Physics

Julian Schwinger was one of the leading theoretical physicists of the 20th century. His contributions are as important, and as pervasive, as those of Richard Feynman, with whom he shared the 1965 Nobel Prize for Physics (along with Sin-itiro Tomonaga). Yet, while Feynman is universally recognised as a cultural icon, Schwinger is little known to many even within the physics community. In his youth, Schwinger was a nuclear physicist, turning to classical electrodynamics after World War II. In the years after the war, he was the first to renormalise quantum electrodynamics. Subsequently, he presented the most complete formulation of quantum field theory and laid the foundations for the electroweak synthesis of Sheldon Glashow, Steven Weinberg, and Abdus Salam, and he made fundamental contributions to the theory of nuclear magnetic resonance as well as many-body theory and quantum optics. Schwinger also developed a unique approach to quantum mechanics, measurement algebra, and a general quantum action principle. His discoveries include ‘Feynman's’ parameters and ‘Glauber's’ coherent states; in later years he also developed an alternative to operator quantum field theory which he called source theory, reflecting his profound phenomenological bent. His late work on the Thomas-Fermi model of atoms and on the Casimir effect continues to be an inspiration to a new generation of physicists. This first full-length biography describes the many strands of his research life, while tracing the personal life of this private and gentle genius.

The book provides a new conceptual scaffold for further research in biology and cognition by introducing the new field of Cognitive Biology. It is a systems biology approach showing that further progress in this field will depend on a deep recognition of developmental processes, as well as on the consideration of the developed organism as an agent able to modify and control its surrounding environment. The role of cognition, the means through which the organism is able to cope with its environment, cannot be underestimated. In particular, it is shown that this activity is grounded on a theory of information based on Bayesian probabilities. The organism is considered as a cybernetic system able to integrate a processor as a source of variety (the genetic system), a regulator of its own homeostasis (the metabolic system), and a selecting system separating the self from the non-self (the membrane in unicellular organisms).

This book offers a grounding in the field of coherent X-ray optics, which in the closing years of the 20th century experienced something of a renaissance with the availability of third-generation synchrotron sources. It begins with a treatment of the fundamentals of X-ray diffraction for both coherent and partially coherent radiation, together with the interactions of X-rays with matter. X-ray sources, optical elements, and detectors are then discussed, with an emphasis on their role in coherent X-ray optics. Various aspects of coherent X-ray imaging are then considered, including holography, interferometry, self imaging, phase contrast, and phase retrieval. The foundations of the new field of singular X-ray optics are examined, focusing on the topic of X-ray phase vortices. Most topics in the book are developed from first principles using a chain of logic which ultimately derives from the Maxwell equations, with numerous references to the contemporary and historical research literature.

The book presents a self-contained exposition of the mode-coupling theory for the evolution of glassy dynamics in liquids. This theory is based on polynomial expressions for the correlations of force fluctuations in terms of those of density fluctua-tions. These mode-coupling polynomials are motivated as descriptions of the cage-effect-induced transient localization of particles in condensed matter. It is proven that the implied regular mode-coupling equations of motion determine uniquely models for a correlation-function description of the dynamics. This holds for all choices of the polynomial coefficients, which serve as coupling constants. The arrested parts of the correlations are solutions of fixed-point equations. They exhibit spontaneous singularities, which are equivalent to the bifurcation singularities of the real roots of real polynomials. They deal with idealized liquid-glass and glass-glass transitions. Driving the coupling constants towards their critical values, the correlation functions exhibit the evolution of complex dynamics. Its subtleties are due to the interplay of nonlinearities and divergent retardation effects. The book discusses that the relaxation features are similar to those observed in experimental and molecular-dynamics-simulation studies of con-ventional liquids and colloids. Asymptotic expansions are derived for the mode-coupling-theory functions for small frequencies and small separations of the coupling constants from the transition values. The leading-order asymptotic contributions provide an understanding of the essential facets of the scenarios. The leading-asymptotic corrections are deduced and applied to quantify the evolution of the leading-order description.

