The Making of the Atomic Bomb

apparently was not yet sufficient to do the job. “On March 9, 1951,” Bethe notes, “… Teller and Ulam published a [classified] paper which contained one-half the new concept.”

But “within a month,” Bethe goes on, “the very important second half of the new concept occurred to Teller, and was given preliminary checks by [Frederick] de Hoffmann. This immediately became the main focus of attention of the thermonuclear design program.” The second half of the new concept was probably a further nesting of cylinders within cylinders: an outside casing of U238 to scatter X rays from the primary into the plastic; a layer next of plastic; a layer next of U238 tamper; a layer next of thermonuclear materials; and at the axis of the cylinder a stick of plutonium. Now the imploding plastic would work not only on the thermonuclear materials. It would also start a second fission chain reaction in the stick of Pu by squeezing it to critical mass. That would add a further huge flux of heat and pressure to the thermonuclear materials and push the fusion reactions over the top. The U238 layer, in turn, would benefit from the dense flux of neutrons released in thermonuclear burning and would fission above the 1 MeV U238 fission threshold. Neutrons from that fission would then contribute to preparing the thermonuclear materials for further burning.[10] Such a design is usually described as fission-fusion-fission. Not without reason did Robert Oppenheimer call the two-part Teller-Ulam invention “technically… sweet.”

The Institute for Advanced Study director, among others, hailed the invention as a breakthrough. “Dr. Oppenheimer warmly supported this new approach,” Teller testifies, “and I understand that he made a statement to the effect that if anything of this kind had been suggested right away [i.e., at the time of the 1949 H-bomb debate] he would never have opposed it.”

Work on a thermonuclear advanced rapidly at Los Alamos through 1951, but by then Teller's relationships had deteriorated to the point of no return. (Three years later, in a time of trial, Oppenheimer would note on a yellow pad a damning remark of Teller's that summarized the Hungarian physicist's turnabout from proponent of world government to aggressive weaponeer, a remark that echoes all the way back to his traumatic experience of revolution and counterrevolution in the Hungary of his youth: “‘Since I cannot work w[ith] the appeasers, I will work with the Fascists.’… Someone heard E. T. say this. Who?”) In 1952, with Ernest Lawrence's support and Defense Department backing, Teller won a second weapons laboratory in the Livermore Valley, fifty miles inland from Berkeley. Los Alamos was left to build the first experimental thermonuclear device, banally coded Mike.

Teller chose not to attend the Mike shot at Eniwetok on November 1, 1952. He was busy starting up his new weapons laboratory and could hardly spare the time; he certainly also felt unwelcome. The Mike device was fueled with liquid tritium and deuterium; the liquids required a cryogenic refrigeration plant to maintain their low temperature. The complex assembly weighed some 65 tons and occupied an entire laboratory building on the small island of Elugelab. Shrouded in black tar paper, shimmering in the heat, the cubic building looked in the distance like a diabolic twin to the Kaaba of Mecca.

Teller contrived nevertheless to follow the progress of the test. He stationed himself at a seismograph in a basement room of the Berkeley geology building. Herbert York, acting director at Livermore, tuned a shortwave radio to the frequency of the Mike shot telemetry. When the shot was fired he called Teller in Berkeley. The two physicists had calculated the time a seismic wave from a successful shot would require to travel under the Pacific basin to northern California — about fifteen minutes, Teller remembers:

I watched with little patience, the seismograph making at each minute a clearly visible vibration which served as a time signal. At last the time signal came that had to be followed by the shock from the explosion and there it seemed to be: the luminous point appeared to dance wildly and irregularly. Was it only that the pencil which I held as a marker trembled in my hand?

Mike was expected to explode with an energy of a few megatons. But its designers had engineered every component to maximize its yield. It yielded 10.4 million tons TNT equivalent, a thousand times more violent than Little Boy. “This thing is the plague of Thebes,” Oppenheimer once complained of the H-bomb. Now the plague found incarnation.

