This article centers on Hume’s position on the intelligibility of natural philosophy. To that end, the controversy surrounding universal gravitation shall be scrutinized. It is very well-known that Hume sides with the Newtonian experimentalist approach rather than with the Leibnizian demand for intelligibility. However, what is not clear is Hume’s overall position on the intelligibility of natural philosophy. It shall be argued that Hume declines Leibniz’s principle of intelligibility. However, Hume does not eschew intelligibility altogether; his concept of (...) causation itself stipulates mechanical intelligibility. (shrink)

This article investigates the relationship between Hume’s causal philosophy and Newton ’s philosophy of nature. I claim that Newton ’s experimentalist methodology in gravity research is an important background for understanding Hume’s conception of causality: Hume sees the relation of cause and effect as not being founded on a priori reasoning, similar to the way that Newton criticized non - empirical hypotheses about the properties of gravity. However, according to Hume’s criteria of causal inference, the law of universal (...) class='Hi'>gravitation is not a complete causal law, since it does not include a reference either to contiguity or to temporal priority. It is still argued that because of the empirical success of Newton ’s theory—the law is a statement of an exceptionless repetition—Hume gives his support to it in interpreting gravity force instrumentally as if it bore a causal relation to motion. (shrink)

In this paper an analysis of Newton’s argument for universal gravitation is provided. In the past, the complexity of the argument has not been fully appreciated. Recent authors like George E. Smith and William L. Harper have done a far better job. Nevertheless, a thorough account of the argument is still lacking. Both authors seem to stress the importance of only one methodological component. Smith stresses the procedure of approximative deductions backed-up by the laws of motion. Harper stresses (...) “systematic dependencies” between theoretical parameters and phenomena. I will argue that Newton used a variety of different inferential strategies: causal parsimony considerations, deductions, demonstrative inductions, abductions and thought-experiments. Each of these strategies is part of Newton’s famous argument. (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)

In this essay, I attempt to assess Henk de Regt and Dennis Dieks recent pragmatic and contextual account of scientific understanding on the basis of an important historical case-study: understanding in Newton’s theory of universal gravitation and Huygens’ reception of universal gravitation. It will be shown that de Regt and Dieks’ Criterion for the Intelligibility of a Theory (CIT), which stipulates that the appropriate combination of scientists’ skills and intelligibility-enhancing theoretical virtues is a condition for scientific (...) understanding, is too strong. On the basis of this case-study, it will be shown that scientists can understand each others’ positions qualitatively and quantitatively, despite their endorsement of different worldviews and despite their convictions as what counts as a proper explanation. (shrink)

Kant's views on the epistemological status of physical science provide an important example of how a philosophical system can be applied to understand the foundation of scientific theories. Michael Friedman has made considerable progress towards elucidating Kant's philosophy of science; in particular, he has argued that Kant viewed Newton's law of universal gravitation as necessary for the possibility of experiencing what Kant called true motion, which is more than the mere relative motion of appearances but is different from (...) Newton's concept of absolute motion. In this context, Friedman has provided an account of how Kant must have viewed Newton's supposed derivation of universal gravitation from Kepler's laws, based on, among other things, Kant's claim that Newton really needed to make extra assumptions in order to derive universal gravitation. In this paper, I argue that Friedman's account is incomplete for three reasons. First, Friedman has overlooked an important aspect of how Newton's third law is applied in the relevant sections of the Principia; as a result, Friedman's account partially misconstrues the relation between the planetary phenomena and the theory of universal gravitation. Second, his account fails to account for Kant's apparent belief that Kepler's laws are only empirically-based rules, even though they seem to be necessary for the derivation of universal gravitation and hence also necessary for Kant's own definition of true motion. Third, Friedman has overlooked some remarks by Kant that indicate that Kant thought the crucial properties of universal gravitation could be known without reference to the empirically determined motions of the planets and hence seemingly without any help from Newton. (shrink)

