"The Making of the Atomic Bomb"

[fiefoe]

Richard Rhodes starts with the atom and does justice to this subject in nearly 900 pages.The physics and the people who worked it out are breathtaking.

• Leo Szilard, the Hungarian theoretical physicist, born of Jewish heritage in Budapest on February 11, 1898, was thirty-five years old in 1933...  “as generous with his ideas as a Maori chief with his wives,”... In photographs he still chose to look soulful. He had reason. His deepest ambition, more profound even than his commitment to science, was somehow to save the world.
• “Mr. Wells’ newest ‘dream of the future’ is its own brilliant justification,” The Times praised, obscurely.3, 4 The visionary English novelist was one among Szilard’s network of influential acquaintances, a network he assembled by plating his articulate intelligence with the purest brass.
• He remembers informing his awed classmates, at the beginning of the Great War, when he was sixteen, how the fortunes of nations should go, based on his precocious weighing of the belligerents’ relative political strength:
    I said to them at the time that I did of course not know who would win the war, but I did know how the war ought to end. It ought to end by the defeat of the central powers, that is the Austro-Hungarian monarchy and Germany, and also end by the defeat of Russia. I said I couldn’t quite see how this could happen, since they were fighting on opposite sides, but I said that this was really what ought to happen.
• Szilard began explaining. “Five or ten minutes” later, he says, Einstein understood. After only a year of university physics, Szilard had worked out a rigorous mathematical proof that the random motion of thermal equilibrium could be fitted within the framework of the phenomenological theory in its original, classical form, without reference to a limiting atomic model.
• Six months later Szilard wrote another paper in thermodynamics, “On the decrease of entropy in a thermodynamic system by the intervention of intelligent beings,” that eventually would be recognized as one of the important foundation documents of modern information theory.
• in 1932, Szilard found or took up for the first time that appealing orphan among H. G. Wells’ books that he had failed to discover before: The World Set Free.
• Szilard was not the first to realize that the neutron might slip past the positive electrical barrier of the nucleus; that realization had come to other physicists as well. But he was the first to imagine a mechanism whereby more energy might be released in the neutron’s bombardment of the nucleus than the neutron itself supplied.
  “As the light changed to green and I crossed the street,” Szilard recalls, “it . . . suddenly occurred to me that if we could find an element which is split by neutrons and which would emit two neutrons when it absorbs one neutron, such an element, if assembled in sufficiently large mass, could sustain a nuclear chain reaction.

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• Max Planck thought otherwise. He doubted that atoms existed at all, as did many of his colleagues—the particulate theory of matter was an English invention more than a Continental, and its faintly Britannic odor made it repulsive to the xenophobic German nose—but if atoms did exist he was sure they could not be mechanical.
• Belief is the oath of allegiance that scientists swear. <> That was how scientists were chosen and admitted to the order. They constituted a republic of educated believers taught through a chain of masters and apprentices to judge carefully the slippery edges of their work. <> Who then guided that work? The question was really two questions: who decided which problems to study, which experiments to perform? And who judged the value of the results?
• Good science, original work, always went beyond the body of received opinion, always represented a dissent from orthodoxy. How, then, could the orthodox fairly assess it? <> Polanyi suspected that science’s system of masters and apprentices protected it from rigidity. The apprentice learned high standards of judgment from his master. At the same time he learned to trust his own judgment: he learned the possibility and the necessity of dissent. Books and lectures might teach rules; masters taught controlled rebellion, if only by the example of their own original—and in that sense rebellious—work.
• Plausibility and scientific value measured an idea’s quality by the standards of orthodoxy; originality measured the quality of its dissent.
• Another, more subtle quality, a braiding of country-boy acuity with a profound frontier innocence, was crucial to his unmatched lifetime record of physical discovery. As his protégé James Chadwick said, Rutherford’s ultimate distinction was “his genius to be astonished.” He preserved that quality against every assault of success and despite a well-hidden but sometimes sickening insecurity, the stiff scar of his colonial birth.
• Since they were lighter than the lightest known kind of matter and identical regardless of the kind of matter they were born from, it followed that they must be some basic constituent part of matter, and if they were a part, then there must be a whole. The real, physical electron implied a real, physical atom.
• Rutherford had been genuinely astonished by Marsden’s results. “It was quite the most incredible event that has ever happened to me in my life,” he said later. “It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you. On consideration I realised that this scattering backwards must be the result of a single collision, and when I made calculations I saw that it was impossible to get anything of that order of magnitude unless you took a system in which the greatest part of the mass of the atom was concentrated in a minute nucleus.”

