Half-Life: The Divided Life of Bruno Pontecorvo, Physicist or Spy

by Close, Frank

  One day in 1935, while listening to a seminar in Copenhagen describing these problems, Niels Bohr suddenly “sat still, his face completely dead.”30 Others in the audience at first thought that he was ill. Then he stood up from his seat and exclaimed, “Now I understand it!”

  Bohr went to the board and explained his vision of the atomic nucleus. He saw it not as a single lump of charge acting like a lone particle, but as a tightly packed cluster of protons and neutrons, which touch one another. During a reaction the constituents are excited into a temporarily unstable compound state, which returns to a stable configuration once the reaction is over.

  Bohr’s picture explained how Fermi’s neutrons were slowed, reduced in energy, and captured, all in a way that was consistent with what the Rome team had found. Like a cue ball in pool hitting the rack, a neutron hitting a crowded nucleus gives up its energy to the nucleus’s individual components, which recoil, bump into one another, and spread the impact around, sharing the energy among themselves. The nucleus becomes hot, and then cools down by radiating gamma rays, but no individual constituent member escapes. Having been the first to envision a picture of the atom, he had now come up with the model of the nucleus that is still, in essence, the foundation of modern nuclear theory.31

  The discovery by the Via Panisperna Boys had inspired Bohr’s explanation of the dynamics of atomic nuclei, and this, along with the breakthrough by the Joliot-Curies, opened up possibilities for mining the energy latent within the nucleus. By the mid-1930s, nuclear physics was fast becoming the frontier area of research worldwide. In the opinion of Maurice Goldhaber, one of the foremost Americans in the field, the leaders were Rutherford’s group in Cambridge, followed by Fermi’s group in Rome and the Joliot-Curies’ group in Paris. Igor Kurchatov, in Leningrad, led the team that Goldhaber ranked fourth.32

  Known as “the General” because he was a leader and liked to give orders, Igor Kurchatov was energetic, argumentative, and prone to expressive swearing. In 1932, at the age of twenty-nine, Kurchatov heard about the discovery of the neutron and the Joliot-Curies’ breakthrough. Although he had been working on the electrical properties of materials, he abruptly changed course to nuclear physics, and when the Via Panisperna Boys discovered the slow-neutron phenomenon, Kurchatov immediately saw its importance and decided to specialize in neutron physics. Between July 1934 and February 1936, his team published seventeen papers on induced radioactivity, one of which particularly impressed Bruno Pontecorvo.33

  Kurchatov was at the start of a stellar career. Within ten years, he would lead the Soviet efforts to develop nuclear weapons, and be recognized as the father of the Soviet atomic bomb. In the 1930s, the number of scientists working in the field of nuclear physics was still small, and its practitioners around the world were all known to one another. The possibility that its future would be full of secrecy, paranoia, and military applications was still undreamed of.

  THE VIA PANISPERNA BOYS HAD BECOME ACKNOWLEDGED LEADERS of a new field of physics. Although their famous breakthrough involved little more than a bucket of water (or perhaps a goldfish pond), many attacks on nuclear structure required large machines. In Cambridge, during 1932, John Cockcroft and Ernest Walton had built a five-meter tower of capacitors, which they could charge to about 500,000 volts. This created powerful electric fields, enabling the Cambridge team to accelerate electrically charged particles, such as protons. When these high-energy protons hit the nuclei of atoms in a target, Cockcroft and Walton discovered that these nuclei were shattered. They had built what later became known as an “atom smasher.”

  In Berkeley, California, Ernest Lawrence built a machine that used a mix of electric and magnetic fields to guide charged particles around curves, speeding them up as the arc grew bigger. This invention, known as a cyclotron, gave birth to what is known today as high-energy physics. Although Rutherford was reluctant to embrace large-scale physics at Cambridge, elsewhere—most notably in Berkeley—a new age of particle accelerators was beginning. Those who didn’t join this new adventure were in danger of being left behind. James Chadwick, discoverer of the neutron, was disappointed in Rutherford’s reluctance and left Cambridge in 1935. He moved to Liverpool, where he built a cyclotron with help from Cockcroft.