From the very day in 1686 when Edmond Halley placed Book I of the Principia before the Royal Society, Robert Hooke's claim to prior discovery has been associated with the law of universal gravitation. If the seventeenth century rejected Hooke's claim summarily, historians of science have not forgotten it, and a steady stream of articles continues the discussion. In our own day particularly, when some of the glitter has worn off, not from the scientific achievement, but from the (...) character of Newton, there has been a tendency vicariously to atone for the treatment Hooke received. The judgement Lohne cites with approval from Vavilov appears to summarize the current estimate of the issue—in the seventeenth century only Newton could have written the Principia; nevertheless Hooke first sketched out its programme. What with all the knocks he has received both alive and dead, one feels guilty in assuming the role of “debunker” at this late date. Apologetically draped in sackcloth then, head covered with ashes I venture softly to suggest that Hooke has received more than his due. There is no question here of justifying Newton's behaviour toward Hooke. Wholly lacking in generosity as it appears to me, Newton's behaviour neither deserves nor can receive justification. The question turns rather on Hooke's scientific theories. Granting always his lack of demonstrations, historians have been prone to interpret his words in the light of Newton's demonstrations. A close examination of Hooke's writings does not sustain the interpretation. Contrary to what is generally asserted, he did not hold a conception of universal gravitation. And if he announced the inverse square relation, he derived it from such a medley of confusion as will not allow his claim to priority. (shrink)

The central problem of the article is the paradox in the history of Newton’s mechanics: prominent researchers of the genesis of the Principia did not believe Newton’s words about the origin of the idea of universal gravity. They did not believe that he could have come up with this idea as early as 1666, considering circular orbits, and believed that Newton invented the story of the falling apple. The article proposes a “subjunctive” scenario leading to the law of (...) class='Hi'>universal gravity and feasible at the level of Galileo’s knowledge and skills in 1611. The basis for such a scenario is the description of a thought experiment in Newton’s manuscript “The System of the World”, preceding the creation of Principia. The proposed reconstruction helps to consider and clarify the concept of “modern physics”, the birth of which was the main event of the Scientific Revolution of the XVI–XVII centuries. The traditional understanding reduces the essence of modern physics to a reliance on experience and on the language of mathematics. Such a definition, however, is not sufficient. The geometry of Euclid and the physics of Archimedes were mathematically perfect, and their axioms were based on objective experience. Despite the importance of the tools of mathematics and experiment, the key innovation of modern physics has become the belief in the hidden fundamental laws of the Universe and in the right of the researcher to invent invisible, “illogical”, “absurd” concepts and postulates, experimentally verifiable only together with the theory based on them. This postulate of fundamental cognitive optimism combines bold ingenuity with a humble need for empirical verification. (shrink)

In his book Philosophie der Raum-Zeit-Lehre (1928) Reichenbach introduced the concept of universal force. Reichenbach's use of this concept was later severely criticized by Grünbaum. In this article it is argued that although Grünbaum's criticism is correct in an important respect, it misses part of Reichenbach's intentions. An attempt is made to clarify and defend Reichenbach's position, and to show that universal force is a useful notion in the physically important case of gravitation.

The generally covariant Lagrangian densityG = ℛ + 2K ℒmatter of the Hamiltonian principle in general relativity, formulated by Einstein and Hilbert, can be interpreted as a functional of the potentialsg ikand φ of the gravitational and matter fields. In this general relativistic interpretation, the Riemann-Christoffel form Γ kl i = kl i for the coefficients г kl i of the affine connections is postulated a priori. Alternatively, we can interpret the LagrangianG as a functional of φ, gik, and the (...) coefficients г kl i . Then the г kl i are determined by the Palatini equations. From these equations and from the symmetry г kl i = г lk i for all matter fields with δℒ/δΓ=0 the Christoffel symbols again result. However, for Dirac's bispinor fields, δℒ/δΓ becomes dependent on the Dirac current, essentially with a coupling factor ∼Khc. In this case, the Palatini equations define a new transport rule for the spinor fields, according to which a second universal interaction results for the Dirac spinors, besides Einstein's gravitation. The generally covariant Dirac wave equations become the general relativistic nonlinear Heisenberg wave equations, and the second universal interaction is given by a Fermi-like interaction term of the V-A type. The geometrically induced Fermi constant is, however, very small and of the order 10−81erg cm3. (shrink)

