Alone among the scientists at the congress Teller knew about the Einstein letter. It was a direct link, he was an emotional man and the encounter with Roosevelt was eerily personal: “We had never met, but I had an irrational feeling he was talking to me.”1322 The President mentioned the German invasion, its challenge to “the continuance of the type of civilization” the people of the Americas valued, the distances of the modern world shortened by modern technology to timetables that removed the “mystic immunity” Americans once felt from European war.1323 “Then he started to talk about the role of the scientist,” Teller recalls, “who has been accused of inventing deadly weapons.1324 He concluded: ‘If the scientists in the free countries will not make weapons to defend the freedom of their countries, then freedom will be lost.’ ” Teller believed Roosevelt was not proposing what scientists may do “but something that was our duty and that we must do—to work out the military problems, because without the work of the scientists the war and the world would be lost.”1325
Teller’s memory of Roosevelt’s speech differs from its text. The President said that most people abhor “conquest and war and bloodshed.”1326 He said that the search for truth was a great adventure but that “in other parts of the world, teachers and scholars are not permitted” that search—an observation of which Teller had personal knowledge. And then, cannily, Roosevelt offered absolution in advance for war work:
You who are scientists may have been told that you are in part responsible for the debacle of today . . . but I assure you that it is not the scientists of the world who are responsible. . . . What has come about has been caused solely by those who would use, and are using, the progress that you have made along lines of peace in an entirely different cause.
“My mind was made up,” Teller reports, “and it has not changed since.”1327
* * *
Vannevar Bush made a similar choice that spring. The sharp-eyed Yankee engineer, who looked like a beardless Uncle Sam, had left his MIT vice presidency for the Carnegie Institution in the first place to position himself closer to the sources of government authority as war approached. Karl Compton had offered to move up to chairman of the MIT corporation and give him the presidency to keep him, but Bush had larger plans.
As a young man, with a doctorate in engineering behind him jointly from MIT and Harvard earned in one intense year, Bush in 1917 had gone patriotically to work for a research corporation developing a magnetic submarine detector. The device was effective, and one hundred sets got built; but because of bureaucratic confusion they were never put to use against German submarines. “That experience,” Bush writes in a memoir, “forced into my mind pretty solidly the complete lack of proper liaison between the military and the civilian in the development of weapons in time of war, and what that lack meant.”1328
In Washington after the invasion of Poland the Carnegie president gathered with a group of fellow science administrators—Frank Jewett, president of Bell Telephone Laboratories and the National Academy of Sciences; James Bryant Conant, the young president of Harvard, a distinguished chemist; Richard Tolman of Caltech, the theoretician who had wooed Einstein; Karl Compton—to worry about the approaching conflict:
It was during the period of the “phony” war. We were agreed that the war was bound to break out into an intense struggle, that America was sure to get into it in one way or another sooner or later, that it would be a highly technical struggle, that we were by no means prepared in this regard, and finally and most importantly, that the military system as it existed . . . would never fully produce the new instrumentalities which we would certainly need.1329
They devised a national organization to do the job. Bush had learned his way around Washington and took the lead. The organization Bush wanted needed independent authority. He thought it should report directly to the President rather than through military channels and should have its own source of funds. He drafted a proposal. Then he arranged an introduction to Harry Hopkins.
A small-town Iowa boy, idealistic and energetic, Harry Lloyd Hopkins had fallen into New York social work after four years at Grinnell and won appointment at the beginning of the Depression administering emergency state relief. When the governor of New York was elected President, Hopkins moved with Roosevelt to Washington to help out with the New Deal. He ran the vast Works Progress Administration, then took over as Secretary of Commerce. His performance moved him closer and closer to the President, who picked up talent wherever he could find it; as war approached, Roosevelt invited Hopkins to dinner at the White House one evening and moved the man in for the duration as his closest adviser and aide. Hopkins was tall, a chain smoker and emaciated to the point of cachexia, his ghastly health the result of cancer surgery that took most of his stomach and left him unable to absorb much protein and therefore slowly starving to death. He kept an office in the White House basement but usually worked out of a cluttered bedroom suite—the Lincoln Bedroom—down the hall from FDR’s.
