"The Making of the Atomic Bomb"
Dec. 7th, 2021 10:33 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
fiefoeThe bombing parts are hard to get through. I must have read the story about sabotaging the Norway heavy water factory when I was very young.
The Fermis could not sell their household goods or entirely empty their savings account without risking discovery. So the money from the Nobel Prize would be a godsend. <> In the meantime they invested surreptitiously in what Fermi called “the refugee’s trousseau.” Laura’s new coat was beaver and they distracted themselves on the day of the Stockholm call shopping for expensive watches.
Two hundred million electron volts is not a large amount of energy, but it is an extremely large amount of energy from one atom. The most energetic chemical reactions release about 5 eV per atom. Ernest Lawrence was that year building a cyclotron with a nearly 200-ton magnet with which he hoped to accelerate particles by as much as 25 MeV. Frisch would calculate later that the energy from each bursting uranium nucleus would be sufficient to make a visible grain of sand visibly jump.
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Which meant that U235 had an inherent energetic advantage over its two competitors: it accrued energy toward fission simply by virtue of its change of mass; they did not.
Lise Meitner and Otto Frisch had realized in Kungälv that a certain amount of energy was necessary to agitate the nucleus to fission, but they had not considered in detail the energetics of that input. They were distracted by the enormous 200 MeV output. In fact, the uranium nucleus required an input of about 6 MeV to fission. That much energy was necessary to roil the nucleus to the point where it elongated and broke apart. The absorption of any neutron, regardless of its velocity, made available a binding energy of about 5.3 MeV. But that left U238 about 1 MeV short, which is why it needed fast neutrons of at least that threshold energy before it could fission.
U235 also earned 5.3 MeV when it absorbed a neutron. But it won Fermi’s “one or two MeV” in addition simply by adjusting from an odd to an even mass. That put its total above 6 MeV. So any neutron at all would fission U235—slow, fast or in between.
Natural uranium masked U235’s continuous fissibility; the more abundant U238 captured most of the neutrons. Only by slowing the neutrons with paraffin below the U238 capture resonance at 25 eV had experimenters like Hahn, Strassmann and Frisch been able to coax the highly fissionable U235 out of hiding.
At close quarters, Einstein’s head was as I had imagined it: magnificent, with a humanizing touch of the comic.
Sachs heard Szilard out. Then, as Szilard wrote Einstein, he “took the position, and completely convinced me, that these were matters which first and foremost concerned the White House and that the best thing to do, also from the practical point of view, was to inform Roosevelt. He said that if we gave him a statement he would make sure it reached Roosevelt in person.”
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Genia Peierls, who was Russian, took the bachelor Austrian in hand. She “ran her house,” writes Frisch, “with cheerful intelligence, a ringing Manchester voice and a Russian’s sovereign disregard of the definite article. She taught me to shave every day and to dry dishes as fast as she washed them, a skill that has come in useful many times since.”
Thus in the first months of 1940 it was already clear to two intelligent observers that nuclear weapons would be weapons of mass destruction against which the only apparent defense would be the deterrent effect of mutual possession. <> Frisch and Peierls finished their two reports and took them to Oliphant.
Allier slipped into Oslo under an assumed name and met with the general manager of Norsk Hydro at the beginning of March. The French officer was prepared to pay up to 1.5 million kroner for the water and even to leave half for the Germans, but once the Norwegian heard what military purpose the substance might serve he volunteered his entire stock and refused payment. The water, divided among twenty-six cans, left Vemork by car soon afterward on a dark midnight. From Oslo Allier’s team flew it to Edinburgh in two loads—German fighters forced down for inspection a decoy plane Allier had pretended to board at the time of the first loading—and then transported it by rail and Channel ferry to Paris, where Joliot prepared through the winter and spring of the phony war to use it in both homogeneous and heterogeneous uranium-oxide experiments.
Exporting gold from Germany was a serious criminal offense and their names were engraved on the medals.1291, 1292 George de Hevesy devised an effective solution—literally: he dissolved the medals separately in acid. As solutions of black liquid in unmarked jars they sat out the war innocently on a laboratory shelf. Afterward the Nobel Foundation recast them and returned them to their owners.
Germany had access to the world’s only heavy-water factory and to thousands of tons of uranium ore in Belgium and the Belgian Congo. It had chemical plants second to none and competent physicists, chemists and engineers . It lacked only a cyclotron for measuring nuclear constants. The Fall of France—Paris was occupied June 14, an armistice signed June 22—filled that need.
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In 1920, at twenty-seven, when Conant was courting the woman he would marry—she was the only child of the Nobel laureate Harvard chemist T. W. Richards, a pioneer in measuring atomic weights—he had shared hopes for a grand future with her that coming from a less able man might have sounded absurd. “I said that I had three ambitions. The first was to become the leading organic chemist in the United States; after that I would like to be president of Harvard; and after that, a Cabinet member, perhaps Secretary of the Interior.”1406 Those may not seem conjoint ambitions, but Conant managed a version of each in turn.
Houtermans emphasized making 94. “Every neutron which, instead of fissioning uranium-235, is captured by uranium-238,” he wrote, “creates in this way a new nucleus, fissionable by thermal neutrons.”1451 He discussed his ideas privately with von Weizsäcker and Heisenberg, but he saw to it that the Post Office kept his report in its safe secure from War Office eyes. He had learned to cooperate for survival in the Soviet Union, where the NKVD—the KGB of its day—had knocked out all his teeth and kept him in solitary confinement for months. But in Germany as in the USSR he withheld as much information as he dared. His private endorsement of 94, to be transmuted by chain reaction from natural uranium, probably contributed to the neglect of isotope separation in Germany.
Oliphant convinced Lawrence, Lawrence convinced Compton, Kistiakowsky convinced Conant. Conant says Compton’s and Lawrence’s attitudes “counted heavily with Bush.” But “more significant” was the MAUD Report, which G. P. Thomson, now British scientific liaison officer in Ottawa, officially transmitted to Conant on October 3.
And deeper even than fear was fatalism. The bomb was latent in nature as a genome is latent in flesh. Any nation might learn to command its expression. The race was therefore not merely against Germany. As Roosevelt apparently sensed, the race was against time. <> There are indications in Bush’s memorandum that Roosevelt was concerned less with a German challenge than with the long-term consequences of acquiring so decisive a new class of destructive instruments.
He “saw himself confronted with the spectre of the atomic bomb,” Elisabeth Heisenberg explains, “and he wanted to signal to Bohr that Germany neither would nor could build a bomb. . . . Secretly he even hoped that his message could prevent the use of an atomic bomb on Germany one day.
Elisabeth Heisenberg thinks “Bohr essentially heard only one single sentence: The Germans knew that atomic bombs could be built. He was deeply shaken by this, and his consternation was so great that he lost track of all else.”1508 But Aage Bohr’s and Oppenheimer’s accounts imply a further response from Bohr: indignation, even incredulity, that Heisenberg would think Bohr might be willing in any way, for any reason, to cooperate with Nazi Germany. Heisenberg, in turn, was aghast that Bohr would fail to see and credit his reservations, would not understand, as his wife writes, that his “bond to his country and its people was not tantamount to a bond to the regime.”