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• Speech is a clumsiness and writing an impoverishment. Not language but the surface of the body is the child’s first map of the world, undifferentiated between subject and object, coextensive with the world it maps until awakening consciousness divides it off. Niels Bohr liked to show how a stick used as a probe—a blind man’s cane, for example—became an extension of the arm.213 Feeling seemed to move to the end of the stick, he said.
• We are “suspended in language,” Bohr liked to say, evoking that abyss; and one of his favorite quotations was two lines from Schiller:230
  Only wholeness leads to clarity,
  And truth lies in the abyss.
  But it was not in Møller that Bohr found solid footing. He needed more than a novel, however apposite, for that. He needed what we all need for sanity: he needed love and work.
• Rutherford looked over the young Dane and liked what he saw despite his prejudice against theoreticians. Someone asked him later about the discrepancy. “Bohr’s different,” Rutherford roared, disguising affection with bluster. “He’s a football player!” Bohr was different in another regard as well; he was easily the most talented of all Rutherford’s many students—and Rutherford trained no fewer than eleven Nobel Prize winners during his life, an unsurpassed record.
• Bohr... realized in the space of a few weeks that radioactive properties originated in the atomic nucleus but chemical properties depended primarily on the number and distribution of electrons. He realized—the idea was wild but happened to be true—that since the electrons determined the chemistry and the total positive charge of the nucleus determined the number of electrons, an element’s position on the periodic table of the elements was exactly the nuclear charge (or “atomic number”): hydrogen first with a nuclear charge of 1, then helium with a nuclear charge of 2 and so on up to uranium at 92.
• his paper was not only an examination of the physical world but also a political document. It proposed, in a sense, to begin a reform movement in physics: to limit claims and clear up epistemological fallacies. Mechanistic physics had become authoritarian. It had outreached itself to claim universal application, to claim that the universe and everything in it is rigidly governed by mechanistic cause and effect. That was Haeckelism carried to a cold extreme. It stifled Niels Bohr as biological Haeckelism had stifled Christian Bohr and as a similar authoritarianism in philosophy and in bourgeois Christianity had stifled Søren Kierkegaard.
• Einstein showed in 1917 that the physical answer to Rutherford’s question is statistical—any frequency is possible, and the ones that turn up happen to have the best odds.
• The “catchwords” here, as Harald Høffding might say, are individual and free choice. Bohr means the changes of state within individual atoms are not predictable; the catchwords color that physical limitation with personal emotion. <> In fact the 1913 paper was deeply important emotionally to Bohr. It is a remarkable example of how science works and of the sense of personal authentication that scientific discovery can bestow. Bohr’s emotional preoccupations sensitized him to see previously unperceived regularities in the natural world. The parallels between his early psychological concerns and his interpretation of atomic processes are uncanny, so much so that without the great predictive ability of the paper its assumptions would seem totally arbitrary. <> Whether or not the will is free, for example, was a question that Bohr took seriously. To identify a kind of freedom of choice within the atom itself was a triumph for his carefully assembled structure of beliefs.
• he rarely mentions the ‘laws of nature,’ but rather refers to ‘regularities of the phenomena.’ ”285 Bohr was not displaying false humility with his choice of terms; he was reminding himself and his colleagues that physics is not a grand philosophical system of authoritarian command but simply a way, in his favorite phrase, of “asking questions of Nature.”286 He apologized similarly for his tentative, rambling habit of speech: “I try not to speak more clearly than I think.”