This book is a historical account of how natural philosophers and scientists have endeavoured to understand the universe at large, first in a mythical and later in a scientific context. Starting with the creation stories of ancient Egypt and Mesopotamia, the book covers all the major events in theoretical and observational cosmology, from Aristotle's cosmos over the Copernican revolution to the discovery of the accelerating universe in the late 1990s. The kind of cosmology it describes and analyses focuses on the physical and astronomical aspects, but these cannot always be separated from aspects of a philosophical and theological nature. The book presents cosmology as a subject including scientific as well as non-scientific dimensions, and tells the story of how it developed into a true science of the heavens. Contrary to most other books on the history of cosmology, it offers an integrated account of the development with emphasis on the modern Einsteinian and post-Einsteinian period. In addition, it pays attention not only to mainstream developments, but also to theories of the universe that are today considered to be blind alleys. Starting in the pre-literary era, the book carries the story of mankind's quest of understanding the universe onwards to the early years of the 21st century.

Nowadays, information technology is based on semiconductor and ferromagnetic materials. Information processing and computation are performed using electron charge in semiconductor transistors and integrated circuits, and the information is stored by electron spins on magnetic high-density hard disks. Recently, a new branch of physics and nanotechnology, called magneto-electronics, spintronics, or spin electronics, has emerged, which aims to exploit both the charge and the spin of electrons in the same device. A broader goal is to develop new functionality that does not exist separately in a ferromagnet or a semiconductor. This book presents new directions in the development of spin electronics in both the basic physics and the technology which will become the foundation of future electronics.

An understanding of thermal physics is crucial to much of modern physics, chemistry, and engineering. This book provides a modern introduction to the main principles that are foundational to thermal physics, thermodynamics, and statistical mechanics. The key concepts are carefully presented in a clear way, and new ideas are illustrated with worked examples as well as a description of the historical background to their discovery. Applications are presented to subjects as diverse as stellar astrophysics, information and communication theory, condensed matter physics, and climate change. Each chapter concludes with detailed exercises. This second edition of the text maintains the structure and style of the first edition but extends its coverage of thermodynamics and statistical mechanics to include several new topics, including osmosis, diffusion problems, Bayes theorem, radiative transfer, the Ising model, and Monte Carlo methods. New examples and exercises have been added throughout.

This book illustrates the interplay between distinct domains of mathematics. Firstly, this book provides an introduction to hyperbolic geometry, based on the Lorentz group. The Lorentz group plays, in relativistic space-time, a role analogue to the rotations in Euclidean space. The hyperbolic geometry is the geometry of the unit pseudo-sphere. The boundary of the hyperbolic space is defined as the set of light rays. Special attention is given to the geodesic and horocyclic flows. Hyperbolic geometry is presented via special relativity to benefit from physical intuition. Secondly, this book introduces basic notions of stochastic analysis: the Wiener process, Itô's stochastic integral, and calculus. This introduction allows study in linear stochastic differential equations on groups of matrices. In this way the spherical and hyperbolic Brownian motions, diffusions on the stable leaves, and the relativistic diffusion are constructed. Thirdly, quotients of the hyperbolic space under a discrete group of isometries are introduced. In this framework some elements of hyperbolic dynamics are presented, as the ergodicity of the geodesic and horocyclic flows. This book culminates with an analysis of the chaotic behaviour of the geodesic flow, performed using stochastic analysis methods. This main result is known as Sinai's central limit theorem.

Quantum phase transitions describe the violent rearrangement of electrons or atoms as they evolve from well defined excitations in one phase to a completely different set of excitations in another. The book chapters give insights into how a coherent metallic or superconducting state can be driven into an incoherent insulating state by increasing disorder, magnetic field, carrier concentration and inter-electron interactions. They illustrate the primary methods employed to develop a multi-faceted theory of many interacting particle systems. They describe how recent experiments probing the microscopic structure, transport, charge and spin dynamics have yielded guiding insights. What sets this book apart is this strong dialog between experiment and theory, which reveals the recent progress and emergent opportunities to solve some major problems in many body physics. The pedagogical style of the chapters has been set for graduate students starting in this dynamic field.

This book presents a biography of Abdus Salam, the first Muslim to win a Nobel Prize for Science (Physics 1979), who was nevertheless excommunicated and branded as a heretic in his own country. His achievements are often overlooked, even besmirched. Realizing that the whole world had to be his stage, he pioneered the International Centre for Theoretical Physics in Trieste, a vital focus of Third World science which remains as his monument. A staunch Muslim, he was ashamed of the decline of science in the heritage of Islam, and struggled doggedly to restore it to its former glory. Undermined by his excommunication, these valiant efforts were doomed.