Gravitation In Astrophysics

With the discovery of pulsars, quasars, and galactic X-ray sources in the late 60's and early 70's, and the coincident expansion in the search for gravitational waves, rela tivistic gravity assumed an important place in the astrophysics of localized objects. Only by pushing Einstein's solar-system-tested general theory of relativity to the study of the extremes of gravitational collapse and its outcomes did it seem that one could explain these frontier astronomical phenomena. This conclusion continues to be true today. Relativistic gravity had always played the central role in cosmology. The discov ery of the cosmic background radiation in 1965, the increasing understanding of matter physics at high energies in the decades following, and the growing wealth of observations on the large scale structure meant that it was possible to make increasingly detailed mod els of the universe, both today and far in the past. This development, not accidentally, was contemporary to that for localized objects described above.

This book describes several basic results and applications of global aspects in gravitation theory and cosmology within the framework of Einstein's theory of gravity. Topics include results on the structure and topology of space-time, exact solutions to Einstein equations and singularities, the status of quantum gravity, and quantum effects near space-time singularities in strong curvature fields. Also covered are the global upper limits in cosmology on elementary particle masses which might constitute the dark matter of the universe. After discussing in detail the fundamental role played by global considerations in gravity and general relativity, the author points out the significant problems that remain: the nature and structure of space-time singularities, the cosmic censorship problem in black hole physics, and the issue of quantum effects in strong gravity fields. The author's treatment of gravitational collapse illustrates how powerfully-strong curvature naked singularities could result from the continual gravitational collapse of matter with several reasonable equations of state--including inflowing radiation, dust, or a perfect fluid. Students and mathematicians, astrophysicists, and physicists will find this theoretically rich book a landmark in relativity theory.

Gravitational Physics assesses the achievements of the field over the past decade in both theory and experiment, identifies the most promising opportunities for research in the next decade, and describes the resources necessary to realize those opportunities. A major theme running through the opportunities is the exploration of strong gravitational fields, such as those associated with black holes. The book, part of the ongoing decadal survey Physics in a New Era, examines topics such as gravitational waves and their detection, classical and quantum theory of strong gravitational fields, precision measurements, and astronomical observations relevant to the predictions of Einstein's theory of general relativity.

General relativity and quantum mechanics have become the two central pillars of theoretical physics. Moreover, general relativity has important applications in astrophysics and high-energy particle physics. Covering the fundamentals of the subject, Principles of Cosmology and Gravitation describes the universe as revealed by observations and presents a theoretical framework to enable important cosmological formulae to be derived and numerical calculations performed. Avoiding elaborate formal discussions, the book presents a practical approach that focuses on the general theory of relativity. It examines different evolutionary models and the gravitational effects of massive bodies. The book also includes a large number of worked examples and problems, half with solutions.

Gravitational waves (GWs) are a hot topic and promise to play a central role in astrophysics, cosmology, and theoretical physics. Technological developments have led us to the brink of their direct observation, which could become a reality in the coming years. The direct observation of GWs will open an entirely new field: GW astronomy. This is expe

This book deals with the relationship between gravitation and elementary particle physics, and the implications of these subjects for astrophysics. There has, in recent years, been renewed interest in theories that connect up gravitation and particle physics, and in the astrophysical consequences of such theories. Some of these accounts involve a time-variation of the Newtonian gravitational parameter, G. In this respect, the present book may be regarded as a companion to my Cosmology and Geophysics (Hilger, Bristol, 1978). There is some overlap as regards the discussion of G-variability, but the emphasis in the present book is on astrophysics while the emphasis in the other one is on geophysics. The subject is a very broad one indeed, and in giving a review of it I have adopted a somewhat unorthodox way of presenting the material involved. The main reason for this is that a review of such a wide subject should aim at two levels: the level of the person who is interested in it, and the level of the person who is professionally engaged in research into it. To achieve such a two-level coverage, I have split the text up into two parts. The first part (Chapters 1-7) represents a relatively non-technical overview of the subject, while the second part (Chapters 8-11) represents a technical examination of the most important aspects of non-Einsteinian gravitational theory and its relation to astrophysics.