LAUSR

Jennifer Coopersmith’s popular book on the principle of least action is titled ‘The lazy universe’. This book is based on the monograph of Lanczos called ‘The variation principles of mechanics’. In the preface, Coopersmith claims that if any of the readers seek out the book of Lanczos after reading her book, then the ‘mission (is) accomplished’. For this reviewer, the mission was indeed accomplished and I am certain that any careful reader of this book will seek out the monograph without fail and benefit from its perusal. According to Coopersmith’s own claims, the book is not a text book – the book is full of equations and the aim is to explain. In my opinion, that is what makes this book the best text book (for self study) or supplementary reader for those who are taught from a different text book. Even though the book of Lanczos is about mechanics, and even though the majority of the discussion in Coopersmith’s book is based on classical mechanics, variation principles are relevant in almost all branches of science and engineering, and hence, the book is of interest and relevance to all physical scientists and engineers. Coopersmith, in the eighth chapter of the book, gives a broad survey indicating the relevance of the principle to classical, quantum and statistical mechanics, to electrodynamics, special and general relativity, and hydrodynamics, among other things. The book is full of interesting problems, anecdotes and asides. For example, Coopersmith makes a very interesting connection between general theory of relativity and materials science: ‘One can even say that materials science has a family connection with Einstein’s Gravitation Theory’; she points out to certain black box problems in classical mechanics that are insoluble using Newtonian mechanics; and, she always has interesting information about the protagonists in her story – such as the one about d’Alembert, for example: ‘Jean le Rond d’Alembert was a foundling, and given the name “Jean La be approximated as thin fronts across which the quasi-steady one-dimensional conservation equations apply. Although there is a change in composition and fluid properties across the combustion front, we shall assume a perfect gas with constant gamma upgream and downstream of the waves. Chemical reactions are treated as external energy addition to the gas across the front ... (next paragraph) The conservation equations of mass and momentum are the same as those for a normal shock given previously ... However, the energy equation has to be modifieded to include the chemical energy release...