The theoretical chemist is accustomed to judging the success of a theoretical prediction according to how well it agrees with an experimental measurement. Since the object of theory is the prediction of the results of experiment, that would appear to be an entirely satisfactory state ofaffairs. However, ifit is true that "the underlying physicallaws ...for the whole ofchemistryare ...completely known" (1), thenit shouldbepossible,atleastinprinciple, topredict theresults of experiment moreaccurately than they canbe measured. Ifthe theoreticalchemist could obtain exact solutions ofthe Schrodinger equation for many-body systems, then the experimental chemist would soon become accustomed to judging the success ofan experimental measurement by how well it agrees with a theoretical prediction. In fact, it is now possible to obtainexact solutions ofthe Schrodinger equation for systems ofa few electrons(2-8). These systems include the molecular ion Ht, the molecule H , the reaction intermediate H-H-H, the unstable pair H-He, the 2 stable dimer He2' and the trimer He3. The quantum Monte Carlo method used in solving the time-independent Schrodinger equation for these systems is exact in that it requires no physical or mathematical assumptions beyond those of the Schrodinger equation. As in most Monte Carlo methods there is a statistical or sampling error which is readily estimated.

th The 13 Winter Workshop on Nuclear Dynamics is the latest installment in a series of workshops that was started in 1978. This series has grown into a tradition, bringing together experimental and theoretical expertise from all areas of the study of nuclear dynamics. As always, the organizers had placed emphasis on the important aspect of cross fertilization between the different energy regimes and wa.ys of viewing a collision of energetic nuclei. This emphasis is reflected in the broad range of topics covered in these proceedings. Phase transitions in nuclear collisions received most of the attention during this workshop, as indicated by the number of contributions on this subject. Many of the questions in connection with these topics remain not settled and will have a huge impact on the physics that can be extracted from experiments at the future Relativistic Heavy Ion Collider. While the experimental program at the AGS is winding down, the NSCL upgrade and RHIC promise a bright future for our field in the USA. In Europe and Asia, major new facilities are under construction as well. The excitement and anticipation in connection with these new opportunities are reflected in these proceedings as well. Wolfgang Bauer Michigan State University Alice Mignerey University of Maryland v PREVIOUS WORKSHOPS The following table contains a list of the dates and locations of the previous Winter Workshops on Nuclear Dynamics as well as the members of the organizing committees. The chairpersons of the conferences are underlined.

The Twenty Fourth Jerusalem Symposium reflected the high standards of these distinguished scientific meetings, which convene once a year at the Israel Academy of Sciences and Humanities in Jerusalem to discuss a specific topic in the broad area of quantum chemistry and biochemistry. The topic at this year's Jerusalem Symposium was mode selective chemistry, which constitutes a truly interdisciplinary subject of central interest in the areas of chemical physics, photochemistry and photobiology. The main theme of the Symposium was built around the exploration of the possibility and conditions for non-statistical reaction dynamics in molecules, van der Waals molecules, clusters and condensed phases. The main issues addressed photoselective and coherent excitation modes, bottlenecks for intramolecular vibrational energy redistribution, the consequences of the internal structure of many-atom systems and of rotational vibrational level structure for intramolecular dynamics, bond selective photodissociation, ultrafast chemical clocks for energy disposal, coherent control of photochemical reactions and nonstatistical unimolecular reaction dynamics. The interdisciplinary nature of this research area was deliberated by intensive and extensive interactions between theory and experiment. This volume provides a record of the invited lectures at the Symposium."

Dissociative Recombination of Molecular Ions with Electrons is a comprehensive collection of refereed papers describing the latest developments in dissociative recombination research. The papers are written by the leading researchers in the field. The topics covered include the use of microwave afterglows, merged beams and storage rings to measure rate coefficients and to identify the products and their yields. The molecules studied range in size from the smallest, H2+, to bovine insulin ions. The theoretical papers cover the important role of Rydberg states and the use of wave packets and quantum defect theory to deduce cross sections, rate constants and quantum yields. Several theoretical and experimental papers address the controversial topic of H3+ dissociative recombination and its importance in the interstellar medium. Dissociative recombination studies of other molecular ions in the interstellar medium and in cometary and planetary atmospheres are covered. Ionization is an important competitive process to dissociative recombination and its competition with predissociation and its role in the reverse process of the association of neutral species is presented. Dissociative attachment, in which an electron attaches to a neutral molecule, has many similarities to dissociative recombination. The topics covered include the accurate calculation of electron affinities, attachment to molecules, clusters, and to species absorbed on solid surfaces and electron scattering by a molecular anion.

