appear at the pertinent levels of approximation. Hence the unexplained residuals of the Vessot-Levine experiment are not due in obvious ways to kinematic and gravitational frequency shifts caused by deviations of the “real” coordinate transformations from the Lorentz transformations. (shrink)

PREFACE: - BY his theory of relativity Albert Einstein has provoked a revolution of thought in physical science. The achievement consists essentially in this Einstein has succeeded in separating far more completely than hitherto the share of the observer and the share of external nature in the things we see happen. The perception of an object by an observer depends on his own situation and circumstances for example, distance will make it appear smaller and dimmer. We make allowance for this (...) almost unconsciously in interpreting what we see. But it now appears that the allowance made for the motion of the observer has hitherto been too crude a fact overlooked because in practice all observers share nearly the same motion, that of the earth. Physical space and time are found to be closely bound up with this motion of the observer and only an amorphous combination of the two is left inherent in the external world. When space and time are relegated to their proper source the observer the world of nature which remains appears strangely unfamiliar but it is in reality simplified, and the underlying unity of the principal phenomena is now clearly revealed. The deductions from this new outlook have, with one doubtful exception, been confirmed when tested by experiment. It is my aim to give an account of this work without intro ducing anything very technical in the way of mathematics, physics, or philosophy. The new view of space and time, so opposed to our habits of thought, must in any case demand unusual mental exercise. The results appear strange and the incongruity is not without a humorous side. For the first nine chapters the task is one of interpreting a clear-cut theory, accepted in all its essentials by a large and growing school of physicists although perhaps not everyone would accept the authors views of its meaning. Chapters x and xi deal with very recent advances, with regard to which opinion is more fluid. As for the last chapter, containing the authors specula tions on the meaning of nature, since it touches on the rudiments of a philosophical system, it is perhaps too sanguine to hope that it can ever be other than controversial. A non-mathematical presentation has necessary limitations and the reader who wishes to learn how certain exact result follow from Einsteins, or even Newtons, law of gravitation m bound to seek the reasons in a mathematical treatise. But thj limitation of range is perhaps less serious than the limitation of intrinsic truth. There is a relativity of truth, as there is a relativity of space. For is and IS-NOT though with Rule and Line And UP-AND-DOWK without, I could define, Alas It is not so simple. We abstract from the phenomena that which is peculiar to the position and motion of the observer but can we abstract that which is peculiar to the limited imagina tion of the human brain We think we can, but only in the symbolism of mathematics. As the language of a poet rings with a truth that eludes the clumsy explanations of his commentators, so the geometry of relativity in its perfect harmony expresses a truth of form and type in nature, which my bowdlerised version misses. But the mind is not content to leave scientific Truth in a dry husk of mathematical symbols, and demands that it shall be alloyed with familiar images. The mathematician, who handles x so lightly, may fairly be asked to state, not indeed the in scrutable meaning of a in nature, but the meaning which x conveys to him. Although primarily designed for readers without technical knowledge of the subject, it is hoped that the book may also appeal to those who have gone into the subject more deeply. A few notes have been added in the Appendix mainly to bridge the gap between this and more mathematical treatises, and to indicate the points of contact between the argument in the text and the parallel analytical investigation. It is impossible adequately to express my debt to con temporary literature and discussion... (shrink)

Experiments witnessing the entanglement between two particles interacting only via the gravitational field have been proposed as a test whether gravity must be quantized. In the language of quantum information, a non-quantum gravitational force would be modeled by local operations with classical communication, which cannot generate entanglement in an initially unentangled state. This idea is criticized as too constraining on possible alternatives to quantum gravity. We present a parametrized model for the gravitational interaction of quantum matter on (...) a classical spacetime, inspired by the de Broglie–Bohm formulation of quantum mechanics, which results in entanglement and thereby provides an explicit counterexample to the claim that only a quantized gravitational field possesses this capability. (shrink)

We examine the problem of deducing the geodesic motion of test particles from Einstein's vacuum field equations and its extension to include gravitational radiation reaction. In the latter case we obtain an equation of motion for a particle which incorporates radiation reaction of the electrodynamical type, but due to shearing radiation, together with a mass-loss formula of the Bondi-Sachs type.

A gyroscope in orbit about a central rotating mass undergoes relativistic nutational oscillations in addition to the well-known precessional motions. The amplitude of the oscillation is proportional to the angular momentum of the rotating mass and its period is the Fokker period of geodetic precession. The amplitude is maximum for a polar orbit and vanishes if the orbit is equatorial. This nodding effect is due to a small divisor phenomenon involving the Fokker frequency, and its existence implies that the applicability (...) of the post-Newtonian approximation of general relativity is limited in time. The dynamical significance of the new effect for the relative motion of neighboring test masses in the field of a rotating mass as well as for the restricted three-body problem in general relativity is investigated and the possibility of its detection is briefly discussed. (shrink)

This thesis introduces a new theoretical tool to explore the notion of time and temporal order in quantum mechanics: the relativistic quantum "clock" framework. It proposes novel thought experiments showing that proper time can display quantum features, e.g. when a "clock" runs different proper times in superposition. The resulting new physical effects can be tested in near-future laboratory experiments (with atoms, molecules and photons as "clocks"). The notion of time holds the key to the regime where quantum theory and general (...) relativity overlap, which has not been directly tested yet and remains largely unexplored by the theory. The framework also applies to scenarios in which causal relations between events become non-classical and which were previously considered impossible to address without refuting quantum theory. The relativistic quantum "clock" framework offers new insights into the foundations of quantum theory and general relativity. (shrink)

