Relativity and quantum theory from Sommerfeld to Dirac

Abstract

Quantum theory and the special theory of relativity emerged almost simultaneously. Through the formative years of quantum theory, from 1900 to about 1928, arguments based on the theory of relativity were of great importance. Starting with Sommerfeld's theory of the hydrogen atom, this paper surveys the ways in which the two fundamental theories have interacted. Relativity was of particular importance in Schrödinger's route to wave mechanics, a theory which was originally conceived as fully integrated with special relativity. The problem of uniting, or harmonising, quantum mechanics and relativity continued to occupy physicists in 1926–27. The paper ends with the solution of this problem, as it was presented in 1928 by Dirac in his seminal paper on the quantum theory of electrons. It also refers to the few attempts there were in the period to formulate a quantum theory in agreement with the general theory of relativity.