Norman Moss - Klaus Fuchs - The Man Who Stole the Atom Bomb

Fuchs and Feynman had adjoining rooms in the bachelors’ building, sharing a bathroom, and sometimes they used to talk late into the night. Feynman used to tease Fuchs about his reticence. More earnestly, he urged him to come out of his shell, and suggested that he take out some girls, for there were a few young single women at Los Alamos. Once they had a light-hearted conversation about spies, and about which of them was a more likely suspect as a Nazi spy (which was the only kind that anyone was thinking about). Fuchs said it would be Feynman because of his frequent trips to Albuquerque, seventy miles away, and Feynman agreed. These trips were to visit his wife. For the clowning, fun-loving Feynman was living in the shadow of tragedy: his wife, whom he had married a few months earlier, was dying of tuberculosis in an Albuquerque hospital.

Among Americans, Fuchs’s reserve was even more conspicuous than it had been in Britain, and it was remarked upon. Mrs Peierls’s penny-in-the-slot description circulated. Wives talked about him, as they always will about a single man. When two of the wives were discussing him, Eleanor Jette summed up the negative impression he made on her: ‘That guy baffles me. I can’t remember what he looks like until the next time I see him.’

And Marjorie Schreiber said: ‘He gives me the creeps. He sits in a corner at parties and never says a word. I’ve never heard him laugh: he has a high-pitched giggle, and it gives me the chills.’

Her hostility was unusual. Another wife described him as ‘a sweet, reticent little guy’. Fuchs’s silences seemed sad, and a lot of people felt vaguely sorry for him. Oppenheimer remarked once that he seemed to be carrying the weight of the world on his shoulders. There was still that barrier across his mind, and behind it lay that other compartment, which contained his commitment to help the Soviet Union, and who knows what else besides among his emotional baggage.

To some, the barrier seemed almost palpable. The Deutschs were convinced that there was another person behind the Fuchs they knew, and they discussed this between themselves. Martin Deutsch was the son of the well-known Viennese psychoanalyst Helen Deutsch, and they often discussed people in psychoanalytic terms. Edward Teller liked him, but also felt that there was something hidden back there; he found him, he said once, ‘taciturn to an almost pathological degree’.

Yet during his time at Los Alamos Fuchs loosened up a little, as he became respected for his work and absorbed into the camaraderie of the place. He danced at parties. At Bristol, Lovell had remarked that he looked as if he never breathed fresh air, but now he sought pleasures in the outdoors, as many others did there. He used to go with others on day-long hikes, sometimes into the mountains. Occasionally, when the others were resting, he would show off his energy and skill by climbing a rock face at the side of the path, grinning at the achievement. When he climbed, his emotional self-control was matched by physical self-control. He went skiing, which he had not done since he was a student in Germany.

He may have been thin and slightly built, but he was not weak. There is a strong daytime sun at Los Alamos for seven or eight months of the year, although the air is thin and dry so that the nights are usually chilly. Fuchs acquired a healthy-looking outdoor tan, and the tautness was not so visible.

He bought a second-hand car, the only kind that could be had during the war, a four-door Buick. Many people at Los Alamos did not have cars, and he was often being asked to give people lifts or run errands, and he was nearly always willing. (Feynman borrowed his car to drive into Albuquerque when his wife died in hospital there.) The car gave him independent mobility; it meant he could drive somewhere if he wanted to without having to rely on someone else or ask for official transport, and without letting anyone else know where he was going.

Oppenheimer, as director, insisted that everyone should know what was going on and he held a weekly meeting, or colloquium as it was called, for all senior staff. It was usually attended by about fifty people, and progress was reviewed. General Groves wanted work compartmentalized, with everyone knowing only what he needed to know for his work, in the interests of security. But Oppenheimer insisted on holding these colloquia, first of all because the work was so new that possible interactions between different areas could not be foreseen, and a new idea in one might unexpectedly solve a problem in another, but also for morale reasons, so that everyone should know what part his work was playing in this huge undertaking.

Fuchs learned for the first time at Los Alamos about a new kind of atomic bomb. As well as a uranium 235 bomb, they were also designing there another kind of fission bomb, made with plutonium. This was something that was first suggested in Britain by Egon Bretscher, a Swiss-born physicist who had worked in the Oxford branch of Tube Alloys, and was now here in Los Alamos.

But it was also suggested at the Berkeley laboratory in California, and there the idea was followed through. Plutonium is a man-made element produced by the fissioning of uranium atoms, and it is fissile, like uranium 235. So a nuclear reactor was built at Hanford, in Washington State, and a chemical separation plant to extract the plutonium from the uranium that had undergone fission in the reactor.

Just before Peierls and Fuchs arrived, it was found that a plutonium bomb could not be made to work in the same way that a uranium 235 Tomb was expected to: that is, by bringing two pieces together very rapidly so that they form a critical mass. Plutonium atoms fission spontaneously, and would do so even in the millionth of a second during which the two pieces are brought together, and the energy would be dissipated rather than concentrated in an explosion. From this time on, the problem of how to detonate a plutonium bomb took up more time and thought at Los Alamos than any other.

The answer turned out to be to make high explosives into a hollow sphere so that they would explode inwards, in an ‘implosion’. Plutonium would then be put inside this sphere and it would be compressed by the blast into a critical mass. This is extremely complicated, and it involves calculating microsecond reactions both in high explosives and in the fissioning of plutonium. The chemist George Kistiakowsky was-brought in from an army specialized explosives programme, and he designed eventually a series of what are called explosive lenses, which ensured that the force of the explosion was precisely the same on all parts of the sphere.

Edward Teller, the brilliant but individualistic Hungarian-born physicist, was calculating plutonium fission reactions. But he was becoming more and more absorbed with another possibility, albeit a remote one: a bomb that would work by nuclear fusion, and would be even more powerful than a fission bomb. When scientists discussed this, they called it the ‘super’. It was what would later be called the thermonuclear bomb, or hydrogen bomb. Oppenheimer and Bethe urged him to concentrate on the task in hand, of building a fission bomb and winning the war, but they could not overcome his enthusiasm for the fusion idea. So Bethe let him go off and work on it, and he assigned Peierls and Fuchs to take over his work on plutonium fission. [8] Teller played a crucial role in the invention of the hydrogen bomb in 1951.

This problem of the premature detonation, or pre-detonation, as it was called, of a plutonium device preoccupied them. So much so that once, when Fuchs telephoned a garage in Santa Fe to say that the timing of his ignition was faulty, he told the garage that it ‘pre-detonated’. Peierls, who was in his office at the time and heard his end of the conversation, chided him jokingly for a lapse in security.