In relativistic theories, the assumption of proper mass constancy generally holds. We study gravitational relativistic mechanics of point particle in the novel approach of proper mass varying under Minkowski force action. The motivation and objective of this work are twofold: first, to show how the gravitational force can be included in the Special Relativity Mechanics framework, and, second, to investigate possible consequences of the revision of conventional proper mass concept (in particular, to clarify a proper mass role in (...) the divergence problem). It is shown that photon motion in the gravitational field can be treated in terms of massless refracting medium, what makes the gravity phenomenon compatible with SR Mechanics framework in the variable proper mass approach.Specifically, the problem of point particle in the spherical symmetric stationary gravitational field is studied in SR-based Mechanics, and equations of motion in the Lorentz covariant form are obtained in the relativistic Lagrangean problem formulation. The dependence of proper mass on potential field strength is derived from the Euler-Lagrange equations as well. One of new results is the elimination of conventional 1/r divergence, which is known to be not removable in Schwarzschild gravitomechanics. Predictions of particle and photon gravitational properties are in agreement with GR classical tests under weak-field conditions; however, deviations rise with potential field strength. The conclusion is made that the approach of field-dependent proper mass is perspective for development of SR gravitational mechanics and further studies of gravitational problems. (shrink)

Historically, a great deal of attention has been addressed to the question of what it would take to test experimentally the metrical structure of spacetime. Arguably, however, consideration of this question has been at the expense of comparable investigations into what it would take to test other structural features of spacetime. In this article, we critique and expand substantially upon an article by Hadley (Hadley in Class Quantum Gravity, 19:4565–4571, 2002), which constitutes one of the best-known paper-length studies of what (...) it would take to test the orientability of spacetime. In so doing, we seek to clarify a number of matters which remain unclear in the wake of Hadley’s article, thereby allowing the literature on this topic to progress. More positively, we also present, compare, and evaluate a number of other potential approaches to testing the orientability of spacetime which have arisen in the recent physics literature. (shrink)

We present here solutions of a non-linear Schrödinger equation in presence of an arbitrary linear external potential. The non-linearity expresses a self-focusing interaction. These solutions are the product of the pilot wave with peaked solitons the velocity of which obeys the guidance equation derived by Louis de Broglie in 1926. The degree of validity of our approximations increases when the size of the soliton decreases and becomes negligible compared to the typical size over which the pilot wave varies. We discuss (...) the possibility to reveal their existence by implementing a humpty-dumpty Stern-Gerlach interferometer in the mesoscopic regime. (shrink)

High throughput time-resolved observations of accreting collapsed objects at X-ray energies provide key information on the motions of matter orbiting a few gravitational radii away from black holes. Predictions of general relativity in the strong field regime, such as relativistic epicyclic motions, precession, light bending and the presence and radius of an innermost stable circular orbit in the close vicinity of a black hole can be verified by making use of two powerful diagnostics, namely relativistically broadened \ lines and (...) variability on dynamical timescales, quasi periodic oscillations in particular. Moreover tomography and reverberation techniques relying upon combined spectral timing and polarimetric timing provide an entirely new perspective in the field. Both the low and high spacetime curvature regimes of gravity can be probed by studying black holes of vastly different masses in X-ray binaries and Active Galactic Nuclei, opening up the possibility of testing also some alternative theories of gravity. To achieve these goals, very large area X-ray instrumentation with good spectral resolution and polarimetric capability is required. Prospects and projects in this area of research are briefly surveyed. (shrink)

The main foundations of the standard \CDM model of cosmology are that: the redshifts of the galaxies are due to the expansion of the Universe plus peculiar motions; the cosmic microwave background radiation and its anisotropies derive from the high energy primordial Universe when matter and radiation became decoupled; the abundance pattern of the light elements is explained in terms of primordial nucleosynthesis; and the formation and evolution of galaxies can be explained only in terms of gravitation within a inflation (...) + dark matter + dark energy scenario. Numerous tests have been carried out on these ideas and, although the standard model works pretty well in fitting many observations, there are also many data that present apparent caveats to be understood with it. In this paper, I offer a review of these tests and problems, as well as some examples of alternative models. (shrink)

Newton's methodology emphasized propositions "inferred from phenomena." These rest on systematic dependencies that make phenomena measure theoretical parameters. We consider the inferences supporting Newton's inductive argument that gravitation is proportional to inertial mass. We argue that the support provided by these systematic dependencies is much stronger than that provided by bootstrap confirmation; this kind of support thus avoids some of the major objections against bootstrapping. Finally we examine how contemporary testing of equivalence principles exemplifies this Newtonian methodological theme.

The paper presents and discusses measurements of gravitational redshift made between 1959 and 1971 by Pound and Rebka, Schiffer and Marshall, Brault, Blamont and Roddier, and finally by Snider. It emphasizes the importance of new measurement techniques such as wavelength modulation, electronic amplification, and scattering of atomic beams to the emergence of new tests of Einstein's GRS prediction, which were perceived by the scientific community as the first ‘clean’ verifications of GRS. In particular, the race to be the (...) first to apply the Mössbauer effect to the GRS problem is described. As soon as the Mössbauer effect was stabilized, it was transformed into a measurement technology that in turn triggered new types of experimental tests of GRS. (shrink)

Cannon and Jensen assert that data from different national time laboratories give a test of the interaction interpretation of special relativity theory. That interpretation is to be applied, however, to clocks in relative uniform motion, and therefore is not tested by the time-rate effects associated with different terrestrial locations of clocks. Those effects are described by the general theory of relativity, and arise with differences in gravitational potential and state of circular motion of the clocks. An argument by the (...) authors against invariance of entropy clocks, on grounds of neglect of relativity of simultaneity, is also criticized. (shrink)

The multiple detections of gravitational waves by LIGO (the Laser Interferometer Gravitational-Wave Observatory), operated by Caltech and MIT, have been acclaimed as confirming Einstein's prediction, a century ago, that gravitational waves propagating as ripples in spacetime would be detected. Yunes and Pretorius (2009) investigate whether LIGO's template-based searches encode fundamental assumptions, especially the assumption that the background theory of general relativity is an accurate description of the phenomena detected in the search. They construct the parametrized post-Einsteinian (ppE) (...) framework in response, which broadens those assumptions and allows for wider testing under more flexible assumptions. Their methods are consistent with work on confirmation and testing found in Carnap (1936), Hempel (1969), and Stein (1992, 1994), with the following principles in common: that confirmation is distinct from testing, and that, counterintuitively, revising a theory's formal basis can make it more broadly empirically testable. These views encourage a method according to which theories can be made abstract, to define families of general structures for the purpose of testing. With the development of the ppE framework and related approaches, multi-messenger astronomy is a catalyst for deep reasoning about the limits and potential of the theoretical framework of general relativity. (shrink)

