Luciano Pietronero – författare

This volume contains the Proceedings of the Special Seminar on: FRAGTALS held from October 9-15, 1988 at the Ettore Majorana Centre for Scientific Culture, Erice (Trapani), Italy. The concepts of self-similarity and scale invariance have arisen independently in several areas. One is the study of critical properites of phase transitions; another is fractal geometry, which involves the concept of (non-integer) fractal dimension. These two areas have now come together, and their methods have extended to various fields of physics. The purpose of this Seminar was to provide an overview of the recent developments in the field. Most of the contributions are theoretical, but some experimental work is also included. Du:cing the past few years two tendencies have emerged in this field: one is to realize that many phenomena can be naturally modelled by fractal structures. So one can use this concept to define simple modele and study their physical properties. The second point of view is more microscopic and tries to answer the question: why nature gives rise to fractal structures. This implies the formulation of fractal growth modele based on physical concepts and their theoretical understanding in the same sense as the Renormalization Group method has allowed to understand the critical properties of phase transitions.

This volume contains the Proceedings of the Special Seminar on: FRAGTALS held from October 9-15, 1988 at the Ettore Majorana Centre for Scientific Culture, Erice (Trapani), Italy. The concepts of self-similarity and scale invariance have arisen independently in several areas. One is the study of critical properites of phase transitions; another is fractal geometry, which involves the concept of (non-integer) fractal dimension. These two areas have now come together, and their methods have extended to various fields of physics. The purpose of this Seminar was to provide an overview of the recent developments in the field. Most of the contributions are theoretical, but some experimental work is also included. Du:cing the past few years two tendencies have emerged in this field: one is to realize that many phenomena can be naturally modelled by fractal structures. So one can use this concept to define simple modele and study their physical properties. The second point of view is more microscopic and tries to answer the question: why nature gives rise to fractal structures. This implies the formulation of fractal growth modele based on physical concepts and their theoretical understanding in the same sense as the Renormalization Group method has allowed to understand the critical properties of phase transitions.

The physics of scale-invariant and complex systems is a novel interdisciplinary field. Its ideas allow us to look at natural phenomena in a radically new and original way, eventually leading to unifying concepts independent of the detailed structure of the systems. The objective is the study of complex, scale-invariant, and more general stochastic structures that appear both in space and time in a vast variety of natural phenomena, which exhibit new types of collective behaviors, and the fostering of their understanding. This book has been conceived as a methodological monograph in which the main methods of modern statistical physics for cosmological structures and density fields (galaxies, Cosmic Microwave Background Radiation, etc. ) are presented in detail. The main purpose is to present clearly, to a workable level, these methods, with a certain mathematical accuracy, providing also some paradigmatic examples of applications. This should result in a new and more general framework for the statistical analysis of the many new data concerning the different cosmic structures which characterize the large scale Universe and for their theoretical interpretation and modeling.