“Tiger!” three times invoked to announce to the listening Japanese Navy that his first wave of 183 planes had achieved complete surprise. The 43 fighters, 49 high-level bombers, 51 dive-bombers and 40 torpedo planes he commanded had flown from six carriers holding station 200 miles to the north, carriers formidably escorted by battleships, heavy cruisers, destroyers and submarines that had left Hitokappu Bay on the northern Japanese island of Etorofu on November 25 and sailed blacked out in radio silence across the stormy but empty northern Pacific for almost two weeks to achieve this stunning rendezvous.
The manufacturer did better. Realizing the weapons were vital to a secret program of unprecedented importance, manager Yukiro Fukuda bent company rules, drove his lathe and assembly crews overtime and delivered the last of the 180 specially modified torpedoes by November 17. Mitsubishi Munitions contributed decisively to the success of the first massive surprise blow of the Pacific War by the patriotic effort of its torpedo factory on Kyushu, the southernmost Japanese island, three miles up the Urakami River from the bay in the old port city of Nagasaki.
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To help Fermi without the friction the two men generated when they worked side by side, Szilard undertook to apply his special talent for enlightened cajolery to the problem of procuring supplies of purified uranium and graphite. The record is thick with his correspondence with American graphite manufacturers dismayed to discover that what they thought were the purest of materials were in fact hopelessly contaminated, usually with traces of boron.
Fermi named the structure a “pile.” “Much of the standard nomenclature in nuclear science was developed at this time,” Segrè writes.1536 “ . . . I thought for a while that this term was used to refer to a source of nuclear energy in analogy with Volta’s use of the Italian term pila to denote his own great invention of a source of electrical energy [i.e., the Voltaic battery]. I was disillusioned by Fermi himself, who told me that he simply used the common English word pile as synonymous with heap”.
The academic physicists were happy to be out from under the Army but chagrined to be consigned to a backwater ministry run by a party hack. Rust delegated authority to the Reich Research Council. That organization was part of the Reich Bureau of Standards. The KWI physicists considered its physics section head, Abraham Esau, incompetent. In effect, the German uranium program had slipped in status to the level of the old U.S. Uranium Committee and now had its Briggs.
With the special tools of ultramicrochemistry the young chemists could work on undiluted quantities of chemicals as slight as tenths of a microgram... The first balance the chemists used consisted of a single quartz fiber fixed at one end like a fishing pole stuck into a riverbank inside a glass housing that protected it from the least breath of air. To weigh their Lilliputian quantities of material they hung a weighing pan, made of a snippet of platinum foil that was itself almost too small to see, to the free end of the quartz fiber and measured how much the fiber bent, a deflection which was calibrated against standard weights. A more rugged balance developed at Berkeley had double pans suspended from opposite ends of a quartz-fiber beam strung with microscopic struts. “It was said,” notes Seaborg, “that ‘invisible material was being weighed with an invisible balance.’ ”
In draft and more moderately in finished form his examination by turns compliments and savages Compton’s leadership: “In talking to Compton I frequently have the feeling that I am overplaying a delicate instrument.”1642, 1643 Beyond personality Szilard pointed to a destructive abdication by those whom Compton led: “I have often thought . . . that things would have been different if Compton’s authority had actually originated with our group, rather than with the OSRD.”
was there sufficient uranium on hand? Nichols told him about a recent and fortuitous discovery: some 1,250 tons of extraordinarily rich pitchblende—it was 65 percent uranium oxide—that the Union Minière had shipped to the United States in 1940 from its Shinkolobwe mine in the Belgian Congo to remove it beyond German reach. Frédéric Joliot and Henry Tizard had independently warned the Belgians of the German danger in 1939. The ore was stored in the open in two thousand steel drums at Port Richmond on Staten Island. The Belgians had been trying for six months to alert the U.S. government to its presence.
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The Norwegians moved out fast. They had descended to the river before the sirens began to sound.
The operation was successful. No one was injured on either side. All eighteen cells had been blown open, spilling nearly half a ton of heavy water into the drains. Not only would the plant require weeks to repair; because it was a cascade, pumping water of increasing deuterium concentration from one cell to the next, it would need almost a year of operation after repair simply to reach equilibrium again on its own and begin producing. General Nikolaus von Falkenhorst, the commander in chief of the occupying German Army in Norway, called the Vemork attack “the best coup I have ever seen.”
The shock wave from that explosion would squeeze the tamper from all sides, which in turn would squeeze the core. Squeezing the core would change its geometry from hollow shell to solid ball. What had been subcritical because of its geometry would be squeezed critical far faster and more efficiently than any mere gun could fire. “The gun will compress in one dimension,” Manley remembers Neddermeyer telling them. “Two dimensions would be better. Three dimensions would be better still.”
A three-dimensional squeeze inward was implosion. Neddermeyer had just defined a possible new way to fire an atomic bomb.
But Oppenheimer had been wrong before—even about the possibility of fission when Luis Alvarez dropped by to report it in 1939, wrong for the fifteen minutes it took him to think past the stubbornness with which he rejected any possibility he had not himself foreseen. Apparently he was learning to steer by that gruding incredulity as Bohr steered by the madness of a truly original idea.
Pathfinder bombers used radar to aid marking, and the initial Hamburg aiming point was chosen not for its strategic significance but for its distinctive radar reflection: a triangle of land at the junction of the Alster and North Elbe rivers, near the oldest part of the city and far from any war industry. Bomber Command had learned to adjust targeting for creep-back, the tendency of bombardiers to release their bombs as quickly as possible upon approaching the flak-infested aiming point that led to a gradual backup of impacts. From the ground the bombs seemed to unroll in the direction of the bomber stream’s approach; survivors named the phenomenon “carpet bombing.”
Small fires had coalesced into larger fires and, greedy for oxygen, had sucked air from around the coalescing inferno and fanned further fires there. That created the wind, a thermal column above the city like an invisible chimney above a hearth; the wind heated the fury at the center of the firestorm to more than 1,400 degrees, heat sufficient to melt the windows of a streetcar, wind sufficient to uproot trees.
We got to the Löschplatz [park] all right but I couldn’t go on across the Eiffestrasse because the asphalt had melted. There were people on the roadway, some already dead, some still lying alive but stuck in the asphalt. They must have rushed on to the roadway without thinking. Their feet had got stuck and then they had put out their hands to try to get out again. They were on their hands and knees screaming.
Women and children were so charred as to be unrecognizable; those that had died through lack of oxygen were half-charred and recognizable. Their brains had tumbled from their burst temples and their insides from the soft parts under the ribs. How terribly these people must have died. The smallest children lay like fried eels on the pavement.1831
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“At one point in the negotiations,” writes Groves, “Nichols . . . said that they would need between five and ten thousand tons of silver. This led to the icy reply: ‘Colonel, in the Treasury we do not speak of tons of silver; our unit is the Troy ounce.’ ”1879 Eventually 395 million troy ounces of silver—13,540 short tons—went off from the West Point Depository to be cast into cylindrical billets, rolled into 40-foot strips and wound onto iron cores at Allis-Chalmers in Milwaukee. Solid-silver bus bars a square foot in cross section crowned each racetrack’s long oval. The silver was worth more than $300 million. Groves accounted for it ounce by ounce, almost as carefully as he accounted for the fissionable isotope it helped separate.