In the following paper, I review and critically assess the four standard routes commonly taken to establish that gravitational waves possess energy-momentum: the increase in kinetic energy a GW confers on a ring of test particles, Bondi/Feynman’s Sticky Bead Argument of a GW heating up a detector, nonlinearities within perturbation theory, taken to reflect the fact that gravity contributes to its own source, and the Noether Theorems, linking symmetries and conserved quantities. Each argument is found to either to presuppose (...) controversial assumptions or to be outright spurious. I finally examine the standard interpretation of binary systems, according to which orbital decay is explained in terms of the system’s energy being via GW energy- momentum transport. I contend that a better interpretation, drawing only on the general-relativistic Equations of Motions and the Einstein Equations, is available - and in fact preferable; thereby also an inference to the best explanation for the vindication of GW energy-momentum is blocked. (shrink)

Recently there has been a great deal of interest in tabletop experiments intended to exhibit the quantum nature of gravity by demonstrating that it can induce entanglement. In order to evaluate these experiments, we must determine if there is any interesting class of possibilities that will be convincingly ruled out if it turns out that gravity can indeed induce entanglement. In particular, since one argument for the significance of these experiments rests on the claim that they demonstrate the existence of (...) superpositions of spacetimes, it is important to keep in mind that different interpretations of quantum mechanics may make different predictions about superpositions of spacetimes. ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-complete interpretations of quantum mechanics, like the Everett interpretation, almost universally predict the existence of superpositions of spacetimes, whereas in ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-incomplete, ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-nonphysical interpretations it seems more natural to predict that spacetime superpositions are not possible. Meanwhile ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-incomplete, ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-supplemented interpretations present us with a more complex picture where we may or may not end up predicting that spacetime superpositions are possible, depending on the particular way in which the coupling between spacetime and matter is constructed. This line of reasoning suggests that what would be ruled out by a successful result to these tabletop experiments is a class of quantum gravity models that we refer to as ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-incomplete quantum gravity —i.e. models of the interaction between quantum mechanics and gravity in which gravity is coupled to non-quantum beables rather than quantum beables. It follows that the results of tabletop experiments can also be regarded as giving us new evidence about the interpretation of quantum mechanics: roughly speaking, a positive result to these experiments should increase our confidence in ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-complete interpretations, whilst a negative result should instead increase our confidence in ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-incomplete interpretations. We introduce these ideas in Sect. 1, and then in Sect. 2 we make the reasoning more precise by presenting a set of inferences that may be made about the ontology of quantum mechanics based on the results of tabletop experiments. In Sect. 3 we discuss some existing PIQG models and consider what more needs to be done to make these sorts of approaches more appealing. There are two competing paradigms for the interpretation of these experiments, which have been dubbed the ‘Newtonian’ paradigm and the ‘tripartite’ paradigm: here we largely work within the tripartite paradigm, because the tripartite view is specifically concerned with ontological aspects of the mediating gravitational interaction and that makes it a suitable setting for enquiries about the ontology of quantum mechanics, but in Sect. 4 we consider what conclusions can be drawn if one does not presuppose the tripartite view. Finally in Sect. 5 we discuss a cosmological phenomenon which could be regarded as providing evidence for PIQG models. (shrink)

It is shown that the equation deduced by Marinov for the gravitational frequency shift does not follow from his assumptions. The correct equation is deduced. It is pointed out that the result of Marinov's absolute spacetime theory concerning the gravitational frequency shift is contained in general relativity as an approximate description. The need for experiments testing the validity of Marinov's measurements is emphasized.

The hybridization of two or more energy sources into a single power station is one of the widely discussed solutions to address the demand and supply havoc generated by renewable production, heating power, and cooling power) and its energy storage issues. Hybrid energy sources work based on the complementary existence of renewable sources. The combined cooling, heating, and power is one of the significant systems and shows a profit from its low environmental impact, high energy efficiency, low economic investment, and (...) sustainability in the industry. This paper presents an economic model of a microgrid system containing the CCHP system and energy storage considering the energy coupling and conversion characteristics, the effective characteristics of each microsource, and energy storage unit is proposed. The random forest regression model was optimized by the gravitational search algorithm. The test results show that the GSA-RFR model improves prediction accuracy and reduces the generalization error. The detail of the MG network and the energy storage architecture connected to the other renewable energy sources is discussed. The mathematical formulation of energy coupling and energy flow of the MG network including wind turbines, photovoltaic, CCHP system, fuel cell, and energy storage devices are presented. The testing system has been analysed under load peak cutting and valley filling of energy utilization index, energy utilization rate, the heat pump, the natural gas consumption of the microgas turbine, and the energy storage unit. The energy efficiency costs were observed as 88.2% and 86.9% with heat pump and energy storage operation comparing with GSA-RFR-based operation costs as 93.2% and 93% in summer and winter season, respectively. The simulation results extended the rationality and economy of the proposed model. (shrink)

A new member of a growing class of unresolved second law paradoxes is examined.(1–7) In a sealed blackbody cavity, a spherical gravitator is suspended in a low density gas. Infalling gas suprathermally strikes the gravitator which is spherically asymmetric between its hemispheres with respect to surface trapping probability for the gas. In principle, this system can be made to perform steady-state work solely at the expense of heat from the heat bath, this in apparent violation of the second law of (...) thermodynamics. Detailed three-dimensional test particle simulations of this system support this prediction. Standard resolutions to the paradox are discussed and found to be untenable. Experiments corroborating a central physical process of the paradox are discussed briefly. The paradox is discussed in the context of the Maxwell demon. (shrink)

We derive, from the Einstein-Maxwell field equations, the Lorentz equations of motion with radiation reaction for a charged mass particle moving in a background gravitational and electromagnetic field by utilizing a line element for the background space-time in a coordinate system specially adapted to the world line of the particle. The particle is introduced via perturbations of the background space-time (and electromagnetic field) which are singular only on the source world line.