The present volume contains the texts of the invited talks delivered at the Sixth International Conference on Recent Progress in Many-Body Theories held in Arad, Israel during the period November 5-10 1989. The host institute was the Physics Department at the Ben Gurion University of the Negev. Beside the invited talks there have been also two poster sessions. The general format and style of the meeting followed closely those which had preceded it and evolved from the earlier conferences in the series: Trieste 1978, Oxtapec 1981, Altenberg 1983, San Francisco 1985 and Oulu 1987. The conferences in this series are intended to cover the broad spectrum of modem physics related to the many body problem. It starts on the smallest length scales in dealing with quark gluon plasmas and ends on the largest length scales in tackling many body problems in astrophysics. In between, it is concerned with nuclear physics, solid state physics, statistical mechanics, field theory, molecular dynamics, hydrodynamics, chaos, etc. Like in the Oulu conference, special emphasis has been put on recent developments in high Tc superconductivity. Beside the half day session devoted to it we have also organized an evening round table discussion on the future of the whole subject. Furthermore, a new, and in the opinion of the editor a very refreshing element which was absent in earlier conferences was the presentation of a few talks by experimentalists.

INSTEAD OF A "FESTSCHRIFT" In June 1998 Hans Primas turned 70 years old. Although he himself is not fond of jubilees and although he likes to play the decimal system of numbers down as contingent, this is nevertheless a suitable occasion to reflect on the professional work of one of the rare distinguished contempo rary scientists who attach equal importance to experimental and theoretical and conceptual lines of research. Hans Primas' interests have covered an enormous range: methods and instruments for nuclear magnetic resonance, theoretical chemistry, C* - and W* -algebraic formulations of quantum me chanics, the measurement problem and its various implications, holism and realism in quantum theory, theory reduction, the work and personality of Wolfgang Pauli, as well as Jungian psychology. In many of these fields he provided important and original food for thought, in some cases going far beyond the everyday business in the scien tific world. As is the case with other scientists who are conceptually inno vative, Hans Primas is read more than he is quoted. His influence is due to his writings. Even with the current flood of publications, he still performs the miracle of having scientists eagerly awaiting his next publication."

The recent discovery of a type II supernova in the Large Magellanic Cloud provides a rare chance to compare models of stellar evolution and nucleosynthesis directly with observations. This workshop covers thermonuclear reaction rates in chaos (experimental and theoretical), stellar evolution, nucleosynthesis and isotopic anomalies in meteorites and, in a final section, the supernovae, in particular SN 1987A. It brings the most interesting news in the rapidly developing field of nuclear astrophysics to researchers and also to graduate students. Recent and future developments are discussed. Special emphasis is placed on experimental and theoretical approaches to obtaining nuclear reaction rates, models of stellar evolution and explosions, and theories of nucleosynthesis. Various aspects of stellar evolution, nucleosynthesis, and thermonuclear reactions of astrophysical interest are reviewed. Several contributions deal with supernova explosions of massive stars, and in particular with Supernova 1987A and its impact on current models of the evolution of massive stars, the gravitational collapse of stellar cores, and neutrino physics and astronomy.

A "z pinch" is a deceptively simple plasma configuration in which a longitudinal current produces a magnetic field that confines the plasma. Z-pinch research is currently one of the fastest growing areas of plasma physics, with revived interest in z-pinch controlled fusion reactors along with investigations of new z-pinch applications, such as very high power x-ray sources, high-energy neutrons sources, and ultra-high magnetic fields generators. This book provides a comprehensive review of the physics of dense z pinches and includes many recent experimental results.

Gaseous Dielectrics VIII covers recent advances and developments in a wide range of basic, applied, and industrial areas of gaseous dielectrics.

