After some decades of work a satisfactory theory of quantum gravity is still not available; moreover, there are indications that the original field theoretical approach may be better suited than originally expected. There, to first approximation, one is left with the problem of quantum field theory on Lorentzian manifolds. Surprisingly, this seemingly modest approach leads to far reaching conceptual and mathematical problems and to spectacular predictions, the most famous one being the Hawking radiation of black holes. Ingredients of this approach are the formulation of quantum physics in terms of C*-algebras, the geometry of Lorentzian manifolds, in particular their causal structure, and linear hyperbolic differential equations where the well-posedness of the Cauchy problem plays a distinguished role, as well as more recently the insights from suitable concepts such as microlocal analysis. This primer is an outgrowth of a compact course given by the editors and contributing authors to an audience of advanced graduate students and young researchers in the field, and assumes working knowledge of differential geometry and functional analysis on the part of the reader.

The physical processes driving the different manifestations of the phe nomenon of active galactic nuclei have been studied extensively during the last decade. A major obstacle in all attempts to understand the relevant pro cesses has always been the wide range of frequencies over which significant fractions of the total power are emitted. During the last decade, orbiting telescopes and instrumental improvements for ground-based instrumenta tion provided the means for major advancements on the observational side. The organizers felt that it was timely to organize a meeting to discuss the impact of this new situation on the understanding of the relevant physical processes. More then 400 astrophysicists were interested in participating in the meeting, in spite of the constraints on overseas travel which were imposed in early 1991. Unfortunately only 220 participants could be hosted by the Max-Planck-Haus, the site of the 1991 Heidelberg conference. The meet ing was organized by Sonderforschungsbereich 328 "Evolution of Galaxies". During 5 sessions, most of which lasted for one day each, 47 invited and con tributed talks and 150 poster papers were given, most, but not all, of which are included in these proceedings. With a few exceptions the order of the written texts follows that of the oral contributions during the meeting. The arrangement of posters into the five sections was not always unambiguous. We hope to have placed them in the most appropriate sections, in which they are listed in alphabetical order.

The Tum of the Tide During centuries physicists were supposed to be studying the physical world. Since the turn of the century this assumption has often been challenged as naive: it was proclaimed that physics is not about the external world but about observers and their manipUlations: that it is meaningless to talk of anything else than observation devices and opera tions: that the laws of physics concern our knowledge rather than the external world. This view of the nature of physical science has old roots in philo sophy but it was independently reinvented by a number of philosophi cally inclined physicists, notably ERNST MACH. These scientists were disgusted with the school philosophies and they were alarmed by the increasing number of physical concepts which they regarded as meta physical or beyond experimental control, such as those of absolute motion, ether, electromagnetic field, and molecule. Reasonably enough, they wished to keep physics testable. To accomplish this goal they adopted the safe method, namely to banish every idea that could not be closely tied to observation. In this way they certainly avoided the risks of untestable speculation but they also failed to enjoy the benefits of theoretical invention. Furthermore they instituted unawares a new meta physics that was to dominate the philosophy of physics for half a century: the metaphysics according to which the world is made of sense experience."

The book provides readers with an understanding of the mutual conditioning of spacetime and interactions and matter. The spacetime manifold will be looked at to be a reservoir for the parametrization of operation Lie groups or subgroup classes of Lie groups. With basic operation groups or Lie algebras, all physical structures can be interpreted in terms of corresponding realizations or representations. Physical properties are related eigenvalues or invariants. As an explicit example of operational spacetime is proposed, called electroweak spacetime, parametrizing the classes of the internal hypercharge - isospin group in the general linear group in two complex dimensions, i.e., the Lorentz cover group, extended by the casual (dilation) and phase group. Its representations and invariants will be investigated with the aim to connect them, qualitatively and numerically, with the properties of interactions and particles as arising in the representations of its tangent Minkowski spaces.

String theories seem to have created a breakthrough in theoretical physics. At long last a unfied theory of all the fundamental interactions, including gravity, looks possible. This, according to theorist Stephen Hawking, will mark the end of theoretical physics as we have known it, since we will then have a single consistent theory within which to explain all natural phenomena from elementary particles to galactic superclusters. Strings themselves are extremely tiny entities, smaller than the Planck scale, which form loops whose vibrational harmonics can be used to model all the standard elementary particles. Of course the mathematical complexities of the theory are daunting, and physicists are still at a very early stage in understanding how strings and their theoretical cousins superstrings can be used. This proceedings volume gives an overview of the intense recent work in the field and reports latest developments.

