Black Hole Physics Basic Concepts and New Developments

It is not an exaggeration to say that one of the most exciting predictions of Einstein’s
theory of gravitation is that there may exist “black holes”: putative objects whose
gravitational fields are so strong that no physical bodies or signals can break free of
their pull and escape. The proof that black holes do exist, and an analysis of their
properties, would have a significance going far beyond astrophysics. Indeed, what is
involved is not just the discovery of yet another even if extremely remarkable, astrophysical object, but a test of the correctness of our understanding of the properties
of space and time in extremely strong gravitational fields.
Theoretical research into the properties of black holes, and into the possible corollaries of the hypothesis that they exist, has been carried out with special vigor since
the beginning of the 1970’s. In addition to those specific features of black holes that
are important for the interpretation of their possible astrophysical manifestations, the
theory has revealed a number of unexpected characteristics of physical interactions
involving black holes. By the middle of the 1980’s a fairly detailed understanding
had been achieved of the properties of the black holes, their possible astrophysical
manifestations, and the specifics of the various physical processes involved. Even
though a completely reliable detection of a black hole had not yet been made at
that time, several objects among those scrutinized by astrophysicists were considered
as strong candidates to be confirmed as being black holes. Furthermore, profound
links were found between black hole theory and such seemingly very distant fields as
thermodynamics, information theory, and quantum theory. The branch of physics
that is now referred to as black hole physics was born and actually took shape as a
full-blooded scientific discipline during the past two decades at the junction of the
theory of gravitation, astrophysics, and classical and quantum field theories.
In 1986 we published in Russian a book “Physics of Black Holes” devoted to this
relatively young and rapidly developing branch of physics. In 1989 the book was
translated and published in English. During the years that have passed since then,
the physics of black holes enjoyed a period of rapid growth. First of all, great progress
was achieved in the observational astrophysics of black holes. Ten years ago there
were only a few black hole candidates in binary systems in which the companion was
a normal star. In spite of enormous efforts, no unequivocal signature of black holes
had been found in these systems. Today after great improvements in the quantity and
quality of the observational material, our confidence that we observe the manifestac
xiv
PREFACE xv
tion of black holes in at least a few binaries is almost a hundred per cent. Moreover,
impressive progress in optical, radio, and X-ray astronomy greatly bolstered the evidence for supermassive black holes (up to several billion solar mass) in the centers
of galaxies. During the same period of time, great progress was made also in the development of the theoretical and mathematical aspects of black hole physics. Black
hole collisions might be one of the most powerful sources of gravitational radiation in
the Universe. The gravitational wave observations that might become possible after
construction of the LIGO and other gravitational antennas of the new generation required developments in numerical relativity and analytical methods for the analysis
of the gravitational radiation generated by black holes.
More than five years ago we were requested to prepare a second edition of the book
to reflect the enormous progress in our knowledge concerning black holes. We started
work on this project, and quite soon we realized that it is virtually impossible to keep
the book unchanged and restrict ourselves to tiny “cosmetic” improvements. As a
result, in order to update the book, we practically rewrote it though we preserved its
original structure and certainly used much of the old material.
This monograph is the result of our attempts to understand the modern status of
black hole physics. This new book is twice longer than the old one; it contains four
new chapters. We also added a lot of new material in the form of appendices which
cover more mathematical subject.
This book is written to introduce the reader to the physics of black holes and
the methods employed in it, and to review the main results of this branch of physics.
But attention is focused primarily on questions that were answered relatively recently,
and thus could not be adequately reflected in earlier textbooks and reviews. Those
aspectsthat are relatively familiar are presented concisely (but as clearly as possible).
We have tried to make the representation lucid not only for a specialist, but also
for a broad spectrum of physicists and astrophysicists who do not have a special
knowledge of black hole physics. An attempt is made to explain, first and foremost,
the physical essentials of the phenomena, and only after this do we pass on to the
mathematical means of describing them. These objectives determined both the spectrum of selected topics and the style of presentation. A conscious attempt has been
made to avoid excessive rigor in the formulations and proofs of theorems on black
holes. Quite often, only the principal idea is given instead of a complete proof; then
the successive stages of the proof are outlined, and references to the original papers
are supplied where the reader will find the required details. This approach was chosen not only because the excellent monographs of Penrose (1968), Hawking and Ellis
(1973), Chandrasekhar (1983), and Thorne, Price and Macdonald (1986) cover most
of the material omitted in this book, but also because we are of the opinion that
excessive rigor stands in the way of understanding the physical ideas that are at the
foundation of the specific properties of black holes.
The material in the book is partly based on the courses of lectures which the
authors have presented during a number of years at the University of Copenhagen
XVI PREFACE
and University of Alberta. One of the authors (V.F.) is grateful to the Killam trust
for it.s financial support during the work on this book. The authors also would like
to thank the Danish National Research Foundation for the support of this project
through its establishment of the Theoretical Astrophysics Center, and the Natural
Sciences and Engineering Research Council of Canada for its financial support.
While working on this monograph, we enjoyed the unfailing support of our col~
leagues from the P.N. Lebedev Physical Institute (Moscow), University Observatory,
NORDITA, and Theoretical Astrophysics Center (Copenhagen), and the University
of Alberta (Edmonton). We wish to express our sincere thanks to Roger Blanford,
Bernard Carr, Vitaly Ginzburg, David Kirzhnitz, Vladimir Lipunov, Draza Markovic,
Michael Nowak, Don Page, Christopher Pethick, Martin Rees, Kip Thorne, and John
Wheeler for helpful discussions of the problems of black holes. We are much indebted
to Werner Israel for numerous stimulating discussions and for his enormous work in
reading the draft of the book. His advice concerning the contents and style were very
important for us in our work. We want also to mention particularly Nils Andersson,
who is a co~author of Chapter 4 and Section 9.9. We also appreciate the help of
Vasily Beskill in preparing the new version of Chapter 8. Their help was invaluable.
Additional thanks go to Patrick Sutton for his help with proofreading.
This book would never have appeared if we had not received support and en~
couragements from our friends and colleagues. We owe the deepest debt, of gratitude
to our wives Raya Frolova and Eleonora Kotok. They were not only patient, but
contributed countless hours helping us in the preparation of the electronic version
of the book. We would also like to thank Andrei Frolov. His skills as the computer
guru helped us t.o overcome numerous problems which are inevitable in any project
of such a scale