The experimental testing of the Lorentz transformations is based on a family of sets of coordinate transformations that do not comply in general with the principle of equivalence of the inertial frames. The Lorentz and Galilean sets of transformations are the only member sets of the family that satisfy this principle. In the neighborhood of regular points of space-time, all members in the family are assumed to comply with local homogeneity of space-time and isotropy of space in at least one (...) free-falling elevator, to be denoted as Robertson'sab initio rest frame [H. P. Robertson,Rev. Mod. Phys. 21, 378 (1949)].Without any further assumptions, it is shown that Robertson's rest frame becomes a preferred frame for all member sets of the Robertson family except for, again, Galilean and Einstein's relativities. If one now assumes the validity of Maxwell-Lorentz electrodynamics in the preferred frame, a different electrodynamics spontaneously emerges for each set of transformations. The flat space-time of relativity retains its relevance, which permits an obvious generalization, in a Robertson context, of Dirac's theory of the electron and Einstein's gravitation. The family of theories thus obtained constitutes a covering theory of relativistic physics.A technique is developed to move back and forth between Einstein's relativity and the different members of the family of theories. It permits great simplifications in the analysis of relativistic experiments with relevant “Robertson's subfamilies.” It is shown how to adapt the Clifford algebra version of standard physics for use with the covering theory and, in particular, with the covering Dirac theory. (shrink)

Change seems missing in Hamiltonian General Relativity's observables. The typical definition takes observables to have $0$ Poisson bracket with \emph{each} first-class constraint. Another definition aims to recover Lagrangian-equivalence: observables have $0$ Poisson bracket with the gauge generator $G$, a \emph{tuned sum} of first-class constraints. Empirically equivalent theories have equivalent observables. That platitude provides a test of definitions using de Broglie's massive electromagnetism. The non-gauge ``Proca'' formulation has no first-class constraints, so everything is observable. The gauge ``Stueckelberg'' formulation has first-class constraints, (...) so observables vary with the definition. Which satisfies the platitude? The team definition does; the individual definition does not. Subsequent work using the gravitational analog has shown that observables have not a 0 Poisson bracket, but a Lie derivative for the Poisson bracket with the gauge generator $G$. The same should hold for General Relativity, so observables change locally and correspond to 4-dimensional tensor calculus. Thus requiring equivalent observables for empirically equivalent formulations helps to address the problem of time. (shrink)

Planck's units define the limits of super GUT and also the possibilities of classical measurements. A “planckion'” is the largest ultrarelativistic elementary particle and also the smallest body that can serve as a classical standard.

In the static field configuration, a spatially-Variable Speed of Light (VSL) scalar gravity model with Lorentz-Poincaré interpretation was shown to reproduce the phenomenology implied by the Schwarzschild metric. In the present development, we effectively cover configurations with source kinematics due to an induced sweep velocity field w. The scalar-vector model now provides a Hamiltonian description for particles and photons in full accordance with the first Post-Newtonian (1-PN) approximation of General Relativity Theory (GRT). This result requires the validity of Poincaré’s Principle (...) of Relativity, i.e. the unobservability of ‘preferred’ frame movement. Poincaré’s principle fixes the amplitude of the sweep velocity field of the moving source, or equivalently the ‘vector potential’ ξ of GRT (e.g.; S. Weinberg, Gravitation and cosmology, [1972]), and provides the correct 1-PN limit of GRT. The implementation of this principle requires acceleration transformations derived from gravitationally modified Lorentz transformations. A comparison with the acceleration transformation in GRT is done. The present scope of the model is limited to weak-field gravitation without retardation and with gravitating test particles. In conclusion the model’s merits in terms of a simpler space, time and gravitation ontology—in terms of a Lorentz-Poincaré-type interpretation—are explained (e.g. for ‘frame dragging’, ‘harmonic coordinate condition’). (shrink)

This book provides the reader with a detailed and captivating account of the story where, for the first time, physicists ventured into proposing a new force of nature beyond the four known ones - the electromagnetic, weak and strong forces, and gravitation - based entirely on the reanalysis of existing experimental data. Back in 1986, Ephraim Fischbach, Sam Aronson, Carrick Talmadge and their collaborators proposed a modification of Newton's Law of universal gravitation. Underlying this proposal were three tantalizing pieces of (...) evidence: 1) an energy dependence of the CP (particle-antiparticle and reflection symmetry) parameters, 2) differences between the measurements of G, the universal gravitational constant, in laboratories and in mineshafts, and 3) a reanalysis of the Eötvos experiment, which had previously been used to show that the gravitational mass of an object and its inertia mass were equal to approximately one part in a billion. The reanalysis revealed that, contrary to Galileo's position, the force of gravity was in fact very slightly different for different substances. The resulting Fifth Force hypothesis included this composition dependence and also added a small distance dependence to the inverse-square gravitational force. Over the next four years numerous experiments were performed to test the hypothesis. By 1990 there was overwhelming evidence that the Fifth Force, as initially proposed, did not exist. This book discusses how the Fifth Force hypothesis came to be proposed and how it went on to become a showcase of discovery, pursuit and justification in modern physics, prior to its demise. In this new and significantly expanded edition, the material from the first edition is complemented by two essays, one containing Fischbach's personal reminiscences of the proposal, and a second on the ongoing history and impact of the Fifth Force hypothesis from 1990 to the present. <. (shrink)

Standard pedagogy treats topics in general relativity (GR) in terms of tensor formulations in curved space-time. An alternative approach based on treating the vacuum as a polarizable medium is presented here. The polarizable vacuum (PV) approach to GR, derived from a model by Dicke and related to the “THεμ” formalism used in comparative studies of gravitational theories, provides additional insight into what is meant by a curved metric. While reproducing the results predicted by GR for standard (weak-field) astrophysical conditions, (...) for strong fields a divergence of predictions in the two formalisms (GR vs. PV) provides fertile ground for both laboratory and astrophysical tests to compare the two approaches. (shrink)

