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 Testing Gravity with Cosmology written by Georgios Valogiannis and published by . This book was released on 2020 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the era of precision cosmology, a wide range of cosmological surveys, such as the LSST, DESI, Euclid and WFIRST will precisely probe the large-scale structure of the universe, shedding light on the nature of the dark sectors. Given how sensitively the growth of structure depends on the nature of the underlying gravitational field, this will be a unique opportunity to constrain the so-called Modified Gravity models (MG), that are theoretical alternatives to dark energy, which attempt to explain cosmic acceleration through a large-scale modification to General Relativity. In order to fully utilize the wealth of incoming data, however, theoretical predictions of structure formation in such alternative scenarios are necessary. Due to the existence of an additional degree of freedom that these models introduce, N-body simulations prove to be highly computationally expensive. In the first chapter of this thesis, we discuss how we can overcome this issue by using Lagrangian hybrid techniques, which can lead to a speed-up by 2 orders of magnitude, compared to the conventional tools, while still achieving % level of accuracy. Then, in chapter 2 we proceed to introduce novel statistics that can help us more confidently detect MG signals hidden in cosmic density fields, by up-weighting the significance of cosmic voids, where the MG-LambdaCDM degeneracy is broken. In the scales where structure formation is analytically tractable, finally, we show that we can make accurate analytical predictions for the two-point statistics of halos in MG, using Lagrangian perturbation theory and the Gaussian Streaming Model, simultaneously capturing, for the first time in modified gravity, the effects of both halo-bias (in chapter 3) and redshift space distortions (in chapter 4), effects crucial for the interpretation of photometric and spectroscopic observations. Our results demonstrate that a series of analytical, semi-analytical and simulation-based tools can be utilized in order to dramatically improve our understanding of the nature of cosmic acceleration and gravity at cosmic scales.
Download or read book Extracting Physics from Gravitational Waves written by Tjonnie G. F. Li and published by Springer. This book was released on 2015-07-03 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tjonnie Li's thesis covers two applications of Gravitational Wave astronomy: tests of General Relativity in the strong-field regime and cosmological measurements. The first part of the thesis focuses on the so-called TIGER, i.e. Test Infrastructure for General Relativity, an innovative Bayesian framework for performing hypothesis tests of modified gravity using ground-based GW data. After developing the framework, Li simulates a variety of General Relativity deviations and demonstrates the ability of the aforementioned TIGER to measure them. The advantages of the method are nicely shown and compared to other, less generic methods. Given the extraordinary implications that would result from any measured deviation from General Relativity, it is extremely important that a rigorous statistical approach for supporting these results would be in place before the first Gravitational Wave detections begin. In developing TIGER, Tjonnie Li shows a large amount of creativity and originality, and his contribution is an important step in the direction of a possible discovery of a deviation (if any) from General Relativity. In another section, Li's thesis deals with cosmology, describing an exploratory study where the possibility of cosmological parameters measurement through gravitational wave compact binary coalescence signals associated with electromagnetic counterparts is evaluated. In particular, the study explores the capabilities of the future Einstein Telescope observatory. Although of very long term-only applicability, this is again a thorough investigation, nicely put in the context of the current and the future observational cosmology.
Download or read book Isaac Newton s Scientific Method written by William L. Harper and published by Oxford University Press. This book was released on 2011-12-08 with total page 443 pages. Available in PDF, EPUB and Kindle. Book excerpt: Includes bibliographical references (p. [397]-410) and index.
Download or read book Theory and Experiment in Gravitational Physics written by Clifford M. Will and published by Cambridge University Press. This book was released on 2018-09-27 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive review of the testing and research conducted on Einstein's theory of general relativity.
Download or read book The Oxford Handbook of the History of Modern Cosmology written by Helge Kragh and published by Oxford University Press. This book was released on 2019-03-06 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific and popular literature on modern cosmology is very extensive; however, scholarly works on the historical development of cosmology are few and scattered. The Oxford Handbook of the History of Modern Cosmology offers a comprehensive and authoritative account of the history of cosmology from the late nineteenth century to the early twenty-first century. It provides historical background to what we know about the universe today, including not only the successes but also the many false starts. Big Bang theory features prominently, but so does the defunct steady state theory. The book starts with a chapter on the pre-Einstein period (1860-1910) and ends with chapters on modern developments such as inflation, dark energy and multiverse hypotheses. The chapters are organized chronologically, with some focusing on theory and others more on observations and technological advances. A few of the chapters discuss more general ideas, relating to larger contexts such as politics, economy, philosophy and world views.
