Download or read book Theoretical and Observational Consistency of Massive Gravity written by Lavinia Heisenberg and published by Springer. This book was released on 2015-06-12 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work is a detailed study of both the theoretical and phenomenological consequences of a massive graviton, within the ghost-free theory of massive gravity, the de Rham-Gabadadze-Tolley (dRGT) theory. Its aim is to test the physical viability of the theory. It begins by putting constraints on the parameters of the theory in the decoupling limit based on purely theoretical grounds, like classical stability in the cosmological evolution of self-accelerating and degravitating solutions. The author then constructs a proxy theory to massive gravity from the decoupling limit resulting in non-minimally coupled scalar-tensor interactions as an example of a subclass of Horndeski theories. Lastly, she addresses the natural question of whether the parameters introduced in the dRGT theory are subject to strong renormalization by quantum loops and shows how the non-renormalization theorem protects the graviton mass from quantum corrections. Beyond the decoupling limit the quantum corrections are found to be proportional to the graviton mass, proving its technical naturalness.
Download or read book Foundations of Massive Gravity written by Andrew Matas and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: General Relativity (GR) is a relativistic theory of gravity which has a large number of theoretical and observational successes. From the perspective of quantum field theory, GR can be thought of as a theory of a massless spin-2 particle called the graviton. It is a fundamental question to ask how the graviton behaves if it has a small but non-zero mass. In this dissertation I shall study the recently constructed theory of ghost-free massive gravity, which avoids the pernicious Boulware-Deser ghost that had thwarted previous attempts to study massive gravity. In Chapter 1 I will give a broad overview of the context, motivation, and model-building issues underlying massive gravity. Then in Chapter 2 I will give a detailed pedagogical introduction to ghost-free massive gravity focusing on concepts that will be used throughout the remainder of the work. In Chapter 3 I will derive the ghost-free structure of massive gravity from an extra dimensional perspective through a process known as Dimensional Deconstruction. Before my work it had been an open question whether Deconstruction could be consistently applied to gravity. The key insight relies on using the elegant formulation of General Relativity in terms of the vielbein. Inspired by Deconstruction, in Chapter 4 I will discuss the possibility of non-standard kinetic interactions in massive gravity. I will show that the only consistent derivative interactions for a massive spin-2 particle must be the same as in GR. This is remarkable because there is no known symmetry reason for this to be the case, since massive gravity breaks diffeomorphism invariance. Finally, in Chapter 5, in order to connect with observations I shall consider the radiation emitted from binary systems in Galileon theories, which are scalar theories that can mimic the behavior of a massive graviton. This work extends the understanding of the Vainshtein screening mechanism into a time-dependent situation.
Download or read book Modifications of Einstein s Theory of Gravity at Large Distances written by Eleftherios Papantonopoulos and published by Springer. This book was released on 2014-11-04 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last few years modified gravity theories have been proposed as extensions of Einstein's theory of gravity. Their main motivation is to explain the latest cosmological and astrophysical data on dark energy and dark matter. The study of general relativity at small scales has already produced important results (cf e.g. LNP 863 Quantum Gravity and Quantum Cosmology) while its study at large scales is challenging because recent and upcoming observational results will provide important information on the validity of these modified theories. In this volume, various aspects of modified gravity at large scales will be discussed: high-curvature gravity theories; general scalar-tensor theories; Galileon theories and their cosmological applications; F(R) gravity theories; massive, new massive and topologically massive gravity; Chern-Simons modifications of general relativity (including holographic variants) and higher-spin gravity theories, to name but a few of the most important recent developments. Edited and authored by leading researchers in the field and cast into the form of a multi-author textbook at postgraduate level, this volume will be of benefit to all postgraduate students and newcomers from neighboring disciplines wishing to find a comprehensive guide for their future research.
