The Age of Radiance

by Craig Nelson

  What Fermi did not mention to Anderson was his deep shame at missing nuclear fission during his epic radioactive study of the periodic table. Emilio Segrè: “One day after the war Fermi and some of his colleagues were studying the architect’s sketches for the future institute for nuclear science at the University of Chicago. The drawing showed a vaguely outlined human figure in bas-relief over the entrance door. When the group began speculating as to the significance of the human figure, Fermi immediately interjected that it was probably ‘a scientist not discovering fission.’ ” Physicist Jay Orear: “If Fermi had published that he had seen fission, the half-sized pieces would have an excess of neutrons and these neutrons could give rise to more fissions most likely in a chain reaction. Then both Germany and the United States might have had atom bombs in time for World War II. The world should be grateful for this one mistake by Fermi!”

  On the night of January 25, 1939, the first American nuclear fission experiment was conducted in the basement of Columbia’s Pupin Hall. Previously that day, John R. Dunning and Enrico Fermi had lunch at the faculty club and discussed the outlines of future experiments with uranium, such as what would be the best state to test—metal, liquid, or gas? Then Fermi left for the train to Washington, and that night a cold front blew in, rattling Pupin’s scraggly Ivy League vines. At about seven o’clock, Dunning and Herb Anderson bombarded uranium oxide with neutrons in an ionization chamber, fully expecting nothing would happen. However, instead of the whispery dots that would be expected on the oscilloscope, great wavy lines appeared.

  John Dunning: “I went up to the thirteenth floor and brought down one of the old standard stand-by neutron sources, the radon plus beryllium sources that had been used so much before. We put it next to the chamber containing the uranium and in considerable excitement we saw with even this very weak source about one big pulse, a huge pulse, on the oscilloscope every minute. The rate, however, was so slow that I had doubts whether this was really real or whether it was maybe a bad electrical contact. So we had another device, and installing that right next to the chamber, the rate went up according to my notes to something like seven or so with that device, huge pulses. We finally quit about 11 p.m. My notebook contains this phrase: ‘Believe we have observed new phenomenon of far reaching consequences.’ ”

  Dunning had never seen anything like it before and took a deep breath. “God!” he said. “This looks like the real thing.” They assumed that something was wrong and spent the next two hours making sure the machine was working properly, but finally the truth was evident. They had split atoms and released nuclear power, confirming the fission discovered by Meitner and Frisch.

  On January 26, the Fifth Annual Conference on Theoretical Physics opened in Washington, DC. Before anyone could present their findings, Bohr and Fermi took the floor of the conference to announce nuclear fission. The audience erupted, with many immediately abandoning the conference to return to their labs and confirm the Meitner and Frisch findings then and there. On January 29, 1939, an excitable New York Times explained this moment to the general reader with the headline “Atomic Explosion Frees 200,000,000 Volts,” and on April 29, the head of the physics division of the Reich Research Council, Abraham Esau, assembled a group of German nuclear scientists to form a new organization, the Uranium Club—the Uranverein—and directed them to investigate the potential battlefield uses of fission. At around the same time, the German Army Weapons Bureau started its own rival committee.

  When Szilard learned of Meitner and Frisch’s theory of fission, he could only think, “All the things which H. G. Wells predicted appeared suddenly real to me.” Until Joliot-Curie discovered man-made radiation, no one paid any attention to Szilard’s chain-reaction theories, but the French technique, combined with the Meitner/Frisch findings, now indicated a clear candidate for the trigger that would lead to radioactive power and weaponry, and Szilard’s H. G. Wells–induced epiphany at a London stoplight would become the wellspring of nuclear science. When uranium fissioned, mass was alchemized into energy . . . and a few stray neutrons were spewed. Enrico Fermi: “It takes one neutron to split one atom of uranium [which then] emits two neutrons. . . . It is conceivable that they might hit two more atoms of uranium, split them, and make them emit two neutrons each. At the end of this second process of fission we would have four neutrons, which would split four atoms. . . . In other words, starting with only a few man-produced neutrons to bombard a certain amount of uranium, we would be able to produce a set of reactions that would continue spontaneously until all uranium atoms were split.” If, as Fermi had found with the paraffin, a tamper could slow the neutrons’ velocity and maximize their strike efficiency, humans could precipitate a controlled chain and extract its energy—a nuclear reactor producing immense amounts of power from small amounts of ore—as well as isotope by-products for medicine, archaeology, and explosives. If they could trigger an uncontrolled chain reaction releasing massive energy simultaneously, though, it would mean a weapon of unimaginable destructive force.

  On February 24, Hungarian Leo Szilard worked with Canadian Walter Zinn at Columbia to determine whether splitting uranium atoms would produce neutrons. At first, their oscilloscope showed nothing whatsoever . . . then they realized they had forgotten to plug it in. Szilard: “We turned the switch and we saw the flashes. We watched them for a little while and then we switched everything off and went home.”

  It was all true; uranium fission produced neutrons.

  Leo: “That night, there was very little doubt in my mind that the world was headed for grief.”