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• Meitner’s father, an attorney—the Meitners were assimilated Austrian Jews, baptized all around—had insisted that she acquire a teacher’s diploma in French before beginning to study physics so that she would always be able to support herself. Only then could she prepare for university work. With the diploma out of the way Meitner crammed eight years of Gymnasium preparation into two.
• The Germans sometimes chose to disguise mustard with xylyl bromide, a tear gas that smells like lilac, and so it came to pass in the wartime spring that men ran in terror from a breeze scented with blossoming lilac shrubs... These are not nearly all the gases and poisons developed in the boisterous, vicious laboratory of the Great War.
• The chemists, like bargain hunters, imagined they were spending a pittance of tens of thousands of lives to save a purseful more. Britain reacted with moral outrage but capitulated in the name of parity.
  It was more than Fritz Haber’s wife could bear. Clara Immerwahr had been Haber’s childhood sweetheart. She was the first woman to win a doctorate in chemistry from the University of Breslau. After she married Haber and bore him a son, a neglected housewife with a child to raise, she withdrew progressively from science and into depression. Her husband’s work with poison gas triggered even more desperate melancholy.
• On the left flank “the Turks got fairly in among our men with a weight which bore all before it, and what followed was a long succession of British rallies to a tussle body to body, with knives and stones and teeth, a fight of wild beasts in the ruined cornfields of The Farm.” Harry Moseley, in the front line, lost that fight.
  When he heard of Moseley’s death, the American physicist Robert A. Millikan wrote in public eulogy that his loss alone made the war “one of the most hideous and most irreparable crimes in history.”
• Charmed because aircraft of any kind were new to the British sky and these were white and large. The results were less charming: 95 killed, 195 injured. The parade ground at Shorncliffe camp was damaged but no one was hurt. <> Folkestone was the little Guernica of the Great War. German Gotha bombers—oversized biplanes—had attacked England for the first time, bringing with them the burgeoning concept of strategic bombing.
• Lloyd George, by then Prime Minister, appealed to the brilliant, reliable Smuts to develop an air program, including a system of home defense. Early-warning mechanisms were devised: oversized binaural gramophone horns connected by stethoscope to keen blind listeners; sound-focusing cavities carved into sea cliffs that could pick up the wong-wong of Gotha engines twenty miles out to sea. Barrage balloons raised aprons of steel cable that girdled London’s airspace; enormous white arrows mounted on the ground on pivots guided the radioless defenders in their Sopwith Camels and Pups toward the invading German bombers.
• As they came to understand strategic bombing, the Germans turned from high explosives to incendiaries, reasoning presciently that fires might cause more damage by spreading and coalescing than any amount of explosives alone. By 1918 they had developed a ten-pound incendiary bomb of almost pure magnesium, the Elektron, that burned at between 2000° and 3000° and that water could not dowse.
• “The War had become undisguisedly mechanical and inhuman,” Siegfried Sassoon allows a fictional infantry officer to see. “What in earlier days had been drafts of volunteers were now droves of victims.”... Whatever its ostensible purpose, the end result of the complex organization that was the efficient software of the Great War was the manufacture of corpses. This essentially industrial operation was fantasized by the generals as a “strategy of attrition.”... “The war machine,” concludes Elliot, “rooted in law, organization, production, movement, science, technical ingenuity, with its product of six thousand deaths a day over a period of 1,500 days, was the permanent and realistic factor
• But the death machine had only sampled a vast new source of raw material: the civilians behind the lines. It had not yet evolved equipment efficient to process them, only big guns and clumsy biplane bombers. It had not yet evolved the necessary rationale that old people and women and children are combatants equally with armed and uniformed young men. That is why, despite its sickening squalor and brutality, the Great War looks so innocent to modern eyes.