Download or read book The Beauty of Falling written by Claudia de Rham and published by Princeton University Press. This book was released on 2024-04-02 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This book explores the subject of gravity in a fresh way, taking the reader from Newton to the frontiers of gravitational physics. Per Einstein's general theory of relativity, gravity is a manifestation of the curvature of spacetime, and this is an excellent and robust framework for understanding gravity in many situations. However, physicists nowadays also often understand gravity as the manifestation of a fundamental particle - the graviton - in the same way that we understand electromagnetism as the manifestation of the photon. And, in the very same way that we can "see" light, which is nothing other than an electromagnetic wave propagating through space and time, we can now "hear" gravity in the form of gravitational waves (waves in the very fabric of spacetime). As we celebrate 6 years since the first direct detection of gravitational waves, the reality of these waves, predicted by Einstein's theory of gravity, is now unquestionable. They offer a cutting-edge opportunity to decipher the many mysteries that our Universe is still hiding. What is the origin of the Universe? What are the dark components of the Universe that explain its structure and evolution? What is our fate? In The Beauty of Falling, de Rahm will explore these mysteries, building up a palpable portrait of gravity - what we know and don't know.The book begins with the Newtonian notion of gravitational force and quickly proceeds to Einstein's theory of relativity, while revealing how much more of our picture there is yet to uncover. The author will emphasize that General Relativity predicts its own downfall, and where the theory breaks down - at the particle level - is exactly where scientists are focusing in their search for new physics. The author brings the reader to a new gravitational frontier and, in doing so, introduces her own work - a theory of "massive gravity."While Einstein's theory of gravity assumes that the graviton is massless, "massive gravity" suggests an alternative - that the graviton may indeed have mass and a finite range, meaning that it "switches off" at cosmological scales. This would explain the current accelerating expansion of the universe that is observed. The author interweaves her personal history and research trajectory throughout, explaining the science but also highlighting the adventure of research, the thrill of questioning nature and challenging it in its deepest realization, and the excitement of discovering something entirely new. The story contains setbacks and breakthroughs, from the challenge of being a woman in a field where the representation of women is typically less than 10%, to dealing with the aftermath of challenging the previous claims of a generation of senior scientists (most of whom are men)"--
Download or read book The Gravitational Constant Generalized Gravitational Theories and Experiments written by V. de Sabbata and published by Springer Science & Business Media. This book was released on 2004-03-31 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: An up-to-date description of progress and current problems with the gravitational constant, both in terms of generalized gravitational theories and experiments either in the laboratory, using Casimir force measurements, or in space at solar system distances and in cosmological observations. Contributions cover different aspects of the state and prediction of unified theories of the physical interactions including gravitation as a cardinal link, the role of experimental gravitation and observational cosmology in discriminating between them, the problem of the precise measurement and stability of fundamental physical constants in space and time, and the gravitational constant in particular. Recent advances discussed include unified and scalar-tensor theories, theories in diverse dimensions and their observational windows, gravitational experiments in space, rotational and torsional effects in gravity, basic problems in cosmology, early universe as an arena for testing unified models, and big bang nucleosynthesis.
Download or read book Introduction to Modified Gravity written by Albert Petrov and published by Springer Nature. This book was released on 2023-11-16 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews various modified gravity models, including those with modifications in the pure gravitational sector; those involving extra fields, that is, scalar-tensor and vector-tensor gravity theories; gravity models with Lorentz symmetry breaking; and nonlocal gravity models. The authors discuss both classical and quantum aspects of these theories. The book is unique in bringing together all the current alternatives to Einstein gravity in one source and serves as an excellent starting point for graduate students and other newcomers seeking an overview. This second edition has been expanded with new results from a variety of approaches including f(R,Q,P) gravity, galileon gravity and massive gravity. Extended discussions of Lorentz-breaking terms and of non-local field theory have been added and a completely new chapter is devoted to models based on non-Riemannian geometry.
