Libros de Estudios y ensayos, página 6 de 142

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

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This work is centred around the role of non-Hermitian Hamiltonians in Physics both at the quantum and classical levels. In our investigations of two-level quantum models we demonstrate the phenomenon of fast transitions developed in the PT-symmetric quantum brachistochrone problem may in fact be attributed to the non- Hermiticity of evolution operator used, rather than to its invariance under PT operation. When it comes to Hilbert spaces of infinite dimension, we show how Lie algebras and Groenewold?Moyal can be explored to construct isospectral Hermitian partners. Alongside, metrics with respect to which the original Hamiltonians are Hermitian are also constructed, allowing to assign meaning to a large class of non-Hermitian Hamiltonians possessing real spectra. Classically, our efforts were concentrated on integrable models presenting PT-symmetry. We use the Painleve test to check whether deformations of integrable systems preserve integrability and we study the pole structure of certain real valued nonlinear integrable systems and establish that they behave as interacting particles whose motion can be extended to the complex plane in a PT-symmetric way.

Since an atomic Bose-Einstein condensate, predicted by Einstein in 1925, was first produced in the laboratory in 1995, the study of ultracold Bose and Fermi gases has become one of the most active areas in contemporary physics. This book explains phenomena in ultracold gases from basic principles, without assuming a detailed knowledge of atomic, condensed matter, and nuclear physics. This new edition has been revised and updated, and includes new chapters on optical lattices, low dimensions, and strongly-interacting Fermi systems. This book provides a unified introduction to the physics of ultracold atomic Bose and Fermi gases for advanced undergraduate and graduate students, as well as experimentalists and theorists. Chapters cover the statistical physics of trapped gases, atomic properties, cooling and trapping atoms, interatomic interactions, structure of trapped condensates, collective modes, rotating condensates, superfluidity, interference phenomena, and trapped Fermi gases. Problems are included at the end of each chapter.

Readership: Students, researchers in physics, chemistry, engineering and mathematics, science writers and general readers.