  Fermi and his team recognized the importance of this new strategy, but they were unable to get the financial support needed to build an accelerator. The team began to break up, partly due to this difficulty, and partly due to the growing threat of fascism. For Pontecorvo, young and ambitious, it was time to move on.

  In 1935, Frédéric and Irène Joliot-Curie won the Nobel Prize for the work that had inspired Fermi and set Pontecorvo on his own research path. Whereas Fermi’s Italian team had shone like a supernova, bursting into brilliance and then fading, the Joliot-Curies’ lab in Paris was emerging as a steady star of nuclear physics. The couple began to attract foreigners to their lab. That same year, Pontecorvo won a scholarship from the Italian Ministry of National Education. Funded by this award, he moved to Paris in 1936 to work alongside the Joliot-Curies. Pontecorvo was certainly well placed within the scientific community: he was a member of one internationally famous team of nuclear researchers and about to join another.

  THREE

  PARIS AND POLITICS

  1936–1940

  BRUNO PONTECORVO’S CHILDHOOD, ADOLESCENCE, AND EARLY adulthood spanned an era bracketed by two world wars. He was born just before World War I started, was five when it ended, and had recently graduated from college when World War II began. It is a cliché to say that much had changed during that quarter century, but for Bruno Pontecorvo and his family this was cruelly true.

  Although Italy was involved in World War I for only three years, it spent more money in that short time than it had during the previous half century, and nearly two million Italian citizens were killed or wounded. Having suffered such extreme costs, both financial and personal, the Italians expected some reward for their contribution to the victory. Such hopes were soon dashed. At the Paris Peace Conference that followed the war, the “Big Three”—the United States, the United Kingdom, and France—regarded Italy’s delegation as minor players. This slap in the face generated great resentment. Italians viewed their government as weak; dissatisfaction festered. Unions were formed. Demonstrations, strikes, and militancy quickly followed.

  Soon, Italy was in turmoil. During 1920, many factories were occupied. Industrial unrest spread rapidly, and at one point half a million workers were involved, spearheaded by the Italian socialist and communist parties. Fascism too began its rise. Benito Mussolini, having been expelled by the socialists in 1914, formed the National Fascist Party. By 1922 he was prime minister, and by 1925 he was the self-styled “Il Duce”—the Leader.

  The Pontecorvo family’s reaction was typical of many intellectuals opposed to fascist rule, with its censorship, overweening propaganda, and (later) active anti-Semitism. In 1936, following Hitler’s example in Germany, Mussolini enacted laws forbidding Jews from holding positions of authority, such as in universities, and limiting their right to work in a variety of ways. Anti-Semitism soon erupted into violent persecution.

  At the time, Italy had large numbers of people who were technically Jewish but didn’t actively practice the religion. The Pontecorvos fell squarely into this category. However, in such a vicious environment, you became Jewish whether you liked it or not. It was in this climate that the Pontecorvo family dispersed.

  The rise of fascism also led to the breakup of Fermi’s group in Rome. Fermi himself emigrated to the United States in 1938. By this time Bruno had already moved to Paris, where he’d joined the team of Frédéric and Irène Joliot-Curie. As it happened, Frédéric was an active communist, and Irène was a fellow traveler. Against the backdrop of the 1936–1939 Spanish Civil War, which caused thinking people around the world to declare their political allegiances, Bruno soon joined Europe’s intellectual nexus in the fight against fascism.

  YEARS LATER, AFTER BRUNO DISAP
PEARED INTO THE SOVIET UNION, the British security services would identify the Paris years as the time when Bruno Pontecorvo had been “exposed to the virus of communism.”1 Their informant identified several communists present in Bruno’s circle, including his cousin Emilio Sereni, as well as Frédéric Joliot and a certain Professor Langevin.

  Paul Langevin was a physicist who had been Marie Curie’s lover after the death of her husband in 1906. Two decades later, his influence pervaded the Joliot-Curies’ laboratory. Indeed, he had been Frédéric’s mentor, and it was through Langevin that Frédéric had gained his introduction to the Curie laboratory. As fascism threatened to engulf Europe, Langevin, like many intellectuals, had chosen communism. By the 1930s, he was one of the most influential people in France, and dreamed of setting up a workers’ university in Paris, built according to Marxist ideals. When Langevin proposed this idea, both Frédéric and Irène offered to give lectures.