The present NATO Advanced Study Institute held in CARGESE (Corsica) from Au- gust 8th to August 18th, 1989 was devoted to Hadronic Physics. We tried to give this school a key educational role in this new and rapidly developing interdisciplinary field. We hope that the combination of the lectures and the open atmosphere of scientific exchange and inquiry afforded by the Cargese format has provided a unique educational and scien- tific opportunity for students and has brought together all the relevant concepts and issues for frontier research in this field. We would like to express our gratitude to NATO for its generous financial support which made this Institute possible. We also wish to thank Dr. Luis V. Da Cunha, Director of the Scientific Affairs Division, for his valuable comments and advice. We acknowledge the support of the Institut de Physique Nucleaire et de Physique des Particules (France), the Commissariat a l'Energie Atomique (France), and the U.S. National Science Fundation, for the attribution of travel grants. Our special appreciation is due to Frederique Dykstra for her oustanding organiza- tional work throughout the preparation and duration of this conference It is also a pleasure to thank the Universite de Nice for making available the facilities of the Cargese Scientific Institute. The pictures of the lecturers included in the present volume were kindly provided by one of the participants, Dr.R.Janner.

For this set of lectures we assumed that the reader has a reasonable back ground in physics and some knowledge of general relativity, the modern theory of gravity in macrophysics, and cosmology. Computer methods are present ed by leading experts in the three main domains: in numerics, in computer algebra, and in visualization. The idea was that each of these subdisciplines is introduced by an extended set of main lectures and that each is conceived as being of comparable 'importance. Therefpre we believe that the book represents a good introduction into scientific I computing for any student who wants to specialize in relativity, gravitation, and/or astrophysics. We took great care to select lecturers who teach in a comprehensible way and who are, at the same time, at the research front of their respective field. In numerics we had the privilege of having a lecturer from the National Center for Supercomputing Applications (NCSA, Champaign, IL, USA) and some from other leading institutions of the world; visualization was taught by a visualization expert from Boeing; and in com puter algebra we took recourse to practitioners of different computer algebra systems as applied to classical general relativity up to quantum gravity and differential geometry.

This book on the theory of three-dimensional spinors and their applications fills an important gap in the literature. It gives an introductory treatment of spinors. From the reviews: "Gathers much of what can be done with 3-D spinors in an easy-to-read, self-contained form designed for applications that will supplement many available spinor treatments. The book...should be appealing to graduate students and researchers in relativity and mathematical physics." --MATHEMATICAL REVIEWS

Because of recent progress in the development of quasistationary toroidal mag- netic confinement systems, especially tokamaks, these systems are at the center of research on controlled thermonuclear fusion. Tokamaks were proposed and first built at the Kurchatov Institute of Atomic Energy. In the 1960s the basic features of plasma behavior in toroidal magnetic confinement systems were investigated in ex- periments on the first tokamaks and the possibility of obtaining effective confine- ment in them was demonstrated. The successes of this first stage led to a rapid ex- pansion in tokamak research around the world. The development of a thermonu- clear power reactor based on the tokamak is now actively under way. During the earliest phase of research on tokamaks, it was already clear that the ohmic heating used in them was not sufficient to obtain the temperatures needed for initiation of a self-sustaining thermonuclear reaction. At the beginning of the 1970s, therefore, a search was begun for methods of heating which could supple- ment ohmic heating. The best of these auxiliary heating techniques are neutral beam injection, various methods based on the collisionless absorption of rf (radio fre- quency) waves, and adiabatic compression of the plasma by a rising magnetic field.

The Cargese Workshop Random Surfaces and Quantum Gravity was held from May 27 to June 2, 1990. Little was known about string theory in the non-perturbative regime before Oetober 1989 when non-perturbative equations for the string partition functions were found by using methods based on the random triangulations of surfaees. This set of methods pro vides a deseription of non-eritical string theory or equivalently of the coupling of matter fields to quantum gravity in two dimensions. The Cargese meeting was very successful in that it provided the first opportunity to gather most of the active workers in the field for a fuH week of lectures and extensive informal discussions about these exeiting new developments. The main results were reviewed, recent advances were explained, new results and conjectures (which appear for the first time in these proceedings) were presented and discussed. Among the most important topics discussed at the workshop were: The relation of KdV theory to loop equations and the Virasoro algebra, new results in Liouville field theory, effective (1 + 1) dimensional theory for 2 - D quantum gravity coupled to c = 1 matter and its fermionization, proposal for a new geometrical interpretation of the string equation and possible definition of quantum Riemann surfaces, discussion of the string equation for the multi-matrix models, links with topological field theories of gravity, issues in using target space supersymmetry to define good theories, definition of the partition function via analytic continuation, new models of random surfaces