The test was secret. No report would reach Los Alamos until security officers on Eniwetok had time to examine and encode it. Teller knew Mike had worked before its builders did. He dictated a telegram to York to send on to Los Alamos. The message was brief but barbed: “It's a boy.”

“The fireball,” writes Leona Marshall Libby, “expanded to 3 miles in diameter. Observers, all evacuated to 40 miles or more away, saw millions of gallons of [atoll] lagoon water, turned to steam, appear as a giant bubble. When the steam had evaporated, they saw that the island of Elugelab, where the bomb [building] had been, had vanished, vaporized also. In its place, a crater ¹/₂ mile deep and 2 miles wide had been torn in the reef.”

The Soviet Union exploded a device with a small hydrogen component in August 1953. Its yield was probably several hundred kilotons, about half the yield of the largest fission weapon the United States had tested up to that time. “This was not a true H-bomb,” Hans Bethe comments, “as I know very well because I was chairman of the committee analyzing the Russian [fallout].”

At 65 tons Mike was too large and complex a mechanism to serve as a deliverable bomb. Its designers had fueled it with liquid deuterium and tritium for simplicity in measuring the thermonuclear reactions it would test. For a deliverable bomb the thermonuclear material of choice would be lithium deuteride, a stable powder, the lithium in the form of the isotope Li6, which constitutes 7.4 percent of natural lithium but can be separated from it relatively easily. Neutrons from the fission components of a lithium-fueled bomb would produce tritium almost instantly from Li6, which would then fuse with the deuteride to develop thermonuclear burning just as the wet and bulky liquid hydrogen isotopes had done in Mike. The dry design was tested during Operation Castle in the spring of 1954; “the very first test of the series,” writes Herbert York, “the Bravo test, was of a device using LiD as its fuel and yielding 15 megatons. It was in a form readily adaptable for delivery by aircraft, and thus was the first large American hydrogen bomb.” A true Soviet thermonuclear, dropped from an aircraft in test, followed on November 23, 1955.

When Niels Bohr arrived at Los Alamos in 1943, writes Robert Oppenheimer, “his first serious question was, ‘Is it really big enough?’” The bomb, Bohr meant: big enough to end world war, big enough to challenge mankind to find its way beyond man-made death to a world more open and more humane. “I do not know whether it was,” Oppenheimer adds; “it did finally get to be.” By 1955, if not before, the bomb had worked an essential change upon the world. Oppenheimer had already found succinct metaphoric expression of that change in a commencement address he delivered early in 1946. “It did not take atomic weapons to make war terrible,” he said then. “… It did not take atomic weapons to make man want peace, a peace that would last. But the atomic bomb was the turn of the screw. It has made the prospect of future war unendurable. It has led us up those last few steps to the mountain pass; and beyond there is a different country.”

Gil Elliot's Twentieth Century Book of the Dead is a useful guide to that progress. Elliot is a Scottish writer of original mind who lives in London. It occurred to him to look into the question of how many human beings have died by man-made violence in this most bloody of centuries. He discovered that few historians or statisticians have bothered to count past the men in uniform. He worked out order-of-magnitude estimates and arrived at a total (including combatants) of about 100 million dead. He calls this uncelebrated multitude a nation of the dead:

We know as much about the nation of the dead as we might have known about any living nation fifty years ago when the techniques of social measurement were still at an early stage. The population is around one hundred million. A proper census has not yet been possible but the latest estimate based on samples of the population suggests a figure of a hundred and ten million. That's about the size of it. A large modern nation. It's very much a twentieth-century nation, as cosmopolitan in its origins as the United States. The people have always been mixed, but the real growth began in 1914. Between then and the early 1920s the population reached twenty million, and steady growth over the next twenty years brought it to almost forty million by the outbreak of the Second World War. In the early 1940s the population more than doubled, with annual increases reaching peaks of 10/12 million. Since 1945 the growth-rate has declined below any previous levels since the late 1920s. This has been accompanied by a gigantic increase in the capacity for expansion.