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The per iod of an oscillator tells us much about its structure. J. J. Thomson's deduction that a particle with the e/rn of an electron was in the atom is perhaps the most stunning instance. For us, the deduction of the mean density of a star from its oscillation period is another important example. What then can we deduce about an oscillator that is not periodic? If there are several frequencies or if the behavior is chaotic, may we not hope to learn even more delicate vital statistics about its workings? The recent progress in the theory of dynamical systems, particularly in the elucidat ion of the nature of chaos, makes it seem reasonable to ask this now. This is an account of some of the ...
'Fractal geometry addressesitselfto questions that many people have been asking themselves. It con cerns an aspect of Nature that almost everybody had been conscious of, but could not address in a formal fashion. ' 'Fractal geometry seems to be the proper language to describe the complezity of many very compli cated shapes around us. ' (Mandelbrot, 1990a) 'I believe that fractals respond to a profound un easiness in man. ' (Mandelbrot, 1990b) The catchword fractal, ever since it was coined by Mandelbrot (1975) to refer to a class of abstract mathematical objects that were already known at the turn ofthe 19th century, has found an unprecedented resonance both inside and outside the scientific...
The nonlinear theory of oscillating systems brings new aspects into the study of variable stars. Beyond the comparison of linear periods and the estimate of stability, the appearance and disappearance of possible modes can be studied in detail. While nonlinearity in stellar pulsations is not a very complicated concept, it generally requires extensive and sometimes so phisticated numerical studies. Therefore, the development of appropriate computational tools is required for applications of nonlinear theory to real phenomena in variable stars. Taking trends in variable star studies into consideration, the International Astronomical Union organized a colloquium for the nonlinear phenomena of v...
This is the first detailed account of a new approach to microphysics based on two leading ideas: (i) the explicit dependence of physical laws on scale encountered in quantum physics, is the manifestation of a fundamental principle of nature, scale relativity. This generalizes Einstein's principle of (motion) relativity to scale transformations; (ii) the mathematical achievement of this principle needs the introduction of a nondifferentiable space-time varying with resolution, i.e. characterized by its fractal properties.The author discusses in detail reactualization of the principle of relativity and its application to scale transformations, physical laws which are explicitly scale dependent, and fractals as a new geometric description of space-time.
This book provides a survey of the basic ideas of the cellular automaton (CA) modelling environment, emphasising the relevance of this framework to astrophysical applications. It contains introductory level lectures on lattice gases, and on CA turbulence, diffusion-reaction processes, percolation and self-organised criticality. Further, it gives a variety of astrophysical applications, including stellar oscillations, galactic evolution, distribution of luminous matter in the universe, etc.
The recently proposed, fully multi-scale theory of doublet mechanics offers unprecented opportunities to reconcile the discrete and continuum representations of solids while maintaining a simple analytical format and full compatibility with lattice dynamics and continuum mechanics. In this monograph, a self-contained account of the state of the art in doublet mechanics is presented. Novel results in the elastodynamics of microstructured media are reported, including the identification of a new class of dispersive surface waves, and the presentation of methods for the experimental determination of the essential microstructural parameters. The relationships between doublet mechanics, lattice dynamics, and continuum theories are examined, leading to the identification of the subject areas in which the use of doublet mechanics is most advantageous. These areas include the analysis of domains as diverse as micro-electro-mechanical systems (MEMS), granular and particulate media, nanotubes, and peptide arrays.
Here, the concept of indistinguishability is defined for identical particles by the symmetry of the state, therefore applying to both the classical and the quantum framework. The author describes symmetric statistical operators and classifies these by means of extreme points. He derives de Finettis theorem for the description of infinitely extendible interchangeable random variables, and presents generalisations covering the Poisson limit and the central limit. Finally, a characterisation and interpretation of the integral representations of classical photon states in quantum optics are derived in abelian subalgebras, and unextendible indistinguishable particles are analysed in the context of non-classical photon states. Suitable for mathematical physicists and philosophers of science.
For many years I was organizing a weekly seminar on dynamical astronomy, and I used to make some historical remarks on every subject, including some anecdotes from my contacts with many leading scientists over the years. I described also the development of various subjects and the emergence of new ideasindynamicalastronomy. Thenseveralpeoplepromptedmetowritedown these remarks, which cannot be found in papers, or books. Thus, I decided to write this book, which contains my experiences over the years. I hope that this book may be helpful to astronomy students all over the world. During my many years of teaching, as a visiting professor, in American Universities (1962-1994, Yale, Harvard, MIT, Cornell, Chicago, Maryland and Florida) I was impressed by the quality of my graduate students. Most of them were very bright, asking penetrating questions, and preparing their homework in a perfect way. In a few cases, instead of a ?nal examination, I assigned to them some small research projects and they presented their results at the end of the course. They were excellent in preparing the appropriate slides and in presenting their results in a concise and clear way.
This volume contains three interrelated, beautiful, and useful topics of quantum scattering theory: inverse scattering theory, algebraic scattering theory and supersymmetrical quantum mechanics. The contributions cover such issues as coupled-channel inversions at fixed energy, inversion of pion-nucleon scattering cross-sections into potentials, inversions in neutron and x-ray reflection, 3-dimensional fixed-energy inversion, inversion of electron scattering data affected by dipole polarization, nucleon-nucleon potentials by inversion versus meson-exchange theory, potential reversal and reflectionless impurities in periodic structures, quantum design in spectral, scattering, and decay control, solution hierarchy of Toda lattices, etc.
So far as the laws of mathematics refer to reality, they are not certain. And so far as they are certain, they do not refer to reality. -A. Einstein The word "instability" in day-to-day language is associated with some thing going wrong or being abnormal: exponential growth of cancer cells, irrational behavior of a patient, collapse of a structure, etc. This book, however, is about "good" instabilities, which lead to change, evolution, progress, creativity, and intelligence; they explain the paradox of irreversi bility in thermodynamics, the phenomena of chaos and turbulence in clas sical mechanics, and non-deterministic (multi-choice) behavior in biological and social systems. The concept o...