Clusters and superclusters of galaxies are the largest objects in the Universe. They have been the subject of intense observational studies at a variety of wavelengths, from radio to X-ray which has provoked much theoretical debate and advanced our understanding of the recent evolution of the large-scale structure of the Universe. The current status of the subject is reviewed in this volume by active researchers who lectured at a NATO Advanced Study Institute held in Cambridge, England in July 1991. Much of the material is presented in a pedagogical manner and will appeal to scientists, astronomers and graduate students interested in extragalactic astronomy.

In many areas of physics, such as astrophysics, solid-state physics, nuclear physics and particle physics, a major outstanding problem is a better understanding of corre lation phenomena. While in most cases the average properties of a system are rather well understood, the correlations and the resulting clustering are poorly understood. They are reflections of the force mediating the interaction among the constituents and play essential roles in determining the structure of a physical system. At the largest scales, in astrophysics, it has recently been realized that there are huge voids in space and almost all matter is concentrated on filaments, raising interesting questions concerning the origin of this clustering of matter. In nuclear physics corre lation phenomena are important in all its subfields. It has been realized that so-called fluctuations in the one-particle density, which are a manifestation of nucleon-nucleon correlations, are crucial. These are important for an understanding of heavy-ion reac tions. This is the subject of modern quantum transport theories. Correlations are also crucial in the description of the high momentum components as observed in quasi-elastic knock-out reactions."

This volume contains the proceedings of the meeting entitled, "The IGM/Galaxy Connection: The Distribution of Baryons at z = 0. " The meeting was held August 8 -10 at the National Center for Atmospheric Research (NCAR) located in Boulder, Colorado on the foothills of the Rocky Mountains (see conference photo). We organized this meeting because we felt it was time to address the link between galaxies and the intergalactic medium at low redshift. In this vein, we posed several questions to the conference participants: Where are the baryons in the local universe and in what phase do they reside? What signatures of galaxy evolution have been imprinted on the IGM? What percentage of intergalactic gas is left from the galaxy formation process? What does the distribution of baryons at z = 0 tell us about the early universe? The conference was an overwhelming success with lots of friendly interaction and discussion among the participants. At lunch we were treated to splendid views from the NCAR terrace and discussions rang ing from the importance of the LSR, GSR, and LGSR velocity frames to how long the desserts would last with 90 astronomers and the hot Boul der sun. From an inventory of the baryons, to the associations between galaxies and Lya absorbers, to the mechanisms by which galaxies obtain and lose gas, the conference covered many topics. The results of these endeavors are contained in these pages and eloquently summarized by Chris Impey.

Today many scientists recognize plasma as the key element in understanding new observations in interplanetary and interstellar space, in stars, galaxies, and clusters of galaxies, and throughout the observable universe. Plasma astrophysics and cosmology, as a unified discipline, cover topics such as the large scale structure and filamentation of the universe; the microwave background; the formation of galaxies and magnetic fields; active galactic nuclei and quasars; the origin and abundance of light elements; star formation and the evolution of solar systems; redshift periodicities and anomalous redshifts; general relativity; electric fields; the acceleration of charged particles to high energies; and cosmic rays. Plasma Astrophysics and Cosmology is an update on the observations made in radio, optical, and high-energy astrophysics, especially over the last decade, and addresses the paradigm changing discoveries made by the planetary probes and satellites, radio telescopes, and the Hubble space telescope. Over twenty contributors, all distinguished plasma scientists, present an entirely new picture of the nature of our plasma universe with articles ranging from the popular level to advanced topics in plasma cosmology.

This is a book about physics, written for mathematicians. The readers we have in mind can be roughly described as those who: I. are mathematics graduate students with some knowledge of global differential geometry 2. have had the equivalent of freshman physics, and find popular accounts of astrophysics and cosmology interesting 3. appreciate mathematical elarity, but are willing to accept physical motiva tions for the mathematics in place of mathematical ones 4. are willing to spend time and effort mastering certain technical details, such as those in Section 1. 1. Each book disappoints so me readers. This one will disappoint: 1. physicists who want to use this book as a first course on differential geometry 2. mathematicians who think Lorentzian manifolds are wholly similar to Riemannian ones, or that, given a sufficiently good mathematical back ground, the essentials of a subject !ike cosmology can be learned without so me hard work on boring detaiis 3. those who believe vague philosophical arguments have more than historical and heuristic significance, that general relativity should somehow be "proved," or that axiomatization of this subject is useful 4. those who want an encyclopedic treatment (the books by Hawking-Ellis [1], Penrose [1], Weinberg [1], and Misner-Thorne-Wheeler [I] go further into the subject than we do; see also the survey article, Sachs-Wu [1]). 5. mathematicians who want to learn quantum physics or unified fieId theory (unfortunateIy, quantum physics texts all seem either to be for physicists, or merely concerned with formaI mathematics).

