Schrödinger , Erwin

(1887–1961) Austrian physicist

Schrödinger, the son of a prosperous Viennese factory owner, was educated at both the gymnasium and the university in his native city, where he obtained his doctorate in 1910. After serving as an artillery officer in World War I, he taught at various German-speaking universities before he succeeded Max Planck as professor of physics at the University of Berlin in 1927.

Before long, however, Schrödinger's bitter opposition to the Nazis drove him, in 1933, into his first period of exile, which he spent in Oxford, England. Homesick, he allowed himself to be tempted by the University of Graz in Austria in 1936 but, after the Anschluss in 1938, he found himself once more under a Nazi government which this time was determined to arrest him. Schrödinger had no alternative but to flee. He was however fortunate in that the prime minister of Eire, Eamonn De Valera, himself a mathematician, was keen to attract him to a newly established Institute of Advanced Studies in Dublin. Working there from 1939 Schrödinger gave seminars that attracted many eminent foreign physicists (as well as the frequent presence of De Valera) until his retirement in 1956 when he returned to Austria.

Starting from the work of Louis de Broglie, Schrödinger in the period 1925–26 developed wave mechanics, one of the several varieties of quantum theory that emerged in the mid-1920s. He was deeply dissatisfied with the early quantum theory of the atom developed by Niels Bohr, complaining of the apparently arbitrary nature of a good many of the quantum rules. Schrödinger took the radical step of eliminating the particle altogether and substituting for it waves alone.

His first step was to derive an equation to describe the behavior of an electron orbiting an atomic nucleus. The de Broglie equation giving the wavelength λ = h/mv (where h is the Planck constant and mv the momentum) presented too simple a picture for in reality, particularly with the inner orbits, the attractive force of the nucleus would result in a very complex and variable configuration. He eventually succeeded in establishing his famous wave equation, which when applied to the hydrogen atom yielded all the results of Bohr and de Broglie. It was for this work that he shared the 1933 Nobel Prize for physics with Paul Dirac.

Despite the considerable predictive success of wave mechanics, as the theory became known, there remained two problems for Schrödinger. He still had to attach some physical meaning to ideas of the nature of an electron, which was difficult if it was nothing but a wave; he also had to interpret the ψ function occurring in the wave equation, which described the wave's amplitude. He tried to locate the electron by constructing stable ‘wave packets’ from many small waves, which it was hoped would behave in the same way as a particle in classical mechanics. The packets were later shown to be unstable.

Nor was his interpretation of the ψ function as a measure of the spread of an electron any more acceptable. Instead the probabilistic interpretation of Max Born soon developed into a new orthodoxy. Schrödinger found such a view totally unacceptable, joining those other founders of quantum theory, Einstein and de Broglie, in an unrelenting opposition to the indeterminism entering physics.

In 1944 Schrödinger published his What is Life?, one of the seminal books of the period. Partly due to its timely publication it influenced a good many talented young physicists who, disillusioned by the bombing of Hiroshima, wanted no part of atomic physics. Schrödinger solved their problem by revealing a discipline free from military applications, significant and, perhaps just as important, largely unexplored. He argued that the gene was not built like a crystal but that it was rather what he termed an ‘aperiodic solid’. He went on to talk of the possibility of a ‘code’ and observed that “with the molecular picture of the gene it is no longer inconceivable that the miniature code should precisely correspond with a highly complicated and specified plan of development.” It is not surprising that such passages, written with more insight than that contained in most contemporary biochemical works, inspired a generation of scientists to explore and decipher such a code.