Intriguingly, I discovered that Einstein did actually use the expression “I made one great mistake in my life,” but in an entirely different context. Linus Pauling spoke with Einstein (as one leading scientist and pacifist to another) at Princeton, on November 16, 1954. Immediately following the conversation, Pauling wrote in his diary that Einstein told him the following (figure 33 shows Pauling’s diary entry): “He had made one great mistake—when he signed the letter to President Roosevelt recommending that atom bombs be made; but that there was some justification—the danger that the Germans would make them.” Clearly, this fact in itself does not necessarily preclude the possibility that Einstein might have used “biggest blunder” also in a scientific context, although the language employed in the conversation with Pauling (“one great mistake”) does make you wonder.

The second question I wanted to try to settle was that of the circumstances; when might Einstein have used this expression with Gamow? In My World Line Gamow gives the impression that he and Einstein were very close friends. He describes how during World War II, the two of them served at the same time as consultants in the Division of High Explosives of the US Navy’s Bureau of Ordnance. Since Einstein was unable at the time to travel from Princeton to Washington, DC, Gamow recounts, Gamow was “selected,” in his words, by the navy to bring documents to Einstein “every other Friday,” since he “happened to have known Einstein earlier, on nonmilitary grounds.” Gamow goes on to depict a very warm and intimate bond between him and Einstein:

Figure 33

Einstein would meet me in his study at home, wearing one of his famous soft sweaters, and we would go through all the proposals, one by one . . . After the business part of the visit was over, we had lunch either at Einstein’s home or at the cafeteria of the Institute for Advanced Study, which was not far away, and the conversation would turn to the problems of astrophysics and cosmology . . . I will never forget these visits to Princeton, during which I came to know Einstein much better than I had known him before.