Solutions to the Semiclassical Theory of Gravity
Author | : Manuela Campanelli |
Publisher | : |
Total Pages | : 129 |
Release | : 1996 |
Genre | : |
ISBN | : |
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Author | : Manuela Campanelli |
Publisher | : |
Total Pages | : 129 |
Release | : 1996 |
Genre | : |
ISBN | : |
Author | : Bei-Lok B. Hu |
Publisher | : Cambridge University Press |
Total Pages | : 615 |
Release | : 2020-03-05 |
Genre | : Science |
ISBN | : 0521193575 |
An overview of semi-classical gravity theory and stochastic gravity as theories of quantum gravity in curved space-time.
Author | : James Mattingly |
Publisher | : |
Total Pages | : 372 |
Release | : 2001 |
Genre | : |
ISBN | : |
Author | : Rosario Martín Menéndez |
Publisher | : |
Total Pages | : 172 |
Release | : 1999 |
Genre | : |
ISBN | : |
Author | : Manuel Diaz |
Publisher | : |
Total Pages | : |
Release | : 2019 |
Genre | : |
ISBN | : |
A full theory of quantum gravity has eluded physicists for over 80 years. It is said by some to be the ``holy grail" of physics, but after all these years, there is both a lack of new insight from physical phenomena and, by and large, a lack of predictions that are falsifiable in all current candidates for a theory of quantum gravity. Therefore, extracting semiclassical quantum gravitational effects from an effective theory might be our best bet for giving us a way of doing meaningful phenomenology that is falsifiable. In this thesis, we applied a canonical effective method to derive semiclassical constraints for spherically symmetric space-times. The semiclassical quantum gravitational effects that we could extract from these constraints are suitable for situations where quantum effects are relevant, yet not dominant. Currently, there are two primary cases in which we know that quantum gravitational effects are relevant. First, black holes, as mathematical solutions to Einstein's field equations, provide environments in which quantum gravity becomes vital since singularities lead to the divergence of curvature and tidal forces. As astrophysical objects, black holes could potentially show properties not predicted by their mathematical counterparts in Einstein's theory of general relativity (GR). Moreover, some think that cosmological observations from the early universe are the most feasible way of detecting quantum gravitational effects. For these reasons, we used spherically symmetric space-time since it allows us to model both black holes and early-universe cosmologies where inhomogeneities are present.The canonical effective method mentioned above involves studying the dynamics due to the back-reaction, i.e., the average properties, of the moments of canonical variables. In this case, the canonical variables consist of real-valued densitized triads and extrinsic curvature components of a foliated general spherically symmetric space-time. Furthermore, a Hamiltonian formulation of GR involves constraints that generate a first-class algebra. This algebra of constraints leads directly to the diffeomorphism invariance of GR, and therefore its gauge symmetries. In order to constrain any arbitrariness and ambiguities associated with the method, we require that the gauge symmetries of GR generated by the classical constraints be preserved by the new semiclassical constraints that we derived using this method.Fortunately, the canonical effective method we used turned out to preserve the closure of the constraint algebra with respect toPoisson brackets such that the new semiclassical constraints still form a first-class algebra. Moreover, the new semiclassical constraints are consistent since they also have the correct classical limit. This means that the form of the constraint algebra itself is preserved in the new semiclassical constraint algebra. For this reason, we can say that we have a new semiclassical theory, which is entirely determined by the semiclassical constraints, that has the same gauge symmetries present in GR, and therefore is covariant. In addition, this new semiclassical theory could potentially help us find some new and unexpected physical phenomena, perhaps in black holes or cosmological scenarios, which could potentially lead, in the long term, to a full theory of quantum gravity.
Author | : Antonino Zichichi |
Publisher | : World Scientific |
Total Pages | : 606 |
Release | : 1993-06-30 |
Genre | : |
ISBN | : 9814553980 |
The papers in this volume provide an updated status of the last developments and current problems in string theory in connection with gravity and the physics at the Planck scale. This volume also contains excellent discussions on fundamental problems of quantum gravity and the physics at the Planck energy scale in the present-day context, irrespective of strings or any other models.
Author | : R.J. Gleiser |
Publisher | : CRC Press |
Total Pages | : 460 |
Release | : 1993-01-01 |
Genre | : Science |
ISBN | : 9780750302616 |
General Relativity and Gravitation 1992 contains the best of 700 papers presented at the tri-annual INT conference, generally recognized as the key conference in the area. The plenary and invited papers are published in full, along with summaries of parallel symposia and workshops. The list of plenary speakers is as impressive as ever, with contributions from Jim Hartle, Roger Penrose, and Lee Smolin among many others.
Author | : Peter G. Bergmann |
Publisher | : Springer Science & Business Media |
Total Pages | : 553 |
Release | : 2012-12-06 |
Genre | : Science |
ISBN | : 9401003475 |
In this XVII Course of the International School of Cosmology and Gravitation devoted to "ADVANCES IN THE INTERPLAY BETWEEN QUANTUM AND GRAVITY PHYSICS" we have considered different aspects of the influence of gravity on quantum systems. In order to achieve this aim, in many lectures, seminars and discussions we have strengthened the interplay between gravity and quantum systems starting from the situation in the early universe based on astrophysical observations, up to the earthly based experiments with atom interferometry for probing the structure of space-time. Thus we have had timely lectures on the quantum field and horizon of a black hole including reviews of the problem of black holes thermodynamics and entropy, quantum information, quantum black holes, quantum evaporation and Hawking radiation, recent advances in stockastic gravity. We have also discussed quantum fluctuations in inflationary universe, quantum effects and reheating after inflation, and superplanckian energies in Hawking radiation. In this regard the subject of spinors in purely affine space-time and Dirac matter according to Weyl in the generalized theory of gravitation were developed . The dualism between space-time and matter has been deeply analyzed in order to see why, for general relativity, this is an obstacle for quantization of the theory. Also canonical Gravity and Mach's principle, torsion and curvature as commutator for Quantum Gravity and Dirac Geometry of real space-time were analysed, together with the problem of 5-Dimensional Projective Unified Field theory and Multidimensional Gravity and Cosmology.
Author | : Christian Pfeifer |
Publisher | : Springer Nature |
Total Pages | : 557 |
Release | : 2023-11-01 |
Genre | : Science |
ISBN | : 3031315200 |
This book discusses theoretical predictions and their comparison with experiments of extended and modified classical and quantum theories of gravity. The goal is to provide a readable access and broad overview over different approaches to the topic to graduate and PhD students as well as to young researchers. The book presents both, theoretical and experimental insights and is structured in three parts. The first addresses the theoretical models beyond special and general relativity such as string theory, Poincare gauge theory and teleparallelism as well as Finsler gravity. In turn, the second part is focused on the observational effects that these models generate, accounting for tests and comparisons which can be made on all possible scales: from the universe as a whole via binary systems, stars, black holes, satellite experiments, down to laboratory experiments at micrometer and smaller scales. The last part of this book is dedicated to quantum systems and gravity, showing tests of classical gravity with quantum systems, and coupling of quantum matter and gravity.
Author | : Kirill Krasnov |
Publisher | : Cambridge University Press |
Total Pages | : 391 |
Release | : 2020-11-26 |
Genre | : Science |
ISBN | : 1108481647 |
Carefully documenting the different formulations of general relativity, the author reveals valuable insight into the nature of the gravitational force and its interaction with matter. This book will interest graduate students and researchers in the fields of general relativity, gravitational physics and differential geometry.