Hex attacked organic materials ferociously: not a speck of grease could be allowed to ooze into the gas stream anywhere along the miles and miles of pipes and pumps and barriers. Pump seals therefore had to be devised that were both gastight and greaseless, a puzzle no one had ever solved before that required the development of new kinds of plastics. (The seal material that eventually served at Oak Ridge came into its own after the war under the brand name Teflon.) A single pinhole leak anywhere in the miles of pipes would confound the entire system; Alfred O. Nier developed portable mass spectrometers to serve as subtle leak detectors. Since pipes of solid nickel would exhaust the entire U.S. production of that valuable resource, Groves found a company willing to nickel-plate all the pipe interiors, a difficult new process accomplished by filling the pipes themselves with plating solution and rotating them as the plating current did its work.
He apparently equated disagreement with disloyalty and scaled the ratio of the two conditions directly: anyone who caused him as much pain as Leo Szilard must be a spy. It followed that he ought to be watched.
The surveillance of an innocent but eccentric man makes gumshoe comedy. Szilard traveled to Washington on June 20, 1943, and in preparation for the visit an Army counterintelligence agent reviewed his file:
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Bohr considered the question in the following perspective. Tell the Soviet Union soon, before the first bombs were nearly built, that a bomb project was under way, and the confidence might lead to negotiations on postwar arms control. Let the Soviet Union discover the information on its own, build the bombs and drop them, oppose the Soviets at the end of the war with an Anglo-American nuclear monopoly, and the likeliest outcome was a nuclear arms race.
Bohr’s revelation of the complementarity of the bomb was far more fundamental than this contemporary political question. But the contemporary political question was an aspect of the larger issue and partly obscured it from view. The bomb was opportunity and threat and would always be opportunity and threat—that was the peculiar, paradoxical hopefulness. But political conditions would necessarily differ before and after it was deployed.
Bohr, who used to say that accuracy and clarity were complementary (and so a short statement could never be precise), was not easy to hear, and all that Churchill seemed to gather was that he was worried about the likely state of the post-war world and that he wanted to tell the Russians about the progress towards the bomb. As regards the post-war world Churchill told him: “I cannot see what you are talking about. After all this new bomb is just going to be bigger than our present bombs. It involves no difference in the principles of war. And as for any post-war problems there are none that cannot be amicably settled between me and my friend, President Roosevelt.”
Bohr had searched the forbidding territory of the atom when he was young and discovered multiple structures of paradox; now he searched it again by the dark light of the energy it released and discovered profound political change.
Nations existed in a condition of international anarchy. No hierarchical authority defined their relations with one another. They negotiated voluntarily as self-interest moved them and took what they could get. War had been their final negotiation, brutally resolving their worst disputes.
Now an ultimate power had appeared. If Churchill failed to recognize it he did so because it was not a battle cry or a treaty or a committee of men. It was more like a god descending to the stage in a gilded car.
By the necessity, commonly understood, to avoid triggering a nuclear holocaust, the deus ex machina would have accomplished then what men and nations had been unable to accomplish by negotiation or by conquest: the abolition of major war. Total security would be indistinguishable from total insecurity. A menacing standoff would be maintained suspiciously, precariously, at the brink of annihilation.
“It appeared to me,” Bohr wrote in 1950 of his lonely wartime initiative, “that the very necessity of a concerted effort to forestall such ominous threats to civilization would offer quite unique opportunities to bridge international divergencies.”2026 That, in a single sentence, was the revelation of the complementarity of the bomb.
A shaped charge is a charge of high explosive arranged in such a way—usually hollowed out like an empty ice cream cone with the open end pointed forward—that its normally divergent, bubble-shaped shock wave converges into a high-speed jet. Such a ferocious jet can punch its way through the thick armor of a tank to spray death inside.
It had just become clear from theoretical work that the several diverging shock waves produced by multiple detonators in Neddermeyer’s experiments reinforced each other where they collided and produced points of high pressure; such pressure nodes in turn caused the jets and irregularities that spoiled the implosion. Rather than continue trying to smooth out a colliding collection of divergent shock waves, Tuck sensibly proposed that the laboratory consider designing an arrangement of explosives that would produce a converging wave to begin with, fitting the shock wave to the shape it needed to squeeze. Such explosive arrangements were called lenses by analogy with optical lenses that similarly focus light.
“It appears reasonable,” Oppenheimer ended, “to discontinue the intensive effort to achieve higher purity for plutonium and to concentrate’ attention on methods of assembly which do not require a low neutron background for their success. At the present time the method to which an over-riding priority must be assigned is the method of implosion.”2081
That necessity was painful, as the Los Alamos technical history makes clear: “The implosion was the only real hope, and from current evidence not a very good one.”
Like his colleagues Oppenheimer had considered only those processes that enriched natural uranium all the way up to bomb grade, a requirement thermal diffusion could not efficiently meet. Now he realized that Abelson’s process offered a valuable alternative, the alternative Abelson had proposed in his report to help Chicago advance its pile work: slight enrichment of larger quantities... “Dr. Oppenheimer . . . suddenly told me that we had [made] a terrible scientific blunder,” Groves testified after the war.2095 “I think he was right. It is one of the things that I regret the most in the whole course of the operation. We had failed to consider [thermal diffusion] as a portion of the process as a whole.” From the beginning the leaders of the Manhattan Project had thought of the several enrichment and separation processes as competing horses in a race. That had blinded them to the possibility of harnessing the processes together.
The Alpha calutrons smeared uranium all over the insides of their vacuum tanks, catching no more than 4 percent of the U235; that valuable fraction, reprocessed and fed into the Beta calutrons, reached the Beta collectors in turn at only 5 percent efficiency. Five percent of 4 percent is two thousandths. A speck of U235 stuck to an operator’s coveralls was well worth searching out with a Geiger counter and retrieving delicately with tweezers. No essence was ever expressed more expensively from the substance of the world with the possible exception of the human soul.
The surf ran red with their blood; so many broken bodies floated in the water that Navy craft overrode them to rescue. Not all the dead had volunteered their sacrifice; many had been rallied, pushed or shot by Japanese soldiers.
The mass suicide on Saipan—a Jonestown of its day—instructed Americans further in the nature of the Jap.
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Long after mother and daughter had been persuaded from the sidelines Fermi sat unbudging, mentally working out the steps. When he was ready he asked Bernice Brode, one of the leaders, to be his partner. “He offered to be head couple, which I thought most unwise for his first venture, but I couldn’t do anything about it and the music began. He led me out on the exact beat, knew exactly each move to make and when. He never made a mistake, then or thereafter, but I wouldn’t say he enjoyed himself. . . . He [danced] with his brains instead of his feet.”
Oppenheimer coded the test and the test site Trinity... There is a poem of John Donne, written just before his death, which I know and love. From it a quotation:
As West and East
In all flatt Maps—and I am one—are one,
So death doth touch the Resurrection.”
The poem was Donne’s “Hymne to God My God, in My Sicknesse,” and among its subtleties it construes a complementarity that parallels the complementarity of the bomb that Bohr had recently revealed to Oppenheimer.
Oppenheimer did not doubt that he would be remembered to some degree, and reviled, as the man who led the work of bringing to mankind for the first time in its history the means of its own destruction.2154 He cherished the complementary compensation of knowing that the hard riddle the bomb would pose had two answers, two outcomes, one of them transcendent. Such understanding justified the work at Los Alamos if anything did, and the work in turn healed the split between self and overweening conscience that hurt him... At Los Alamos, if only for a time, he located that detachment in duties to men and to the commonwealth that Bohr was teaching him to believe might be worthy, not macabre. He was not the first man to find himself in war.