Download or read book Gravity a Geometrical Course written by Pietro Giuseppe Frè and published by Springer Science & Business Media. This book was released on 2012-10-24 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: ‘Gravity, a Geometrical Course’ presents general relativity (GR) in a systematic and exhaustive way, covering three aspects that are homogenized into a single texture: i) the mathematical, geometrical foundations, exposed in a self consistent contemporary formalism, ii) the main physical, astrophysical and cosmological applications, updated to the issues of contemporary research and observations, with glimpses on supergravity and superstring theory, iii) the historical development of scientific ideas underlying both the birth of general relativity and its subsequent evolution. The book is divided in two volumes. Volume Two is covers black holes, cosmology and an introduction to supergravity. The aim of this volume is two-fold. It completes the presentation of GR and it introduces the reader to theory of gravitation beyond GR, which is supergravity. Starting with a short history of the black hole concept, the book covers the Kruskal extension of the Schwarzschild metric, the causal structures of Lorentzian manifolds, Penrose diagrams and a detailed analysis of the Kerr-Newman metric. An extensive historical account of the development of modern cosmology is followed by a detailed presentation of its mathematical structure, including non-isotropic cosmologies and billiards, de Sitter space and inflationary scenarios, perturbation theory and anisotropies of the Cosmic Microwave Background. The last three chapters deal with the mathematical and conceptual foundations of supergravity in the frame of free differential algebras. Branes are presented both as classical solutions of the bulk theory and as world-volume gauge theories with particular emphasis on the geometrical interpretation of kappa-supersymmetry. The rich bestiary of special geometries underlying supergravity lagrangians is presented, followed by a chapter providing glances on the equally rich collection of special solutions of supergravity. Pietro Frè is Professor of Theoretical Physics at the University of Torino, Italy and is currently serving as Scientific Counsellor of the Italian Embassy in Moscow. His scientific passion lies in supergravity and all allied topics, since the inception of the field, in 1976. He was professor at SISSA, worked in the USA and at CERN. He has taught General Relativity for 15 years. He has previously two scientific monographs, “Supergravity and Superstrings” and “The N=2 Wonderland”, He is also the author of a popular science book on cosmology and two novels, in Italian.
Download or read book Gravity a Geometrical Course written by Pietro Giuseppe Frè and published by Springer Science & Business Media. This book was released on 2012-10-24 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: ‘Gravity, a Geometrical Course’ presents general relativity (GR) in a systematic and exhaustive way, covering three aspects that are homogenized into a single texture: i) the mathematical, geometrical foundations, exposed in a self consistent contemporary formalism, ii) the main physical, astrophysical and cosmological applications, updated to the issues of contemporary research and observations, with glimpses on supergravity and superstring theory, iii) the historical development of scientific ideas underlying both the birth of general relativity and its subsequent evolution. The book, divided in two volumes, is a rich resource for graduate students and those who wish to gain a deep knowledge of the subject without an instructor. Volume One is dedicated to the development of the theory and basic physical applications. It guides the reader from the foundation of special relativity to Einstein field equations, illustrating some basic applications in astrophysics. A detailed account of the historical and conceptual development of the theory is combined with the presentation of its mathematical foundations. Differentiable manifolds, fibre-bundles, differential forms, and the theory of connections are covered, with a sketchy introduction to homology and cohomology. (Pseudo)-Riemannian geometry is presented both in the metric and in the vielbein approach. Physical applications include the motions in a Schwarzschild field leading to the classical tests of GR (light-ray bending and periastron advance) discussion of relativistic stellar equilibrium, white dwarfs, Chandrasekhar mass limit and polytropes. An entire chapter is devoted to tests of GR and to the indirect evidence of gravitational wave emission. The formal structure of gravitational theory is at all stages compared with that of non gravitational gauge theories, as a preparation to its modern extension, namely supergravity, discussed in the second volume. Pietro Frè is Professor of Theoretical Physics at the University of Torino, Italy and is currently serving as Scientific Counsellor of the Italian Embassy in Moscow. His scientific passion lies in supergravity and all allied topics, since the inception of the field, in 1976. He was professor at SISSA, worked in the USA and at CERN. He has taught General Relativity for 15 years. He has previously two scientific monographs, “Supergravity and Superstrings” and “The N=2 Wonderland”, He is also the author of a popular science book on cosmology and two novels, in Italian.
Download or read book Modified Gravity and Cosmology written by Emmanuel N. Saridakis and published by Springer Nature. This book was released on 2021-12-10 with total page 631 pages. Available in PDF, EPUB and Kindle. Book excerpt: With a focus on modified gravity this book presents a review of the recent developments in the fields of gravity and cosmology, presenting the state of the art, high-lighting the open problems, and outlining the directions of future research. General Relativity and the ΛCDM framework are currently the standard lore and constitute the concordance paradigm of cosmology. Nevertheless, long-standing open theoretical issues, as well as possible new observational ones arising from the explosive development of cosmology in the last two decades, offer the motivation and lead a large amount of research to be devoted in constructing various extensions and modifications. In this review all extended theories and scenarios are first examined under the light of theoretical consistency, and are then applied in various geometrical backgrounds, such as the cosmological and the spherical symmetric ones. Their predictions at both the background and perturbation levels, and concerning cosmology at early, intermediate and late times, are then confronted with the huge amount of observational data that astrophysics and cosmology has been able to offer in the last two decades. Theories, scenarios and models that successfully and efficiently pass the above steps are classified as viable and are candidates for the description of Nature, allowing readers to get a clear overview of the state of the art and where the field of modified gravity is likely to go. This work was performed in the framework of the COST European Action “Cosmology and Astrophysics Network for Theoretical Advances and Training Actions” - CANTATA.
