Erwin Schrödinger and the genesis of wave mechanics

In his famous Lectures on Physics,Richard Feynman reflects on the origins of the Schrödinger equation and states: ''Where did we get that from? Nowhere! It is not possible to derive from anything you know. It came out of the mind of Schrödinger, invented in his struggle to find an understanding of the experimental observation of the real world.'' In my talk, I attempt to improve over Feynman's account of the genesis of wave mechanics by presenting evidence from Schrödinger's unpublished research notebooks.

After an introduction into the history of quantum theory from 1900 up to the advent of matrix and wave mechanics in 1925-1926, I will discuss Schrödinger's route to wave mechanics, arguing that its formulation was driven by the study of an analogy that had been established already in the 1830s by Hamilton as an abstract attempt at unifying optics and dynamics. Schrödinger encountered this this optical-mechanical analogy already in the late 1910s, and in the fall of 1925 began to exploit it trying to extend de Broglie's ideas about matter waves. Schrödinger's notebooks show that he only realized the full potential of the analogy in early 1926: Classical mechanics is an approximation to a new and more general ''undulatory mechanics,'' just as ray optics is only an approximation to a more general wave optics. This completion of Hamilton's analogy led Schrödinger to his famous wave equation and convinced him to stick to a realist interpretation of the wavefunction, in opposition to the emerging mainstream interpretation.