The idea that the universe is a single thing, governed by a single set of rules accessible to mathematics, strikes me as stirring, terrifying, and intensely mystical—a word that undoubtedly would have caused Einstein to wince or laugh, or perhaps both. "Mysticism is in fact the only reproach that people cannot level at my theory," he once retorted when a fan praised him for this aspect of relativity. Yet his snipe against mysticism told only half the story, since the outspokenly atheistic Einstein frequently adopted the language of theology. As in politics, as in science, he reached for a deeper truth by redefining and extending commonly used terms. "What I see in Nature is a grand design that we can understand only imperfectly, one which a responsible person must look at with humility," he said. "This is a genuinely religious feeling and has nothing to do with mysticism."
Once again Einstein plays the role of thoughtful revolutionary, reinventing familiar terms to expose broader truths. He implicitly argued that science (aided in no small part by his theories) had expanded to the point where it redefined not only humanity's relationship to the universe but also humanity's relationship to the divine. Einstein's cosmos leaves no place for a literal heaven, no physical realm where our earthly laws of physics do not apply. But in religion as in science, when Einstein overthrew the old order he exposed a new, deeper order. He found a religious interpretation of this deeper order in the philosophy of Baruch Spinoza and came to regard physical law itself as divine. "I believe in Spinoza's God who reveals himself in the harmony of all that exists, not in a God who concerns himself with the fate and actions of human beings," he said.
Einstein's much repeated use of the word "God" was not an indulgence and not a purely symbolic act. It was a well-considered philosophical position. He acknowledged that a truly universal theory of physics has theological implications; at the same time, he worried intensely about the destructive power of religions whose adherents imagine they can pray for their success or for others' failure. Einstein believed, passionately if a bit naively, that his logical approach could help here, too. "After religious teachers accomplish the refining process indicated, they will surely recognize with joy that true religion has been ennobled and made more profound by scientific knowledge," he wrote in 1941.
I admire the dogged conviction Einstein displayed as he parsed the meaning of God and religion again and again to clarify his self-proclaimed "new religion." Just as his belief in beautiful, orderly scientific theories mirrored a child's view of the world, so his belief in God as the ultimate manifestation of that order expressed an idealistic notion that God is so much greater than humankind that He cannot be found in any one faith. Einstein devoted great energy to publicizing this view. He repeatedly described the "cosmic religious feeling" that accompanies great scientific discoveries and declared in The New York Times Magazine that "in this materialistic age of ours the serious scientific workers are the only profoundly religious people." Although there is no deity to communicate with in Einstein's universe, he presented the possibility of a cosmic connection based on an intellectual comprehension of the rules of reality.
So far, this path to spiritual enlightenment is a lonely one. The theoretical legacy of Einstein's foray into cosmology is everywhere. General relativity provided the underpinning of the Big Bang and introduced the concept of a cosmological constant, the model for the "dark energy" thought to be causing the expansion of the universe to accelerate. Modern cosmology depends so thoroughly on Einsteinian notions of curved space-time, the large-scale homogeneity of matter, and the equivalence of all reference frames that many scientists forget that these ideas were radical speculations less than a century ago. Try looking for Einstein's philosophical legacy, however, and the cupboard looks rather bare.
I cannot recall a researcher ever discussing the cosmic religious feeling. Many scientists and historians dismiss Einstein's use of the terms "religious" and "God" as sloppy shorthand for the beauty of science. Cosmologists today rarely talk about God; if they do, it is in the self-conscious manner of Stephen Hawking, who once asked "What place, then, for a creator?" They largely ignore Einstein's philosophical language and the broad, emotive way in which he spoke about his research. In his groundbreaking book The Inflationary Universe, for example, Alan Guth of MIT, who codeveloped the leading model of the Big Bang, speculates provocatively about whether it would be possible to create a new universe in a basement laboratory, but he treats such a Genesis-on-demand merely as a scientific thought problem. As cosmology grows ever larger, its aesthetic grows paradoxically smaller and in many ways more impoverished.
This is the saddest aspect of Einstein's legacy. Politicians and activists have taken up his dream of a peaceful, unified world. Physicists have carried on his program to unify the laws of nature. The search for uniformity and harmony, which Einstein regarded as the core aesthetic of his science, guides almost all advanced ideas in physics today, from the most far-out theories of universal beginnings to string theory. The unification of science and religion, by contrast, has drawn few takers. The uncompromising rigor that Gell-Mann lauded in Einstein's science drew little support when Einstein applied it in a theological direction. The modern resurgence of religious extremism seems only to have driven people farther from Einstein's ideal.
Perhaps it is just a matter of time. Smashing icons is never a popular business. Special and general relativity, among the grandest theories of our time (rivaled only by quantum mechanics and Darwinian evolution), took years to gain wide acceptance and never received a Nobel Prize. Cosmic religion is far more controversial and far less concrete: there is no equivalent of a solar eclipse experiment to show that Einstein was on the right track in pursuing "the secrets of the Old One." Meanwhile, I continue to commune with Einstein and do what little I can to follow his uncompromising creation: a science that rejects patchwork theorizing but also rejects the notion that rational inquiry cannot speak to the hunger for spiritual truth.
Read what science's best minds love—and hate—about Einstein.
Brad Lemley also writes about the many lives of Einstein.
Also, check out DISCOVER's feature about Einstein's theory of fidelity.