The implosion lens system von Neumann designed was made up of truncated pyramidal blocks about the size of car batteries...
The fast-burning outer layer functioned for the detonation wave as air around an optical lens functions for light. The slower-burning shaped inclusion functioned as a magnifying glass, directing and reshaping the wave. A detonator would ignite the fast-burning explosive. That material would develop a spherical detonation wave. When the apex of the wave advanced into the apex of the inclusion, however, it would begin burning more slowly. The delay would give the rest of the wave time to catch up. As the detonation wave encountered and burned through the inclusion it thus reshaped itself from convex to concave, from a spherical wave expanding from a point to a spherical wave converging on a point, emerging fitted to the convex curve of the spherical tamper.
Thomas shipped the Po on platinum foil in sealed containers, but another nasty characteristic of polonium caused shipping troubles: for reasons never satisfactorily explained by experiment, the metal migrates from place to place and can quickly contaminate large areas. “This isotope has been observed to migrate upstream against a current of air,” notes a postwar British report on polonium, “and to translocate under conditions where it would appear to be doing so of its own accord.”
Thus checked out, Major General Curtis LeMay rode a C-54 to India late in August to take over the 20th Bomber Command, based in India with forward airfields in China from which it was attempting with fewer than two hundred B-29’s to bomb Japan. The bombers had to ferry their own fuel and ordnance from India to China over the Himalayas before each mission—seven supply flights for each bombing strike, up to twelve gallons burned for each one gallon delivered. “It didn’t work,” LeMay writes in his autobiography. “No one could have made it work. It was founded on an utterly absurd logistic basis. Nevertheless, our entire Nation howled like a pack of wolves for an attack on the Japanese homeland.”
The progress and destructive features of the conflagration were consequently much greater than those of [a] fire storm, for the fire continued to spread until it could reach no more material. . . . The 28-mile-per-hour wind, measured a mile from the fire, increased to an estimated 55 miles at the perimeter, and probably more within.2229 An extended fire swept over 15 square miles in 6 hours. Pilots reported that the air was so violent that B-29s at 6,000 feet were turned completely over, and that the heat was so intense, even at that altitude, that the entire crew had to don oxygen masks.
Bertrand Goldschmidt, the French chemist who worked with Glenn Seaborg, puts the Manhattan Engineer District at the height of its wartime development in perspective with a startling comparison. It was, he writes in a memoir, “the astonishing American creation in three years, at a cost of two billion dollars, of a formidable array of factories and laboratories—as large as the entire automobile industry of the United States at that date.”
Why he failed to confront the issue himself until late 1943, when George Marshall asked him directly to do so, he chooses not to say. One reason was certainly security, a Groves obsession; in order to know what to look for, intelligence agents would have to be briefed on at least isotope-separation technologies and nuclear-fission research, which would mean that any agent captured or turned might well give American secrets away.
But it was impossible to assemble a complete critical mass by stacking bars; such an assembly would run away, kill its sponsors with radiation and melt down. Frisch nearly caused a runaway reaction one day by leaning too close to a naked assembly—he called it a Lady Godiva—that was just subcritical, allowing the hydrogen in his body to reflect back neutrons.
The idea was that the compound of uranium-235, which by then had arrived on the site, enough to make an explosive device, should indeed be assembled to make one, but leaving a big hole so that the central portion was missing; that would allow enough neutrons to escape so that no chain reaction could develop.2263 But the missing portion was to be made, ready to be dropped through the hole so that for a split second there was the condition for an atomic explosion, although only barely so.
Brilliant young Richard Feynman laughed when he heard Frisch’s plan and named it: he said it would be like tickling the tail of a sleeping dragon.2264 The Dragon experiment it became.
It was Robert Oppenheimer at his best:
We have been living through years of great evil, and of great terror. Roosevelt has been our President, our Commander-in-Chief and, in an old and unperverted sense, our leader. All over the world men have looked to him for guidance, and have seen symbolized in him their hope that the evils of this time would not be repeated; that the terrible sacrifices which have been made, and those that are still to be made, would lead to a world more fit for human habitation. . . .
In the Hindu scripture, in the Bhagavad-Gita, it says, “Man is a creature whose substance is faith. What his faith is, he is.” The faith of Roosevelt is one that is shared by millions of men and women in every country of the world. For this reason it is possible to maintain the hope, for this reason it is right that we should dedicate ourselves to the hope, that his good works will not have ended with his death.
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He spoke to the newly sworn President following the brief cabinet meeting Truman called after taking the oath of office on the evening of the day Roosevelt died. “Stimson told me,” Truman reports in his memoirs, “that he wanted me to know about an immense project that was under way—a project looking to the development of a new explosive of almost unbelievable destructive power. That was all he felt free to say at the time, and his statement left me puzzled. It was the first bit of information that had come to me about the atomic bomb,
Truman assayed the South Carolinian most shrewdly a few months after their April discussion in a private diary he intermittently kept:
Had a long talk with my able and conniving Secretary of State. My but he has a keen mind! And he is an honest man. But all country politicians are alike. They are sure all other politicians are circuitous in their dealings. When they are told the straight truth, unvarnished, it is never believed—an asset sometimes.2278
A politician’s politician, Byrnes
"When other countries acquired nuclear weapons, as they would in “just a few years,” that advantage would be lost: “Perhaps the greatest immediate danger which faces us is the probability that our ‘demonstration’ of atomic bombs will precipitate a race in the production of these devices between the United States and Russia.”... But Szilard echoed Bohr in pleading for what no one among the national leaders concerned with the problem seemed able to grasp, that “these decisions ought to be based not on the present evidence relating to atomic bombs, but rather on the situation which can be expected to confront us in this respect a few years from now.” By present evidence the bombs were modest and the United States held them in monopoly; the difficulty was deciding what the future would bring.
LeMay was also keeping busy. “The 3 reserved targets for the first unit of this project were announced. With current and prospective rate of [Twentieth Air Force] H.E. bombing, it is expected to complete strategic bombing of Japan by 1 Jan 46 so availability of future targets will be a problem.” If the Manhattan Project did not hurry, that is, there would be no cities left in Japan to bomb.
Completely filing off the blisters would expose the plutonium. The metallurgists salvaged the castings by grinding only partway through the blisters and smoothing the bumpy fit with sheets of gold foil. The core of the first atomic bomb would go to its glory dressed in improvised offerings of nickel and gold.
Teller passed the lotion around and the strange prophylaxis disturbed one observer: “It was an eerie sight to see a number of our highest-ranking scientists seriously rubbing sunburn lotion on their faces and hands in the pitch-blackness of the night, twenty miles from the expected flash.”
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__ Truman reports his Berlin tour:...
I thought of Carthage, Baalbec, Jerusalem, Rome, Atlantis; Peking, Babylon, Nineveh; Scipio, Rameses II, Titus, Hermann, Sherman, Jenghis Khan, Alexander, Darius the Great. But Hitler only destroyed Stalingrad—and Berlin. I hope for some sort of peace—but I fear that machines are ahead of morals by some centuries and when morals catch up perhaps there’ll be no reason for any of it.