  Langevin was also a foreign member of the Soviet Academy of Sciences. In 1933, when he invited Frédéric to join him for ten days of scientific meetings in Leningrad and Moscow, Frédéric was only too happy to come along. Langevin introduced him to many Soviet intellectuals. On that occasion, Irène was unwell and stayed in France, but she joined her husband on several visits to the Soviet Union later.

  With the rise of Hitler and Mussolini, France had become a haven for left-wing intellectuals fleeing fascist persecution. Communists in France joined the strategic Popular Front, which included all the parties of the left and center. Irène and Frédéric were strong supporters.

  This vibrant cosmopolitan community awaited Bruno as he set out from Italy in February 1936. After an overnight train journey, during which he had to stand, leaning against a window, Bruno Pontecorvo arrived at the Gare de Lyon in Paris on Leap Day, February 29.2

  Irène and Frédéric Joliot-Curie were at the height of their power and influence: they had won the Nobel Prize the previous December for their discovery of induced radioactivity; in the month of Bruno’s arrival they attended the first Mendeleev Conference in Moscow, where Frédéric gave the opening address, discussing their breakthrough. Following the conference, the couple spent nearly a month in the Soviet Union, meeting many influential people, in both science and government. Meanwhile, in France, within weeks of Bruno’s arrival, the Popular Front swept to power, led by Léon Blum. Blum immediately invited Irene to serve as undersecretary of state for scientific research.3

  At twenty-three years of age, Bruno Pontecorvo could hardly have failed to be impressed.

  LEFT WING ON THE LEFT BANK

  The picturesque narrow streets of Paris’s Latin Quarter, on the Left Bank of the River Seine, weave in and around the buildings of the Sorbonne and the Collège de France. A ten-minute walk south of the former Joliot-Curie laboratory is the Panthéon. Originally a church, the Panthéon is now a secular mausoleum, containing the remains of French “national heroes,” including Pierre and Marie Curie, though not their daughter or son-in-law. Immediately in front of the edifice is the Place du Panthéon, where, among the cafés and offices, stands an eighteenth-century building: the Hôtel des Grands Hommes. Eighty years ago, when Bruno arrived in Paris, this grandly named residence was quite basic, even sleazy. Its main attraction for students and young researchers at the Collège de France was that the accommodations were cheap.

  Bruno rented a room there. As it happened, the owner supplemented his income by renting out rooms by the hour during the day for assignations. Bruno discovered this when he arrived home one afternoon and encountered the novelist André Malraux in the corridor, along with a “very showy girl.”4

  The rooms were cheap, but even so the bed linens were changed once a week, and there was a sink in each room, though it only provided cold water. The toilet was in the corridor, and if you gave reasonable notice, and paid in advance, you could bathe in the communal bathroom. Such was student life in prewar Paris. During this period, Bruno met and befriended several people who would have a huge influence on his life, both by establishing him as one of the world’s leading nuclear experts and by igniting his passionate belief in communist ideology.

  In Germany, Nazi thugs were rampant. Anti-Semitic laws were expanded, an axis of alliance with Mussolini was formed, and the Berlin Olympics were exploited to promote Nazism and Aryan supremacy. In Spain, with its brewing civil war, the contest between fascism and socialism was about to erupt into violence. Meanwhile, in France, Léon Blum led the democratically elected Popular Front of socialists and communists. After the Popular Front’s victory in May (but before Blum took office as prime minister in June), the workers’ movement launched a general strike, which led to a series of agreements known as the “Magna Carta of French Labor.” Bruno Pontecorvo thus arrived in Paris at a time of vibrant political activism. His background had prepared him for such an environment. In Italy, his friends had embraced the Italian antifascist movement, as well as the ideals of Antonio Gramsci, founder of the Communist Party of Italy.