The generalized Brans–Dicke theory (GBD), as one of the modified gravitational theories, was proposed previously and some interesting properties were found in this theory. Here we investigate the traversable-wormhole physics for GBD theory. Firstly, we derive the gravitational field equation in the framework of GBD wormhole geometry. The traversable wormhole could be gained in this theory. Secondly, using the classical reconstruction technique we originally derive an Lagrangian function for describing gravity in GBD theory. And the derived Lagrangian function (...) for gravity could be satisfied with the requirement of the viable conditions, such as the local gravity tests and the cosmological constraints, etc. Thus, the viable model for cosmology, local gravity and traversable WH can be unified in a uniform Lagrangian quantity within the framework of GBD theory. Thirdly, given that the violation of the energy conditions (ECs) often induce some problems in theory, we explore the ECs of matter in the traversable wormhole. It is shown that the null EC, the weak EC and the dominated EC for the matter can be satisfied in the traversable-wormhole physics of GBD theory, which are different from the results given in GR. It seems that the theory of GBD owns the more logic technically and consistency formally than the theory of GR. Fourthly, some other properties of GBD traversable WH are explored, such as the total gravitational energy, the volume integral quantifier, the dynamical stability of the anisotropic matter, and the difference of the propagation of sound within the matter configuration. The results support the GBD to provide an interesting candidate for traversable WH. (shrink)

Nelson’s stochastic quantum mechanics provides an ideal arena to test how the Born rule is established from an initial probability distribution that is not identical to the square modulus of the wavefunction. Here, we investigate numerically this problem for three relevant cases: a double-slit interference setup, a harmonic oscillator, and a quantum particle in a uniform gravitational field. For all cases, Nelson’s stochastic trajectories are initially localized at a definite position, thereby violating the Born rule. For the double slit (...) and harmonic oscillator, typical quantum phenomena, such as interferences, always occur well after the establishment of the Born rule. In contrast, for the case of quantum particles free-falling in the gravity field of the Earth, an interference pattern is observed before the completion of the quantum relaxation. This finding may pave the way to experiments able to discriminate standard quantum mechanics, where the Born rule is always satisfied, from Nelson’s theory, for which an early subquantum dynamics may be present before full quantum relaxation has occurred. Although the mechanism through which a quantum particle might violate the Born rule remains unknown to date, we speculate that this may occur during fundamental processes, such as beta decay or particle-antiparticle pair production. (shrink)

Implementing Poincaré’s geometric conventionalism a scalar Lorentz-covariant gravity model is obtained based on gravitationally modified Lorentz transformations (or GMLT). The modification essentially consists of an appropriate space-time and momentum-energy scaling (“normalization”) relative to a nondynamical flat background geometry according to an isotropic, nonsingular gravitational affecting function Φ(r). Elimination of the gravitationally unaffected S 0 perspective by local composition of space–time GMLT recovers the local Minkowskian metric and thus preserves the invariance of the locally observed velocity of light. The associated (...) energy-momentum GMLT provides a covariant Hamiltonian description for test particles and photons which, in a static gravitational field configuration, endorses the four ‘basic’ experiments for testing General Relativity Theory: gravitational (i) deflection of light, (ii) precession of perihelia, (iii) delay of radar echo, (iv) shift of spectral lines. The model recovers the Lagrangian of the Lorentz–Poincaré gravity model by Torgny Sjödin and integrates elements of the precursor gravitational theories, with spatially Variable Speed of Light (VSL) by Einstein and Abraham, and gravitationally variable mass by Nordström. (shrink)

Recent work on inference to the best explanation has come to an impasse regarding the proper way to coordinate the theoretical virtues in explanatory inference with probabilistic confirmation theory, and in particular with aspects of Bayes's Theorem. I argue that the theoretical virtues are best conceived heuristically and that such a conception gives us the resources to explicate the virtues in terms of ceteris paribus theorems. Contrary to some Bayesians, this is not equivalent to identifying the virtues with likelihoods or (...) priors per se; the virtues may be more accessible epistemically than likelihoods or priors. I then prove a ceteris paribus theorem regarding theoretical consilience, use it to correct a recent application of Reichenbach's common cause principle, and apply it to a test case of scientific reasoning. Explanation and confirmation The heuristic conception of theoretical virtues Abduction and the accessibility of explanatory power Evidential and theoretical consilience A test case: gravitational lensing Conclusion Thus natural science appears completely to lose from sight the large and general questions; but all the more splendid is the success when, groping in the thicket of special questions, we suddenly find a small opening that allows a hitherto undreamt of outlook on the whole. (L. Boltzmann, Theoretical Physics and Philosophical Problems). (shrink)

Recent work on the history of General Relativity by Renn, Sauer, Janssen et al. shows that Einstein found his field equations partly by a physical strategy including the Newtonian limit, the electromagnetic analogy, and energy conservation. Such themes are similar to those later used by particle physicists. How do Einstein's physical strategy and the particle physics derivations compare? What energy-momentum complex did he use and why? Did Einstein tie conservation to symmetries, and if so, to which? How did his work (...) relate to emerging knowledge of the canonical energy-momentum tensor and its translation-induced conservation? After initially using energy-momentum tensors hand-crafted from the gravitational field equations, Einstein used an identity from his assumed linear coordinate covariance x'=Mx to relate it to the canonical tensor. Usually he avoided using matter Euler-Lagrange equations and so was not well positioned to use or reinvent the Herglotz-Mie-Born understanding that the canonical tensor was conserved due to translation symmetries, a result with roots in Lagrange, Hamilton and Jacobi. Whereas Mie and Born were concerned about the canonical tensor's asymmetry, Einstein did not need to worry because his Entwurf Lagrangian is modeled not so much on Maxwell's theory as on a scalar theory. Einstein's theory thus has a symmetric canonical energy-momentum tensor. But as a result, it also has 3 negative-energy field degrees of freedom. Thus the Entwurf theory fails a 1920s-30s a priori particle physics stability test with antecedents in Lagrange's and Dirichlet's stability work; one might anticipate possible gravitational instability. This critique of the Entwurf theory can be compared with Einstein's 1915 critique of his Entwurf theory for not admitting rotating coordinates and not getting Mercury's perihelion right. One can live with absolute rotation but cannot live with instability. Particle physics also can be useful in the historiography of gravity and space-time, both in assessing the growth of objective knowledge and in suggesting novel lines of inquiry to see whether and how Einstein faced the substantially mathematical issues later encountered in particle physics. This topic can be a useful case study in the history of science on recently reconsidered questions of presentism, whiggism and the like. Future work will show how the history of General Relativity, especially Noether's work, sheds light on particle physics. (shrink)