As is generally known, Newton’s notion of universal gravitation surpassed various theories of particular gravities in the early modern age, as represented mainly by Kepler and Hooke. In his seminal work “Hooke and the Law of Universal Gravitation: A Reappraisal of a Reappraisal” Richard S. Westfall argues that Hooke could not reach beyond the concept of spatially bounded particular gravities, as he deployed the method of analogy between the material principle of congruity and incongruity and the (...) extension of gravitational spheres and their action at a distance. However, the doctrine of universal gravitation does not exclude the nature of particular gravities; it is predicated on the notion of an infinite expansion of individual-gravitational spheres and their uniform nature, namely the mutual and centripetal attraction. In my treatise I attempt to reinvestigate the nature and structure of gravitation, as established historically in the framework of Newtonian Classical Mechanics, by a method of structural intuition. It examines how the structural intuition, as represented in the celestial-mechanical intuitions of Hooke and Kepler, could unfold into an innovative process within the context of early modern mechanical philosophy, attaining thus a historical significance and legitimacy as against the prevailing Newtonian method of geometric-mathematical axiomatization of mechanical principles. It also explores the actual demonstrative features of the tidal phenomenon with regard to its lunar- and solar-gravitational causation, which has been considered to date to be an important piece of empirical evidence for the theory of universal gravitation. (shrink)

According to Whitehead, nature is disclosed to mind by an ensemble of events characterized by unobservable hidden intrinsic factors (e.g., mass, gravitation) and observable extrinsic factors (e.g., motion, density). Mass is not the substratum of dynamics. It implies spatial extension and temporal duration, which are both necessary conditions of observable natural phenomena. Therefore, an instant, deprived of duration, is immeasurable. Whitehead’s claims on mass, space, and time corroborate Verlinde’s alternative conception of quantum gravitation. Within the de Sitter space-time, (...) this conception starts from the competition of the short distance degrees of freedom of the Ryn-Takanayagi tensor with long-distance thermalized excitations. This enables the creation of a baryonic mass and a decrease in de Sitter entropy. The memory effect of the original baryon creation leads to gravitation and the production of extensive thermodynamic entropy. However, the baryon production shrinks, and the dissipating space-time transforms into a space-timeless cold sink with an accompanying strong contracting memory effect. This is equivalent to the alternate motion of a giant Carnot engine, where the heat source and sink energy exchange produce the eternal periodic dynamics of the Universe. This suggests that the Universe did not start from Big Bang but oscillated eternally as a Big Bounce Universe. (shrink)

Gravity’s Ghost is a book about the search for gravitational waves , which are predicted by the general theory of relativity to be ripples in space–time that propagate at the speed of light. The direct detection of GWs, if they exist at all, is exceptionally difficult, because they are theoretically expected to be very weakly coupled to matter. To this date, there is yet no conclusive evidence for the direct detection of GWs. The search for GWs was started by a (...) series of experiments performed by Joseph Weber in the 1960s. The history of the early GW detection experiments, as well as Weber’s claimed detection of GWs, which was eventually discredited, has been examined in great details by Harry Collins .Collins has long advocated a sociological approach to the study of scientific research groups that is premised on the view that in order to understand how scientific knowledge is produced collectively by a group of researchers, it is necessary to engage in the cultu .. (shrink)

This paper analyzes the metaphysical system developed in Cheyne’s Philosophical Principles of Religion. Cheyne was an early proponent of Newtonianism and tackled several philosophical questions raised by Newton’s work. The most pressing of these concerned the causal origin of gravitational attraction. Cheyne rejected the occasionalist explanations offered by several of his contemporaries in favor of a model on which God delegated special causal powers to bodies. Additionally, he developed an innovative approach to divine conservation. This allowed him to argue that (...) Newton’s findings provided evidence for God’s existence and providence without the need for continuous divine intervention in the universe. (shrink)

