The Making of the Atomic Bomb: 25th Anniversary Edition

by Richard Rhodes

He announced his recent confirmation, only briefly reported the month before, that the alpha particle was in fact helium.156 The confirming experiment was typically elegant. Rutherford had a glassblower make him a tube with extremely thin walls. He evacuated the tube and filled it with radon gas, a fertile source of alpha particles. The tube was gastight, but its thin walls allowed alpha particles to escape. Rutherford surrounded the radon tube with another glass tube, pumped out the air between the two tubes and sealed off the space. “After some days,” he told his Stockholm audience triumphantly, “a bright spectrum of helium was observed in the outer vessel.” Rutherford’s experiments still stun with their simplicity.157 “In this Rutherford was an artist,” says a former student. “All his experiments had style.”

Bohr’s contributions to twentieth-century physics would rank second only to Einstein’s.

Ratiocination—that is the technical term for what the licentiate does, the term for what the young Bohr did as well—is a defense mechanism against anxiety. Thought spirals, panicky and compulsive. Doubt doubles and redoubles, paralyzing action, emptying out the world. The mechanism is infinitely regressive because once the victim knows the trick, he can doubt anything, even doubt itself. Philosophically the phenomenon could be interesting, but as a practical matter ratiocination is a way of stalling. If work is never finished, its quality cannot be judged. The trouble is that stalling postpones the confrontation and adds that guilt to the burden. Anxiety increases; the mechanism accelerates its spiraling flights; the self feels as if it will fragment; the multiplying “I” dramatizes the feeling of impending breakup. At that point madness reveals its horrors; the image that recurred in Bohr’s conversation and writing throughout his life was the licentiate’s “bottomless abyss.”

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.

“It is wrong,” he told his colleagues repeatedly, “to think that the task of physics is to find out how nature is”—which is the territory classical physics had claimed for itself. “Physics concerns what we can say about nature.”

Before then, the German attacking and the British defending, the two armies had run a race to the sea. The Germans had hoped to win the race to turn the flank of the Allies. Not yet fully mobilized for war, they even threw in Ersatz Corps of ill-trained high school and university students to bolster their numbers and took 135,000 casualties in what the German people came to call the Kindermord, the murder of the children.

Masses of Africans and Canadians stumbled back in retreat. Other masses, surprised and utterly uncomprehending, staggered out of their trenches into no-man’s-land. Men clawed at their throats, stuffed their mouths with shirttails or scarves, tore the dirt with their bare hands and buried their faces in the earth. They writhed in agony, ten thousand of them, serious casualties; and five thousand others died. Entire divisions abandoned the line.

By the end of the war at least 200,000 tons of chemical warfare agents had been manufactured and used, half by Germany, half by the several Allies together.

Phosgene then became a staple of the war, dispensed from cylinders, artillery shells, trench mortars, canisters fired from mortarlike “projectors” and bombs. It smelled like new-mown hay but it was by far the most toxic gas used, ten times as toxic as chlorine, fatal in ten minutes at a concentration of half a milligram per liter of air. At higher concentrations one or two breaths killed in a matter of hours. Phosgene—carbonyl chloride—hydrolyzed to hydrochloric acid in contact with water; that was its action in the water-saturated air deep in the delicate bubbled tissue of the human lung. It caused more than 80 percent of the war’s gas fatalities.

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. “She began to regard poison gas not only as a perversion of science but also as a sign of barbarism,” a Haber biographer explains. “It brought back the tortures men said they had forgotten long ago. It degraded and corrupted the discipline [i.e., chemistry] which had opened new vistas of life.”351 She asked, argued, finally adamantly demanded that her husband abandon gas work. Haber told her what he had told Hahn, adding for good measure, patriot that he was, that a scientist belongs to the world in times of peace but to his country in times of war.352 Then he stormed out to supervise a gas attack on the Eastern Front. Dr. Clara Immerwahr Haber committed suicide the same night.

At Folkestone on a sunny, warm Friday afternoon, May 25, 1917, housewives came out in crowds to shop for the Whitsun weekend.

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. The England Squadron had been headed for London but had met a solid wall of clouds inland from Gravesend. Twenty-one aircraft turned south then and searched for alternative targets.