I hope not. But we are only termites on a planet and maybe when we bore too deeply into the planet there’ll be a reckoning—who knows?
The Fermis could not sell their household goods or entirely empty their savings account without risking discovery. So the money from the Nobel Prize would be a godsend. <> In the meantime they invested surreptitiously in what Fermi called “the refugee’s trousseau.” Laura’s new coat was beaver and they distracted themselves on the day of the Stockholm call shopping for expensive watches.
Two hundred million electron volts is not a large amount of energy, but it is an extremely large amount of energy from one atom. The most energetic chemical reactions release about 5 eV per atom. Ernest Lawrence was that year building a cyclotron with a nearly 200-ton magnet with which he hoped to accelerate particles by as much as 25 MeV. Frisch would calculate later that the energy from each bursting uranium nucleus would be sufficient to make a visible grain of sand visibly jump.
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Which meant that U235 had an inherent energetic advantage over its two competitors: it accrued energy toward fission simply by virtue of its change of mass; they did not.
Lise Meitner and Otto Frisch had realized in Kungälv that a certain amount of energy was necessary to agitate the nucleus to fission, but they had not considered in detail the energetics of that input. They were distracted by the enormous 200 MeV output. In fact, the uranium nucleus required an input of about 6 MeV to fission. That much energy was necessary to roil the nucleus to the point where it elongated and broke apart. The absorption of any neutron, regardless of its velocity, made available a binding energy of about 5.3 MeV. But that left U238 about 1 MeV short, which is why it needed fast neutrons of at least that threshold energy before it could fission.
U235 also earned 5.3 MeV when it absorbed a neutron. But it won Fermi’s “one or two MeV” in addition simply by adjusting from an odd to an even mass. That put its total above 6 MeV. So any neutron at all would fission U235—slow, fast or in between.
Natural uranium masked U235’s continuous fissibility; the more abundant U238 captured most of the neutrons. Only by slowing the neutrons with paraffin below the U238 capture resonance at 25 eV had experimenters like Hahn, Strassmann and Frisch been able to coax the highly fissionable U235 out of hiding.
At close quarters, Einstein’s head was as I had imagined it: magnificent, with a humanizing touch of the comic.
Sachs heard Szilard out. Then, as Szilard wrote Einstein, he “took the position, and completely convinced me, that these were matters which first and foremost concerned the White House and that the best thing to do, also from the practical point of view, was to inform Roosevelt. He said that if we gave him a statement he would make sure it reached Roosevelt in person.”
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Genia Peierls, who was Russian, took the bachelor Austrian in hand. She “ran her house,” writes Frisch, “with cheerful intelligence, a ringing Manchester voice and a Russian’s sovereign disregard of the definite article. She taught me to shave every day and to dry dishes as fast as she washed them, a skill that has come in useful many times since.”
Thus in the first months of 1940 it was already clear to two intelligent observers that nuclear weapons would be weapons of mass destruction against which the only apparent defense would be the deterrent effect of mutual possession. <> Frisch and Peierls finished their two reports and took them to Oliphant.
Allier slipped into Oslo under an assumed name and met with the general manager of Norsk Hydro at the beginning of March. The French officer was prepared to pay up to 1.5 million kroner for the water and even to leave half for the Germans, but once the Norwegian heard what military purpose the substance might serve he volunteered his entire stock and refused payment. The water, divided among twenty-six cans, left Vemork by car soon afterward on a dark midnight. From Oslo Allier’s team flew it to Edinburgh in two loads—German fighters forced down for inspection a decoy plane Allier had pretended to board at the time of the first loading—and then transported it by rail and Channel ferry to Paris, where Joliot prepared through the winter and spring of the phony war to use it in both homogeneous and heterogeneous uranium-oxide experiments.
Exporting gold from Germany was a serious criminal offense and their names were engraved on the medals.1291, 1292 George de Hevesy devised an effective solution—literally: he dissolved the medals separately in acid. As solutions of black liquid in unmarked jars they sat out the war innocently on a laboratory shelf. Afterward the Nobel Foundation recast them and returned them to their owners.
Germany had access to the world’s only heavy-water factory and to thousands of tons of uranium ore in Belgium and the Belgian Congo. It had chemical plants second to none and competent physicists, chemists and engineers . It lacked only a cyclotron for measuring nuclear constants. The Fall of France—Paris was occupied June 14, an armistice signed June 22—filled that need.
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In 1920, at twenty-seven, when Conant was courting the woman he would marry—she was the only child of the Nobel laureate Harvard chemist T. W. Richards, a pioneer in measuring atomic weights—he had shared hopes for a grand future with her that coming from a less able man might have sounded absurd. “I said that I had three ambitions. The first was to become the leading organic chemist in the United States; after that I would like to be president of Harvard; and after that, a Cabinet member, perhaps Secretary of the Interior.”1406 Those may not seem conjoint ambitions, but Conant managed a version of each in turn.
Houtermans emphasized making 94. “Every neutron which, instead of fissioning uranium-235, is captured by uranium-238,” he wrote, “creates in this way a new nucleus, fissionable by thermal neutrons.”1451 He discussed his ideas privately with von Weizsäcker and Heisenberg, but he saw to it that the Post Office kept his report in its safe secure from War Office eyes. He had learned to cooperate for survival in the Soviet Union, where the NKVD—the KGB of its day—had knocked out all his teeth and kept him in solitary confinement for months. But in Germany as in the USSR he withheld as much information as he dared. His private endorsement of 94, to be transmuted by chain reaction from natural uranium, probably contributed to the neglect of isotope separation in Germany.
Oliphant convinced Lawrence, Lawrence convinced Compton, Kistiakowsky convinced Conant. Conant says Compton’s and Lawrence’s attitudes “counted heavily with Bush.” But “more significant” was the MAUD Report, which G. P. Thomson, now British scientific liaison officer in Ottawa, officially transmitted to Conant on October 3.
And deeper even than fear was fatalism. The bomb was latent in nature as a genome is latent in flesh. Any nation might learn to command its expression. The race was therefore not merely against Germany. As Roosevelt apparently sensed, the race was against time. <> There are indications in Bush’s memorandum that Roosevelt was concerned less with a German challenge than with the long-term consequences of acquiring so decisive a new class of destructive instruments.
He “saw himself confronted with the spectre of the atomic bomb,” Elisabeth Heisenberg explains, “and he wanted to signal to Bohr that Germany neither would nor could build a bomb. . . . Secretly he even hoped that his message could prevent the use of an atomic bomb on Germany one day.
Elisabeth Heisenberg thinks “Bohr essentially heard only one single sentence: The Germans knew that atomic bombs could be built. He was deeply shaken by this, and his consternation was so great that he lost track of all else.”1508 But Aage Bohr’s and Oppenheimer’s accounts imply a further response from Bohr: indignation, even incredulity, that Heisenberg would think Bohr might be willing in any way, for any reason, to cooperate with Nazi Germany. Heisenberg, in turn, was aghast that Bohr would fail to see and credit his reservations, would not understand, as his wife writes, that his “bond to his country and its people was not tantamount to a bond to the regime.”
