ABSTRACT
Werner Heisenberg’s 1925 paper “Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen” is one of the pivotal papers in the development of modern physics. It is also one of the most perplexing. The novel formulas, which effectively initiated matrix mechanics, are simply presented as if they were intuitively obvious. They were, in fact, counterintuitive. Heisenberg’s new methodology was ostensibly justified by the doctrine that scientific formulations must be restricted to observable quantities. Yet his success really hinged on the skillful use of a model of the atom embodying virtual processes which are in principle unobservable. Most vexing of all, at least for those trying to understand the development of quantum theory, is the absence of any indication of the process that led Heisenberg to his formulation of quantum theory. The present paper attempts to fill a part of this gap by explaining the way Heisenberg came to introduce his distinctively new methods for quantum calculations. Before entering into the details of this development I will outline the features that play a distinctive role in the present interpretation.