  5

  The Birth of Radiance

  ENRICO FERMI and Leo Szilard now began a series of experiments together at Columbia to create the first sustained chain reaction—the world’s first nuclear reactor—with various arrangements of neutron sources and uranium to understand the quantity needed, what medium would work best to slow down the neutrons, what kind of uranium worked effectively, what layout of ore and tamper meant the most likely success, and what could be used to stop the reaction, as well as control its speed.

  The two fought constantly. Enrico believed in careful, incremental progress and hard work in the lab; Leo loved debate, being a catalyst, and thinking through original ideas at their earliest, most primitive stages. Eugene Wigner believed that Fermi’s most striking trait was “his willingness to accept facts and men as they were” with an approach to research as shoe-plain as the man himself: “One must take experimental data, collect experimental data, organize experimental data, begin to make a working hypothesis, try to correlate so on, until eventually a pattern springs to life and one has only to pick out the results.” Szilard challenged conventions, upended every authority in every hierarchy, did not mind charging into battle like a scientific Quixote, and tended to operate independently (to put it politely); while Enrico had spent decades leading teams of scientists; he was so enthusiastic about his employees’ efforts and so willing to pitch in at every level that he made it easy to join Team Fermi—and he attracted professional colleagues in droves with his otherworldly mental powers. One said that Enrico had such a feel for neutrons that he could “predict what would happen in any given experiment to within statistical error, and followed his predictions with detailed calculations and these almost always confirmed his intuitions.”

  Szilard, meanwhile, was impulsive and bold, made intuitive leaps, would spew a torrent of possibilities, and was almost too original. Enrico was particularly stunned that Leo didn’t appreciate lab work, seeing one’s theories and calculations rendered manifest in the material world. When Enrico described the experiment that won him a Nobel, the bombarding with neutrons of every element of the periodic table, Leo said that, under a similar situation, he would have hired someone else to do such a “boring task.” Then at Columbia, Leo took one look at the greasy, dust-spewing graphite that he had determined could be used in immense amounts to slow the neutrons for an industrial-strength reactor, as the paraffin had show
ed them in Rome, and declined to take part, saying he didn’t want to “work and dirty my hands like a painter’s assistant.” Yet Leo wasn’t shy about showing up in others’ labs to give them unasked-for advice and interrogating scientists about their work and their findings “with the precision of a prosecuting attorney.” When one afternoon the tactless Szilard barged into Isidor Rabi’s lab, criticizing his techniques, Rabi told Szilard that he should go do his own work and kicked him out: “You are reinventing the field. You have too many ideas. Please, go away!”

  Szilard and Fermi argued over everything—even what the numbers actually meant. Szilard: “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 percent.” 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 it’s ten percent, I get excited about it.” The relationship was so fraught that a few weeks after this encounter, Szilard wrote a letter to Fermi outlining their difficulties, and concluding that if each had worked separately, a chain reaction would surely have occurred by now. He never sent this letter, but instead on July 4 wrote a more tentative proposal of collaboration, asking Pegram, the department chair, to adjudicate.

  After learning that Leo was physically inept, Enrico finally accepted this state of affairs, as the last thing he wanted was an accident-prone physicist working with slippery graphite bricks and uranium. Herbert Anderson: “Szilard was not willing to do his share of experimental work, even the preparation in the conduct of the measurements. He hired an assistant to do what we would’ve required of him. . . . Fermi’s vigor and energy always made it possible for him to contribute somewhat more than his share, so that any dragging of feet on the part of the others stood out the more sharply in contrast. . . . That experiment was important in a number of ways, but it was the first and also the last experiment in which Fermi and Szilard collaborated.” That experiment was important in a number of ways—as it would be the birth of both nuclear power and atomic bombs.

  Eventually, Fermi and Szilard arrived at a satisfactory professional modus operandi. First they would brainstorm theory together, then Fermi would design and execute the experiments with students, share the results with Szilard and the two would debate the next steps. While Fermi was in the lab, Szilard both conceptualized and got the needed graphite and uranium from suppliers. The Italian and the Hungarian essentially worked separately, together, and communicated through a “conduit” by the name of Edward Teller: “During the summer of 1939, I taught summer school at Columbia. I lectured graduate students, but I was invited primarily as a consultant peacemaker on the Fermi-Szilard chain reaction project. Fermi and Szilard both had asked me to work with them. They were barely speaking to each other. Temperamentally, the two men were almost opposites. . . . Fermi seldom said anything that he could not demonstrate. Szilard seldom said anything that was not startling and new. Fermi was humble and self-effacing. Szilard could not talk without giving orders. Only if they had an intermediary could they be in contact with each other for any length of time. Because I admired and enjoyed working with both men and they were comfortable with me, I became a conduit of information, able to solve problems between them unobtrusively, sometimes even before they occurred.”

  Leo Szilard: “On matters scientific or technical there was rarely any disagreement [but] Fermi and I disagreed from the very start of our collaboration about every issue that involved not science but principles of action in the face of the approaching war. . . . Of all the many occasions which I had to observe Fermi I liked him best on the rather rare occasions when he got mad (except, of course, when he got mad at me). . . . If the nation owes us gratitude—and it may not—it does so for having stuck it out together as long as it was necessary.”

