Classical and Quantum Aspects of Gravity in Relation to the Emergent Paradigm

by Sumanta Chakraborty

Author	: Sumanta Chakraborty
Publisher	: Springer
Total Pages	: 268
Release	: 2017-08-01
Genre	: Science
ISBN	: 3319637339

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This thesis explores the connection between gravity and thermodynamics and provides a unification scheme that opens up new directions of exploration. Further elaborating on the Hawking effect and the possibility of singularity avoidance, the author not only discusses the information loss paradox at a broader level but also provides a possible solution to it. As the final frontier, it describes some novel effects arising from the microscopic structure of spacetime. Taken as a whole, the thesis addresses three major research areas in gravitational physics: it starts with classical gravity, proceeds to the black hole information loss paradox, and closes with Planck scale physics. The thesis is written in a lucid and pedagogical style, with an introduction accessible to researchers from other branches of physics and a d iscussion presenting open questions and future directions, which will benefit and hopefully inspire next-generation researchers.

Classical and Quantum Cosmology

by Gianluca Calcagni

Author	: Gianluca Calcagni
Publisher	: Springer
Total Pages	: 854
Release	: 2017-01-06
Genre	: Science
ISBN	: 3319411276

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This comprehensive textbook is devoted to classical and quantum cosmology, with particular emphasis on modern approaches to quantum gravity and string theory and on their observational imprint. It covers major challenges in theoretical physics such as the big bang and the cosmological constant problem. An extensive review of standard cosmology, the cosmic microwave background, inflation and dark energy sets the scene for the phenomenological application of all the main quantum-gravity and string-theory models of cosmology. Born of the author's teaching experience and commitment to bridging the gap between cosmologists and theoreticians working beyond the established laws of particle physics and general relativity, this is a unique text where quantum-gravity approaches and string theory are treated on an equal footing. As well as introducing cosmology to undergraduate and graduate students with its pedagogical presentation and the help of 45 solved exercises, this book, which includes an ambitious bibliography of about 3500 items, will serve as a valuable reference for lecturers and researchers.

Philosophy Beyond Spacetime

by Christian Wüthrich

Author	: Christian Wüthrich
Publisher	: Oxford University Press
Total Pages	: 305
Release	: 2021
Genre	: Philosophy
ISBN	: 019884414X

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Quantum gravity seeks a unified theory in which quantum matter is dynamically related to generally relativistic spacetime. Although a continuing work in progress, research programmes in the field such as string theory, loop quantum gravity, and causal set theory make it clear that a successful theory of quantum gravity will raise important challenges to our conceptions of space, time, and matter-perhaps abolishing them altogether as fundamental entities. But just as important, there is good reason to think that some of the problems in finding a theory of quantum gravity are themselves conceptual, in need of philosophical analysis. Philosophy Beyond Spacetime: Implications from Quantum Gravity assembles original papers from philosophers (and one physicist), establishing a definitive statement of the current state of play, on which future research into this area can build. Aiming to expand knowledge and understanding of the philosophy of quantum gravity, it emphasizes how debates in metaphysics--regarding emergence, composition, or grounding for example--shed light on the conceptual questions of quantum gravity. And conversely, how quantum theories of space and time call into question philosophical views grounded in classical spacetime. Furthermore, the philosophy of quantum gravity raises methodological questions, for instance concerning the relation between physics and metaphysics. The essays have been chosen to demonstrate to a wide range of philosophers the significance of the subject, as well as making novel contributions to it.

The Problem of Time

by Edward Anderson

Author	: Edward Anderson
Publisher	: Springer
Total Pages	: 917
Release	: 2017-09-18
Genre	: Science
ISBN	: 3319588486

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This book is a treatise on time and on background independence in physics. It first considers how time is conceived of in each accepted paradigm of physics: Newtonian, special relativity, quantum mechanics (QM) and general relativity (GR). Substantial differences are moreover uncovered between what is meant by time in QM and in GR. These differences jointly source the Problem of Time: Nine interlinked facets which arise upon attempting concurrent treatment of the QM and GR paradigms, as is required in particular for a background independent theory of quantum gravity. A sizeable proportion of current quantum gravity programs - e.g. geometrodynamical and loop quantum gravity approaches to quantum GR, quantum cosmology, supergravity and M-theory - are background independent in this sense. This book's foundational topic is thus furthermore of practical relevance in the ongoing development of quantum gravity programs. This book shows moreover that eight of the nine facets of the Problem of Time already occur upon entertaining background independence in classical (rather than quantum) physics. By this development, and interpreting shape theory as modelling background independence, this book further establishes background independence as a field of study. Background independent mechanics, as well as minisuperspace (spatially homogeneous) models of GR and perturbations thereabout are used to illustrate these points. As hitherto formulated, the different facets of the Problem of Time greatly interfere with each others' attempted resolutions. This book explains how, none the less, a local resolution of the Problem of Time can be arrived at after various reconceptualizations of the facets and reformulations of their mathematical implementation. Self-contained appendices on mathematical methods for basic and foundational quantum gravity are included. Finally, this book outlines how supergravity is refreshingly different from GR as a realization of background independence, and what background independence entails at the topological level and beyond.