A convention with regard to geometry, accepting nonholonomic aether motion and coordinate-dependent units, is always valid as an alternative to Einstein's convention. Choosing flat spacetime, Newtonian gravitation is extended, step by step, until equations closely analogous to those of Einstein's theory are obtained. The first step, demanded by considerations of inertia, is the introduction of a vector potential. Treating the electromagnetic and gravitational fields as real and imaginary components of a complex field (gravitational mass being treated as imaginary charge), (...) the Maxwell stress-momentum-energy tensor for the complex field is then used as the source for both fields. The spherically symmetric solution of these unified field equations describes the electron. Third, effects arising from motion of aether fluid with respect to the artificial reference systems of flat spacetime are included. On the grounds that attraction between likes and repulsion between likes are, a priori, equally possible, it is suggested that gravitational and electromagnetic phenomena should enjoy equal status. This can be achieved on the scale of an infinite cosmos by introducing a hierarchy of isolated systems, each of which is a universe when viewed internally and an elementary particle when viewed externally. A universe (defined by the Hubble radius), an electron, and a neutrino are three consecutive isolated systems of the hierarchy. Implied is the existence of antiuniverses where gravitational mass has opposite sign and antimatter predominates. Remarkable relationships between physical constants emerge. (shrink)

David Malament, now emeritus at the University of California, Irvine, where since 1999 he served as a Distinguished Professor of Logic and Philosophy of Science after having spent twenty-three years as a faculty member at the University of Chicago , is well known as the author of numerous articles on the mathematical and philosophical foundations of modern physics with an emphasis on problems of space-time structure and the foundations of relativity theory. Malament’s Topics in the foundations of general relativity and (...) Newtonian gravitation theory has grown out of a set of lecture notes on the foundations of general relativity that he has taught for many years. In full agreement with Manchak , it should be pointed out from the beginning that the book neither is and was never intended to be a graduate general relativity a .. (shrink)

The author, who was Schrödinger's assistant during his last years in Vienna, gives an account of Schrödinger's views and activities during that time which lead him to a different approach to research on the relations between gravitation and quantum phenomena. Various features of past research are outlined in nontechnical terms. A heuristic argument is presented for the role of the zero-point energy of massive particles in counteracting gravitational collapse and the formation of horizons. Arguments are presented for the view (...) that progress in describing extreme gravitational phenomena can be achieved by the new outlook obtained from the introduction of the analog of Maxwell's vacuum displacement term with a quasiconstant parameter, rather than from renormalization of special processes, even if this is successful. The results can be expected to be in accord with Schrödinger's conjectures.A physical interpretation for the change of sign of the differential invariant of Karlhede, Lindström, and Åman at the horizon is suggested.Some important historical details about Schrödinger are touched upon. (shrink)

All quantum-physical and cosmological causal/non-causal dilemmas have superluminally causal solutions if existents are processual by extension-change impact-transfer. Fixing the extent of applicability of mathematics to physics demonstrates Universal Causality for cosmogenetic theories. Whether the cosmos is of finite or infinite content, the Gravitational Coalescence Paradox in cosmogenetic theories yields a philosophical cosmology of infinite-eternal continuous creation: specifically, the Gravitational Coalescence Cosmology.

This paper reviews recent applications of the Einstein- Rosen type space-times to some problems of modern cosmology. An extensive overview of inhomogeneous universes filled with gravitational waves, classical fields, and relativistic fluids is given. The dynamics of primordial inhomogeneities, such as gravitational and matter waves and shocks, their interactions, and the global evolution of the models considered, is presented in detail.

In the present paper a relativistic theory of gravitation (RTG) is unambiguously constructed on the basis of the special relativity and geometrization principle. In this a gravitational field is treated as the Faraday-Maxwell spin-2 and spin-0 physical field possessing energy and momentum. The source of a gravitational field is the total conserved energy-momentum tensor of matter and of a gravitational field in Minkowski space. In the RTG the conservation laws are strictly filfilled for the energy-momentum and for the angular (...) momentum of matter and a gravitational field. The theory explains the whole available set of experiments on gravity. By virtue of the geometrization principle, the Riemannian space in our theory is of field origin, since it appears as an effective force space due to the action of a gravitational field on matter. The RTG leads to an exceptionally strong prediction: The universe is not closed but just “flat.” This suggests that in the universe a “missing mass” should exist in a form of matter. (shrink)

Generic self-gravitating quantum solutions that are not critically dependent on the specifics of microscopic interactions are presented. The solutions incorporate curvature effects, are consistent with the universality of gravity, and have appropriate correspondence with Newtonian gravitation. The results are consistent with known experimental results that indicate the maintenance of the quantum coherence of gravitating systems, as expected through the equivalence principle.