  At the start, Szilard immediately wanted to make the leap to fission, while Fermi thought it was merely a curiosity and continued his steady, meticulous investigations. Their split in thinking was echoed in the press: On January 29 and 30, 1939, the Washington Evening Star reported on page 1, “Power of New Atomic Blast Greatest Achieved on Earth,” but that “as a practical power source, the new finding has at present no significance.” On February 5 the New York Times said, “Hope is revived that we may yet be able to harness the energy of the atom,” but called it “remotely possible.” The same week, Newsweek quoted Einstein, echoing Rutherford on the improbability of nuclear energy: “It is like shooting birds in the dark in a country where there are not many birds.”

  In Paris, the Joliot-Curies were also investigating fission, and Szilard urged the Americans and the French to keep their studies private to safeguard this information from the Fascists. Beginning at the start of the Enlightenment in the seventeenth century with the Journal des sçavans and Philosophical Transactions of the Royal Society, publishing scientific findings became a method of announcing one’s achievements, expanding the understanding of the natural world, contributing to the public good, and, of course, competing with your professional colleagues—the highway of hive mind. Szilard’s insistence that scientists should not publish was such a shocking and contrary notion that a number of physicists in 1939 couldn’t comprehend it. I. I. Rabi even took Szilard aside to warn that, by promoting such a bizarre notion, his guest status at Columbia was in danger. Bohr thought there was little future in atomic bombs since it was so difficult to produce the needed U-235 isotope that was known to be an effective source for a chain reaction and so didn’t feel this remote possibility meant upending a three-hundred-year scientific tradition of free discourse, even if it involved Hitler. Fermi agreed with Bohr.

  The Joliot-Curie team did not honor Szilard’s request, publishing in Nature on March 18 that the U-235 isotope could produce 3.5 neutrons per fission (later revised to 2.9) and chain-react. Secrecy was not thoroughly maintained in the United States, either, for after Bohr gave a speech at the American Physical Society on fission’s potential for explosion, the Times said, “The creation of a nuclear explosion which would wreck an area as large as New York City would be comparatively easy,” since a remarkably small quantity of uranium could “blow a hole in the earth 100 miles in diameter. It would wipe out the entire City of New York, leaving a deep crater half way to Philadelphia and a third of the way to Albany and out to Long Island as far as Patchogue.”

  As it turned out, Szilard was right. German scientists brought Joliot-Curie’s results to the attentions of both the Berlin War Office and the Reich Ministry of Education. When Fermi’s Columbia tests showed that very pure graphite worked but the average industrial product did not, Szilard got Pegram to convince Fermi not to publish. This secrecy may have tricked the Germans, who had failed with impure graphite in their test reactor, to switch to heavy water as a moderator, which crippled their program.

  When he heard Fermi had accepted Szilard’s argument, Bohr did, too. “Contrary to perhaps what is the most common belief about secrecy, secrecy was not started by generals, was not started by security officers, but was started by physicists,” Fermi remembered. “And the man who is most responsible for this certainly extremely novel idea for physicists was Szilard. He is certainly a very peculiar man, extremely intelligent. I see that this is an understatement. He is extremely brilliant and he seemed somewhat to enjoy, at least that is the impression that he gives to me, he seems to enjoy startling people. So he proceeded to startle physicists by proposing to them that given the circumstances of the period—you see it was early 1939 and war was very much in the air—given the circumstances of that period, given the danger that atomic energy and possibly atomic weapons could become the chief tool
for the Nazis to enslave the world, it was the duty of the physicists to depart from what had been the tradition of publishing significant results as soon as the physical review or other scientific journals might turn them out, and that instead one had to go easy, keep back some results until it was clear whether these results were potentially dangerous or potentially helpful to our side.”

  During that summer of 1939, Fermi, Anderson, and Szilard got five hundred pounds of uranium and tried to initiate a chain reaction using water as a moderator. It failed, and secrecy or no secrecy, this would be the last American experiment with fission for nearly a year. While Fermi then spent the rest of the season at an Ann Arbor conference, where he experimented with cosmic rays, Szilard settled on carbon (graphite) or deuterium (heavy water) as promising candidates for the moderator. He and brother Bela met at the Waldorf-Astoria with a group of investors, to whom Szilard described energy generated by what Fermi and Szilard called “piles,” and a business plan with a majority of shares controlled by physicists. The financiers regretfully declined.

  When a chemist at the Kaiser Wilhelm Institute then published “Can Nuclear Energy Be Utilized for Practical Purposes?” in June 1939, the Hungarians in America became certain that Germany was on the road to atomic weapons and that Washington had to understand the threat. Their fears were valid; three months later, the Nazi War Office began conducting secret conferences on nuclear bombs attended by Bagge, Geiger, Bothe, Hahn, and Heisenberg. In time, the War Office would oversee atomic bomb research and would take over the Kaiser Wilhelm Institute as part of this mission. To drive away curious passersby, they called KWI’s nuclear research facility the Virus House.