Download or read book Gravitation Cosmology and Cosmic Ray Physics written by National Research Council and published by National Academies Press. This book was released on 1986-02-01 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Epistemology of Experimental Gravity Scientific Rationality written by Nicolae Sfetcu and published by MultiMedia Publishing. This book was released on with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: The evolution of gravitational tests from an epistemological perspective framed in the concept of rational reconstruction of Imre Lakatos, based on his methodology of research programmes. Unlike other works on the same subject, the evaluated period is very extensive, starting with Newton's natural philosophy and up to the quantum gravity theories of today. In order to explain in a more rational way the complex evolution of the gravity concept of the last century, I propose a natural extension of the methodology of the research programmes of Lakatos that I then use during the paper. I believe that this approach offers a new perspective on how evolved over time the concept of gravity and the methods of testing each theory of gravity, through observations and experiments. I argue, based on the methodology of the research programmes and the studies of scientists and philosophers, that the current theories of quantum gravity are degenerative, due to the lack of experimental evidence over a long period of time and of self-immunization against the possibility of falsification. Moreover, a methodological current is being developed that assigns a secondary, unimportant role to verification through observations and/or experiments. For this reason, it will not be possible to have a complete theory of quantum gravity in its current form, which to include to the limit the general relativity, since physical theories have always been adjusted, during their evolution, based on observational or experimental tests, and verified by the predictions made. Also, contrary to a widespread opinion and current active programs regarding the unification of all the fundamental forces of physics in a single final theory, based on string theory, I argue that this unification is generally unlikely, and it is not possible anyway for a unification to be developed based on current theories of quantum gravity, including string theory. In addition, I support the views of some scientists and philosophers that currently too much resources are being consumed on the idea of developing quantum gravity theories, and in particular string theory, to include general relativity and to unify gravity with other forces, as long as science does not impose such research programs. CONTENTS: Introduction Gravity Gravitational tests Methodology of Lakatos - Scientific rationality The natural extension of the Lakatos methodology Bifurcated programs Unifying programs 1. Newtonian gravity 1.1 Heuristics of Newtonian gravity 1.2 Proliferation of post-Newtonian theories 1.3 Tests of post-Newtonian theories 1.3.1 Newton's proposed tests 1.3.2 Tests of post-Newtonian theories 1.4 Newtonian gravity anomalies 1.5 Saturation point in Newtonian gravity 2. General relativity 2.1 Heuristics of the general relativity 2.2 Proliferation of post-Einsteinian gravitational theories 2.3 Post-Newtonian parameterized formalism (PPN) 2.4 Tests of general relativity and post-Einsteinian theories 2.4.1 Tests proposed by Einstein 2.4.2 Tests of post-Einsteinian theories 2.4.3 Classic tests 2.4.3.1 Precision of Mercury's perihelion 2.4.3.2 Light deflection 2.4.3.3 Gravitational redshift 2.4.4 Modern tests 2.4.4.1 Shapiro Delay 2.4.4.2 Gravitational dilation of time 2.4.4.3 Frame dragging and geodetic effect 2.4.4.4 Testing of the principle of equivalence 2.4.4.5 Solar system tests 2.4.5 Strong field gravitational tests 2.4.5.1 Gravitational lenses 2.4.5.2 Gravitational waves 2.4.5.3 Synchronization binary pulsars 2.4.5.4 Extreme environments 2.4.6 Cosmological tests 2.4.6.1 The expanding universe 2.4.6.2 Cosmological observations 2.4.6.3 Monitoring of weak gravitational lenses 2.5 Anomalies of general relativity 2.6 The saturation point of general relativity 3. Quantum gravity 3.1 Heuristics of quantum gravity 3.2 The tests of quantum gravity 3.3 Canonical quantum gravity 3.3.1 Tests proposed for the CQG 3.3.2. Loop quantum gravity 3.4 String theory 3.4.1 Heuristics of string theory 3.4.2. Anomalies of string theory 3.5 Other theories of quantum gravity 3.6 Unification (The Final Theory) 4. Cosmology Conclusions Notes Bibliography DOI: 10.13140/RG.2.2.35350.70724
Download or read book Dark Energy written by Luca Amendola and published by Cambridge University Press. This book was released on 2010-06-10 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introducing the theoretical ideas, observational methods and results in dark energy, this textbook is a thorough introduction to dark energy for graduate courses.