What if someone asked you to keep a four-kilometer-long ruler absolutely still so that you could measure deformations of length of ~1x10^-18m using light? On September 14, 2015, physicists and engineers at the Laser Interferometer Gravitational-Wave Observatory (LIGO) accomplished this absurd feat when they first detected gravitational wave signals—the result of the most violent events in our universe, such as the collision of two black holes—using two immense L-shaped instruments with arms four-kilometers in length and placed in what seemed to (...) be the middle of nowhere. -/- The focus of this dissertation centers on how scientists must have an intricate understanding of the environment surrounding LIGO’s instruments to understand the vast and active universe through the detection of gravitational waves. I explore how LIGO physicists and engineers constructed stillness to distinguish the surrounding natural and built environment from gravitational wave signals. I explore how the pre-LIGO and LIGO laboratory spaces became an expanded laboratory extending as an overlay into the surrounding environment and beyond. I show that the metes and bounds of the expanded laboratory are defined by what the interferometers are sensitive to. I further explore how physicists, engineers, and data scientists theorized an experiment that required such an extreme sensitivity (i.e., imagining stillness), developed methods to investigate, understand, and abate noise, disturbances, and aberrations (i.e., engineering stillness), found sites with minimal noise profiles, both physical and social, that would accommodate the size and function of the instruments despite land uses in conflict with the experiment (i.e., finding stillness), and understood the overlapping human and non-human uses of the land that jeopardized the ability to make these highly precise detections and mediate solutions that would allow for concurrent use of the land (i.e., negotiating stillness). -/- Through this history, I conclude that the level of sensitivity the physicists and engineers can attain in the LIGO interferometers is predicated on constructed stillness. This determines the instruments’ ability to measure the minute deformations in length caused by gravitational waves such that the physicists, engineers, and data scientists can rule out the geography of noise and make the claim that the heterogeneity of their locations at Hanford and Livingston does not negate their assertion of twin detections of gravitational wave signals across their two sites. (shrink)

Robert Hooke’s theory of gravitation is a promising case study for probing the fruitfulness of Menachem Fisch’s insistence on the centrality of trading zone mediators for rational change in the history of science and mathematics. In 1679, Hooke proposed an innovative explanation of planetary motions to Newton’s attention. Until the correspondence with Hooke, Newton had embraced planetary models, whereby planets move around the Sun because of the action of an ether filling the interplanetary space. Hooke’s model, instead, consisted in (...) the idea that planets move in the void space under the influence of a gravitational attraction directed toward the sun. There is no doubt that the correspondence with Hooke allowed Newton to conceive a new explanation for planetary motions. This explanation was proposed by Hooke as a hypothesis that needed mathematical development and experimental confirmation. Hooke formulated his new model in a mathematical language which overlapped but not coincided with Newton’s who developed Hooke’s hypothetical model into the theory of universal gravitation as published in the Mathematical Principles of Natural Philosophy (1687). The nature of Hooke’s contributions to mathematized natural philosophy, however, was contested during his own lifetime and gave rise to negative evaluations until the last century. Hooke has been often contrasted to Newton as a practitioner rather than as a “scientist” and unfavorably compared to the eminent Lucasian Professor. Hooke’s correspondence with Newton seems to me an example of the phenomenon, discussed by Fisch in his philosophical works, of the invisibility in official historiography of “trading zone mediators,” namely, of those actors that play a role, crucial but not easily recognized, in promoting rational scientific framework change. (shrink)

In Roger Boscovich’s Theory of Natural Philosophy, the dynamics of matter is described by the curve of forces, either attractive or repulsive – depending on the distances of the centres of forces. At great distances, the curve of forces is manifested similar to Newton’s gravitation. The gravitation is integrative for the visible universe, but not for the hypothetical multitude of universes that possibly parallelly exist separated by a repulsive force, comparable to the contemporary concept of the dark energy. (...) In the concept of continuous forces in a discontinuous matter, Faraday recognises the idea of a dynamic electromagnetic field, completed by Maxwell, while Einstein later predicted the existence of gravitational waves recently detected. The wave-nature of real space-time matter is found in Boscovich’s model at the small scale of the curve of forces, while the atomic-corpuscular dynamics of classical mechanics is found at the large scale. (shrink)

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)

A highly ordered universe is described in terms of neutrino and electrino alone as basic particles, and length and time alone as dimensional units. New theories are obtained of particles, nuclides, atomic spectra, general relativity, and gravitation.