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• Out of the prospering but vulnerable Hungarian Jewish middle class came no fewer than seven of the twentieth century’s most exceptional scientists: in order of birth, Theodor von Kármán, George de Hevesy, Michael Polanyi, Leo Szilard, Eugene Wigner, John von Neumann and Edward Teller.
• his friend Fritz Houtermans, a theoretical physicist, proposed the popular theory that “these people were really visitors from Mars; for them, he said, it was difficult to speak without an accent that would give them away and therefore they chose to pretend to be Hungarians whose inability to speak any language without accent is well known;
• It was a Hungarian classic, taught in the schools, The Tragedy of Man.”... It runs Adam through history with Lucifer as his guide, rather as the spirits of Christmas lead Ebenezer Scrooge, enrolling Adam successively as such real historical personages as Pharaoh, Miltiades, the knight Tancred, Kepler. Its pessimism resides in its dramatic strategy. Lucifer demonstrates to Adam the pointlessness of man’s faith in progress by staging not imaginary experiences, as in Faust or Peer Gynt, but real historical events. Pharaoh frees his slaves and they revile him for leaving them without a dominating god; Miltiades returns from Marathon and is attacked by a murderous crowd of citizens his enemies have bribed; Kepler sells horoscopes to bejewel his faithless wife.
• Arthur Koestler remembers that food was scarce, especially if you tried to buy it with the regime’s ration cards and nearly worthless paper money, but for some reason the same paper would purchase an abundance of Commune-sponsored vanilla ice cream, which his family therefore consumed for breakfast, lunch and dinner. He mentions this curiosity, he remarks, “because it was typical of the happy-go-lucky, dilettantish, and even surrealistic ways in which the Commune was run.”... The Hungarian Soviet Republic
• “That [the] insecure and contradictory foundation [of Bohr’s quantum hypotheses],” Einstein would say, “was sufficient to enable a man of Bohr’s unique instinct and perceptiveness to discover the major laws of spectral lines and of the electron shells of the atom as well as their significance for chemistry appeared to me like a miracle. . . . This is the highest form of musicality in the sphere of thought.”
• In 1516 a rich silver lode was discovered in Joachimsthal (St. Joachim’s dale), in the territory of the Count von Schlick, who immediately appropriated the mine. In 1519 coins were first struck from its silver at his command. Joachimsthaler, the name for the new coins, shortened to thaler, became “dollar” in English before 1600... It was from Joachimsthal pitchblende residues that Marie and Pierre Curie laboriously separated the first samples of the new elements they named radium and polonium.
• The Jemez Caldera is a bowl-shaped volcanic crater twelve miles across with a grassy basin inside 3,500 feet below the rim, the basin divided by mountainous extrusions of lava into several high valleys. It is a million years old and one of the largest calderas in the world, visible even from the moon. Northward four miles from the Cañon de los Frijoles a parallel canyon took its Spanish name from the cottonwoods that shaded its washes: Los Alamos. Young Robert Oppenheimer first approached it in the summer of 1922.
• There is something frantic in all this grinding, however disguised in traditional Harvard languor. Oppenheimer had not yet found himself—is that more difficult for Americans than for Europeans like Szilard or Teller, who seem all of a piece from their earliest days.
• Schrödinger came down with a cold and took to his bed. Unfortunately he was staying at the Bohrs’. “While Mrs. Bohr nursed him and brought in tea and cake, Niels Bohr kept sitting on the edge of the bed talking at [him]: ‘But you must surely admit that . . .’ ”489 Schrödinger approached desperation. “If one has to go on with these damned quantum jumps,” he exploded, “then I’m sorry that I ever started to work on atomic theory.”
• “Two magnitudes are complementary when the measurement of one of them prevents the accurate simultaneous measurement of the other.497 Similarly, two concepts are complementary when one imposes limitations on the other.”
  Carefully Bohr then examined the conflicts of classical and quantum physics one at a time and showed how complementarity clarified them. In conclusion he briefly pointed to complementarity’s connection to philosophy. The situation in physics, he said, “bears a deep-going analogy to the general difficulty in the formation of human ideas, inherent in the distinction between subject and object.”498 That reached back all the way to the licentiate’s dilemma in Adventures of a Danish Student, and resolved it: the I who thinks and the I who acts are different, mutually exclusive, but complementary abstractions of the self.

