Transformation Theory and the Development of the Probabilistic Interpretation

Abstract

On 28 October, Heisenberg replied to Pauli with profuse thanks.¹ The letter had been handed round to Bohr, Dirac and Hund, and had been generally discussed. Above all, Heisenberg wrote, he had been inspired by the discussion of collision processes, and he now understood much better the significance of Born’s formulation. In particular, Pauli’s discussion of the rotator indicated generally that “wherever in classical mechanics one type of motion changes discontinuously into another, quantum mechanics supplies a continuous transition which, so far as it may be thought of graphically, signifies a probability dictum”.² In the wake of Schrodinger’s controversial lecture,³ and of the arrival of Dirac, attention at Copenhagen was focussed very much on the problem of relating Born’s formulation to matrix mechanics, and on that of demonstrating that Schrodinger’s theory could not be continuously interpreted but must share the essential discreteness of matrix mechanics. Pauli’s letter clearly contributed much to both problems, and on 4 November Heisenberg wrote to him again, declaring himself “more and more inspired by the content of your last letter every time I reflect on it.”⁴ Two days later, he submitted a paper on the energy fluctuations of a gas, in which both problems were brought together.⁵