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)

In early April 1911 Albert Einstein arrived in Prague to become full professor of theoretical physics at the German part of Charles University. It was there, for the first time, that he concentrated primarily on the problem of gravitation. Before he left Prague in July 1912 he had submitted the paper "Relativität und Gravitation: Erwiderung auf eine Bemerkung von M. Abraham" in which he remarkably anticipated what a future theory of gravity should look like. At the occasion of (...) the Einstein-in-Prague centenary an international meeting was organized under a title inspired by Einstein's last paper from the Prague period: "Relativity and Gravitation, 100 Years after Einstein in Prague". The main topics of the conference included: classical relativity, numerical relativity, relativistic astrophysics and cosmology, quantum gravity, experimental aspects of gravitation, and conceptual and historical issues. The conference attracted over 200 scientists from 31 countries, among them a number of leading experts in the field of general relativity and its applications. This volume includes abstracts of the plenary talks and full texts of contributed talks and articles based on the posters presented at the conference. These describe primarily original results of the authors. Full texts of the plenary talks are included in the volume "General Relativity, Cosmology and Astrophysics--Perspectives 100 Years after Einstein in Prague", editions. J. Bičák and T. Ledvinka, published also by Springer Verlag. (shrink)

This study investigates the characteristics of the generalized gravitation equation in a complex spacetime manifold. The newly applied complex spacetime coordinates were designed to integrate peculiar velocity and the receding velocity of the particle into a single coordinate system. On this basis, the Schwarzschild metric solution was extended to a complexified version, and a generalized geodesic equation was derived in the complex spacetime manifold. It was found from the derived gravitation equation that the gravitation interaction depends on (...) the space deceleration parameter \ and can act as a repulsive force in the giant space scale that satisfies \. These results require a rapid expansion of space in the early universe and suggest that the gravitational interactions of matter are fundamentally linked to the space expansion characteristics. (shrink)

We study the possible interpretation of the "universal constants" by the classification of J.-M. Lévy-Leblond. The Planck constant and the speed of light in vacuum are the most common examples of constants of this type. Using Fock’s principle of the relativity w.r.t. observation means, we show that these two constants can be viewed as manifestations of certain relativity. We also show that there is a possibility to interpret the Boltzmann constant in a similar way, and make some comments about (...) the relativistic interpretation of the constant spacetime curvature and gravitational constant G. (shrink)

Modern observations based on general relativity indicate that the spatial geometry of the expanding, large-scale Universe is very nearly Euclidean. This basic empirical fact is at the core of the so-called “flatness problem”, which is widely perceived to be a major outstanding problem of modern cosmology and as such forms one of the prime motivations behind inflationary models. An inspection of the literature and some further critical reflection however quickly reveals that the typical formulation of this putative problem is fraught (...) with questionable arguments and misconceptions and that it is moreover imperative to distinguish between different varieties of problem. It is shown that the observational fact that the large-scale Universe is so nearly flat is ultimately no more puzzling than similar “anthropic coincidences”, such as the specific values of the gravitational and electromagnetic coupling constants. In particular, there is no fine-tuning problem in connection to flatness of the kind usually argued for. The arguments regarding flatness and particle horizons typically found in cosmological discourses in fact address a mere single issue underlying the standard FLRW cosmologies, namely the extreme improbability of these models with respect to any “reasonable measure” on the “space of all spacetimes”. This issue may be expressed in different ways and a phase space formulation, due to Penrose, is presented here. A horizon problem only arises when additional assumptions—which are usually kept implicit and at any rate seem rather speculative—are made. (shrink)