“Tiger!” three times invoked to announce to the listening Japanese Navy that his first wave of 183 planes had achieved complete surprise. The 43 fighters, 49 high-level bombers, 51 dive-bombers and 40 torpedo planes he commanded had flown from six carriers holding station 200 miles to the north, carriers formidably escorted by battleships, heavy cruisers, destroyers and submarines that had left Hitokappu Bay on the northern Japanese island of Etorofu on November 25 and sailed blacked out in radio silence across the stormy but empty northern Pacific for almost two weeks to achieve this stunning rendezvous.
The manufacturer did better. Realizing the weapons were vital to a secret program of unprecedented importance, manager Yukiro Fukuda bent company rules, drove his lathe and assembly crews overtime and delivered the last of the 180 specially modified torpedoes by November 17. Mitsubishi Munitions contributed decisively to the success of the first massive surprise blow of the Pacific War by the patriotic effort of its torpedo factory on Kyushu, the southernmost Japanese island, three miles up the Urakami River from the bay in the old port city of Nagasaki.
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To help Fermi without the friction the two men generated when they worked side by side, Szilard undertook to apply his special talent for enlightened cajolery to the problem of procuring supplies of purified uranium and graphite. The record is thick with his correspondence with American graphite manufacturers dismayed to discover that what they thought were the purest of materials were in fact hopelessly contaminated, usually with traces of boron.
Fermi named the structure a “pile.” “Much of the standard nomenclature in nuclear science was developed at this time,” Segrè writes.1536 “ . . . I thought for a while that this term was used to refer to a source of nuclear energy in analogy with Volta’s use of the Italian term pila to denote his own great invention of a source of electrical energy [i.e., the Voltaic battery]. I was disillusioned by Fermi himself, who told me that he simply used the common English word pile as synonymous with heap”.
The academic physicists were happy to be out from under the Army but chagrined to be consigned to a backwater ministry run by a party hack. Rust delegated authority to the Reich Research Council. That organization was part of the Reich Bureau of Standards. The KWI physicists considered its physics section head, Abraham Esau, incompetent. In effect, the German uranium program had slipped in status to the level of the old U.S. Uranium Committee and now had its Briggs.
With the special tools of ultramicrochemistry the young chemists could work on undiluted quantities of chemicals as slight as tenths of a microgram... The first balance the chemists used consisted of a single quartz fiber fixed at one end like a fishing pole stuck into a riverbank inside a glass housing that protected it from the least breath of air. To weigh their Lilliputian quantities of material they hung a weighing pan, made of a snippet of platinum foil that was itself almost too small to see, to the free end of the quartz fiber and measured how much the fiber bent, a deflection which was calibrated against standard weights. A more rugged balance developed at Berkeley had double pans suspended from opposite ends of a quartz-fiber beam strung with microscopic struts. “It was said,” notes Seaborg, “that ‘invisible material was being weighed with an invisible balance.’ ”
In draft and more moderately in finished form his examination by turns compliments and savages Compton’s leadership: “In talking to Compton I frequently have the feeling that I am overplaying a delicate instrument.”1642, 1643 Beyond personality Szilard pointed to a destructive abdication by those whom Compton led: “I have often thought . . . that things would have been different if Compton’s authority had actually originated with our group, rather than with the OSRD.”
was there sufficient uranium on hand? Nichols told him about a recent and fortuitous discovery: some 1,250 tons of extraordinarily rich pitchblende—it was 65 percent uranium oxide—that the Union Minière had shipped to the United States in 1940 from its Shinkolobwe mine in the Belgian Congo to remove it beyond German reach. Frédéric Joliot and Henry Tizard had independently warned the Belgians of the German danger in 1939. The ore was stored in the open in two thousand steel drums at Port Richmond on Staten Island. The Belgians had been trying for six months to alert the U.S. government to its presence.
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The Norwegians moved out fast. They had descended to the river before the sirens began to sound.
The operation was successful. No one was injured on either side. All eighteen cells had been blown open, spilling nearly half a ton of heavy water into the drains. Not only would the plant require weeks to repair; because it was a cascade, pumping water of increasing deuterium concentration from one cell to the next, it would need almost a year of operation after repair simply to reach equilibrium again on its own and begin producing. General Nikolaus von Falkenhorst, the commander in chief of the occupying German Army in Norway, called the Vemork attack “the best coup I have ever seen.”
The shock wave from that explosion would squeeze the tamper from all sides, which in turn would squeeze the core. Squeezing the core would change its geometry from hollow shell to solid ball. What had been subcritical because of its geometry would be squeezed critical far faster and more efficiently than any mere gun could fire. “The gun will compress in one dimension,” Manley remembers Neddermeyer telling them. “Two dimensions would be better. Three dimensions would be better still.”
A three-dimensional squeeze inward was implosion. Neddermeyer had just defined a possible new way to fire an atomic bomb.
But Oppenheimer had been wrong before—even about the possibility of fission when Luis Alvarez dropped by to report it in 1939, wrong for the fifteen minutes it took him to think past the stubbornness with which he rejected any possibility he had not himself foreseen. Apparently he was learning to steer by that gruding incredulity as Bohr steered by the madness of a truly original idea.
Pathfinder bombers used radar to aid marking, and the initial Hamburg aiming point was chosen not for its strategic significance but for its distinctive radar reflection: a triangle of land at the junction of the Alster and North Elbe rivers, near the oldest part of the city and far from any war industry. Bomber Command had learned to adjust targeting for creep-back, the tendency of bombardiers to release their bombs as quickly as possible upon approaching the flak-infested aiming point that led to a gradual backup of impacts. From the ground the bombs seemed to unroll in the direction of the bomber stream’s approach; survivors named the phenomenon “carpet bombing.”
Small fires had coalesced into larger fires and, greedy for oxygen, had sucked air from around the coalescing inferno and fanned further fires there. That created the wind, a thermal column above the city like an invisible chimney above a hearth; the wind heated the fury at the center of the firestorm to more than 1,400 degrees, heat sufficient to melt the windows of a streetcar, wind sufficient to uproot trees.
We got to the Löschplatz [park] all right but I couldn’t go on across the Eiffestrasse because the asphalt had melted. There were people on the roadway, some already dead, some still lying alive but stuck in the asphalt. They must have rushed on to the roadway without thinking. Their feet had got stuck and then they had put out their hands to try to get out again. They were on their hands and knees screaming.
Women and children were so charred as to be unrecognizable; those that had died through lack of oxygen were half-charred and recognizable. Their brains had tumbled from their burst temples and their insides from the soft parts under the ribs. How terribly these people must have died. The smallest children lay like fried eels on the pavement.1831
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“At one point in the negotiations,” writes Groves, “Nichols . . . said that they would need between five and ten thousand tons of silver. This led to the icy reply: ‘Colonel, in the Treasury we do not speak of tons of silver; our unit is the Troy ounce.’ ”1879 Eventually 395 million troy ounces of silver—13,540 short tons—went off from the West Point Depository to be cast into cylindrical billets, rolled into 40-foot strips and wound onto iron cores at Allis-Chalmers in Milwaukee. Solid-silver bus bars a square foot in cross section crowned each racetrack’s long oval. The silver was worth more than $300 million. Groves accounted for it ounce by ounce, almost as carefully as he accounted for the fissionable isotope it helped separate.