In General Relativity (GR), it has been claimed that inertia receives a dynamical explanation. This is in contrast to the situation in other theories, such as Special Relativity, because the geodesic principle of GR can be derived from Einstein’s field equations. The claim can be challenged in different ways, all of which question whether the status of inertia in GR is physically different from its status in previous spacetime theories. In this paper I state the original argument for the claim (...) precisely, discuss the different objections to it and then propose a formulation that avoids the problems the original claim encounters. My conclusion is that one can say meaningfully that inertia is dynamically explained in GR. There are two senses in which the derivation of geodetic motion can be said to provide a (more) dynamical explanation of inertia in GR: it holds for any material test body that is a source of the gravitational field; and it is derivable without assuming inertial structures that are fixed independently of matter. (shrink)

I argue that, contrary to folklore, Einstein never really cared for geometrizing the gravitational or the electromagnetic field; indeed, he thought that the very statement that General Relativity geometrizes gravity "is not saying anything at all". Instead, I shall show that Einstein saw the "unification" of inertia and gravity as one of the major achievements of General Relativity. Interestingly, Einstein did not locate this unification in the field equations but in his interpretation of the geodesic equation, the law of (...) motion of test particles. (shrink)

The reason for physics’ failure to find a final theory of the universe is examined. Problems identified are: the lack of unequivocal definitions for its fundamental elements (time, length, mass, electric charge, energy, work, matter-waves); the danger of relying too much on mathematics for solutions; especially as philosophical arguments conclude the universe cannot have a mathematical basis. It does not even need the concept of number to exist. Numbers and mathematics are human inventions arising from the human predilection for measurement. (...) Following Aristotle, a single fundamental cause is proposed to explore the efficacy of using pure non-mathematical philosophy to explain the universe, contrary to current quantum physical views. The cause is taken as Time, which is then defined, surprisingly leading automatically to a definition of a three-dimensional space answering the question into what can a universe be placed (space before space seems non-sensical). This enables the philosophical arguments to derive a universal rule giving clear-cut descriptions (definitions) of force (both gravitational and electromagnetic), motion, energy, and particles. The formation of atomic nuclei and atomic properties together with an unexpected role for neutrinos follow. In particular, a Popper-test can be prepared by introducing the concept of measurement to allow the philosophy arguments to be tested in another discipline - mathematics. The solution agrees with human physical observations to a remarkable degree of accuracy, automatically explaining and predicting values for Planck’s and the fine-structure constants. Although mathematical, it is included as confirming the efficacy of philosophy in attaining a final theory. (shrink)

Peter Kosso discusses the weak gravitational lensing observations of the Bullet Cluster and argues that dark matter can be detected in this system solely through the equivalence principle without the need to specify a full theory of gravity. This paper argues that Kosso gets some of the details wrong in his analysis of the implications of the Bullet Cluster observations for the Dark Matter Double Bind and the possibility of constructing robust tests of theories of gravity at galactic (...) and greater scales. Even the Bullet Cluster evidence is not sufficiently detailed to allow precision tests of General Relativity that would distinguish it from its rivals at galactic and greater scales. Taking into account the total evidence available, we cannot rule out “ugly” solutions to the dynamical discrepancy in astrophysics that involve both a large quantity of dark matter and a theory of gravity whose predictions differ significantly from those of General Relativity for interactions taking place at galactic and greater scales. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Standing at the Intersections: Navigating Life as a Black Intersex ManSean Saifa WallAs I sit down to write this narrative, my mind is reflecting on the past year. This year has seen numerous protests against state–sanctioned violence with the declaration that “Black Lives Matter”. As a Black intersex man, I have witnessed the impact of state–sanctioned violence on my family and my community, both from the police state and (...) medical community. I charge the police state and the medical community with state– sanctioned violence: Each targets non–normative bodies—the former through incarceration and execution, and the latter by means of surgical and hormonal intervention. As a Black intersex man, I stand at the intersection bearing witness to how this violence has incarcerated my friends and loved ones as well as being subjected to medically unnecessary surgical intervention. Although this is where I stand now, both socially and politically, I have not always existed here.I was born in the winter of 1978 at Columbia–Presbyterian Hospital in New York City. I was the youngest of five children and one of three children in my family who were born with an intersex trait now known as androgen insensitivity syndrome (AIS). At the time, AIS was referred to as “testicular [End Page 117] feminization syndrome.” Upon receiving my medical records years later at the age of twenty–five, I noticed scribbling and a barrage of notes indicating the process by which the doctors assigned my gender as female. Although I had ambiguous genitalia, which caused some initial confusion among the doctors, XY chromosomes were not enough for me to be raised as male. My mother was told I would be raised as a girl and, according to the medical records, “function as such.”Unlike my sisters who were also born with AIS, my mom was not swayed by the surgical recommendations doctors made about my body. As a matter of protocol, my sisters’ gonads were removed in infancy, however, my mom made the decision that my testes would remain with me until they had to be removed.Because of intense pain in my groin area, my testicles were removed when I was thirteen years old. The pain that I felt following the surgery was perhaps the worst pain that I have experienced in my entire life. After surgery, my pediatrician prescribed estrogen and Provera as a hormonal replacement regimen. Fatty deposits changed the shape and contours of my face. Once robust and chiseled thighs now harbored cellulite. The beginnings of facial hair and prominent body hair became wispy and nonexistent. What was hard and defined became soft.At no point did anyone ask me what I wanted to do with my body.I actually missed the effects of my natural testosterone such as a deepening voice, increased hair and muscle mass; when I asked if I could take both testosterone and estrogen after surgery, my mother remarked, “You would look too weird.”The hormone therapy was coupled with intense social conditioning. I feel as if the social conditioning for young women raised with AIS is suffocating. When doctors prescribed hormones for me to take, my mother constantly reminded me how “beautiful” the little yellow pills would make me. As a means of reassurance, my pediatrician told my mom that “a lot of fashion models” have AIS and that I would most certainly be beautiful. In our dominant US culture, gender norms can already be oppressive, but for women with AIS, there is the impact of gender norms and the underlying fear that women with AIS are not really women since they have XY chromosomes. I did not succumb to the pressure to be more feminine, but actually gravitated toward masculinity. Before transitioning to live as a man, I considered myself a butch woman. When I came out of the closet at fourteen years old and presented as a masculine young woman, I never felt safe. Because I dated women who were more feminine than I, my relationship with these women seemed threatening to men who repeatedly reminded me through harassment and threats that “I was not a man.” Of course, I wasn’t trying to be a... (shrink)