A squadron flew against London by daylight on June 13, nineteen days after Folkestone, dropped almost 10,000 pounds of bombs and caused the most numerous civilian bombing casualties of the war, 432 injured and 162 killed, including sixteen horribly mangled children in the basement of a nursery school.

With what a British observer could now call “the great importance attached in America to this branch of warfare,” Army Ordnance began construction in November 1917 of a vast war-gas arsenal at Edgewood, Maryland, on waste and marshy land.

The plant, which cost $35.5 million—a complex of 15 miles of roads, 36 miles of railroad track, waterworks and power plants and 550 buildings for the manufacture of chlorine, phosgene, chlorpicrin, sulfur chloride and mustard gas—was completed in less than a year. Ten thousand military and civilian workers staffed it. By the end of the war it was capable of filling 1.1 million 75-mm gas shells a month as well as several million other sizes and types of shells, grenades, mortar bombs and projector drums. “Had the war lasted longer,” the British observer notes, “there can be no doubt that this centre of production would have represented one of the most important contributions by America to the world war.”

Of a total of some 21 million battle casualties gas caused perhaps 5 percent, about 1 million. It killed at least 30,000 men, but at least 9 million died overall.

Americans invented the machine gun: Hiram Stevens Maxim, a Yankee from Maine; Colonel Isaac Lewis, a West Pointer, director of the U.S. Army coast artillery school; William J. Browning, a gun maker and businessman; and their predecessor Richard Jordan Gatling, who correctly located the machine gun among automated systems.

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.

Hans Bethe once remarked that he considered everything before 1932 “the prehistory of nuclear physics, and from 1932 on the history of nuclear physics.”603 The difference, he said, was the discovery of the neutron.

Einstein’s crowning achievement ameliorated for him the universal madness of the war: I begin to feel comfortable amid the present insane tumult, in conscious detachment from all things which preoccupy the crazy community. Why should one not be able to live contentedly as a member of the service personnel in the lunatic asylum? After all, one respects the lunatics as the people for whom the building in which one lives exists. Up to a point, you can make your own choice of institution—though the distinction between them is smaller than you think in your younger years.

The English were the first to expel the Jews entirely. The Jews of England belonged to the Crown, which had systematically extracted their wealth through a special Exchequer to the Jews. By 1290 it had bled them dry. Edward I thereupon confiscated what little they had left and threw them out. They crossed to France, but expulsion from that country followed in 1392; from Spain, at the demand of the Inquisition, in 1492; from Portugal in 1497. Since Germany was a region of multiple sovereignties, German Jews could not be generally expelled. They had been fleeing eastward from bitter German persecution in any case since the twelfth century.

The Jews expelled from Western Europe fled to Poland, a large and thinly populated kingdom where elected monarchs welcomed them with generous charters. The medieval German of these emigrant Ashkenazim evolved to Yiddish; they founded villages and towns; they dispersed up and down the long eastern Polish frontier and lived in relative peace for two hundred years.

Russia, which soon controlled more than three-fourths of what had been the Polish commonwealth, then also controlled the fates of most of the Eastern Jews. But while Poland had welcomed them, Russia despised them. Its economy was too primitive to need their commercial skills and it abhorred their religion. To Catherine the Great her one million new subjects were first and foremost “the enemies of Christ.”

Emancipations as they progressed within less revolutionary states included Holland-Belgium, 1795; Sweden, 1848; Denmark and Greece, 1849; England by a gradual unmuddling completely in 1866; Austria, 1867; Spain by the withdrawal of its 1492 order of expulsion in 1868; the new German Empire, 1871. Though they were influential out of all proportion to their numbers, the emancipated Jews of Western Europe, many of whom moved directly to assimilate, were only a minute fraction of the Diaspora. The preponderance of the Jewish people, increased by 1850 to 2.5 million, by 1900 to 5 million, struggled in increasing misery in the Pale.

Between 1881 and 1900 more than 1 million Jews emigrated from Russia and central Europe to the United States and another 1.5 million between 1900 and 1920.