Hex attacked organic materials ferociously: not a speck of grease could be allowed to ooze into the gas stream anywhere along the miles and miles of pipes and pumps and barriers. Pump seals therefore had to be devised that were both gastight and greaseless, a puzzle no one had ever solved before that required the development of new kinds of plastics. (The seal material that eventually served at Oak Ridge came into its own after the war under the brand name Teflon.) A single pinhole leak anywhere in the miles of pipes would confound the entire system; Alfred O. Nier developed portable mass spectrometers to serve as subtle leak detectors. Since pipes of solid nickel would exhaust the entire U.S. production of that valuable resource, Groves found a company willing to nickel-plate all the pipe interiors, a difficult new process accomplished by filling the pipes themselves with plating solution and rotating them as the plating current did its work.
He apparently equated disagreement with disloyalty and scaled the ratio of the two conditions directly: anyone who caused him as much pain as Leo Szilard must be a spy. It followed that he ought to be watched.
The surveillance of an innocent but eccentric man makes gumshoe comedy. Szilard traveled to Washington on June 20, 1943, and in preparation for the visit an Army counterintelligence agent reviewed his file:
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Bohr considered the question in the following perspective. Tell the Soviet Union soon, before the first bombs were nearly built, that a bomb project was under way, and the confidence might lead to negotiations on postwar arms control. Let the Soviet Union discover the information on its own, build the bombs and drop them, oppose the Soviets at the end of the war with an Anglo-American nuclear monopoly, and the likeliest outcome was a nuclear arms race.
Bohr’s revelation of the complementarity of the bomb was far more fundamental than this contemporary political question. But the contemporary political question was an aspect of the larger issue and partly obscured it from view. The bomb was opportunity and threat and would always be opportunity and threat—that was the peculiar, paradoxical hopefulness. But political conditions would necessarily differ before and after it was deployed.
Bohr, who used to say that accuracy and clarity were complementary (and so a short statement could never be precise), was not easy to hear, and all that Churchill seemed to gather was that he was worried about the likely state of the post-war world and that he wanted to tell the Russians about the progress towards the bomb. As regards the post-war world Churchill told him: “I cannot see what you are talking about. After all this new bomb is just going to be bigger than our present bombs. It involves no difference in the principles of war. And as for any post-war problems there are none that cannot be amicably settled between me and my friend, President Roosevelt.”
Bohr had searched the forbidding territory of the atom when he was young and discovered multiple structures of paradox; now he searched it again by the dark light of the energy it released and discovered profound political change.
Nations existed in a condition of international anarchy. No hierarchical authority defined their relations with one another. They negotiated voluntarily as self-interest moved them and took what they could get. War had been their final negotiation, brutally resolving their worst disputes.
Now an ultimate power had appeared. If Churchill failed to recognize it he did so because it was not a battle cry or a treaty or a committee of men. It was more like a god descending to the stage in a gilded car.
By the necessity, commonly understood, to avoid triggering a nuclear holocaust, the deus ex machina would have accomplished then what men and nations had been unable to accomplish by negotiation or by conquest: the abolition of major war. Total security would be indistinguishable from total insecurity. A menacing standoff would be maintained suspiciously, precariously, at the brink of annihilation.
“It appeared to me,” Bohr wrote in 1950 of his lonely wartime initiative, “that the very necessity of a concerted effort to forestall such ominous threats to civilization would offer quite unique opportunities to bridge international divergencies.”2026 That, in a single sentence, was the revelation of the complementarity of the bomb.
A shaped charge is a charge of high explosive arranged in such a way—usually hollowed out like an empty ice cream cone with the open end pointed forward—that its normally divergent, bubble-shaped shock wave converges into a high-speed jet. Such a ferocious jet can punch its way through the thick armor of a tank to spray death inside.
It had just become clear from theoretical work that the several diverging shock waves produced by multiple detonators in Neddermeyer’s experiments reinforced each other where they collided and produced points of high pressure; such pressure nodes in turn caused the jets and irregularities that spoiled the implosion. Rather than continue trying to smooth out a colliding collection of divergent shock waves, Tuck sensibly proposed that the laboratory consider designing an arrangement of explosives that would produce a converging wave to begin with, fitting the shock wave to the shape it needed to squeeze. Such explosive arrangements were called lenses by analogy with optical lenses that similarly focus light.
“It appears reasonable,” Oppenheimer ended, “to discontinue the intensive effort to achieve higher purity for plutonium and to concentrate’ attention on methods of assembly which do not require a low neutron background for their success. At the present time the method to which an over-riding priority must be assigned is the method of implosion.”2081
That necessity was painful, as the Los Alamos technical history makes clear: “The implosion was the only real hope, and from current evidence not a very good one.”
Like his colleagues Oppenheimer had considered only those processes that enriched natural uranium all the way up to bomb grade, a requirement thermal diffusion could not efficiently meet. Now he realized that Abelson’s process offered a valuable alternative, the alternative Abelson had proposed in his report to help Chicago advance its pile work: slight enrichment of larger quantities... “Dr. Oppenheimer . . . suddenly told me that we had [made] a terrible scientific blunder,” Groves testified after the war.2095 “I think he was right. It is one of the things that I regret the most in the whole course of the operation. We had failed to consider [thermal diffusion] as a portion of the process as a whole.” From the beginning the leaders of the Manhattan Project had thought of the several enrichment and separation processes as competing horses in a race. That had blinded them to the possibility of harnessing the processes together.
The Alpha calutrons smeared uranium all over the insides of their vacuum tanks, catching no more than 4 percent of the U235; that valuable fraction, reprocessed and fed into the Beta calutrons, reached the Beta collectors in turn at only 5 percent efficiency. Five percent of 4 percent is two thousandths. A speck of U235 stuck to an operator’s coveralls was well worth searching out with a Geiger counter and retrieving delicately with tweezers. No essence was ever expressed more expensively from the substance of the world with the possible exception of the human soul.
The surf ran red with their blood; so many broken bodies floated in the water that Navy craft overrode them to rescue. Not all the dead had volunteered their sacrifice; many had been rallied, pushed or shot by Japanese soldiers.
The mass suicide on Saipan—a Jonestown of its day—instructed Americans further in the nature of the Jap.
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Long after mother and daughter had been persuaded from the sidelines Fermi sat unbudging, mentally working out the steps. When he was ready he asked Bernice Brode, one of the leaders, to be his partner. “He offered to be head couple, which I thought most unwise for his first venture, but I couldn’t do anything about it and the music began. He led me out on the exact beat, knew exactly each move to make and when. He never made a mistake, then or thereafter, but I wouldn’t say he enjoyed himself. . . . He [danced] with his brains instead of his feet.”
Oppenheimer coded the test and the test site Trinity... There is a poem of John Donne, written just before his death, which I know and love. From it a quotation:
As West and East
In all flatt Maps—and I am one—are one,
So death doth touch the Resurrection.”
The poem was Donne’s “Hymne to God My God, in My Sicknesse,” and among its subtleties it construes a complementarity that parallels the complementarity of the bomb that Bohr had recently revealed to Oppenheimer.
Oppenheimer did not doubt that he would be remembered to some degree, and reviled, as the man who led the work of bringing to mankind for the first time in its history the means of its own destruction.2154 He cherished the complementary compensation of knowing that the hard riddle the bomb would pose had two answers, two outcomes, one of them transcendent. Such understanding justified the work at Los Alamos if anything did, and the work in turn healed the split between self and overweening conscience that hurt him... At Los Alamos, if only for a time, he located that detachment in duties to men and to the commonwealth that Bohr was teaching him to believe might be worthy, not macabre. He was not the first man to find himself in war.