  Nonetheless, Paris opened his eyes to a whole new way of life. Workers mingled with students and ate with them in the canteen. Back home, Bruno’s only contact with a manual worker had been when one of his father’s employees periodically came to their home for discussions. However, Bruno later recalled, “I never ate at the same table” as the worker.5

  In Rome, Fermi had always claimed that his research work left him uninterested in politics. Bruno had formed the impression that this was a general truth in science. However, at the university in Paris he was surrounded by political activism, quite unlike his previous experiences. Rome and Pisa began to seem rather provincial, while Paris seemed like the center of the world.

  Bruno had gone to Paris because he was impressed by the Joliot-Curies as scientists. When he visited Irène and Frédéric at their home, he was surprised by their intense discussions of politics. What’s more, the majority of his colleagues were actively left-wing or communist. All the framework was in place for Bruno’s political confirmation. The completion of his journey, from antifascism to a lifelong belief in communism, occurred through the influence of his cousin Emilio Sereni.6

  Sereni had fled from the Italian fascist police in 1935, and immediately became immersed in the communist organization in France. When the cousins met again in Paris—Sereni now thirty years old, and Bruno just twenty-three—Sereni had a huge effect on his young relative. Sereni took Bruno along to political rallies, where they befriended communist intellectuals and party officials. Soon Bruno was attending meetings almost daily.7

  In particular Bruno recalled joining Sereni and a group of Italian émigrés in the fall of 1936 at a large rally led by Maurice Thorez, head of the French Communist Party. Decades later, Bruno still had a vivid memory of the enthusiastic and excited crowd, who waved flags, raised their fists, and had red handkerchiefs or scarves wrapped around their necks.

  Sereni inspired in Bruno a surge of enthusiasm for what was happening in the Soviet Union “where the proletariat were in power” and were constructing “the new man.”8 Bruno made no attempt to hide these sympathies, at least while he was in France. In fact, he inspired his older sister, Giuliana, and his younger siblings Laura and Gillo to convert to communism.9 Years later, in the 1980s, Bruno confirmed, “I went over to politics when I went to Paris in 1936, the years of the Popular Front, and had the opportunity to meet with political emigrants such as Sereni, Luigi Longo [a leader of the Communist Party of Italy, who became its secretary in the 1960s], Giuseppe Dozza [later elected five times as the communist mayor of Bologna] . . . and others.”10

  Bruno Pontecorvo’s life would confirm Ernest Hemingway’s observation: “If you are lucky enough to have lived in Paris as a young man, then wherever you go for the rest of your life, it stays with you.”11

  MARIANNE

  During the spring of 1936, as Bruno was becoming immersed in Parisian life, eighteen-year-old Marianne Nordblom was nearing the end of a yearlong correspondence course in Sweden. In May
she graduated with a pass in shorthand, and distinction in typing. As for commercial correspondence, she passed in Swedish but was “not approved” in German, English, or French. At the end of the summer, on September 7, she spent the day packing suitcases. The following day she left her parents’ home in Sandviken, took the train one hundred miles south to Stockholm, and boarded the SS Burgundie. Her final destination would be France, where she planned to work as a nanny, study the language, and have adventures.12

  Her diary records that there was “lots of rough sea. Everyone was ill except for a few—including me.” She arrived at the Gare de Lyon in Paris late on the afternoon of September 15, reached her lodgings at 37 rue d’Anjou, north of the Place de la Concorde, and spent the next day “unpacking.”13 Her visa would allow her to stay for up to two years.

  She had been in Paris a fortnight when she was introduced to La Bohème—a dance club in Montparnasse frequented by students. She went there regularly. On the evening of Thursday, November 12, Bruno too was at La Bohème. Marianne noted the fateful encounter in her diary: “At La Bohème, met Bruno Pontecorvo.”

  Slender and fair-haired, with high cheekbones, Marianne had classic Nordic features, the blond counterpart to Bruno, with his dark Latin charms. The encounter seems to have been a coup de foudre, as her diary records that they met regularly. Their first date occurred just two evenings later, on Saturday the fourteenth, when she accompanied Bruno to a “big ball at the Cité Universitaire.” Her diary includes the comment “great.” The two were soon spending a lot of time together. Sometimes they went to see the Paris Opera Ballet or visited a museum, but dancing at La Bohème seems to have remained one of their favorite activities.14