Emil Cohn’s electrodynamics of moving bodies Available to Purchase

A now forgotten figure, Emil Cohn was one of the leading experts in electrodynamics at the turn of the century. Unsatisfied with Lorentz’s electron theory, he proposed an alternative electrodynamics of moving bodies based on a modification of Maxwell’s macroscopic field equations that managed to account for all relevant electrodynamic and optical experiments, including that of Michelson and Morley. Some of his insights foreshadow aspects of Einstein’s relativity theory, especially the elimination of the ether and the criticism of Lorentz’s implicit distinction between true and measured coordinates of space and time. However, Cohn did not believe in the general validity of the relativity principle, and did not require a revision of the usual concepts of space and time.