The subject matter of the article is a standard cosmological model of the Universe. Contemporary opinion regarding origin, structure, and evolution of the Universe is of great interest. The answer to the question of the Universe origin is given by the Big Bang Theory. Is it possible to be sure in this theory correctness, which persuading of the Universe origination from the singularity fluctuation, when the World had appeared from nowhere, that is from abstract nothingness, further accelerated expansion of the (...) Universe following the Big Bang, and its development up to present with inexplicable source of energy for that. However, in the extreme end of the meta-universe the speed of stellar formations runaway is about the light velocity. Further, there is a new problem, the finiteness of the Universe. There are two counter-opinions, if the expanding Universe is finite or infinite. A very important question arises here, the question regarding isolatedness of the Universe as a system. The problem of the Universe heat death is closely connected with it. For this reason it is the time to discuss the Universe entropy. There is a short description of notions and problems with reference to this branch of knowledge, as well as of Doppler and Ritz effects alongside with Habble Law. The authors’ detailed interpretation of an entropy is also suggested. The analysis of the existing model is followed by the idea of the authors about the Universe organization. The style of the article is popular-science. In the first part of the article the existing concept of the Expanding Universe Theory and the dynamical Friedmann-Lemaitre models are described; it deals with the existing concept of the Big Bang Theory as well as the dark energy and the dark matter notions. In the second part the author gives detailed interpretation of an entropy. In the last part the problem of theoretical basis and fact nonconformity within the Expanding Universe Model Theory and the authors’ idea about the Universe organization are considered. (shrink)

In the framework of contemporary cosmology, the age-old aspiration to inquire the outer limits of the universe translates into our effort to observe the initial stages of cosmic history. Thanks to a fortunate combination of astronomical circumstances, and pushing mm-wave technology to its limits, today we are able to image the early universe in great detail, back at a time when cosmic age was only 0.0027% of its present value. The state of the art in the field has been set (...) by the ESA Planck mission, launched in 2009, dedicated to precision measurements of the cosmic microwave background. Planck observed the full sky for 4 years in a wide frequency range, reaching μK sensitivity both in temperature and polarization. The latest results, published by the Planck Collaboration in 2018, are in exquisite agreement with the simplest 6-parameter ΛCDM model and constrain the main cosmological parameters with percent-level accuracy. Furthermore, the Planck data yield insight on the very early universe, opening the way to a new generation of experiments searching for the possible signatures of primordial gravitational waves in the CMB polarization pattern. (shrink)

The Weyl-Dirac theory of gravitation and electromagnetism is modified by the introduction of a background metric characterized by a scale constant related to the size of the universe. One is led to a natural gauge giving ${{\dot G} \mathord{\left/ {\vphantom {{\dot G} G}} \right. \kern-0em} G} = - 5.5 \times 10^{ - 12} y^{ - 1} $ . This is smaller by about a factor of ten than the value obtained on the basis of Dirac's large number hypothesis.

References to energy of the universe have focussed upon the matter contribution, whereas the conservation laws must include a gravitational contribution as well. The conservation laws as applied to FRW cosmologies suggest a zero total energy irrespective of the spatial curvature when the value of the cosmological constant is taken to be zero. This result provides a useful constraint on models of the early universe and lends support to currently studied theories of the universe arising as a quantum fluctuation of (...) the vacuum. (shrink)

M. Nordmann has presented Einstein's principle in words which lift the average reader over many of the difficulties he must encounter in trying to take it in. Remembering Goethe's maxim that he who would accomplish anything must limit himself, he has not aimed at covering the full field to which Einstein's teaching is directed. But he succeeds in making many abstruse things intelligible to the layman. Perhaps the most brilliant of his efforts in this direction are Chapters V and VI, (...) in which he explains with extra- ordinary lucidity the new theory of gravitation and of its relation to inertia. (shrink)

They had to be, because they were the creations of a perfect God, and a circle is the most perfect of geometrical objects. When Johannes Kepler, after spending most of his career trying to make sense of the meticulous planetary observations of Tycho Brahe, concluded that the orbits of the planets were not circles but ellipses, the discovery sent shock waves through the community of natural philosophers. The discovery led Newton and others to arrive at the inverse square law of (...) gravitational attraction. (shrink)