The Schwarzschild solution (Schwarzschild, 1915/16) to Einstein’s General Theory of Relativity (GTR) is accepted in theoretical physics as the unique solution to GTR for a central-mass system. In this paper I propose an alternative solution to GTR, and argue it is both logically consistent and empirically realistic as a theory of gravity. This solution is here called K-gravity. The introduction explains the basic concept. The central sections go through the technical detail, defining the basic solution for the geometric tensor, the (...) Christoffel symbols, Ricci tensor, Ricci scalar, Einstein tensor, stress-energy tensor and density-pressure for the system. The density is integrated, and some consistency properties are demonstrated. A notable feature is the disappearance of the event horizon singularity, i.e. there are no black holes. So far this is for a single central mass. A generalization of the solution for multiple masses is then proposed. This is required to support K-gravity as a viable general interpretation of gravity. Then the question of empirical tests is discussed. It is argued that current observational data is almost but not quite sufficient to verify or falsify K-gravity. The Pioneer spacecraft trajectory data is of particular interest, as this is capable of providing a test; but the data (which originally showed anomalies that match K-gravity) is now uncertain. A new and very practical experiment is proposed to settle the matter. This would provide a novel test of GTR, and a novel test of the cause of the Pioneer anomalies. In conclusion, K-gravity has extensive ramifications for gravitational physics and for the philosophy of GTR and space-time. (shrink)

S CIENTISTS often claim that an experiment or observation tests certain hypotheses within a complex theory but not others. Relativity theorists, for example, are unanimous in the judgment that measurements of the gravitational red shift do not test the field equations of general relativity; psychoanalysts sometimes complain that experimental tests of Freudian theory are at best tests of rather peripheral hypotheses; astronomers do not regard observations of the positions of a single planet as a test of (...) Kepler's third law, even though those observations may test Kepler's first and second laws. Observations are regarded as relevant to some hypotheses in a theory but not relevant to others in that same theory. There is another kind of scientific judgment that may or may not be related to such judgments of relevance: determinations of the accuracy of the predictions of some theories are not held to provide tests of those theories, or, at least, positive results are not held to support or confirm the theories in question. There are, for example, special relativistic theories of gravity that predict the same phenomena as does general relativity, yet the theories are regarded as.. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Dwelling in the GapsGalen SanderlinHave you ever wondered what it would be like to be a mythical being? As a hermaphrodite, I exist in a culture that sees only male or female. Those of us who don’t fit into the rigid sex binary are left out of many of the protections offered to our cousins who more neatly fit the two categories. This leaves an enormous gap in cultural (...) definitions and societal acceptance of my fundamental being.My journey has three main threads: 1) My personal and often rocky self–development, as I have come to understand and accept what it means to be a hermaphrodite, and finding others of my tribe; 2) recognizing the harm done by my medical treatment and actively seeking to change how the medical system treats hermaphrodites, starting from birth onwards; and 3) identifying what was done to me as a human rights violation.I was born in January of 1975. No genetic test was done at the time. My body looked male and my assigned sex/gender was male. As a child, I gravitated toward “male” toys. In 1989, a rural– MD noted that I was not experiencing puberty like my peers and she recommended that my parents take me to a teaching hospital in Seattle for tests. A pediatrician referred me to the adolescent medical division, and from there I was referred to an endocrinologist. After conducting many invasive tests, including drawing blood and comparing my testicles to a bead ring of ersatz testicles, the endocrinologist diagnosed me with Klinefelter’s Syndrome and a karyotype of 47,XXY. I was prescribed testosterone injections to affirm and strengthen the male identity I was assigned at birth and to prevent my body from developing secondary female sex characteristics (breasts and hips).Soon after the shots started I bulked up, adding muscle and hair everywhere. I also became dangerously aggressive and moody. I began to have serious self–esteem issues and a drastic increase in risk–taking behavior as my body was subjected to medical intervention that my parents innocently followed.The prescribed hormone treatment fractured my psyche—what I know now to be a common defense mechanism experienced in trauma survivors. The portion of my consciousness that existed prior to testosterone became deeply buried to prevent harm, and I experienced the emergence of a new “entity.” With each change in prescription, new fractures occurred: testosterone cypionate to enanthate shots, to patches, to gels.The physicians did not consider my feelings or preferences during recommendations or treatment. I feel I was forced into a “male” body based on a medical emergency they created to ease societal concerns.Last February I decided to stop hiding. Tearing the mask off has brought a flood of emotions hidden behind old traumas. I’d been living openly as an intersex person, but still deeply closeted, if not from the public—worse, from myself.Here is the writing that came pouring out of me as I’ve been accessing my repressed memories:I felt the first stirrings of my existence in August of 1989, like a fleeting visage of a long lost lover passing just out of view. The timing of the universe—Out of the infinite we are born, but in this case the body we are to occupy was already housing many other souls. Is this some mistake? Asked to be patient I waited... Late in the year of 1989 I was borne on testosterone wings into an imaginary masculine role/body.Molded in the image of Adonis, Hermes was forced to submit. No longer sexless or ageless—lost in a sea of supposed pressures and roles. My assumed gender [End Page E10] was male. Why!?! Screaming, thrashing, and damaging all around me, no way to express the horror of being so brutally manhandled.My guide Galen/Juniper were excised from our psyche—lost behind a barrier. The only solace was a shared beat: 1,2,3,4 over and over. Was this the pounding of our heart? Thank god for our love of music least we lose ourselves entirely.Why do they insist on calling me Galen? I no longer knew who this was. I... (shrink)