This symposium was organized at the B.M. Birla Science Centre, Hyderabad, India, and provided a platform for frontier physicists to exchange ideas and review the latest work and developments on a variety of interrelated topics. A feature of the symposium, as well as the proceedings, is the B.M. Birla Memorial Lecture by Nobel Laureate Professor Gerard 't Hooft. There were participants from the USA, several European countries, Russia and CIS countries, South Africa, Japan, India and elsewhere, of whom some forty scientists presented papers. Spanning a wide range of contemporary issues in fundamental physics from string theory to cosmology, the proceedings present many of these talks and contributions.

Atomic Physics is certainly the oldest field in which Quantum Mechanics has been used and has provided the most significant proofs of this new theory. Most of the basic concepts, except those more recently developed in field quantization, have been understood for quite a time. Atomic Physics began to serve as a basis for other fields such as molecu lar, solid state or nuclear physics. A renewal of interest in Atomic Physics began in the sixties, after the discovery of Quantum Electro dynamics, and later when it provided some basic tests of fundamental questions like parity violation, time reversal or Dirac theory. More recently the development of new technologies led to the ex ploration of very extreme cases in which the most secrete aspects of atoms have been observed. - Rydberg states where the atoms are so big that they can be described by classical theories; - Heavy or super-heavy ions or exotic atoms where unknown QED or relativistic effects can be observed (very heavy hydrogenlike or helium like ions, positron production in very violent collisions **. ); - Huge external perturbations as those appearing in super-dense plasmas or ultra-high fields. The aim of this school was to gather atomic physicists from all over the world working in all these areas of Atomic Physics.

Seldom does a physical system, particularly one as apparently simple as the flow of a Newtonian fluid between concentric rotating cylinders, retain the interest of scientists, applied mathematicians and engineers for very long. Yet, as this volume goes to press it has been nearly 70 years since G. I. Taylor's outstanding experimental and theoretical study of the linear stability of this flow was published, and a century since the first experiments were performed on rotating cylinder viscometers. Since then, the study of this system has progressed enormously, but new features of the flow patterns are still being uncovered. Interesting variations on the basic system abound. Connections with open flows are being made. More complex fluids are used in some experiments. The vigor of the research going on in this particular example of nonequilibrium systems was very apparent at the NATO Advanced Research Workshop on "Ordered and Turbulent Patterns in Taylor Couette Flow," held in Columbus, Ohio, USA May 22-24, 1991. A primary goal of this ARW was to bring together those interested in pattern formation in the classic Taylor Couette problem with those looking at variations on the basic system and with those interested in related systems, in order to better define the interesting areas for the future, the open questions, and the features common (and not common) to closed and open systems. This volume contains many of the contributions presented during the workshop.

The management and disposal of radioactive wastes are key international issues requiring a sound, fundamental scientific basis to insure public and environmental protection. Large quantities of existing nuclear waste must be treated to encapsulate the radioactivity in a form suitable for disposal. The treatment of this waste, due to its extreme diversity, presents tremendous engineering and scientific challenges. Geologic isolation of transuranic waste is the approach currently proposed by all nuclear countries for its final disposal. To be successful in this endeavor, it is necessary to understand the behavior of plutonium and the other actinides in relevant environmental media. Conceptual models for stored high level waste and waste repository systems present many sCientific difficulties due to their complexity and non-ideality. For example, much of the high level nuclear waste in the US is stored as alkaline concentrated electrolyte materials, where the chemistry of the actinides under such conditions is not well understood. This lack of understanding limits the successful separation and treatment of these wastes. Also, countries such as the US and Germany plan to dispose of actinide bearing wastes in geologic salt deposits. In this case, understanding the speciation and transport properties of actinides in brines is critical for confidence in repository performance and risk assessment activities. Many deep groundwaters underlying existing contaminated sites are also high in ionic strength. Until recently, the scientific basis for describing actinide chemistry in such systems was extremely limited."

Multiphoton Processes in Atoms in intense laser-light fields is gaining ground as a spectroscopic diagnostic tool. The authors present descriptions of processes occurring in atoms under the action of strong electromagnetic radiation, in particular, the shift, broadening, and mixing of atomic states. The topics include tunneling ionization, above-threshold ionization, ionization of multiply charged ions, resonance-enhanced ionization, super-intense radiation fields, and properties of Rydberg states strongly perturbed by laser radiation.