The main feature of this book is the emphasis on "practice." This approach, unusual in the relativistic literature, may be clarified by quoting some problems discussed in the text: - the analysis of rocket acceleration to relativistic velocities - the influence of gravitational fields on the accuracy of time measurements - the operation of optical rotation sensors - the evaluation of the Doppler spectrum produced by the linear (or ro- tional) motion of an antenna or scatterer - the use of the Cerenkov effect in the design of millimeter-wave power generators - the influence of the motion of a plasma on the transmission of electrom- netic waves through this medium. A correct solution of these (and analogous) problems requires the use of re lativistic principles. This remark remains valid even at low velocities, since first-order terms in (v/c) often playa fundamental role in the equations. The "applicational" approach used in the text should be acceptable to space engineers, nuclear engineers, electrical engineers, and more generally, ap plied physicists. Electrical engineers, in particular, are concerned with re lativity by way of the electrodynamics of moving bodies. This discipline is of decisive importance for power engineers, who are confronted with problems such as - the justification of a forcing function (-D /Dt) in the circuit equation of a moving loop - a correct formulation of Maxwell's equations in rotating coordinate systems - the resolution of "sliding contact" paradoxes - a theoretically satisfying analysis of magnetic levitation systems."

Stephen Webb, author of WHERE IS EVERYBODY?, takes the interested amateur on a thrilling and enlightening tour of the amazing, even bizarre, new ideas of modern physics, including alternatives to the Big Bang, parallel universes, and an imaginary trip to the other side of the black hole.

This book is an updated and modified translation of the Russian edition of 1984. In the present edition, certain sections have been abridged (in particular, Sects. 6.1 and 8.3) and the bibliography has been expanded. There are more detailed discus sions of the group properties of integrable systems of equations of mathematical physics (Sect. 3.4) and of the Riemannian problem in the context of the infinite dimensional internal symmetry groups of these systems of equations. There is an extended discussion of the reasons for the acceleration and retardation of pulsars in connection with more recent achievements of X-ray astronomy. Part of the material of Chap. 8 of the Russian edition has been included in Chap. 7; thus the number of chapters has been reduced to seven. S. Chandrasekhar set for me an example of brilliant analytical penetration into the essence of physical problems, and my book touches on his work in many in stances. The results of modem quantum theories of strong fields are not presented, but they can be found in the fundamental monographs Quantwn Electrodynamics of Strong Fields by W. Greiner, B. Muller, J. Rafelski (Sprioger-Verlag, Berlin, Heidelberg, New York 1985) and Quantwn Effects in Intense External Fields in Russian] by A. Grib, S. Mamaev, W. Mostepanenko (Energoatomizdat, Moscow 1988). This book was translated by Dr. N. M. Queen; I am very grateful to him. I thank sincerely H. Latta, C.-D. Bachem, V. Rehman, S. von Kalckreuth for preparing of the english manuscript."

Many large-scale projects for detecting gravitational radiation are currently being developed, all with the aim of opening a new window onto the observable Universe. As a result, numerical relativity has recently become a major field of research, and Elements of Numerical Relativity and Relativistic Hydrodynamics is a valuable primer for both graduate students and non-specialist researchers wishing to enter the field.

A revised and significantly enlarged edition of LNP 673 Elements of Numerical Relativity, this book starts with the most basic insights and aspects of numerical relativity before it develops coherent guidelines for the reliable and convenient selection of each of the following key aspects: evolution formalism; gauge, initial, and boundary conditions; and various numerical algorithms. And in addition to many revisions, it includes new, convenient damping terms for numerical implementations, a presentation of the recently-developed harmonic formalism, and an extensive, new chapter on matter space-times, containing a thorough introduction to relativistic hydrodynamics.

While proper reference is given to advanced applications requiring large computational resources, most tests and applications in this book can be performed on a standard PC.

