Libros de Física, página 19 de 362

This book presents a unified approach to a rich and rapidly evolving research domain at the interface between statistical physics, theoretical computer science/discrete mathematics, and coding/information theory. It is accessible to graduate students and researchers without a specific training in any of these fields. The selected topics include spin glasses, error correcting codes, satisfiability, and are central to each field. The approach focuses on large random instances and adopts a common probabilistic formulation in terms of graphical models. It presents message passing algorithms like belief propagation and survey propagation, and their use in decoding and constraint satisfaction solving. It also explains analysis techniques like density evolution and the cavity method, and uses them to study phase transitions.

The highly successful Clementine mission to the Moon in 1994 gave scientists their first global look at the Moon, and both the near and far side were mapped. This atlas is based on the data collected by the Clementine mission. It covers the entire Moon in 144 Lunar Astronautical Charts (LACs), and represents the most complete lunar nomenclature database in existence, listing virtually all named craters and other features. This is the first atlas to show the entire lunar surface in uniform scale and format. A section of colour plates show lunar composition and physical properties, and the ...

This invaluable textbook presents the basic elements needed to understand and research into semiconductor physics. It deals with elementary excitations in bulk and low-dimensional semiconductors, including quantum wells, quantum wires and quantum dots. The basic principles underlying optical nonlinearities are developed, including excitonic and many-body plasma effects. Fundamentals of optical bistability, semiconductor lasers, femtosecond excitation, the optical Stark effect, the semiconductor photon echo, magneto-optic effects, as well as bulk and quantum-confined Franz-Keldysh effects, are covered. The material is presented in sufficient detail for graduate students and researchers with a general background in quantum mechanics.

This is the third, significantly expanded edition of the comprehensive textbook published in 1990 on the theory and applications of path integrals. It is the first book to explicitly solve path integrals of a wide variety of nontrivial quantum-mechanical systems, in particular the hydrogen atom. The solutions have become possible by two major advances. The first is a new euclidean path integral formula which increases the restricted range of applicability of Feynman''s famous formula to include singular attractive 1/r and 1/r2 potentials. The second is a simple quantum equivalence principle governing the transformation of euclidean path integrals to spaces with curvature and torsion, which leads to time-sliced path integrals that are manifestly invariant under coordinate transformations. In addition to the time-sliced definition, the author gives a perturbative definition of path integrals which makes them invariant under coordinate transformations. A consistent implementation of this property leads to an extension of the theory of generalized functions by defining uniquely integrals over products of distributions. The powerful Feynman -- Kleinert variational approach is explained and developed systematically into a variational perturbation theory which, in contrast to ordinary perturbation theory, produces convergent expansions. The convergence is uniform from weak to strong couplings, opening a way to precise approximate evaluations of analytically unsolvable path integrals. Tunneling processes are treated in detail. The results are used to determine the lifetime of supercurrents, the stability of metastable thermodynamic phases, and the large-order behavior of perturbationexpansions. A new variational treatment extends the range of validity of previous tunneling theories from large to small barriers. A corresponding extension of large-order perturbation theory also applies now to small orders. Special attention is devoted to path integrals with topological restrictions. These are relevant to the understanding of the statistical properties of elementary particles and the entanglement phenomena in polymer physics and biophysics. The Chem-Simons theory of particles with fractional statistics (anyohs) is introduced and applied to explain the fractional quantum Hall effect. The relevance of path integra

This introductory text treats thermodynamics as an incomplete description of quantum systems with many degrees of freedom. Its main goal is to show that the approach to equilibrium - with equilibrium characterized by maximum ignorance about the open system of interest - neither requires that many particles nor is the precise way of partitioning, relevant for the salient features of equilibrium and equilibration. Furthermore, the text depicts that it is indeed quantum effects that are at work in bringing about thermodynamic behavior of modest-sized open systems, thus making Von Neumann's concept of entropy appear much more widely useful than sometimes feared, far beyond truly macroscopic systems in equilibrium. This significantly revised and expanded second edition pays more attention to the growing number of applications, especially non-equilibrium phenomena and thermodynamic processes of the nano-domain. In addition, to improve readability and reduce unneeded technical details, a large portion of this book has been thoroughly rewritten.

The treatment of time in quantum mechanics continues to be a key challenge in the foundation of quantum theory. This book follows Time in Quantum Mechanics-Volume 1 and is the second volume to detail the problems, attempts and achievements in defining, formalizing and measuring different time quantities in quantum theory. It touches upon numerous related issues as well. Time in Quantum Mechanics-Volume 2 opens with a brief historical overview. It then offers eleven tutorial reviews which cover many open questions regarding fundamental concepts and time observables as well as a number of quantum dynamical effects and their associated characteristic time scales. In addition, the volume contains a tutorial review on atomic clocks that explains that while we do not know what time is, we know very well how to measure it with exceptional accuracy. Thorough and lucid, this book is written as an introductory guide for newcomers to the subject. However, it is also useful as a reference for

The treatment of time in quantum mechanics is still an important and challenging open question in the foundation of the quantum theory. This multi-authored book, written as an introductory guide for newcomers to the subject, as well as a useful source of information for the expert, covers many of the open questions. The book describes the problems, and the attempts and achievements in defining, formalizing and measuring different time quantities i

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Wasserman, Robert H.Review from previous edition Clearly written and self-contained and, in particular, the author has succeeded in combining mathematical rigor with a certain degree of informality in a satisfactory way. As such, this work will certainly be appreciated by a wide audience.' -Mathematical Reviews, August 1993. This book sets forth the basic principles of tensors and manifolds and describes how the mathematics underlies elegant geometrical models of classical mechanics, relativity and elementary particle physics.

The search for a quantum theory of the gravitational field is one of the great open problems in theoretical physics. This book presents a self-contained discussion of the concepts, methods and applications that can be expected in such a theory. The two main approaches to its construction - the direct quantization of Einstein''s general theory of relativity and string theory - are covered. Whereas the first attempts to construct a viable theory for the gravitational field alone, string theory assumes that a quantum theory of gravity will be achieved only through a unification of all the interactions. However, both employ the general method of quantization of constrained systems, which is described together with illustrative examples relevant for quantum gravity. There is a detailed presentation of the main approaches employed in quantum general relativity: path integral quantization, the background-field method and canonical quantum gravity in the metric, connection and loop formulations. The discussion of string theory centers around its quantum-gravitational aspects and the comparison with quantum general relativity. Physical applications discussed at length include the quantization of black holes, quantum cosmology, the indications of a discrete structure of spacetime, and the origin of irreversibility. This book will be of interest to researchers and students working in relativity and gravitation, cosmology, quantum field theory and related topics. It will also be of interest to mathematicians and philosophers of science. This book maintains a high level of clarity throughout, and is written with admirable patience. It will be found very useful by a begining researcher in quantum gravity who wants to have a comprehensive overview of the subject. Equally well, senior researchers in the field will find it a handy reference for standard analyses of various aspects of the subject. Gen.Realtiv.Gravi. (2006) 38(1): 183-185 `Review from previous edition This book maintains a high level of clarity throughout, and is written with admirable patience. It will be found very useful by a beginning researcher in quantum gravity who wants to have a comprehensive overview of the subject. Equally well, senior researchers in the field will find it a handy reference for standard analyses of various aspects of the subject.'' General Relativity and Gravitation `... a