String theory is the candidate for the unification of all fundamental interactions including gravity. In the past few years this active field of research has developed very rapidly and in several different directions. The aim of the conference is to give an overview of the status of the art in string theory through the contributions of the major experts in this field. The main topics include: string unification and effective Lagrangians, N=2 string theories, 2-d quantum gravity, stringy black holes, topological field theory, conformal field theories, strings and quantum field theory.

String theory is a model of fundamental physics whose building blocks are one-dimensional extended objects called strings, rather than the zero-dimensional point particles that form the basis for the standard model of particle physics. The phrase is often used as shorthand for Superstring theory, as well as related theories such as M-theory. By replacing the point-like particles with strings, an apparently consistent quantum theory of gravity emerges. Moreover, it may be possible to 'unify' the known natural forces (gravitational, electromagnetic, weak nuclear and strong nuclear) by describing them with the same set of equations. Studies of string theory have revealed that it predicts higher-dimensional objects called branes. String theory strongly suggests the existence of ten or eleven (in M-theory) space-time dimensions, as opposed to the usual four (three spatial and one temporal) used in relativity theory.

The areas covered in this volume include: duality in string theory and supersymmetric gauge theories; phenomenological applications of string theory; strings in curved spacetime; quantum gravity; SUSY conformal field theories; QCD strings; aspects of mathematical physics, including: mirror symmetry, W-algebras, representation theory.

The recent high precision results from the LEP supercollider at CERN appear favorable for supergravity unification of the electroweak and the strong forces. The proceedings of the SUSY 93 Workshop focus on further precise predictions of unification which may be observed in the laboratory. In addition, the proceedings cover a wide range of other topics in supersymmetry, supergravity, particle physics, string theory and cosmology and their interconnections. They include both theoretical and experimental papers, hence presenting a complete and comprehensive picture of this important subject.

Ever since 1911, the Solvay Conferences have shaped modern physics. The 25th edition held in October 2011 in Brussels and chaired by David Gross continued this tradition and celebrated the first centennial of this illustrious series of conferences. The development and applications of quantum mechanics have always been the main threads in the history of the Solvay Conferences, hence the 25th Solvay conference gathered many of the leading figures working on a wide variety of profound problems in physics where quantum mechanical effects play a central role. The conference addressed some of the most pressing open questions in the field of physics.The proceedings contain the “rapporteur talks” which give a broad overview with unique insights by distinguished and renowned scientists. These lectures cover the seven sessions: “History and Reflections”, “Foundations of Quantum Mechanics and Quantum Computation”, “Control of Quantum Systems”, “Quantum Condensed Matter”, “Particles and Fields”, “Quantum Gravity and String Theory” and it ended with a general discussion attempting to arrive at a synthesis.In the Solvay tradition, the proceedings also include the prepared comments to the rapporteur talks. The discussions among the participants — some of which quite lively and involving dramatically divergent points of view — have been carefully edited and are reproduced in full.

This volume gives an up-to-date, useful review of the recent results and new ideas concerning the following topics: precision tests of the standard model, search for Higgs bosons, CP violation, flavour physics, neutrino physics, testing extensions of the standard model, supersymmetry, particle physics, cosmology and new results in strong interactions.

One of modern science's most famous and controversial figures, Jerzy Plebanski was an outstanding theoretical physicist and an author of many intriguing discoveries in general relativity and quantum theory. Known for his exceptional analytic talents, explosive character, inexhaustible energy, and bohemian nights with brandy, coffee, and enormous amounts of cigarettes, he was dedicated to both science and art, producing innumerable handwritten articles — resembling monk's calligraphy — as well as a collection of oil paintings.As a collaborator but also an antagonist of Leopold Infeld's (a coauthor of Albert Einstein's), Plebanski is recognized for designing the “heavenly” and “hyper-heavenly” equations, for introducing new variables to describe the gravitational field, for the exact solutions in Einstein's gravity and in quantum theory, for his classification of the tensor of matter, for some outstanding results in nonlinear electrodynamics, and for analyzing general relativity with continuous sources long before Chandrasekhar et al.A tribute to Plebański's contributions and the variety of his interests, this is a unique and wide-ranging collection of invited papers, covering gravity quantization, strings, branes, supersymmetry, ideas on the deformation quantization, and lesser known results on the continuous Baker-Campbell-Hausdorff problem.