The last thing one discovers in composing a work is what to put first.Blaise Pascal, Pensées no. 19.
In the last two decades or so the astrophysical community – students, teachers and researchers alike – have become aware of a new kind of activity in physics. Some researchers, science historians and philosophers have gone as far as calling it a ‘new science’ or ‘new physics’, while others see it as a mere natural extension of ‘old’ classical mechanics and fluid dynamics. In any case, the subject, variously referred to as dynamical systems theory, nonlinear dynamics or simply chaos, has undergone an explosive development, causing a lot of excitement in the scientific community and even in the general public. The discoveries look fundamental and there is hope that we will quite soon gain new and basic scientific understanding of the most complex aspects of nature.
The most striking quality of this modern approach to dynamical systems theory is, in my view, its extremely diverse range of applicability. Mechanics, fluid dynamics, chemical kinetics, electronic circuits, biology and even economics, as well as astrophysics, are among the subjects in which chaotic behaviour occurs. At the heart of the theory lies the quest for the universal and the generic, from which an understanding of complicated and seemingly heterogeneous phenomena can emerge. The ideas of bifurcations, strange attractors, fractal sets and so on, seem to provide the tools for such an unexpected conceptual unification.
My own experience in discussing the subject with astrophysicists suggests that they and their students would like to know more about the new developments in nonlinear dynamics.