When Bush met Hopkins, though the presidential aide was a liberal Democrat and the Carnegie president an admirer of Herbert Hoover and a self-styled Tory, “something meshed,” writes Bush, “and we found we spoke the same language.”1330 Hopkins had a scheme for an Inventors Council. Bush countered with his more comprehensive National Defense Research Council. “Each of us was trying to sell something to the other.”1331 Bush won. Hopkins liked his plan.
In early June Bush made the rounds of Washington touching bases: the Army, the Navy, Congress, the National Academy of Sciences. On June 12 “Harry and I then went in to see the President. It was the first time I had met Franklin D. Roosevelt. . . . I had the plan for N.D.R.C. in four short paragraphs in the middle of a sheet of paper. The whole audience lasted less than ten minutes (Harry had no doubt been there before me). I came out with my ‘OK-FDR’ and all the wheels began to turn.”
The National Defense Research Council immediately absorbed the Uranium Committee. That had been part of its purpose. Briggs was a cautious and frugal man, but his committee had also lacked the authority of a source of funds independent of the military. The white-haired director of the National Bureau of Standards would continue to be responsible for fission work. He would report now to James Bryant Conant, Harvard’s wiry president, boyish in appearance but in practice cool and reserved, whom Bush had enlisted as soon as FDR authorized the new council.
The NDRC gave research in nuclear fission an articulate lobby within the executive branch. But though Bush and Conant felt challenged by German science—“the threat of a possible atomic bomb,” writes Bush, “was in all our minds”—both men, concerned about scarce scientific resources, were initially more interested in proving the impossibility of such a weapon than in rushing to build one: the Germans could not do what could not be done.1332, 1333 When Briggs wrapped up his pre-NDRC committee work in a report to Bush on July 1 he asked for $140,000, $40,000 of it for research on cross sections and other fundamental physical constants, $100,000 for the Fermi-Szilard large-scale uranium-graphite experiment (the military had decided to grant $100,000 on its own through the Naval Research Laboratory to isotope-separation studies). Bush allotted Briggs only the $40,000. Once again Fermi and Szilard were left to bide their time.
* * *
Winston Churchill had accepted George VI’s invitation to form a government upon Neville Chamberlain’s resignation the day Germany invaded the Lowlands; he shouldered the prime ministership calmly but felt the somber weight of office. C. P. Snow recalls a more paradoxical mood:
I remember—I shall not forget it while I live—the beautiful, cloudless, desperate summer of 1940. . . . Oddly enough, most of us were very happy in those days. There was a kind of collective euphoria over the whole country. I don’t know what we were thinking about. We were very busy. We had a purpose. We were living in constant excitement, usually, if we examined the true position, of an unpromising kind. In one’s realistic moments, it was difficult to see what chance we had. But I doubt if most o
f us had many realistic moments, or thought much at all. We were all working like mad. We were sustained by a surge of national emotion, of which Churchill was both symbol and essence, evocator and voice.1334
Not only native-born Englishmen felt that surge. So did the emigré scientists whom Britain had sheltered. Franz Simon, an outstanding chemist whom Frederick Lindemann had extracted from Germany in 1933 for the Clarendon, wrote his old friend Max Born on the eve of the Battle of France that he longed to “use my whole force in the struggle for this country.”1335, 1336 Though he may not yet have realized it, Simon’s opportunity had already arrived. Early in the year, when Frisch and Peierls were first beginning to discuss the ideas that would lead to their important memoranda, Peierls had consulted Simon about methods of isotope separation. Frisch had chosen to work with gaseous thermal diffusion—his Clusius tube—because it seemed to him the simplest method, but Simon had begun then to think about other systems. Half a dozen approaches had been tried in the past. You couldn’t spit on the floor without separating isotopes, Simon joked; the problem was to collect them.1337 He wanted to find a method adaptable to mass production, because with a 1:139 isotope ratio, uranium separation would have to proceed on a vast scale, as Frisch’s calculation of 100,000 Clusius tubes demonstrated. Frisch dramatized the difficulty with a simile: “It was like getting a doctor who had after great labour made a minute quantity of a new drug and then saying to him: ‘Now we want enough to pave the streets.’ ”1338
The surge of national emotion sustained Mark Oliphant as well, and in that mood he found even less patience than usual for obstructive rules. When P. B. Moon questioned the assumption that gaseous thermal diffusion was the method of choice for isotope separation, he won no encouragement from the Thomson committee, but back in Birmingham Oliphant simply told him to go ahead and talk it over with Peierls. “Within a week or two,” writes Moon, “Peierls identified ordinary diffusion as a logically superior process and wrote directly to Thomson on the matter.”1339 Peierls proposed that the Thomson committee consult with Simon, the best man around. The committee hesitated, even though Simon was a naturalized citizen. Oliphant then authorized Peierls out of hand to visit Simon at Oxford.