Puts the emphasis on conceptual questions: Why is there no such thing as absolute motion? What is the physical meaning of relativity of simultaneity? But, the most important question that is addressed in this book is "what is the nature of spacetime?" or, equivalently, "what is the dimensionality of the world at the macroscopic level?"

Develops answers to these questions via a thorough analysis of relativistic effects and explicitly asking whether the objects involved in those effects are three-dimensional or four-dimensional.

Discusses the implication of the result (this analysis clearly shows that if the world and the physical objects were three-dimensional, none of the kinematic relativistic effects and the experimental evidence supporting them would be possible) for physics, philosophy, and our entire world view are discussed.

This volume consists of invited talks and contributed papers presented at the NATO Advanced Study Institute "The Post Recombination Universe" which was held in Cambridge in the summer of 1987. There have, in recent years, been numerous meetings devoted to problems in observational cosmology. The attention given reflects the exciting rate of de velopment of the subject, and a survey of the proceedings from these symposia reveals that a great deal of emphasis has been given to consideration of the very early universe on the one hand, and to large scale structure in the universe at the present epoch on the other. The theme of this meeting was chosen to comple ment these efforts by focussing on the state of the universe at quite early times, but at those epochs which are still accessible to direct observations. The meet ing provided a broad coverage of the post recombination universe by drawing on experts from a wide variety of fields covering theory, background radiation fields and discrete sources at high redshift. Events in the moderately early universe will have left their mark in a great range of wavebands, from X-rays to the microwave region, and the evolution of the universe can be revealed by studies of the inter galactic medium, gravitational lensing and the abundance and clustering of high redshift sources. All of these subjects received much attention at the meeting, and the papers demonstrate the rich interplay between these areas in the rapidly expanding world of observational cosmology."

When my colleague Dr. Paul Kent asked me which branch of Physics was most lively and which would lend itself best to a small high quality Symposium, I had no hesitation in answering 'Cosmology'. It seemed very timely that a meeting should take place which would bring together scientists interested in all branches of Astronomy, including Cosmic Rays, and Elementary Particles too and endeavour to put at least some of the pieces of the jigsaw together. The vast majority of the papers presented were later produced ~n appropriate camera-ready form and are published in this volume. I am very grateful to the authors for their ready cooperation. Grateful thanks are also extended to the Board of Management of the Foster-Wills and Theodor Heuss Scholarships, Oxford University and the Deutscher Akademischer Austauschdienst (German Academic Exchange Service) who funded the Symposium. The Director of the German Academic Exchange Service, Frau M.E. Schmitz and her colleague Mrs. Susan Putt, organized the whole meeting in a most exemplary fashion. Finally, on behalf of all participants and guests, s~ncere thanks are offered to Paul Kent as Convenor for initiating the Symposium, arranging the social events and organizing accommodation in such magnificent surroundings. Christ Church was the horne of Lewis Carrol and we were ever mindful - and appropriately so - of Alice. A. W. Wolfendale Durham, February 10th, 1982 vii A. W. Wolfendale (ed.), Progress in Cosmology, vii.

This volume is based on the lectures given at the First Inter University Graduate School on Gravitation and Cosmology organized by IUCAA, Pune, in 1989. This series of Schools have been carefully planned to provide a sound background and preparation for students embarking on research in these and related topics. Consequently, the contents of these lectures have been meticulously selected and arranged. The topics in the present volume offer a firm mathematical foundation for a number of subjects to be de veloped later. These include Geometrical Methods for Physics, Quantum Field Theory Methods and Relativistic Cosmology. The style of the book is pedagogical and should appeal to students and research workers attempt ing to learn the modern techniques involved. A number of specially selected problems with hints and solutions have been included to assist the reader in achieving mastery of the topics. We decided to bring out this volume containing the lecture notes since we felt that they would be useful to a wider community of research workers, many of whom could not participate in the school. We thank all the lecturers for their meticulous lectures, the enthusiasm they brought to the discussions and for kindly writing up their lecture notes. It is a pleasure to thank G. Manjunatha for his meticulous assistence over a long period, in preparing this volume for publication."

Based on class-tested notes, this text offers an introduction to Conformal Field Theory with a special emphasis on computational techniques of relevance for String Theory. It introduces Conformal Field Theory at a basic level, Kac-Moody algebras, one-loop partition functions, Superconformal Field Theories, Gepner Models and Boundary Conformal Field Theory. Eventually, the concept of orientifold constructions is explained in detail for the example of the bosonic string. In providing many detailed CFT calculations, this book is ideal for students and scientists intending to become acquainted with CFT techniques relevant for string theory but also for students and non-specialists from related fields.