The last decade has witnessed significant advances in the ability to generate short light pulses throughout the optical spectrum. These developments have had a tremendous impact on the field of chemical dynamics. Fundamental questions concerning chemical reactions, once thought to be unaddressable, are now easily studied in real-time experiments. Ultrafast spectroscopies are currently being used to study a variety of fundamental chemical phenomena. This book focuses on some of the experimental and associated theoretical studies of reactions in clusters, liquid and solid media. Many of the advances in our understanding of the fundamental details of chemical reactivity result from the interplay of experiment and theory. This theme is present in many of the chapters, indicating the pervasiveness of a combined approach for eludicating molecular models of chemical reactions. With parallel developments in computer simulation, complex chemical sys tems are being studied at a molecular level. The discussions presented in this book recount many areas at the forefront of "ultrafast chemistry". They serve the purpose of both bringing the expert up to date with the work being done in many laboratories as well as introducing those not directly involved in this field to the diverse set of problems that can be studied. I hope that this book conveys the excitement that both I and the other authors in this volume feel about the field of ultrafast chemistry. John D. Simon 1993 1.D. Simon (ed.), Ultrafast Dynamics of Chemical Systems, vii.

The book contains the notes of the lectures presented by outstanding experts at the 7th EADN School on plasma astrophysics. It is an up-to-date review of a number of basic topics in the physics of cosmic plasmas. The subject is treated both from a theoretical point of view and from that of the observational and diagnostic tools that provide us with the physically relevant data. The reader will have at hands a comprehensive and rather complete presentation of the subject, thanks also to the parallel development of the theoretical and experimental aspects. The book addresses graduate students and researchers in different areas who want to have a rapid and up-to-date introduction to this subject.

Paul Harteck Rensselaer Polytechnic Institute Troy, New York When the Maser and the Laser Were discovered, people were speculating if this was the beginning of a new page, or even a new chapter, in the Book of Physics. The Second Workshop on "Laser Interaction and Related Plasma Phenomena" held in Hartford made it clear that the perspective had changed, that people now question if the consequences of these discoveries constitute a new chapter, or possibly a new era in Physics. While the papers presented were all stimulating and of out standing quality, of special interest were the experiments which demonstrated that triggering of thermonuclear fusion by Laser techniques is indeed in the realm of the possible. Along these lines, I enjoy recalling an anecdote concerning the late F. G. Houtermans. I think that all who knew him will agree that he was an unusual genius and at the same time a very amusing colleague.

Review articles on three topics of considerable current interest make up the present volume. The first, on A-hypernuclei, was solicited by the editors in order to provide nuclear physicists with a general description of the most recent developments in a field which this audience has largely neglected or, perhaps, viewed as a novelty in which a bizarre nuclear system gave some information about the lambda-nuclear intersection. That view was never valid. The very recent developments reviewed here-particularly those pertaining to hypernuclear excitations and the strangeness exchange reactions-emphasize that this field provides important information about the models and central ideas of nuclear physics. The off-shell behavior of the nucleon-nucleon interaction is a topic which was at first received with some embarrassment, abuse, and neglect, but it has recently gained proper attention in many nuclear problems. Interest was first focused on it in nuclear many-body theory, but it threatened nuclear physicists'comfortable feeling about nonrelativistic potential theory, and many no doubt hoped that it would remain merely an esoteric diversion within the many-body cult. In the editors' opinion, this subject is now emi nently respectable and a review of it indeed timely. The third topic, nuclear charge distributions, is one which almost every nuclear physicist believed had been weIl in hand for some years."

As in the days following Skylab, solar physics came to the end of an era when the So lar Maximum Mission re-entered the earth's atmosphere in December 1989. The 1980s had been a pioneering decade not only in space- and ground-based studies of the solar atmosphere (Solar Maximum Mission, Hinotori, VLA, Big Bear, Nanc;ay, etc.) but also in solar-terrestrial relations (ISEE, AMPTE), and solar interior neutrino and helioseismol ogy studies. The pace of development in related areas of theory (nuclear, atomic, MHD, beam-plasma) has been equally impressive. All of these raised tantalizing further questions about the structure and dynamics of the Sun as the prototypical and best observed star. This Advanced Study Institute was timed at a pivotal point between that decade and the realisation of Yohkoh, Ulysses, SOHO, GRANAT, Coronas, and new ground-based optical facilities such as LEST and GONG, so as to teach and inspire the up and coming young solar researchers of the 1990s. The topics, lecturers, and students were all chosen with this goal in mind, and the result seems to have been highly successful by all reports."