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• Finally, Rutherford established that the H atoms came in fact from the nitrogen and not from the radioactive source alone. And then he made his stunning announcement, couching it as always in the measured understatement of British science: “From the results so far obtained it is difficult to avoid the conclusion that the long-range atoms arising from collision of [alpha] particles with nitrogen are not nitrogen atoms but probably atoms of hydrogen. . . . If this be the case, we must conclude that the nitrogen atom is disintegrated.”510 Newspapers soon published the discovery in plainer words: Sir Ernest Rutherford, headlines blared in 1919, had split the atom.
• It then subjected the beam to a strong electrostatic field; that sorted the different nuclei into separated beams. The separated beams proceeded onward through a magnetic field; that further sorted nuclei according to their mass, producing separated beams of isotopes. Finally the sorted beams struck the plateholder of a camera and marked their precise locations on a calibrated strip of film. How much the magnetic field bent the separated beams—where they blackened the strip of film—determined the mass of their component nuclei to a high degree of accuracy.
  Aston called his invention a mass-spectrograph because it sorted elements and isotopes of elements by mass much as an optical spectrograph sorts light by its frequency. The mass-spectrograph was immediately and sensationally a success.

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__ Leopold Infeld, riding the train through New Jersey from New York to Princeton, “was astonished at so many wooden houses; in Europe they are looked down upon as cheap substitutes which do not, like brick, resist the attack of passing time.”
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• The previous summer the tall, blond, powerfully built Odessan and his wife Rho, also a physicist, had tried to escape by paddling a faltboat—a collapsible rubber kayak—170 miles south from the Crimea to Turkey across the Black Sea without benefit of a weather report...The only document they carried was Gamow’s Danish motorcycle-driver’s license, souvenir of the 1930 winter he spent in Copenhagen after working with Rutherford at the Cavendish.
• On August 2, 1932, working with a carefully prepared cloud chamber, an American experimentalist at Caltech named Carl Anderson had discovered a new particle in a shower of cosmic rays. The particle was an electron with a positive instead of a negative charge, a “positron,” the first indication that the universe consists not only of matter but of antimatter as well. (Its discovery earned Anderson the 1936 Nobel Prize.) Physicists everywhere immediately looked through their files of cloud-chamber photographs and identified positron tracks they had misidentified before (the Joliot-Curies, who had missed the neutron, saw that they had also missed the positron).
• The Joliot-Curies... had demonstrated that it was possible not only to chip pieces off the nucleus, as Rutherford had done, but also to force it artificially to release some of its energy in radioactive decay.
• two months after the Solvay Conference, Fermi completed the major theoretical work of his life, a fundamental paper on beta decay. Beta decay, the creation and expulsion by the nucleus of highenergy electrons in the course of radioactive change, had needed a detailed, quantitative theory, and Fermi supplied it entire. He introduced a new type of force, the “weak interaction,” completing the four basic forces known in nature: gravity and electromagnetism, which operate at long range, and the strong force and Fermi’s weak force, which operate within nuclear dimensions. He introduced a new fundamental constant, now called the Fermi constant, determining it from existing experimental data.
• Amaldi and Segrè had not been wrong about aluminum. They had simply irradiated different samples of the element on different tables. The hydrogen in the wooden table had slowed down some of the neutrons and enhanced the almost-three-minute activity. As Hans Bethe once noted wittily, the efficiency of slow neutrons “might never have been discovered if Italy were not rich in marble. . . . A marble table gave different results from a wooden table.826 If it had been done [in America], it all would have been done on a wooden table and people would never have found out.”
• Thus by the mid-1930s the three most original living physicists had each spoken to the question of harnessing nuclear energy. Rutherford had dismissed it as moonshine; Einstein had compared it to shooting in the dark at scarce birds; Bohr thought it remote in direct proportion to understanding.