In 1923 the Austrian Erwin Schrödinger, professor of physics in Zurich, and his Dutch colleague Hendrik Lorentz, grand old man of classical physics, engaged in a fascinating correspondence on the foundations of quantum physics. In this lecture I will go back to that year, give a sketch of the personalities of Lorentz and Schrödinger and of their respective careers, and explain the importance for the history of physics of their remarkable exchange of ideas.
In 1923 the Austrian Erwin Schrödinger, professor of physics in Zurich, and his Dutch colleague Hendrik Lorentz, grand old man of classical physics, engaged in a fascinating correspondence on the foundations of quantum physics. In this lecture I will go back to that year, give a sketch of the personalities of Lorentz and Schrödinger and of their respective careers, and explain the importance for the history of physics of their remarkable exchange of ideas.
On 13 March 1926, the first of six papers on wave mechanics by Erwin Schrödinger was published in the Annalen der Physik with the title Quantisation as an eigenvalue problem (Part 1) (Schrödinger, 1926b). The startling first paragraph reads: ‘In this paper, I wish to consider, first, the simple case of the hydrogen atom (nonrelativistic and unperturbed), and show that the customary quantum conditions can be replaced by another postulate, in which the concept of “whole numbers”, merely as such, is not introduced. Rather, when integralness does appear, it arises in the same natural way as it does in the case of node-numbers of a vibrating string. The new conception is capable of generalisation, and strikes, I believe, very deeply at the true nature of quantum rules.’ These papers were the fruits of an extraordinary burst of creativity on Schrödinger's part which resulted from his interactions with Einstein in the latter part of 1925. Central to these exchanges were de Broglie's remarkable researches which culminated in his famous PhD dissertation and published papers of 1924. These events have already be recounted in Chap. 9. The subsequent developments which led to Schrödinger's discovery of the equation which bears his name will be taken up in Sect. 14.2, but let us first understand more about Schrödinger's background. Schrödinger's background in physics and mathematics Education and career up to 1925 Unlike Heisenberg, Jordan, Pauli and Dirac, Erwin Schrödinger was not one of the young Turks who developed Knabenphysik , young man's physics.
This book describes the many aspects of the life and scientific work of Erwin Schrödinger, who, perhaps more than anyone else, serves to represent the whole of modern physics. The contributions to the book are from many hands, and so it seemed useful to me to precede them with a short note giving an uncontroversial account of his life which will serve as a framework into which they can be fitted. Such a collection as this still leaves out many aspects of Schrödinger's thought, for it considers his philosophy only in passing, his poetry not at all and ignores his wide and deep interest in sculpture and painting and in the classics. Schrödinger was born in Vienna on August 12, 1887, and entered the University there to read physics in 1906. He worked there as an assistant from 1910 till his war service, and again after the war. Some short term appointments at Jena, Stuttgart and Breslau led up to his appointment to the chair of theoretical physics in Zürich in 1921. He was already treating a wide range of topics, but concentrating on atomic theory, for the old quantum theory had now entered on its heroic phase of final collapse. His six papers founding wave mechanics came at the end of his Zürich years, and in 1927 he went to the chair in Berlin, to remain there till the advent of Hitler in 1933.
In the context of a new analysis of the notebooks of Erwin Schrödinger, the paper deals with the question of the relation between Schrödinger's creation of wave mechanics and the contemporary efforts by Werner Heisenberg and his colleagues to establish a new quantum mechanics. How can one explain, from a broader historical and epistemological perspective, the astonishing simultaneity and complementarity of these discoveries? The paper argues that neither the physical problems with which both approaches deal nor what ultimately turned out to be their common mathematical ground are sufficient to explain their complementarity. Instead, their closeness is explained by analyzing their common roots in classical mechanics and its transformation in the light of the most fundamental new quantum law, the relation between energy and frequency found by Planck. It is shown, in particular, that for both approaches a bridge between quantum and classical aspects involving this relation was crucial. In the case of Heisenberg, this bridge was given by Bohr’s correspondence principle. In the case of Schrödinger it was constituted by Hamilton’s optical-mechanical analogy.
When the Great War began in August, 1914, Erwin schrödinger at the age of twenty-seven was a Privatdozent at Vienna University, at the outset of a promising career in physics. He served throughout the war as a commissioned officer in the Austrian fortress artillery, first on the Italian front and later assigned to the imperial meteorology department in Vienna. On October 7,1915, his revered professor of theoretical physics, Fritz Hasenöhrl, was killed by a grenade in an Italian attack on Mount Plaut in the South Tirol. Early in 1918, schrödinger received word that he was being seriously considered for the position of Professor Extraordinarius [associate professor] in theoretical physics at the University of Czernowitz. ‘I made up my mind to lecture there on honest theoretical physics, first of all according to the pattern of the splendid lectures of my beloved teacher Fritz Hasenöhrl, fallen in the war, but besides to concern myself with philosophy, deeply immersed as I then was in the writings of Spinoza, Schopenhauer, Mach, Richard Semon, and Richard Avenarius. My good angel intervened, since soon Czernowitz no longer belonged to us. So nothing came of it. I had to stick to theoretical physics, and, to my astonishment, something occasionally emerged from it.’ Even on active duty, schrödinger found time to read deeply in philosophy, and indeed it was the only thing that kept him from despair during the long years of senseless killing and destruction. A serious interest in philosophy was not unusual among German and Austrian physicists, but with schrödinger at that time it was so important that he was even tempted to sacrifice scientific research to devote his life to philosophical study. Much later, in 1963, Max Born wrote: ‘I am convinced that theoretical physics is actually philosophy. It has revolutionized fundamental concepts, e.g., about space and time (relativity), about causality (quantum theory), and about substance and matter (atomistics). It has taught us new methods of thinking (complementarity), which are applicable far beyond physics.’ By his discovery of wave mechanics, Erwin schrödinger contributed in a major way to this revolutionary change in our view of the world [ Weltanschauunung ].
Quantum theory originated from the constant introduced by Max Planck in his radiation law in 1900. Later Niels Bohr used the idea of matter waves for the explanation of atomic spectra. Heisenberg gave an algebraic treatment, called matrix mechanics, while Erwin Schrödinger formulated his wave mechanics. He published the first of four papers containing the celebrated equation in the Annalen der Physik in 1927, and showed that the atomic spectra resulted from solving his wave equation for the vibrational states. Schrödinger moved from Zürich to Berlin as Planck’s successor. In the year 1933 he shared the Nobel Prize for Physics with Dirac. With Hitler’s coming to power, however, Schrödinger was outraged and decided to leave Germany to take up a fellowship in Oxford. In 1934 he was offered a permanent position at Princeton University, but he did not accept it. He took a position at the Institute for Advanced Studies in Dublin in 1938, where he stayed till his retirement in 1955.