Download or read book Gravitation and Cosmology written by Steven Weinberg and published by John Wiley & Sons. This book was released on 1972 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt: Weinberg's 1972 work, in his description, had two purposes. The first was practical to bring together and assess the wealth of data provided over the previous decade while realizing that newer data would come in even as the book was being printed. He hoped the comprehensive picture would prepare the reader and himself to that new data as it emerged. The second was to produce a textbook about general relativity in which geometric ideas were not given a starring role for (in his words) too great an emphasis on geometry can only obscure the deep connections between gravitation and the rest of physics.
Download or read book Relativity Gravitation and Cosmology written by Robert J. Lambourne and published by Cambridge University Press. This book was released on 2010-06 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: The textbook introduces students to basic geometric concepts, such as metrics, connections and curvature, before examining general relativity in more detail. It shows the observational evidence supporting the theory, and the description general relativity provides of black holes and cosmological spacetimes. --
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.
Download or read book Black Holes A Laboratory for Testing Strong Gravity written by Cosimo Bambi and published by Springer. This book was released on 2017-06-01 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook introduces the current astrophysical observations of black holes, and discusses the leading techniques to study the strong gravity region around these objects with electromagnetic radiation. More importantly, it provides the basic tools for writing an astrophysical code and testing the Kerr paradigm. Astrophysical black holes are an ideal laboratory for testing strong gravity. According to general relativity, the spacetime geometry around these objects should be well described by the Kerr solution. The electromagnetic radiation emitted by the gas in the inner part of the accretion disk can probe the metric of the strong gravity region and test the Kerr black hole hypothesis. With exercises and examples in each chapter, as well as calculations and analytical details in the appendix, the book is especially useful to the beginners or graduate students who are familiar with general relativity while they do not have any background in astronomy or astrophysics.“/p>
Download or read book Gravity Where Do We Stand written by Roberto Peron and published by Springer. This book was released on 2015-12-14 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an overview of the current understanding of gravitation, with a focus on the current efforts to test its theory, especially general relativity. It shows how the quest for a deeper theory, which would possibly incorporate gravity in the quantum realm, is more than ever an open field. The majority of the contributions deals with the manifold facets of “experimental gravitation”, but the book goes beyond this and covers a broad range of subjects from the foundations of gravitational theories to astrophysics and cosmology. The book is divided into three parts. The first part deals with foundations and Solar System tests. An introductory pedagogical chapter reviews first Newtonian gravitational theory, special relativity, the equivalence principle and the basics of general relativity. Then it focuses on approximation methods, mainly the post-Newtonian formalism and the relaxed Einstein equations, with a discussion on how they are used in treating experimental tests and in the problem of generation and detection of gravitational waves. Following this is a set of chapters describing the most recent experiments, techniques and observations on the testing of gravity theories in the laboratory, around the Earth and in the Solar System. The second part is dedicated to astrophysical topics deeply linked with the study of gravitation, namely binary pulsars and the perspective of direct detection of gravitational waves. These cases are paradigmatic in that the gravitational signals act at the same time as messengers helping us to understand the properties of important and wide classes of astrophysical objects. The third part explores the many open issues in current knowledge of gravitation machinery, especially related to astrophysical and cosmological problems and the way possible solutions to them impact the quest for a quantum theory of gravitation and unified theory. Included is a selection of the many possible paths, giving a hint to the subtleties one is called upon. Whenever possible, a close link to observational constraints and possible experimental tests is provided. In selecting the topics of the various contributions, particular care has been devoted to ensure their fit in a coherent representation of our understanding of gravitational phenomena. The book is aimed at graduate level students and will form a valuable reference for those working in the field.
Download or read book Cosmological Physics written by J. A. Peacock and published by Cambridge University Press. This book was released on 1999 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive and authoritative introduction to contemporary cosmology for advanced undergraduate and graduate students.
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 Modified Gravity written by Baojiu Li and published by World Scientific Publishing Company. This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gravity beyond general relativity / Kazuya Koyama -- Parametrizations for tests of gravity / Lucas Lombriser -- Simulation techniques / Claudio Llinares -- Approximation methods in modified gravity models / Baojiu Li -- Large-scale structure probes of modified gravity / Catherine Heymans and Gong-Bo Zhao -- Tests of gravity with galaxy clusters / Matteo Cataneo -- Towards testing gravity with cosmic voids / Yan-Chuan Cai -- Astrophysical tests of screened modified gravity / Jeremy Sakstein -- Laboratory constraints / Philippe Brax.
