The Fifth Solvay International Conference in Brussels, which took place in 1927, may have been the greatest gathering of scientific minds ever in one place. The headliners were Albert Einstein and Niels Bohr, but 17 of the 29 attendees were past or future Nobel Prize winners in their own right, including the sole woman attendee, Marie Curie, who won twice. The conference is perhaps best known for a famous exchange between Einstein and Bohr over the Heisenberg uncertainty principle, which states that the behavior of elementary particles is a matter of probabilities and cannot not be precisely determined. Einstein famously disputed this, saying, “God does not play dice.” To which Bohr replied, “Einstein, stop telling God what to do.”
Less well known is the exchange that took place among some of the conference’s younger participants, who were unsettled by Einstein’s frequent references to God. Did the great man actually believe in a Supreme Being? Paul Dirac, then only 25 and a future Nobel laureate as a co-founder of quantum mechanics, was the most outspoken. "I don't know why we are talking about religion," he groused. "If we are honest—and scientists have to be—we must admit that religion is a jumble of false assertions, with no basis in reality. The very idea of God is a product of the human imagination.” His colleague Wolfgang Pauli then quipped, “Our friend Dirac, too, has a religion, and its guiding principle is ‘God does not exist and Dirac is His prophet.'”
Dirac had conceded, “It is quite understandable why primitive people, who were so much more exposed to the overpowering forces of nature than we are today, should have personified these forces in fear and trembling.” Certainly there is no lack of evidence that the gods and goddesses of so-called primitive peoples, as well as of the ancient world in general, bear all the earmarks of human imagination. They are a fantastic menagerie of every creature imaginable and humans writ large*, plus various hybrids of man and beast.
Dirac is undoubtedly correct in asserting that gods are a product of human imagination, since imagination, broadly speaking, is what enables us to ascribe invisible causes to visible effects. When faced with the overpowering forces of nature, early human cultures searched for the best explanations then available. But just because humans use their imaginations doesn’t mean their explanations are always imaginary. Dirac, for example, used precisely the same faculty to penetrate the invisible forces operating in the subatomic realm. The difference is that he used sophisticated mathematical tools to find his answers. Are they necessarily any less imaginary than the gods and goddesses of yore? It’s hard to say, since oftentimes the only evidence is the math itself.
“Imagination is everything,” Einstein once said, deeming it to be more important than knowledge. Here perhaps it should be noted that he was not employing the term in the same sense that Dirac did when he denigrated the idea of God as a product of human imagination. For Dirac, “imagination” was used in the sense of fantasizing, with God as a mere figment. For Einstein, “imagination” was regarded as the wellspring of scientific creativity. The quantum physicist Richard Feynman made a similar distinction when he said, “Our imagination is stretched to the utmost, not, as in fiction, to imagine things which are not really there, but just to comprehend those things which are there.”
For mystics like Jakob Boehme and William Blake, imagination was not only the hallmark of our humanity but also a quality we share in common with our Maker. They would not have recoiled from the thought that God was a product of our imagination, just as we are a product of his. Rabbi Moses ben Naḥman, a medieval Spanish scholar, pointed out that when the Book of Genesis said humans were created in the image and likeness of God, the root of the word “likeness” in Hebrew was dimyon, meaning “imagination.” Blake summed it up this way: “Man is a little God, his imagination acting upon nature in the same way that, in the beginning, the spirit of God gave form to the void.”
*The 19th-century German philosopher Ludwig Feuerbach argued that humans make gods in their own image. He wrote, “God is man writ large.”