Later, during the war, Einstein helped with less secret matters. A Navy lieutenant came to visit him at the Institute to enlist him in analyzing ordnance capabilities. He was enthusiastic. As Aydelotte noted, he had felt neglected since his brief flurry of work on uranium isotopes. Among the issues Einstein explored, as part of a $25- per-day consulting arrangement, were ways to shape the placement of sea mines in Japanese harbors, and his friend the physicist George Gamow got to come pick his brain on a variety of topics. “I am in the Navy, but not required to get a Navy haircut,” Einstein joked to colleagues, who probably had trouble picturing him with a crew cut.29
Einstein also helped the war effort by donating a manuscript of his special relativity paper to be auctioned off for a War Bond drive. It was not the original version; he had thrown that away back when it was published in 1905, not knowing it would ever be worth millions. To re-create the manuscript, he had Helen Dukas read the paper to him aloud as he copied down the words. “Did I really say it that way?” he griped at one point. When Dukas assured him that he had, Einstein lamented, “I could have put it much more simply.” When he heard that the manuscript, along with one other, had sold for $11.5 million, he declared that “economists will have to revise their theories of value.”30
The physicist Otto Stern, who had been one of Einstein’s friends since their days together in Prague, had been secretly working on the Manhattan Project, mainly in Chicago, and had a good sense by the end of 1944 that it would be successful. That December, he made a visit to Princeton. What Einstein heard upset him. Whether or not the bomb was used in the war, it would change the nature of both war and peace forever. The policymakers weren’t thinking about that, he and Stern agreed, and they must be encouraged to do so before it was too late.
So Einstein decided to write to Niels Bohr. They had sparred over quantum mechanics, but Einstein trusted his judgment on more earthly issues. Einstein was one of the few people to know that Bohr, who was half Jewish, was secretly in the United States. When the Nazis overran Denmark, he had made a daring escape by sailing with his son in a small boat to Sweden. From there he had been flown to Britain, given a fake passport with the name Nicholas Baker, then sent to America to join the Manhattan Project at Los Alamos.
Einstein wrote to Bohr, using his real name, in care of Denmark’s embassy in Washington, and somehow the letter got to him. In it Einstein described his worrisome talk with Stern about the dearth of thinking about how to control atomic weapons in the future. “The politicians do not appreciate the possibilities and consequently do not know the extent of the menace,” Einstein wrote. Once again, he made his argument that it would take an empowered world government to prevent an arms race once the age of atomic weaponry arrived. “Scientists who know how to get a hearing with political leaders,” Einstein urged, “should bring pressure on the political leaders in their countries in order to bring about an internationalization of military power.”31
Thus began what would be the political mission that would dominate the remaining decade of Einstein’s life. Since his days as a teenager in Germany, he had been repulsed by nationalism, and he had long argued that the best way to prevent wars was to create a world authority that had the right to resolve disputes and the military power to impose its resolutions. Now, with the impending advent of a weapon so awesome that it could transform both war and peace, Einstein viewed this approach as no longer an ideal but a necessity.
Bohr was unnerved by Einstein’s letter, but not for the reason Einstein would have hoped. The Dane shared his desire for the internationalization of atomic weaponry, and he had advocated that approach in meetings with Churchill, and then with Roosevelt, earlier in the year. But instead of persuading them, he had prompted the two leaders to issue a joint order to their intelligence agencies saying that “enquiries should be made regarding the activities of Professor Bohr and steps taken to ensure that he is responsible for no leakage of information, particularly to the Russians.”32
So upon receiving Einstein’s letter, Bohr hurried to Princeton. He wanted to protect his friend by warning him to be circumspect, and he also hoped to repair his own reputation by reporting to government officials on what Einstein said.
During their private talk at the Mercer Street house, Bohr told Einstein that there would be “the most deplorable consequences” if anyone who knew about the development of the bomb shared that information. Responsible statesmen in Washington and London, Bohr assured him, were aware of the threat caused by the bomb as well as “the unique opportunity for furthering a harmonious relationship between nations.”
Einstein was persuaded. He promised that he would refrain from sharing any information he had surmised and would urge his friends not do anything to complicate American or British foreign policy. And he immediately set out to make good on his word by writing a letter to Stern that was, for Einstein, remarkable in its circumspection. “I have the impression that one must strive seriously to be responsible, that one does best not to speak about the matter for the time being, and that it would in no way help, at the present moment, to bring it to public notice,” he said. He was careful not to reveal anything, even that he had met with Bohr. “It is difficult for me to speak in such a nebulous way, but for the moment I cannot do anything else.”33
Einstein’s only intervention before the end of the war was prompted again by Szilard, who came to visit in March 1945 and expressed anxiety about how the bomb might be used. It was clear that Germany, now weeks away from defeat, was not making a bomb. So why should the Americans rush to complete one? And shouldn’t policymakers think twice about using it against Japan when it might not be needed to secure victory?
Einstein agreed to write another letter to President Roosevelt urging him to meet with Szilard and other concerned scientists, but he went out of his way to feign ignorance. “I do not know the substance of the considerations and recommendations which Dr. Szilard proposes to submit to you,” Einstein wrote. “The terms of secrecy under which Dr. Szilard is working at present do not permit him to give me information about his work; however, I understand that he now is greatly concerned about the lack of adequate contact between scientists who are doing this work and those members of your Cabinet who are responsible for formulating policy.”34
Roosevelt never read the letter. It was found in his office after he died on April 12 and was passed on to Harry Truman, who in turn gave it to his designated secretary of state, James Byrnes. The result was a meeting between Szilard and Byrnes in South Carolina, but Byrnes was neither moved nor impressed.
The atom bomb was dropped, with little high-level debate, on August 6, 1945, on the city of Hiroshima. Einstein was at the cottage he rented that summer on Saranac Lake in the Adirondacks, taking an afternoon nap. Helen Dukas informed him when he came down for tea. “Oh, my God,” is all he said.35
Three days later, the bomb was used again, this time on Nagasaki. The following day, officials in Washington released a long history, compiled by Princeton physics professor Henry DeWolf Smyth, of the secret endeavor to build the weapon. The Smyth report, much to Einstein’s lasting discomfort, assigned great historic weight for the launch of the project to the 1939 letter he had written to Roosevelt.
Between the influence imputed to that letter and the underlying relationship between energy and mass that he had formulated forty years earlier, Einstein became associated in the popular imagination with the making of the atom bomb, even though his involvement was marginal.