Discusses Hahn's contributions to science and his reflections of scientific and social responsibility. The author concludes that Hahn's ideas can still serve as a foundation for responsible and moral actions by scientists.

"If there would be no God ~ then what a staff-captain am I?" ~ said one of the characters in a novel by Dostoevskii. In a similar way we can exclaim: "If there would be no nonlinearity ~ than what physics would that be'?". Really, the most interesting and exciting effects are described by non linear equations, and vanish in the linear approximation. For example, the general theory of relativity by A.Einstein comes to mind first - one of the most beautiful physical theories, which is in fact essentially nonlinear. Next, the phase transitions crystal ~ liquid and liquid ~ gas are due to the anhar monicity of inter-particle interactions, to dissociation and infinite motion. Similarly, transitions into the superconducting state or the superftuid would be impossible with purely harmonic interaction potentials. Another bril liant achievement in nonlinear physics was the construction of a laser and the subsequent development of nonlinear optics. The latter describes the in teraction of the matter with light of super-high intensity, when multi-quanta intra-molecular transitions become essential. Last, we should note here the very beautiful mathematical theory ~ the theory of catastrophes. Its subject is the study of invariant general properties of multi-dimensional surfaces in the vicinity of bifurcation points with respect to continuous transformations.

Nowadays the realm of intermediate energy as a bridge between nuclear and particle physics attracts considerable interest. This volume surveys recent developments in the theory of quark correlations in hadronic matter and also informs about experimental findings. The main themes are: dynamicalsymmetries of heavy quarks, diquarks, weak interactions, hadron spectroscopyand quark models, chiral invariant quark forces, quark confinement and quarkaspects of hadronic interactions.

Electroweak Phase Transition and the Early Universe, a NATO Advanced Re- search Workshop, was held March 23-25, 1994, at the Hotel Tivoli in Sintra, Portugal. The meeting was co-sponsored by three other Lisbon-based institutions: the Fundac;ao Gulbenkian, J. N.!. C. T. (Junta Nacional para Investigac;ao Cientifica e Tecnologica) and G. T. A. E. (Grupo Teorico de Alta Energias). The workshop brought together a large number of theoretical physicists who are actively researching topics relevant to the understanding of the standard model of electroweak interactions in the early universe. We were pleased and overwhelmed by the positive, and sometimes instan- taneous response that our enterprise raised right from its inception. The old town of Sintra provided a serene and pleasant environment for the par- ticipants. Some heated and controversial discussions on many unanswered questions in the standard model took place throughout the three days of the workshop. If one consensus emerged from the meeting, it was the imperative need for non-perturbative techniques for the understanding of the electroweak phase transition.

My aim in this book has been to give an account of the theoretical methods of analysis of multiphoton processes in atomic physics. In this account I have emphasized systematic methods as opposed to ad hoc approaches. Both perturbative and nonperturbative methods are presented with il- lustrative results of concrete applications. The perturbation theory is the primary tool of analysis of nonresonant multiphoton processes. It is developed here in conjunction with a diagrammatic language and is also renormalized to free it from the unwanted divergences which accompany the ordinary treatment when higher-order corrections are considered. The nonperturbative methods (i.e., methods other than that of power series ex- pansion in the field strength) become particularly important for consistent treatments of problems involving, for example, intermediate resonances, high field strengths, and finite pulse duration. The specifically nonpertur- bative methods for multiphoton transitions are presented in Chapters 6-11. The methods of resolvent equations and of effective Hamiltonians are developed for both the stationary and the time-dependent fields. The densi- ty matrix method is presented in conjunction with the problems of relaxa- tion and of fluctuating fields. The Floquet theory is presented both in the energy domain and in the time domain. Also treated are the methods of continued fractions, recursive iterative equations, and chain Hamiltonians.