capture) should be quite something. What do you think? It is I think exciting, not in the rare way of positrons and mesotrons, but in a good honest practical way.
The next day, in a letter to George Uhlenbeck at Columbia, “quite something” became “might very well blow itself to hell.” One of Oppenheimer's students, the American theoretical physicist Philip Morrison, recalls that “when fission was discovered, within perhaps a week there was on the blackboard in Robert Oppenheimer's office a drawing — a very bad, an execrable drawing — of a bomb.”
Enrico Fermi made similar estimates. George Uhlenbeck, who shared an office with him in Pupin Hall, was there one day to overhear him. Fermi was standing at his panoramic office window high in the physics tower looking down the gray winter length of Manhattan Island, its streets alive as always with vendors and taxis and crowds. He cupped his hands as if he were holding a ball. “A Uttle bomb like that,” he said simply, for once not lightly mocking, “and it would all disappear.”
PART TWO
A PECULIAR SOVEREIGNTY
The Manhattan District bore no relation to the industrial or social life of our country; it was a separate state, with its own airplanes and its own factories and its thousands of secrets. It had a peculiar sovereignty, one that could bring about the end, peacefully or violently, of all other sovereignties.
We must be curious to learn how such a set of objects — hundreds of power plants, thousands of bombs, tens of thousands of people massed in national establishments — can be traced back to a few people sitting at laboratory benches discussing the peculiar behavior of one type of atom.
10
Neutrons
At the end of January 1939, still ill with a feverish cold that had laid him low for more than a week but determined to prevent information on the possibility of a chain reaction in uranium from reaching physicists in Nazi Germany, Leo Szilard raised himself from his bed in the King's Crown Hotel on West 116th Street in Manhattan and went out into the New York winter to take counsel of his friend Isador Isaac Rabi. Rabi, no taller than Szilard but always a trimmer and cooler man, who would be the 1944 Nobel laureate in physics, was born in Galicia in 1898 and emigrated to the United States with his family as a small child. Yiddish had been his first language; he grew up on New York's Lower East Side, where his father worked in a sweatshop making women's blouses until he accumulated enough savings to open a grocery store. Because his family was Orthodox and fundamentalist in its Judaism, Rabi had not known that the earth revolved around the sun until he read it in a library book. A frightening vision of the vast yellow face of the rising moon seen as a child down a New York street had begun his turn toward science, as had his childhood reading of the cosmological first verses of the Book of Genesis. He was a man of abrupt and honest bluntness who did not easily tolerate fools. One reason for his impatience was certainly that it guarded from harm his deeply emotional commitment to science: he thought physics “infinite,” he told a biographer in late middle age, and he was disappointed that young physicists of that later day, intent on technique, seemed to miss what he had found, “the mystery of it: how very different it is from what you can see, and how profound nature is.”
Szilard learned from Rabi that Enrico Fermi had discussed the possibility of a chain reaction in his public presentation at the Fifth Washington Conference on Theoretical Physics that had met the week before. Szilard adjourned to Fermi's office but did not find him there. He went back to Rabi and asked him to talk to Fermi “and say that these things ought to be kept secret.” Rabi agreed and Szilard returned to his sickbed.
He was recovering; a day or two later he again sought Rabi out:
I said to him: “Did you talk to Fermi?” Rabi said, “Yes, I did.” I said, “What did Fermi say?” Rabi said, “Fermi said ‘Nuts!’” So I said, “Why did he say ‘Nuts!'?” and Rabi said, “Well, I don't know, but he is in and we can ask him.” So we went over to Fermi's office, and Rabi said to Fermi, “Look, Fermi, I told you what Szilard thought and you said ‘Nuts!’ and Szilard wants to know why you said ‘Nuts!’” So Fermi said, “Well… there is the remote possibility that neutrons may be emitted in the fission of uranium and then of course perhaps a chain reaction can be made.” Rabi said, “What do you mean by ‘remote possibility'?” and Fermi said, “Well, ten per cent.” Rabi said, “Ten per cent is not a remote possibility if it means that we may die of it. If I have pneumonia and the doctor tells me that there is a remote possibility that I might die, and it's ten percent, I get excited about it.”
But despite Fermi's facility with American slang and Rabi's with probabilities Fermi and Szilard were unable to agree. For the time being they left the discussion there.
Fermi was not misleading Szilard. It was easy to estimate the explosive force of a quantity of uranium, as Fermi would do standing at his office window overlooking Manhattan, if fission proceeded automatically from mere assembly of the material; even journalists had managed that simple calculation. But such obviously was not the case for uranium in its natural form, or the substance would long ago have ceased to exist on earth. However energetically interesting a reaction, fission by itself was merely a laboratory curiosity. Only if it released secondary neutrons, and those in sufficient quantity to initiate and sustain a chain reaction, would it serve for anything more. “Nothing known then,” writes Herbert Anderson, Fermi's young partner in experiment, “guaranteed the emission of neutrons. Neutron emission had to be observed experimentally and measured quantitatively.” No such work had yet been done. It was, in fact, the new work Fermi had proposed to Anderson immediately upon returning from Washington. Which meant to Fermi that talk of developing fission into a weapon of war was absurdly premature.
Many years later Szilard succinctly summed up the difference between his position and Fermi's. “From the very beginning the line was drawn,” he said. “… Fermi thought that the conservative thing was to play down the possibility that [a chain reaction] may happen, and I thought the conservative thing was to assume that it would happen and take all the necessary precautions.”
Once he was well again Szilard had catching up to do. He cabled Oxford to ship him the cylinder of beryllium he had left behind at the Clarendon when he came to the United States, preliminary to mounting a neutron-emission experiment of his own. At Lewis Strauss's request he spent a day with the financier discussing the possible consequences of fission, which included, Strauss notes wistfully in his memoirs, making “the performance of our surge generator in Pasadena insignificant. The device had just been completed.” The surge generator in which he had invested some tens of thousands of dollars had been cut down to size. The Strausses were scheduled to leave that evening by overnight train for a Palm Beach vacation; Szilard rode along as far as Washington to continue the discussion. He was massaging his patron: he needed to rent radium to combine with his beryllium to make a neutron source and hoped Strauss might be persuaded to support the expense.
Arriving late at Union Station in Washington, Szilard called the Edward Tellers. They were still recovering from the work of hosting the Washington Conference. Mici Teller protested the surprise visit, her husband remembers: “No! We are both much too tired. He must go to a hotel.” They met Szilard anyway, whereupon to
