The Rise And Fall Of The Black Hole Paradigm

Black holes have turned out to be the cornerstone of both physics and popular belief. But what if we were to realize that exact black holes cannot exist, even though their existence is apparently suggested by exact general relativistic solutions, and Roger Penrose won the 2020 Nobel Prize in Physics ‘for the discovery that black hole formation is a robust prediction of the general theory of relativity’? While it might seem far-fetched to claim so, it will be worth remembering that the finest theoretical physicists like Albert Einstein and Paul Dirac did not believe in black holes, and Stephen Hawking finally thought that there are no exact black holes. While the black hole paradigm has become commonplace in popular consciousness, in the last decade, noise has consistently grown about the many physical effects which can inhibit the formation of exact mathematical black holes. In The Rise and Fall of the Black Hole Paradigm, Abhas Mitra shows us how, much before these developments, he had proven why the so-called black holes must only be black hole pretenders. He identified these black hole candidates to be Magnetospheric Eternally Collapsing Objects (MECOs) and, along with Darryl J. Leiter and Stanley L. Robertson, generalized them. Recent evidence for the existence of strong magnetic fields around so-called black holes may provide confirmations of his claim.

As a result of significant research over the past 20 years, black holes are now linked to some of the most spectacular and exciting phenomena in the Universe, ranging in size from those that have the same mass as stars to the super-massive objects that lie at the heart of most galaxies, including our own Milky Way. This book first introduces the properties of simple isolated holes, then adds in complications like rotation, accretion, radiation, and magnetic fields, finally arriving at a basic understanding of how these immense engines work. Black Hole Astrophysics • reviews our current knowledge of cosmic black holes and how they generate the most powerful observed pheonomena in the Universe; • highlights the latest, most up-to-date theories and discoveries in this very active area of astrophysical research; • demonstrates why we believe that black holes are responsible for important phenomena such as quasars, microquasars and gammaray bursts; • explains to the reader the nature of the violent and spectacular outfl ows (winds and jets) generated by black hole accretion.

A pedagogical introduction to the physics of black holes. The membrane paradigm represents the four-dimensional spacetime of the black hole's "event horizon" as a two-dimensional membrane in three-dimensional space, allowing the reader to understand and compute the behavior of black holes in complex astrophysical environments.

Black holes are a source of wide fascination. In this Very Short Introduction, Katherine Blundell addresses a variety of questions, including what a black hole actually is, how they are characterised and discovered, to what happens if you get too close to one. Explaining how black holes formand grow across cosmic time, as well as how many there are in the Universe, she also considers how black holes interact with matter - by stealing material that belongs to other stars, and how black holes give rise to quasars and other spectacular, yet exotic phenomena in outer space.

Black holes are one of the most fascinating predictions of general relativity. They are the natural product of the complete gravitational collapse of matter and today we have a body of observational evidence supporting the existence of black holes in the Universe. However, general relativity predicts that at the center of black holes there are spacetime singularities, where predictability is lost and standard physics breaks down. It is widely believed that spacetime singularities are a symptom of the limitations of general relativity and must be solved within a theory of quantum gravity. Since we do not have yet any mature and reliable candidate for a quantum gravity theory, researchers have studied toy-models of singularity-free black holes and of singularity-free gravitational collapses in order to explore possible implications of the yet unknown theory of quantum gravity. This book reviews all main models of regular black holes and non-singular gravitational collapses proposed in the literature, and discuss the theoretical and observational implications of these scenarios.

This 2004 textbook fills a gap in the literature on general relativity by providing the advanced student with practical tools for the computation of many physically interesting quantities. The context is provided by the mathematical theory of black holes, one of the most elegant, successful, and relevant applications of general relativity. Among the topics discussed are congruencies of timelike and null geodesics, the embedding of spacelike, timelike and null hypersurfaces in spacetime, and the Lagrangian and Hamiltonian formulations of general relativity. Although the book is self-contained, it is not meant to serve as an introduction to general relativity. Instead, it is meant to help the reader acquire advanced skills and become a competent researcher in relativity and gravitational physics. The primary readership consists of graduate students in gravitational physics. It will also be a useful reference for more seasoned researchers working in this field.

The formation of the first supermassive black holes is one of the main open questions in our understanding of high-redshift structure formation. In this book, we aim to provide a summary of state-of-the-art modern research on this topic, exploring the formation of massive black holes from a fluid-dynamical, stellar-dynamical and chemical perspective. The book thus presents a solid theoretical foundation, a comparison with current observations and future observational perspectives with upcoming missions such as the Square Kilometre Array, the European Extremely Large Telescope, the Euclid satellite as well as possible detections via gravitational waves.