Simon in the meantime had been working to convert a skeptical Lindemann. At Simon’s suggestion Peierls had written to Lindemann on June 2. Together at Oxford later in June they approached Lindemann in person. “I do not know him sufficiently well to translate his grunts correctly,” Peierls reported of the meeting. But he felt sure he had “convinced him that the whole thing ought to be taken seriously.”1340
Like Peierls, Simon had settled on “ordinary” gaseous diffusion (as opposed to gaseous thermal diffusion) as the best method of isotope separation after winnowing through the alternatives. Gases diffuse through porous materials at rates that are determined by their molecular weight, lighter gases diffusing faster than heavier gases. Francis Aston had applied this principle in 1913 when he separated two isotopes of neon by diffusing a mixed sample several thousand times over and over through pipe clay—that is, unglazed bisque of the sort used to make clay pipes. Thick materials like pipe clay worked too slowly to be effective at factory scale; Simon sought a more efficient mechanism and concluded that a metal foil punctured with millions of microscopic holes would work faster. Divide a cylinder down its length with such a foil barrier, pump a gas of mixed isotopes into one side of the divided cylinder, and gas would diffuse through the barrier as it flowed from one end of the cylinder to the other. Compared to the gas left behind, the gas that diffused through the barrier would be selectively enriched in lighter isotopes. In the case of uranium hexafluoride the enrichment factor would be slight, 1.0043 under ideal conditions. But with enough repetitions of the process any degree of enrichment was possible, up to nearly 100 percent.
The immediate problem, Simon saw, was barrier material. The smaller the holes, the higher the pressures a separation system could sustain, and the higher the pressure, the smaller the equipment could be. Whatever the material, it would have to resist corrosion by uranium hexafluoride—“hex,” they were beginning to call it, not necessarily in tribute to its evil contrarities—or the gas would clog its microscopic pores.
One morning that June, inspired, Simon took a hammer to a wire strainer he found in his kitchen.1341 He carried the results to the Clarendon and called together two of his assistants—a Hungarian, Nicholas Kurti, and a big Rhodes scholar from Idaho, H. S. Arms. “Arms, Kurti,” Simon announced, holding up the strainer, “I think we can now separate the isotopes.”1342 He had hammered the wires flat in demonstration, reducing the spaces between to pinholes.
“The first thing we used,” Kurti recalls, “was ‘Dutch cloth,’ as I think it is called—a very fine copper gauze which has many hundreds of holes to the inch.”1343 The assistants hammered the holes even finer by hand. They tested the copper barrier not with hex but with a mixture of water vapor and carbon dioxide, “in other words something much like ordinary sodawater”—the first in an urgent series of experiments carried out through the summer and fall to study materials, pore size, pressures and other basic parameters preliminary to any equipment design.
In late June G. P. Thomson gave his committee a new name to disguise its activities: MAUD. The initials appear to form an acronym but do not. They arrived as a mysterious word in a cable from Lise Meitner to an English friend: MET NIELS AND MARGRETHE RECENTLY BOTH WELL BUT UNHAPPY ABOUT EVENTS PLEASE INFORM COCKCROFT AND MAUD RAY KENT.1344 Meitner’s friend passed the message to Cockcroft, who decided, he wrote Chadwick, that MAUD RAY KENT was “an anagram for ‘radium taken.’ This agrees with other information that the Germans are getting hold of all the radium they can.”1345 Thomson borrowed the first word of Cockcroft’s mysterious anagram for a suitably misleading name. The committee members did not learn until 1943 that Maud Ray was the governess who had taught Bohr’s sons English; she lived in Kent.
