Diana Preston - Before the Fallout

So alarmed was Szilard that such a process could be used to create an explosive device that in the spring of 1934 he had applied for a patent for the process he envisaged. He had assigned his patent to the British Admiralty for safekeeping but had done nothing further. Now that, four years later, fission had been shown to be a reality, Szilard wanted urgently to test his theory of chain reaction. Although he had no formal university appointment, he secured special permission to conduct experiments at Columbia University. He borrowed two thousand dollars from a friend, rented some radium, and, using some of the university’s equipment, carefully set up his experiment. As he later described, “All we needed to do was to get a gram of radium, get a block of beryllium, expose a piece of uranium to the neutrons which come from beryllium,” and then see whether neutrons were emitted in the process.

On 3 March 1939 “everything was ready and all we had to do was to turn an [electrical] switch, lean back, and watch the screen of a television tube. If flashes of light appeared on the screen, that would mean that neutrons were emitted in the fission process of uranium and this in turn would mean that the large-scale liberation of atomic energy was just around the corner. We turned the switch and we saw the flashes.” The pulses of light proved that bombarding uranium with neutrons could indeed spark a chain reaction. The spectacle left Szilard with “very little doubt in my mind that the world was headed for grief.” He was the first to perceive that a race would soon begin.

That night Szilard phoned Edward Teller in Washington, announced tersely in Hungarian, “I have found the neutrons,” and hung up. Teller had been contentedly playing the piano when the phone rang. As he returned to the instrument the thought came that “the world might change in a radical manner. The prospect of harnessing nuclear energy seemed chillingly real.”

ADDRESSING DIGNITARIES at the Nobel Prize ceremony in Stockholm in 1905, Pierre Curie had posed a disturbing question: “One may imagine that in criminal hands radium might become very dangerous…. we may ask ourselves if humanity has anything to gain by learning the secrets of nature.” He had not doubted the answer, adding reassuringly, “I am among those who think, with Nobel, that humanity will obtain more good than evil from the new discoveries.” Thirty-four years later, scientists had greater knowledge and faced more difficult judgments.

As Leo Szilard had quickly grasped, the fact that nature’s “secrets” might pose a risk to humanity implied new roles and responsibilities for scientists. Even before he had had a chance to conduct his own experiments at Columbia University confirming the viability of a nuclear chain reaction, Szilard launched a campaign to keep “nature’s secrets” secret. The specter of an explosive atomic device in Nazi hands haunted him. It would be only too easy, he reasoned, for scientists in Nazi Germany to comb through the technical journals and piece together snippets of information. It was a standard technique of intelligence gathering, which in the current international climate might prove disastrous. The answer was to persuade scientists in the free world to adopt a policy of self-censorship.

Szilard correctly identified Enrico Fermi as one of the scientists most likely to solve the mysteries of a chain reaction and targeted him accordingly. Fermi had recently arrived in the United States with his wife, Laura, and their two children to take up a professorship at Columbia, one of six American universities eager to appoint him. Laura Fermi was the daughter of a Jewish naval officer, and they had decided it was not safe for the family to remain in Mussolini’s Italy. Their opportunity to flee had come late in 1938 when Fermi was awarded the Nobel Prize for Physics for his identification of new radioactive elements and his discovery of how nuclear reactions were affected by slow neutrons. He was notified of the award the day that the Italian authorities announced that Jews were to be deprived of their rights of citizenship and their passports withdrawn.

By this time, the Italian authorities viewed the Nobel Prize with some disfavor. Their German allies had banned their citizens from accepting it after the 1935 Nobel Peace Prize was awarded to a German author and pacifist imprisoned as an enemy of the state. However, no one prevented the Fermis from traveling to Stockholm for the Nobel ceremony. Here they collected their prize money and never went home. Stepping onto American soil on 2 January 1939, Fermi declared, “We have founded the American branch of the Fermi family.” Within days his wife was exploring what she called “the marvels of pudding powders” and of frozen food, just then appearing on the market. The process of Americanization was, she quickly realized, less tangible. It was “more than learning language and customs and setting one’s self to do whatever Americans can do.” It would take time to understand “New England pride” and “the long suffering of the South” and even longer, perhaps, to think of Shakespeare before Dante.

When Szilard first explained his concerns to Fermi in February 1939, the Italian was skeptical. He considered the likelihood of a chain reaction to be less than Szilard did, and regarded his censorship plans as alarmist and against the spirit of science. Fermi had seen intellectual freedom stamped out in Fascist Italy and was reluctant to participate in any scheme to suppress knowledge. Under the circumstances, as Szilard recalled, “Fermi thought that the conservative thing was to play down the possibility that this [a chain reaction] may happen, and I thought the conservative thing was to assume that it would happen and take the necessary precautions.” Fermi and Szilard “had high regard for each other” but were “extremely different in personality, habits of work, outlook on life, and almost everything else” and “could scarcely work together on the same experiment,” recalled Emilio Segre. One of the problems was, as another physicist described, that “Szilard’s way of working on an experiment did not appeal to Fermi. Szilard was not willing to do his share of experimental work, either in the preparation or in the conduct of the measurements. He hired an assistant.”

With his hallmark persistence, Szilard continued relentlessly to lobby Fermi with the help of an intermediary: the American-born physicist Isidor I. Rabi, one of the first Jewish physicists appointed at Columbia and selected thanks to glowing references from Werner Heisenberg. As Szilard later recounted, the debate resembled a quick-fire comedy routine rather than a serious debate between scientists.

I went to see Rabi, and 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 percent 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 that it’s ten per cent, I get excited about it.”