Gravity and the Quantum

by Jasjeet Singh Bagla

Author	: Jasjeet Singh Bagla
Publisher	: Springer
Total Pages	: 491
Release	: 2017-02-23
Genre	: Science
ISBN	: 3319517007

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This book provides a compilation of in-depth articles and reviews on key topics within gravitation, cosmology and related issues. It is a celebratory volume dedicated to Prof. Thanu Padmanabhan ("Paddy"), the renowned relativist and cosmologist from IUCAA, India, on the occasion of his 60th birthday. The authors, many of them leaders of their fields, are all colleagues, collaborators and former students of Paddy, who have worked with him over a research career spanning more than four decades. Paddy is a scientist of diverse interests, who attaches great importance to teaching. With this in mind, the aim of this compilation is to provide an accessible pedagogic introduction to, and overview of, various important topics in cosmology, gravitation and astrophysics. As such it will be an invaluable resource for scientists, graduate students and also advanced undergraduates seeking to broaden their horizons.

Emergent Quantum Mechanics

by Jan Walleczek

Author	: Jan Walleczek
Publisher	: MDPI
Total Pages	: 544
Release	: 2019-04-02
Genre	: Science
ISBN	: 3038976164

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Emergent quantum mechanics explores the possibility of an ontology for quantum mechanics. The resurgence of interest in "deeper-level" theories for quantum phenomena challenges the standard, textbook interpretation. The book presents expert views that critically evaluate the significance—for 21st century physics—of ontological quantum mechanics, an approach that David Bohm helped pioneer. The possibility of a deterministic quantum theory was first introduced with the original de Broglie-Bohm theory, which has also been developed as Bohmian mechanics. The wide range of perspectives that were contributed to this book on the occasion of David Bohm’s centennial celebration provide ample evidence for the physical consistency of ontological quantum mechanics. The book addresses deeper-level questions such as the following: Is reality intrinsically random or fundamentally interconnected? Is the universe local or nonlocal? Might a radically new conception of reality include a form of quantum causality or quantum ontology? What is the role of the experimenter agent? As the book demonstrates, the advancement of ‘quantum ontology’—as a scientific concept—marks a clear break with classical reality. The search for quantum reality entails unconventional causal structures and non-classical ontology, which can be fully consistent with the known record of quantum observations in the laboratory.

Springer Handbook of Spacetime

by Abhay Ashtekar

Author	: Abhay Ashtekar
Publisher	: Springer
Total Pages	: 883
Release	: 2014-09-01
Genre	: Science
ISBN	: 3642419925

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The Springer Handbook of Spacetime is dedicated to the ground-breaking paradigm shifts embodied in the two relativity theories, and describes in detail the profound reshaping of physical sciences they ushered in. It includes in a single volume chapters on foundations, on the underlying mathematics, on physical and astrophysical implications, experimental evidence and cosmological predictions, as well as chapters on efforts to unify general relativity and quantum physics. The Handbook can be used as a desk reference by researchers in a wide variety of fields, not only by specialists in relativity but also by researchers in related areas that either grew out of, or are deeply influenced by, the two relativity theories: cosmology, astronomy and astrophysics, high energy physics, quantum field theory, mathematics, and philosophy of science. It should also serve as a valuable resource for graduate students and young researchers entering these areas, and for instructors who teach courses on these subjects. The Handbook is divided into six parts. Part A: Introduction to Spacetime Structure. Part B: Foundational Issues. Part C: Spacetime Structure and Mathematics. Part D: Confronting Relativity theories with observations. Part E: General relativity and the universe. Part F: Spacetime beyond Einstein.

Semiclassical and Stochastic Gravity

by Bei-Lok B. Hu

Author	: Bei-Lok B. Hu
Publisher	: Cambridge University Press
Total Pages	: 615
Release	: 2020-03-05
Genre	: Science
ISBN	: 0521193575

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An overview of semi-classical gravity theory and stochastic gravity as theories of quantum gravity in curved space-time.

Progress in Group Field Theory and Related Quantum Gravity Formalisms

by Steffen Gielen

Author	: Steffen Gielen
Publisher	: MDPI
Total Pages	: 338
Release	: 2020-07-01
Genre	: Mathematics
ISBN	: 3039361783

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Following the fundamental insights from quantum mechanics and general relativity, geometry itself should have a quantum description; the search for a complete understanding of this description is what drives the field of quantum gravity. Group field theory is an ambitious framework in which theories of quantum geometry are formulated, incorporating successful ideas from the fields of matrix models, ten-sor models, spin foam models and loop quantum gravity, as well as from the broader areas of quantum field theory and mathematical physics. This special issue collects recent work in group field theory and these related approaches, as well as other neighbouring fields (e.g., cosmology, quantum information and quantum foundations, statistical physics) to the extent that these are directly relevant to quantum gravity research.