Download or read book Was Einstein Wrong written by Marcus Högås and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gravity Strings and Particles written by Maurizio Gasperini and published by Springer. This book was released on 2014-05-12 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: New fundamental forces of Nature? New forms of "dark'' energy? Signals from epochs preceding the Big Bang? Is our space-time unique? Only a joint study of the three topics examined in this book – gravity, strings and particles – may provide answers to these questions. Such a study may also provide the key to solving one of the most fascinating mysteries of modern science, namely: Besides time and the three spatial dimensions, how many other dimensions exist in our universe? The book is primarily addressed to readers who do not necessarily have a specific background in physics but are nevertheless interested in discovering the originality and the possible implications of some of the amazing ideas in modern theoretical physics. The emphasis is on conveying ideas rather than explaining formulas, focusing not on what is known but -- mainly -- on what is still unknown. Many parts of the book are devoted to fundamental theoretical models and results which are potentially highly relevant for a deeper understanding of Nature, but are still waiting to be confirmed (or disproved) by experiments. From this point of view, the material of this book may also be of interest to professional physicists, whether or not they work in the field of fundamental interactions.
Download or read book Gravitation and Modern Cosmology written by N. Sánchez and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Peter Gabriel Bergmann started his work on general relativity in 1936 when he moved from Prague to the Institute for Advanced Study in Princeton. Bergmann collaborated with Einstein in an attempt to provide a geometrical unified field theory of gravitation and electromagnetism. Within this program they wrote two articles together: A. Einstein and P. G. Bergmann, Ann. Math. 39, 685 (1938) ; and A. Einstein, V. Bargmann and P. G. Bergmann, Th. von Karman Anniversary Volume 212 (1941). The search for such a theory was intense in the ten years following the birth of general relativity. In recent years, some of the geometrical ideas proposed in these publications have proved essential in contemporary attempts towards the unification of all interactions including gravity, Kaluza-Klein type theories and supergravity theories. In 1942, Bergmann published the book "Introduction to the Theory of Relativity" which included a foreword by Albert Einstein. This book is a reference for the subject, either as a textbook for classroom use or for individual study. A second corrected and enlarged edition of the book was published in 1976. Einstein said in his foreword to the first edition: "Bergmann's book seems to me to satisfy a definite need. . . Much effort has gone into making this book logically and pedagogically satisfactory and Bergmann has spent many hours with me which were devoted to this end.
Download or read book Gravity Gauge Theories and Quantum Cosmology written by J.V. Narlikar and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: For several decades since its inception, Einstein's general theory of relativity stood somewhat aloof from the rest of physics. Paradoxically, the attributes which normally boost a physical theory - namely, its perfection as a theoreti cal framework and the extraordinary intellectual achievement underlying i- prevented the general theory from being assimilated in the mainstream of physics. It was as if theoreticians hesitated to tamper with something that is manifestly so beautiful. Happily, two developments in the 1970s have narrowed the gap. In 1974 Stephen Hawking arrived at the remarkable result that black holes radiate after all. And in the second half of the decade, particle physicists discovered that the only scenario for applying their grand unified theories was offered by the very early phase in the history of the Big Bang universe. In both cases, it was necessary to discuss the ideas of quantum field theory in the background of curved spacetime that is basic to general relativity. This is, however, only half the total story. If gravity is to be brought into the general fold of theoretical physics we have to know how to quantize it. To date this has proved a formidable task although most physicists would agree that, as in the case of grand unified theories, quantum gravity will have applications to cosmology, in the very early stages of the Big Bang universe. In fact, the present picture of the Big Bang universe necessarily forces us to think of quantum cosmology.
