The Quantum Postulate and Atomic Theory

William Wilson

Abstract The principles of the quantum are, as is well known, not compatible with classical dynamics and electrodynamics, nor, indeed, with the extended dynamics and electrodynamics of the theory of relativity, although they do not appear to violate the principles of the theory of relativity themselves. The chief hypothesis of the quantum theory, and the one which is most at variance with classical theories, is the hypothesis of stationary states, and this is so well established by experimental evidence that it can hardly be doubted that some parts of the classical electrodynamics, at any rate, will have to be given up or modified. In the present communication, a more general form of the postulate, put fonvard by the writer some years ago, will be described, which facilitates the application of the quantum theory to problems such as that of the Zeeman phenomenon, involving magnetic fields, and restricts the region within which the classical and quantum theories are in conflict. The postulates of the quantum theory, in its present state, are as follows:— (i) Atoms, or other systems contemplated by the quantum theory, can only exist normally in one or other of certain states called stationary states. While in one of its stationary states the atom does not emit or absorb energy. This is the chief postulate of Bohr’s theory of spectra.

Niels Henrik David Bohr

Introductory survey 1. Atomic theory and mechanics 2. The quantum postulate and the recent development of atomic theory 3. The quantum of action and the description of nature 4. The atomic theory and the fundamental principles underlying the description of nature.