The war crossed the Channel first in the air. As a result of the German bombing of Warsaw in the autumn of 1939, an act Germany represented as tactical because the Polish city was heavily fortified, the British Air Ministry had repudiated its pledge to refrain from strategic bombing.1346 But neither belligerent was eager to exchange bombing raids, and although nightly blackouts added inconvenience and apprehension to the wartime burden of the people of both nations, the implicit truce held until mid-May 1940. Then within a week two events triggered British action. German raiders targeted for French airfields at Dijon lost their way and bombed the southern German city of Freiburg instead, killing fifty-seven people; the German Ministry of Propaganda brazenly denounced the bombing as British or French and threatened fivefold retaliation. Blacker and more violent non sequitur destroyed the city center of Rotterdam. Dutch forces were holding out stubbornly as late as May 14 in the northern section of that old Netherlands port. The German commanding general ordered a “short but devastating air raid” that he hoped might decide the battle.1347 Negotiations with the Dutch advanced, the air raid was canceled, but the abort message arrived too late to stop half the hundred Heinkel lll’s ordered into action from dropping 94 tons of bombs. The bombs started massive fires in stores of fats and margarine. The first official Dutch statement, issued from the embassy in Washington, placed casualties in the devastated city at 30,000, and the Western democracies responded with outrage. Actual deaths totaled about 1,000; some 78,000 people went homeless.
The British retaliated on May 15 by dispatching ninety-nine bombers to attack railway centers and supply depots in the Ruhr. Busy with the Battle of France, Hitler did not immediately strike back, but he issued a directive that prepared the way. He ordered the Luftwaffe “to undertake a full-scale offensive against the British homeland as soon as sufficient forces are available.”1348
The initial German air attack, the Battle of Britain, began in mid-August: a month of ferocious daylight contests between the Luftwaffe and British Fighter Command for air supremacy in advance of Operation Sea
Lion, Germany’s planned cross-Channel invasion. It was not yet an attack on cities. British airfields and aircraft factories were primary targets. Hitler had reserved for himself the decision to bomb London, just as the Kaiser had done before him.1349 Cities would soon go on the targeting list, however; the Luftwaffe was scheduled to raid Liverpool at night on August 28. Accident again intervened: German bombers aiming for oil storage tanks along the Thames overflew their targets on August 24 and bombed central London instead.
Churchill immediately retaliated, hurling four bombing raids in one week at Berlin. They accomplished little physical damage but incited Hitler to hysterical revenge:
And if the British air force drops two or three or four thousand kilograms of bombs, then we will drop in a single night 150,000, 180,000, 230,000, 300,000, 400,000, a million kilograms. If they announce that they will attack our cities on a large scale, then we shall wipe their cities out!1350
The Luftwaffe was losing the Battle of Britain in any case, taking unacceptable losses—some 1,700 German aircraft compared to about 900 British. Night bombing would alleviate the losses, curtaining the bombers in dark asylum. But night bombing was notably less accurate than daylight bombing in those days before effective radar and required correspondingly larger targets. Cities and their civilian populations thus fell victim partly by default, because the technology necessary for more accurate targeting was not yet at hand. In any case terror was a weapon that Hitler especially prized, the destruction of what he called the enemy’s “will-to-resist,” and early in September he told his Sea Lion planners that “a systematic and long-drawn-out bombardment of London might produce an attitude in the enemy which will make Sea Lion unnecessary.”1351, 1352 He ordered the bombardment. Since it rained from the skies for months, it was hardly Blitzkrieg, lightning war, but the citizens exposed beneath it were not in the mood for fine distinctions, and they soon named it the Blitz.
Making of the Atomic Bomb Page 47