The Conceptual Foundations of the Statistical Approach in Mechanics

By Paul and Tatiana Ehrenfest, translated by Michael J. Moravcsik Ithaca: Cornell University Press; London: Oxford University Press. Pp. xvi + 114. Price 24s. This little book is a long overdue translation of the famous article on the conceptual foundations of statistical mechanics which the Ehrenfests wrote for the Encyklopadie der mathematischen Wissenschaften of 1912. The book falls into three parts: Firstly, a beautifully clear account of the assumptions underlying the original kinetic approach of Maxwell and Boltzmann—this leads naturally to the paradoxes of Loschmidt and Zermelo; secondly, as the centre piece of the book, a concise and systematic exposition of the basis of the ensemble formulation or—as the Ehrenfests put it—of the statistical kinetics of the gas model rather than of the gas molecule .