Download or read book Bounds on the Effective Theory of Gravity in Models of Particle Physics and Cosmology written by Michael Atkins and published by Springer. This book was released on 2014-05-13 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effective theory of quantum gravity coupled to models of particle physics is being probed by cutting edge experiments in both high energy physics (searches for extra dimensions) and cosmology (testing models of inflation). This thesis derives new bounds that may be placed on these models both theoretically and experimentally. In models of extra dimensions, the internal consistency of the theories at high energies are investigated via perturbative unitarity bounds. Similarly it is shown that recent models of Higgs inflation suffer from a breakdown of perturbative unitarity during the inflationary period. In addition, the thesis uses the latest LHC data to derive the first ever experimental bound on the size of the Higgs boson's non-minimal coupling to gravity.
Download or read book Everything About Gravity Proceedings Of The Second Lecospa International Symposium written by Pisin Chen and published by World Scientific. This book was released on 2016-12-29 with total page 681 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proceedings of the 2nd LeCosPA International Symposium, 'Everything about Gravity', collects 78 papers contributed by the symposium's Plenary Session and Parallel Session speakers. Organizers of the Parallel Sessions have in addition prepared summaries for their own sessions. The topics range from quasi-local energy in GR in the presence of gravitational radiations, a gauge theory perspective of gravity, naked black hole firewalls related to the black hole information loss paradox, a new theory of spacetime quantization, relations between the Schwinger effect and the Hawking radiation and Unruh effect, conformal frames in cosmology, surprises in nonrelativistic naturalness, inflation and tensor fluctuations, emergent spacetime for quantum gravity, understanding strongly coupled magnetism through holographic principle, the detections of dark matter, ultra-high energy cosmic neutrinos and cosmic rays, etc. Last but not least, the closing remark delivered by John Ellis raised the following question: Does cosmological inflation require a modification of Einstein's gravity?After 100 years of remarkable success of Einstein's general relativity, the development of a successful quantum theory of gravity has become a major goal in physics in the 21st century. This volume serves as a valuable reference for scientists who are interested in frontier research topics of gravity.
Download or read book Massive Gravity on a Brane written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: At present no theory of a massive graviton is known that is consistent with experiments at both long and short distances. The problem is that consistency with long distance experiments requires the graviton mass to be very small. Such a small graviton mass however implies an ultraviolet cutoff for the theory at length scales far larger than the millimeter scale at which gravity has already been measured. In this paper we attempt to construct a model which avoids this problem. We consider a brane world setup in warped AdS spacetime and we investigate the consequences of writing a mass term for the graviton on a the infrared brane where the local cutoff is of order a large (galactic) distance scale. The advantage of this setup is that the low cutoff for physics on the infrared brane does not significantly affect the predictivity of the theory for observers localized on the ultraviolet brane. For such observers the predictions of this theory agree with general relativity at distances smaller than the infrared scale but go over to those of a theory of massive gravity at longer distances. A careful analysis of the graviton two-point function, however, reveals the presence of a ghost in the low energy spectrum. A mode decomposition of the higher dimensional theory reveals that the ghost corresponds to the radion field. We also investigate the theory with a brane localized mass for the graviton on the ultraviolet brane, and show that the physics of this case is similar to that of a conventional four dimensional theory with a massive graviton, but with one important difference: when the infrared brane decouples and the would-be massive graviton gets heavier than the regular Kaluza-Klein modes, it becomes unstable and it has a finite width to decay off the brane into the continuum of Kaluza-Klein states.
Download or read book Modified Gravity Progresses And Outlook Of Theories Numerical Techniques And Observational Tests written by Baojiu Li and published by World Scientific. This book was released on 2019-10-10 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modified gravity theories have been a main focus of theoretical cosmology research in the past decade or so, and have been quickly developing into a mature research field that attracts attention, interest and effort from both theoretical and observational cosmologists. To be prepared for fully exploiting the future observational data, and to provide a guidance for people who are new to this field, it is useful to have a comprehensive review to summarise the current state of knowledge and to foresee the future developments.This book presents expert reviews on different topics in the field, which are then coordinated and organised in a self-consistent and self-contained manner. It is suitable for graduate students and researchers interested in the frontier research of gravity theories.
