Introduction

Abstract

There are many questions which are central to the study of galactic dynamics. In this book we wish to concentrate on two of the more fundamental questions. The first is concerned with the identification of the physical processes which determine the anisotropic pressure that we observe in all galaxies, and which in turn determine the shapes of these systems. The second question is concerned with the way these physical processes relate to the process by which galaxies may have been formed. An understanding of this second question then would enable us to say something about Cosmology and the way galaxies may have been formed from just looking at their dynamics today. In this introduction I hope to set out why I believe that studying unstable models of galaxies can lead to an understanding of the answers to these two fundamental questions.