Author: Tiberiu Harko
Publisher: Cambridge University Press
ISBN: 1108428746
Category : Science
Languages : en
Pages : 475
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Book Description
Presents a detailed analysis of modified theories of gravity, discussing their development, cosmological and astrophysical implications and outstanding challenges.
Author: Tiberiu Harko
Publisher: Cambridge University Press
ISBN: 1108584578
Category : Science
Languages : en
Pages : 476
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Book Description
Recent cosmological observations have posed a challenge for traditional theories of gravity: what is the force driving the accelerated expansion of the universe? What if dark energy or dark matter do not exist and what we observe is a modification of the gravitational interaction that dominates the universe at large scales? Various extensions to Einstein's General Theory of Relativity have been proposed, and this book presents a detailed theoretical and phenomenological analysis of several leading, modified theories of gravity. Theories with generalised curvature-matter couplings are first explored, followed by hybrid metric-Palatini gravity. This timely book first discusses key motivations behind the development of these modified gravitational theories, before presenting a detailed overview of their subsequent development, mathematical structure, and cosmological and astrophysical implications. Covering recent developments and with an emphasis on astrophysical and cosmological applications, this is the perfect text for graduate students and researchers.
Author: Francesco Bajardi
Publisher: Cambridge University Press
ISBN: 100920873X
Category : Science
Languages : en
Pages : 452
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Book Description
This volume summarizes the many alternatives and extensions to Einstein's General Theory of Relativity, and shows how symmetry principles can be applied to identify physically viable models. The first part of the book establishes the foundations of classical field theory, providing an introduction to symmetry groups and the Noether theorems. A quick overview of general relativity is provided, including discussion of its successes and shortcomings, then several theories of gravity are presented and their main features are summarized. In the second part, the 'Noether Symmetry Approach' is applied to theories of gravity to identify those which contain symmetries. In the third part of the book these selected models are tested through comparison with the latest experiments and observations. This constrains the free parameters in the selected models to fit the current data, demonstrating a useful approach that will allow researchers to construct and constrain modified gravity models for further applications.
Author: Albert Petrov
Publisher: Springer Nature
ISBN: 3030528626
Category : Science
Languages : en
Pages : 77
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Book Description
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.
Author: Emmanuel N. Saridakis
Publisher: Springer Nature
ISBN: 3030837157
Category : Science
Languages : en
Pages : 631
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Book Description
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.
Author: Stephen W. Hawking
Publisher: Cambridge University Press
ISBN: 1009253182
Category : Science
Languages : en
Pages : 414
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Book Description
First published in 1973, this influential work discusses Einstein's General Theory of Relativity to show how two of its predictions arise: first, that the ultimate fate of many massive stars is to undergo gravitational collapse to form 'black holes'; and second, that there was a singularity in the past at the beginning of the universe. Starting with a precise formulation of the theory, including the necessary differential geometry, the authors discuss the significance of space-time curvature and examine the properties of a number of exact solutions of Einstein's field equations. They develop the theory of the causal structure of a general space-time, and use it to prove a number of theorems establishing the inevitability of singularities under certain conditions. A Foreword contributed by Abhay Ashtekar and a new Preface from George Ellis help put the volume into context of the developments in the field over the past fifty years.
Author: Mokhtar Hassaine
Publisher: World Scientific
ISBN: 9814730947
Category : Science
Languages : en
Pages : 149
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Book Description
"This book grew out of a set of lecture notes on gravitational Chern–Simons (CS) theories developed over the past decade for several schools and different audiences including graduate students and researchers. CS theories are gauge-invariant theories that can include gravity consistently. They are only defined in odd dimensions and represent a very special class of theories in the Lovelock family. Lovelock gravitation theories are the natural extensions of General Relativity for dimensions greater than four that yield second-order field equations for the metric. These theories also admit local supersymmetric extensions where supersymmetry is an off-shell symmetry of the action, as in a standard gauge theory. Apart from the arguments of mathematical elegance and beauty, the gravitational CS actions are exceptionally endowed with physical attributes that suggest the viability of a quantum interpretation. CS theories are gauge-invariant, scale-invariant and background independent; they have no dimensional coupling constants. All constants in the Lagrangian are fixed rational coefficients that cannot be adjusted without destroying gauge invariance. This exceptional status of CS systems makes them classically interesting to study, and quantum mechanically intriguing and promising."--Provided by publisher.
Author: George F. R. Ellis
Publisher: Cambridge University Press
ISBN: 0521381150
Category : Science
Languages : en
Pages : 637
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Book Description
Surveying key developments and open issues in cosmology for graduate students and researchers, this book focuses on the general concepts and relations that underpin the standard model of the Universe. It also examines anisotropic and inhomogeneous models, and deeper issues, such as quantum cosmology and the multiverse proposal.
Author: Salvatore Capozziello
Publisher: Nova Science Pub Incorporated
ISBN: 9781616685003
Category : Science
Languages : en
Pages : 235
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Book Description
This book presents information on the study of gravitational theories which can be seen as modifications or extensions of General Relativity. The basic principles that a gravitational theory should follow, and their geometrical interpretation, are analysed in a broad perspective which highlights the basic assumptions of General Relativity and suggests possible modifications. In particular, the invariance principles that are related to the gravitational field are presented, showing how gravity can emerge as a gauge theory. Also, the boundle approach to gravity and derive geometrical quantities which intervene in the construction of gravitational field are discussed.
Author: P I Pronin
Publisher: World Scientific
ISBN: 9814498912
Category : Science
Languages : en
Pages : 528
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Book Description
This volume comprises original and review articles on the frontier problems of the gravitation theory, theoretical and mathematical physics. The volume is dedicated to the memory of Professor Dmitri Ivanenko who made the great contribution to the physical science of the twentieth century. Contents:A Gauge-Invariant Theory of Motion of Charged Test Particles (D Chruscinski & J Kijowski)Heisenberg Picture for Quantized Fields Interacting with Nonstationary Electromagnetic or Gravitational Background (A A Lobashov & V M Mostepanenko)General Relativity as a Gauge Theory of Orthogonal Groups in Three Dimensions (M Raiteri et al.)Quantum Spacetime (D Finkelstein et al.)Jacobi's Principle and Hertz' Definition of Time (H-J Treder et al.)Placing Limits on Cartan's Torsion from Non-Riemannian Crystals (L C G de Andrade)Spinors as Differential Forms, and Applications to Electromagnetism and Quantum Mechanics (W A Rodrigues, Jr & J Vaz, Jr)Black Holes, Time Arrow, and Vacuum in Quantum Electrodynamics (M E Gertsenstein)One-Loop Background Calculations in the General Field Theory (P I Pronin & K V Stepanyantz)Energy–Momentum Superpotential in Gravitation Theory (G Giachetta & G Sardanashvily)and other papers Readership: Physicists, astronomists, high energy physicists, cosmologists and astrophysicists. keywords:Gravitation Theory;Riemannian Geometry;Gauge Theory;Spinor Field;Dirac Operator;Clifford Algebra;Torsion;Quantum Field;Black Hole;Conservation Law“… the book properly reflects the state of the art in a sector of current research on gravitation (and, less so, other fundamental interactions) and spacing geometry.”H Goenner Classical and Quantum Gravity