Under official Emergency Committee auspices thirty scientists and scholars arrived in 1933, thirty-two in 1934, only fifteen in 1935; but forty-three came in 1938, ninety-seven in 1939, fifty-nine in 1940, fifty in 1941.726 Nor were many of these physicists: with their international network of friendships and acquaintances the physicists were better able than most to provide for each other. About one hundred refugee physicists emigrated to the United States between 1933 and 1941.727

Since the neutron carries no charge, there is no strong electrical repulsion to prevent its entry into nuclei. In fact, the forces of attraction which hold nuclei together may pull the neutron into the nucleus. When a neutron enters a nucleus, the effects are about as catastrophic as if the moon struck the earth. The nucleus is violently shaken up by the blow, especially if the collision results in the capture of the neutron. A large increase in energy occurs and must be dissipated, and this may happen in a variety of ways, all of them interesting.

Everyone had assumed that faster neutrons were better for nuclear bombardment because faster protons and alpha particles always had been better. But the analogy ignored the neutron’s distinctive neutrality. A charged particle needed energy to push through the nucleus’ electrical barrier. A neutron did not. Slowing down a neutron gave it more time in the vicinity of the nucleus, and that gave it more time to be captured.

The Anschluss—the annexation—made Meitner a German citizen to whom all the ugly anti-Semitic laws applied that the Nazi state had been accumulating since 1933. “The years of the Hitler regime . . . were naturally very depressing,” she wrote near the end of her life. “But work was a good friend, and I have often thought and said how wonderful it is that by work one may be granted a long respite of forgetfulness from oppressive political conditions.”

They had discovered the reason no elements beyond uranium exist naturally in the world: the two forces working against each other in the nucleus eventually cancel each other out.

Hahn found that uranium breaks into two parts when it absorbs a neutron. . . . When I heard this I immediately saw that these fragments, being heavier than corresponds to their charge, must emit neutrons, and if enough neutrons are emitted . . . then it should be, of course, possible to sustain a chain reaction.

More Londoners by far lived out the dangerous raids in their homes than in shelters: 27 percent fled to corrugated-iron Anderson shelters in back gardens, 9 percent to street shelters, only 4 percent into the Tube.

London civilian deaths in 1940 and 1941 totaled 20,083, civilian deaths elsewhere in Britain 23,602, for a total death by Blitz in the second and third year of the war (about which the United States was still officially neutral) of 43,685.1354 After that the bombing went the other way. Only twenty-seven Londoners lost their lives to bombs in 1942.

Churchill had sent over Henry Tizard in the late summer of 1940 with a delegation of experts and a black-enameled metal steamer trunk, the original black box, full of military secrets. The prize specimen among them was the cavity magnetron developed in Mark Oliphant’s laboratory at Birmingham. John Cockcroft, a future Nobel laureate with a vital mission, traveled along to explain the high-powered microwave generator. The Americans had never seen anything like it before. Cockcroft got together one weekend in October with Ernest Lawrence and multimillionaire physicist-financier Alfred Loomis, the last of the gentlemen scientists, at Loomis’ private laboratory in the elegant suburban New York colony of Tuxedo Park. That meeting laid the groundwork for a major new NDRC laboratory at MIT. To keep its work secret it was named the Radiation Laboratory, as if serious scientists might actually be pursuing applications so dubious as those bruited by visionaries from nuclear physics. Loomis wanted Lawrence to direct the new laboratory. Lawrence preferred to stay at Berkeley laying plans and raising funds for a new 184-inch cyclotron but was willing to encourage his best people to move to Cambridge. He convinced McMillan: “I left Berkeley in November 1940 to take part in the development of radar for national defense.”1384 Lawrence’s and McMillan’s priorities are a measure of the priorities of American science in late 1940. Peacetime cyclotrons and radar for air defense came first befo...

The hydrogen bomb was thus under development in the United States onward from July 1942.

In July the first physics experiment completed at Los Alamos counted the number of secondary neutrons Pu239 emitted when it fissioned. “In this experiment,” says the Los Alamos technical history, “the neutron number was measured from an almost invisible speck of plutonium and found to be somewhat greater even than for U235.”1836 The experiment thus established what had not yet been confirmed despite the expensive rush of building: that plutonium emitted sufficient secondary neutrons to chain-react.

The Strategic Bombing Survey estimates that “probably more persons lost their lives by fire at Tokyo in a 6-hour period than at any [equivalent period of] time in the history of man.”