The Early Development of Quantum Theory

Jagdish Mehra, Helmut Rechenberg

K Paulus

P A M Dirac London: Gordon and Breach 1971 pp x + 66 price £2·90 ( cloth ) £1·25 ( paper ) This slim booklet contains the text of Dirac's speech accepting the first J Robert Oppenheimer Memorial Prize of the University of Miami. Although the lecture follows the development of quantum theory during its early days step by step, it is rather more about the motivations and emotions of the scientists that pursued it.

Hendrik B. G. Casimir

Helge Kragh

In this essay I discuss the origin and early development of the first relativistic wave equation, known as the Klein–Gordon equation. In 1926 several physicists, among them Klein, Fock, Schrödinger, and de Broglie, announced this equation as a candidate for a relativistic generalization of the usual Schrödinger equation. In most of the early versions the Klein–Gordon equation was connected with the general theory of relativity. Klein and some other physicists attempted to express quantum mechanics within a five-dimensional unified theory, embracing general relativity as well as electrodynamics. Although this ambitious attempt attracted some interest in 1926, its impact on the mainstream of development in quantum mechanics was virtually nil.

Ronald F. Peierls

Michael A. Parker

The study of light through the centuries has produced a number of theories and experiments. Newton advanced the corpuscular theory, building on the early Greek view of matter composed of atoms. Then Young essentially proved the wave nature of light through the interference experiments. Maxwell provided the firm theoretical basis for the wave nature. During the late 1800s and early 1900s, further experiments showed predictions based on a continuous wave led to the well-known ultraviolet catastrophe. Plank and Einstein originated and developed the notion of the photon as an elementary quantum of propagating electromagnetic (EM) energy. The first half of the 20th century saw the development of the field quantization and the quantum electrodynamics (QED). Feynmann labeled QED as ‘‘the best theory we have’’ to describe the matter-light interaction. The second half of the 20th century witnessed the development of the coherent and squeezed optical states attributable to Glauber and Yuen. The study of light and electromagnetic fields has a long history. This chapter explores the nature of light in terms of quantum optics.