The Other 1905 Revolution
A half century after his miracle year, in the final sentence of his final letter to his friend and intellectual sparring partner, the physicist Max Born, a dying Albert Einstein wrote, "In the present circumstances, the only profession I would choose would be one where earning a living had nothing to do with the search for knowledge." And so the man whose thought experiments revolutionized science concluded his life posing a thought experiment about himself: Where would we be if Einstein had become a "plumber or peddler," jobs he once rhetorically suggested he'd prefer, instead of a physicist?
One place to look to start answering that question is the science itself, which is where Rigden's book begins. Another is the man himself, whose personality is abundantly on display in the letters he exchanged with Born between 1916 and 1955. Those letters, which first appeared in German in 1969 and in English two years later, have now been republished along with Born's commentary, Werner Heisenberg's original introduction and a useful new preface by Diana Buchwald and Kip Thorne. The Einstein that comes through in the letters is self-aware, philosophical, politically conscious (if sometimes naïve), modest, generous, an aesthete and--in his exchanges with Born's wife, Hedi--an occasional flirt. From these epistolary glimpses of Einstein the person it's possible to see how his science, which "seems to be so far removed from all things human," is nonetheless, as Heisenberg writes in his introduction, "fundamentally determined by philosophical and human attitudes."
By the time Einstein began corresponding with Born in 1916, his best work was behind him, and he was already an international celebrity. Their letters document the final chapter of Einstein's career, the forty years during which he was an outsider to the quantum physics revolution and alone in his pursuit of a single unified theory capable of explaining all of physics. Ironically, it was at the height of his fame that Einstein was furthest from the scientific mainstream. The aging revolutionary never ceased to be a radical.
Like Einstein, Born was an assimilated German Jew who fled the country's rising anti-Semitism in the early 1930s. Many of their letters from that period concern the deteriorating political situation in Europe and attempts to arrange teaching posts for exiled German scientists. But unlike Einstein, who perceived an inveterate savagery at the heart of German culture and never again set foot on German soil, Born was more forgiving. After sojourning in Edinburgh during World War II, he returned to Göttingen in 1953. They also differed on their shared Jewish heritage. While Einstein was a moderate Zionist, Born saw no difference between Jewish nationalism and all other embodiments of nationalism that he despised. Their political differences, though, were nowhere near as deep as their scientific disagreements.
Einstein considered Born and himself "Antipodean in our scientific expectations." Born was a leading proponent of quantum theory and was awarded the 1954 Nobel Prize for his work establishing the theory's mathematical basis. Einstein was quantum theory's foremost critic. Even though his 1905 paper on the photoelectric effect helped create the field of quantum mechanics, Einstein could never reconcile himself to its nondeterministic implications. He was adamant that the theory provided only a superficial explanation of the universe, and that a deeper theory would someday be found. This conviction was based almost entirely in aesthetic instincts about what the laws of physics ought to look like.
"Quantum mechanics is certainly imposing," he famously told Born. "But an inner voice tells me that it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the 'old one.' I, at any rate, am convinced that He is not playing at dice." Einstein believed that there had to be an "objective reality" at the heart of the universe. If quantum mechanics proved correct, he wrote, again teasing with one of his occupational counterfactuals, "I would rather be a cobbler, or even an employee in a gaming-house, than a physicist."
Their quarrel over quantum theory dragged out for more than three decades, but the content of their arguments changed little from the first letters they exchanged on the subject in 1919 right up until Einstein's death. In a 1953 letter Born declares, "I hope to be able to convince you at last that quantum mechanics is complete and as realistic as the facts permit." His attempt to persuade his friend after all those years seems almost comic. He goes on to call Einstein's stubbornness on the subject "quite unbearable."