Einstein’s worldview – Part 4
Let us step back for a moment to contemplate that word “unbearable.” It is reinforced by a passage in Einstein’s “Autobiographical Notes”: “By and by I despaired [verzweifelte ich] of discovering the true laws by means of constructive efforts based on known facts. The longer and the more despairingly I tried, the more I came to the conviction that only the discovery of a universal formal principle could lead us to assured results.” He might have added that the same postulational method had already been pioneered in their main works by two of his heroes, Euclid and Newton. Other physicists, for example Bohr and Heisenberg, also reported that at times they were brought to despair in their research. Still other scientists were evidently even brought to suicide by such disappointment. For researchers fiercely engaged at the very frontier, the psychological stakes can be enormous. Einstein was able to resolve his discomfort by turning, as he did in his 1905 relativity paper, to the postulation of two formal principles (the principle of relativity throughout physics, and the constancy of the velocity of light in vacuo), and adopting such postulations as one of his tools of thought.
Einstein also had a second method to bridge the unbearable differences in a theory: generalizing it, so that the apparently differently grounded phenomena are revealed to be coming from the same base. We know from a letter to Max von Laue of January 17, 1952, found in the archive, that Einstein’s early concern with the physics of fluctuation phenomena was the common root of his three great papers of 1905, on such different topics as the quantum property of light, Brownian movement, and relativity. But even earlier, in a letter of April 14, 1901, to his school friend Marcel Grossmann, Einstein had revealed his generalizing approach to physics while working on his very first published paper, on capillarity. There he tried to bring together in one theory the opposing behaviors of bodies: moving upward when a liquid is in a capillary tube, but downward when the liquid is released freely. In that letter, he spelled out his interpenetrating emotional and scientific needs in one sentence: “It is a wonderful feeling [ein herrliches Gefuhl] to recognize the unity of a complex of appearances which, to direct sense experiences, appear to be quite separate things.”
The postulation of universal formal principles, and the discovery among phenomena of a unity, of Einheitlichkeit, through the generalization of the basic theory – those were two of Einstein’s favorite weapons,2 as his letters and manuscripts show. Writing to Willem de Sitter on November 4, 1916, he confessed: “I am driven by my need to generalize [mein Verallgemeinerungsbeduerfnis].” That need, that compulsion, was also deeply entrenched in German culture and resonated with, and supported, Einstein’s approach. Let me just note in passing that while still a student at the Polytechnic Institute in Zurich, in order to get his certificate to be a high school science teacher, Einstein took optional courses on Immanuel Kant and Goethe, whose central works he had studied since his teenage years.
That Verallgemeinerungsbeduerfnis was clearly a driving force behind Einstein’s career trajectory. Thus he generalized from old experimental results, like Faraday’s, to arrive at special relativity, in which he unified space and time, electric and magnetic forces, energy and mass, and so resolved the whole long dispute among scientists between adherence to a mechanistic versus an electromagnetic world picture. Then he generalized the special theory to produce what he first significantly called, in an article of 1913, not the general but the generalized relativity theory. Paul Ehrenfest wrote him in puzzlement: “How far will this Verallgemeinerung go on?” And, finally, Einstein threw himself into the attempt of a grand unification of quantum physics and of gravity: a unified field theory. It is an example of an intense and perhaps unique, life-long, tenacious dedication, despite Einstein’s failure at the very end – which nevertheless, as a program, set the stage for the ambition of some of today’s best scientists, who have taken over that search for the Holy Grail of physics – a theory of everything.