The implosion lens system von Neumann designed was made up of truncated pyramidal blocks about the size of car batteries...
The fast-burning outer layer functioned for the detonation wave as air around an optical lens functions for light. The slower-burning shaped inclusion functioned as a magnifying glass, directing and reshaping the wave. A detonator would ignite the fast-burning explosive. That material would develop a spherical detonation wave. When the apex of the wave advanced into the apex of the inclusion, however, it would begin burning more slowly. The delay would give the rest of the wave time to catch up. As the detonation wave encountered and burned through the inclusion it thus reshaped itself from convex to concave, from a spherical wave expanding from a point to a spherical wave converging on a point, emerging fitted to the convex curve of the spherical tamper.
Thomas shipped the Po on platinum foil in sealed containers, but another nasty characteristic of polonium caused shipping troubles: for reasons never satisfactorily explained by experiment, the metal migrates from place to place and can quickly contaminate large areas. “This isotope has been observed to migrate upstream against a current of air,” notes a postwar British report on polonium, “and to translocate under conditions where it would appear to be doing so of its own accord.”
Thus checked out, Major General Curtis LeMay rode a C-54 to India late in August to take over the 20th Bomber Command, based in India with forward airfields in China from which it was attempting with fewer than two hundred B-29’s to bomb Japan. The bombers had to ferry their own fuel and ordnance from India to China over the Himalayas before each mission—seven supply flights for each bombing strike, up to twelve gallons burned for each one gallon delivered. “It didn’t work,” LeMay writes in his autobiography. “No one could have made it work. It was founded on an utterly absurd logistic basis. Nevertheless, our entire Nation howled like a pack of wolves for an attack on the Japanese homeland.”
The progress and destructive features of the conflagration were consequently much greater than those of [a] fire storm, for the fire continued to spread until it could reach no more material. . . . The 28-mile-per-hour wind, measured a mile from the fire, increased to an estimated 55 miles at the perimeter, and probably more within.2229 An extended fire swept over 15 square miles in 6 hours. Pilots reported that the air was so violent that B-29s at 6,000 feet were turned completely over, and that the heat was so intense, even at that altitude, that the entire crew had to don oxygen masks.
Bertrand Goldschmidt, the French chemist who worked with Glenn Seaborg, puts the Manhattan Engineer District at the height of its wartime development in perspective with a startling comparison. It was, he writes in a memoir, “the astonishing American creation in three years, at a cost of two billion dollars, of a formidable array of factories and laboratories—as large as the entire automobile industry of the United States at that date.”
Why he failed to confront the issue himself until late 1943, when George Marshall asked him directly to do so, he chooses not to say. One reason was certainly security, a Groves obsession; in order to know what to look for, intelligence agents would have to be briefed on at least isotope-separation technologies and nuclear-fission research, which would mean that any agent captured or turned might well give American secrets away.
But it was impossible to assemble a complete critical mass by stacking bars; such an assembly would run away, kill its sponsors with radiation and melt down. Frisch nearly caused a runaway reaction one day by leaning too close to a naked assembly—he called it a Lady Godiva—that was just subcritical, allowing the hydrogen in his body to reflect back neutrons.
The idea was that the compound of uranium-235, which by then had arrived on the site, enough to make an explosive device, should indeed be assembled to make one, but leaving a big hole so that the central portion was missing; that would allow enough neutrons to escape so that no chain reaction could develop.2263 But the missing portion was to be made, ready to be dropped through the hole so that for a split second there was the condition for an atomic explosion, although only barely so.
Brilliant young Richard Feynman laughed when he heard Frisch’s plan and named it: he said it would be like tickling the tail of a sleeping dragon.2264 The Dragon experiment it became.
It was Robert Oppenheimer at his best:
We have been living through years of great evil, and of great terror. Roosevelt has been our President, our Commander-in-Chief and, in an old and unperverted sense, our leader. All over the world men have looked to him for guidance, and have seen symbolized in him their hope that the evils of this time would not be repeated; that the terrible sacrifices which have been made, and those that are still to be made, would lead to a world more fit for human habitation. . . .
In the Hindu scripture, in the Bhagavad-Gita, it says, “Man is a creature whose substance is faith. What his faith is, he is.” The faith of Roosevelt is one that is shared by millions of men and women in every country of the world. For this reason it is possible to maintain the hope, for this reason it is right that we should dedicate ourselves to the hope, that his good works will not have ended with his death.
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He spoke to the newly sworn President following the brief cabinet meeting Truman called after taking the oath of office on the evening of the day Roosevelt died. “Stimson told me,” Truman reports in his memoirs, “that he wanted me to know about an immense project that was under way—a project looking to the development of a new explosive of almost unbelievable destructive power. That was all he felt free to say at the time, and his statement left me puzzled. It was the first bit of information that had come to me about the atomic bomb,
Truman assayed the South Carolinian most shrewdly a few months after their April discussion in a private diary he intermittently kept:
Had a long talk with my able and conniving Secretary of State. My but he has a keen mind! And he is an honest man. But all country politicians are alike. They are sure all other politicians are circuitous in their dealings. When they are told the straight truth, unvarnished, it is never believed—an asset sometimes.2278
A politician’s politician, Byrnes
"When other countries acquired nuclear weapons, as they would in “just a few years,” that advantage would be lost: “Perhaps the greatest immediate danger which faces us is the probability that our ‘demonstration’ of atomic bombs will precipitate a race in the production of these devices between the United States and Russia.”... But Szilard echoed Bohr in pleading for what no one among the national leaders concerned with the problem seemed able to grasp, that “these decisions ought to be based not on the present evidence relating to atomic bombs, but rather on the situation which can be expected to confront us in this respect a few years from now.” By present evidence the bombs were modest and the United States held them in monopoly; the difficulty was deciding what the future would bring.
LeMay was also keeping busy. “The 3 reserved targets for the first unit of this project were announced. With current and prospective rate of [Twentieth Air Force] H.E. bombing, it is expected to complete strategic bombing of Japan by 1 Jan 46 so availability of future targets will be a problem.” If the Manhattan Project did not hurry, that is, there would be no cities left in Japan to bomb.
Completely filing off the blisters would expose the plutonium. The metallurgists salvaged the castings by grinding only partway through the blisters and smoothing the bumpy fit with sheets of gold foil. The core of the first atomic bomb would go to its glory dressed in improvised offerings of nickel and gold.
Teller passed the lotion around and the strange prophylaxis disturbed one observer: “It was an eerie sight to see a number of our highest-ranking scientists seriously rubbing sunburn lotion on their faces and hands in the pitch-blackness of the night, twenty miles from the expected flash.”
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__ Truman reports his Berlin tour:...
I thought of Carthage, Baalbec, Jerusalem, Rome, Atlantis; Peking, Babylon, Nineveh; Scipio, Rameses II, Titus, Hermann, Sherman, Jenghis Khan, Alexander, Darius the Great. But Hitler only destroyed Stalingrad—and Berlin. I hope for some sort of peace—but I fear that machines are ahead of morals by some centuries and when morals catch up perhaps there’ll be no reason for any of it.
I hope not. But we are only termites on a planet and maybe when we bore too deeply into the planet there’ll be a reckoning—who knows?