The aim of the experiment was to evaluate the adaptive responses of biomechanical and electromyographic parameters to vertical unloading when walking during the 4-month isolation experiment SIRIUS-19 in the ground-based space station model. The study involved 6 healthy international crew members of the SIRIUS-19 project aged 34 ± 6.2 years. Body Weight Unloading conditions was created by the h/p/cosmos airwalk system. The locomotor test included walking with a sequential change of BWU modes: 5-min walking with 0% BWU, 5-min walking with (...) 65% BWU and 5-min walking with 85% BWU. Ground Reaction Force was recorded by the h/p/cosmos treadmill device. Muscle Lab Model 4000e device was used to record the electromyographic signals of the hip and shin muscles. The locomotor test was performed twice before GBI, monthly during GBI and 1 week after leaving isolation. The results obtained before GBI demonstrate that the changes of support and proprioceptive afferentation signals play significant role in reorganizing of the biomechanical structure of motor acts and the development of new movement patterns. The results of the study are consistent with the previously obtained results of other studies in this direction. Despite the fact that during the GBI the participants of the experiment performed regular physical training, a decrease in the performance indicators values was detected, especially pronounced after 100 days of GBI. This is probably due to limited space of a space station model, as well as the development of a special motor stereotype in it. Noteworthy are the results obtained after the 4th session of the experiment, indicating the effect of sensorimotor learning. We think that the data obtained in this study will be useful in research both in gravitational physiology and in clinical medicine. (shrink)

This dissertation explores the influence of time constraints on different research practices. The first two parts present case studies, which serve as a basis for discussing the epistemological and ethical implications of temporal limitations in scientific research. Part I is a case study on gravitational wave research, conducted by the LIGO Scientific Collaboration. This exemplifies fundamental research – without immediate societal applications, open-ended in terms of timeline and in terms of research goals. It is based, in part, on qualitative (...) interviews conducted with gravitational wave physicists. I show that considerations about time and speed play a role in every stage of research: goal setting, method design, and the evaluation and communication of results. Part II provides a case study on translational medicine, an approach explicitly dedicated to accelerating research in order to develop and implement new therapies. This epitomizes applied research with high social stakes, motivated by non-epistemic goals. Here, epistemic trade-offs between speed and reliability intersect with ethical trade-offs between different types of harms. In Part III, the insights from both of these case studies are used as the basis for a more general discussion concerning the pragmatic aspects of epistemic practices, especially in relation to current debates centered on the role of values in science. A particular focus is on the value of speed and the ability to generate reliable results, either via choice of methods, or via decisions about which goals to set, as well as decisions about when to stop further testing. The primary thesis of the dissertation is that pragmatic considerations stemming from limitations of resources are a necessary feature of the pursuit of epistemic aims, and that the epistemic is thus inherently pragmatic. (shrink)

In his [1937, 1938], Paul Dirac proposed his “Large Number Hypothesis” (LNH), as a speculative law, based upon what we will call the “Large Number Coincidences” (LNC’s), which are essentially “coincidences” in the ratios of about six large dimensionless numbers in physics. Dirac’s LNH postulates that these numerical coincidences reflect a deeper set of law-like relations, pointing to a revolutionary theory of cosmology. This led to substantial work, including the development of Dirac’s later [1969/74] cosmology, and other alternative cosmologies, such (...) as the Brans-Dicke modification of GTR, and to extensive empirical tests. We may refer to the generic hypothesis of “Large Number Relations” (LNR’s), as the proposal that there are lawlike relations of some kind between the dimensionless numbers, not necessarily those proposed in Dirac’s early LNH. Such relations would have a profound effect on our concepts of physics, but they remain shrouded in mystery. Although Dirac’s specific proposals for LNR theories have been largely rejected, the subject retains interest, especially among cosmologists seeking to test possible variations in fundamental constants, and to explain dark energy or the cosmological constant. In the first two sections here we briefly summarize the basic concepts of LNR’s. We then introduce an alternative LNR theory, using a systematic formalism to express variable transformations between conventional measurement variables and the true variables of the theory. We demonstrate some consistency results and review the evidence for changes in the gravitational constant G. The theory adopted in the strongest tests of Ġ/G, by the Lunar Laser Ranging (LLR) experiments, assumes: Ġ/G = 3(dr/dt)/r – 2(dP/dt)/P – (dm/dt)/m, as a fundamental relationship. Experimental measurements show the RHS to be close to zero, so it is inferred that significant changes in G are ruled out. However when the relation is derived in our alternative theory it gives: Ġ/G = 3(dr/dt)/r – 2(dP/dt)/P – (dm/dt)/m – (dR/dt)/R. The extra final term (which is the Hubble constant) is not taken into account in conventional derivations. This means the LLR experiments are consistent with our LNR theory (and others), and they do not really test for a changing value of G at all. This failure to transform predictions of LNR theories correctly is a serious conceptual flaw in current experiment and theory. (shrink)