Lande A. Foundations of quantum theory. A Study in Continuity and Symmetry

NEW HAVEN: YALE University Press, 1955 , 106 p.
The aim of this book is to show that quantum mechanics in its basic concepts and its formalistic rules is not dependent on a refined interpretation of experiments on a microphysical scale but can be developed as a straightforward consequence of elementary physical principles of continuity and symmetry. A general postulate of continuity for cause-effect relations was the backbone of the philosophy of the great Leibniz and the leading idea of his calculus of fluxions. When applied to energy and entropy the continuity postulate leads by simple reasoning to a theoretical structure whose empirical counter-part is the world of quantum physics, with its discrete states and probability rules of transition, with a mechanics of super-position, and with characteristic rules of interaction between like particles leading to exchange forces and quantum statistics. When thus arriving at the structure of quantum theory from the postulate of thermodynamic continuity, one can avoid the idea that the basic aim of nature is that of presenting us with an enigmatic duality between wave and particle traits of matter. At the same time, the very fact that quantum theory can be developed from a postulate anchored in the entropy law of thermodynamics is reason enough for the impossibility of ever reducing quantum phenomena to individual causality. Chapter i is devoted to the development of various concepts and rules of quantum theory as general consequences of entropy continuity. Chapter 2 contains further developments, in particular the necessity of a mechanics of superposition for reasons of symmetry or "equal rights" for all states in a general scheme of interrelations between states. In Chapter 3 one will find a new and simple definition of conjugacy between dynamical variables, less specific than the Schrodinger and Born rules introducing Planck's quantum, yet leading to those same rules as immediate consequences. As a whole the book is not an introduction for beginners but rather a postscript to more traditional books on quantum mechanics. It is attuned to the philosophy of Leibniz that there is " a pre-established harmony which removes any notion of miracles from purely natural actions, and makes things run their course in an intelligible manner."