by Kit Chapman
This is as far as I can go. Fermi’s former lab is behind a wall 15m (50ft) high, tucked into what is now the Italian Ministry of the Interior. The entrances to the complex are guarded by the Carabinieri police force, and the façades are covered in CCTVs to discourage anyone with a bright idea. All I can do is sit on the steps leading up to the villa, eat an ice cream and marvel at how Rome’s unique attitude to the past means its greatest scientific son doesn’t even get a plaque. Perhaps that’s what happens when you have 2,500 years of history to spare.
Back in 1934, the Via Panisperna discovery of ‘transuranic’ or ‘transuranium’ elements (elements beyond uranium) became an overnight sensation. There were a few doubters – most notably the German chemist and element discoverer Ida Noddack, who thought that the nucleus had split apart into much smaller elements – but nobody listened. Mussolini’s press proclaimed a triumph as great as ancient Rome, boasting of ‘Fascist victories in the field of culture’. ‘One second-rate paper went so far as to state that Fermi had presented a small bottle of [element] 93 to the Queen of Italy,’ Laura Fermi recalled in her biography of her husband, Atoms in the Family (he hadn’t; Fermi knew all too well that Marie Curie was dying of cancer caused by radiation, and that carrying a vial of radium in her breast pocket to show off at parties probably hadn’t been her greatest idea). A proud Mussolini pressured Fermi to name his elements after the lictors of ancient Rome, whose symbol, the fasces, gave fascism its name; uncomfortable with the attention, Fermi instead chose ‘ausonium’ and ‘hesperium’, after the Greek names for Italy.
While he worked to confirm his findings, Fermi stumbled onto something even more exciting. If they put something in the way of the beam that reduced the speed of neutrons, such as paraffin wax, they got much better results. Fermi realised it was the hydrogen atoms in the molecules of wax slowing down the neutrons, and reportedly yelling ‘Fantastic! Incredible! Black magic!’, he snatched up the equipment, ran downstairs and leaped into the institute’s fish pond – bathing the device in the most hydrogen-rich environment he could find: water. Fermi had just uncovered the principle that powers today’s nuclear reactors. Slow neutrons mean they spend longer near the nucleus, and thus are more likely to get captured – resulting in more reactions. Water was the perfect way to slow them down. When the friends went to type up their discovery later that evening, the whole lab was in such a good mood the maid assumed they were drunk.
Fermi’s idea of using slow neutrons to attack the nucleus was soon copied by bigger teams with better machines to see if they could make new elements and isotopes too. The Americans, French and Germans threw themselves into experiments in a race to fill in all the missing spaces in the chemical world: it was new, exciting science that offered a host of possibilities. In 1937 Segrè, who had struck out on his own in Sicily, asked for spare parts from one of the American ‘atom smashers’ at the University of California, Berkeley. Investigating a filter sent from the Berkeley team, he found they had created the missing element 43 without noticing. Segrè and his collaborator were credited with the discovery. Italian punk science was filling up the periodic table.
Yet the smiles and happiness soon vanished. The days of the Via Panisperna were over. As Europe tumbled toward war, Adolf Hitler’s Nazi Germany fuelled a climate of anti-Semitism that Mussolini was only too eager to embrace. Fermi and the Boys realised just who their patron was – and knew they had to get out of Italy.
In 1938, while Segrè was on a trip to the US to further explore his element 43, Mussolini decreed that ‘Jews do not belong to the Italian race’ and barred any member of the religion from holding a university position. Segrè was a Sephardic Jew and had married a Jewish refugee from Nazi Germany. Wisely, the couple decided to cut their losses and make California their new home.
Laura Fermi was also Jewish. If Enrico Fermi’s wife and children were to be safe, he knew they would all have to flee Italy, taking only what they could carry. Already, he had spied a possible escape route. Earlier that year, while attending a conference, he had been taken aside by Niels Bohr and told he was being considered for the Nobel Prize. With it, Fermi knew, would come enough prize money to start a new life in the US. All the Italian could do was wait and hope the Royal Swedish Academy of Sciences, who judged the award, agreed with Bohr’s assessment.
On 10 November 1938 the Fermis woke to the news of Kristallnacht. In Germany, Jewish families had been beaten and killed, their shops smashed and their synagogues burned to ash. Shortly after, the telephone rang: Fermi was told to expect a phone call from Stockholm, home of the Nobel Committee, at 6 p.m. Fermi, making one of his rough calculations, estimated his chance of receiving the world’s greatest prize at 90 per cent. He took his wife to buy a pair of expensive watches. Knowing his hatred for retail therapy, Laura understood he was turning their money into something a refugee could pawn. Together, hand in hand, they walked the streets with no real destination in mind as the hours ticked down. It was a silent goodbye to their old life.
That evening, Laura listened to the 6 p.m. news on the radio. Anti-Semitic laws were being introduced across Italy, limiting rights and freedoms, excluding Jewish children from schools, confiscating passports. Her heart sank. Then the phone rang. Enrico Fermi had won the Nobel Prize, on his own, ‘for his demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of nuclear reactions brought about by slow neutrons’.6
It was deliverance. Without a moment’s hesitation, Enrico accepted a trip to Sweden to collect the medal in person, then humbly agreed to a ‘temporary’ lecture position in the US. Naturally, his family accompanied him. By the time the Fascists realised what was happening, the Fermis had slipped out of Europe and were on the next liner to New York.
It was there Fermi learned of shocking news: he and the Boys had been completely wrong. Worse, they had missed out on the discovery of the century.
* * *
The Nobel Committee has made some howling errors in its time. In 1949 it gave a prize to the man who invented lobotomies, a practice now banned across the world. In 1926 it awarded a medal to Johannes Fibiger, who thought parasitic worms caused cancer (they don’t). And in 1938 it honoured Enrico Fermi for creating the first elements beyond uranium. He hadn’t.
One of the great problems when it comes to making new elements is how to prove you’ve actually done it. It’s perhaps the defining problem of element discovery: you’re dealing with something nobody has ever seen before. Fermi had made an honest mistake. If he had checked his results a little more thoroughly, he’d have seen that the ‘new elements’ were just barium, krypton and other atomic debris.
If he had realised at the time, Fermi would have been far from disappointed – he probably would have done cartwheels in delight. Never mind new elements, the Via Panisperna Boys had done something even more miraculous: they had made an atom explode.
The discovery ended up falling to a German group. Otto Hahn was working at the Kaiser Wilhelm Institute for Chemistry in Berlin. In late 1938 Hahn and his assistant Fritz Strassmann were experimenting with slow neutrons and uranium, much as Fermi had done. However, the results were confusing. No matter how hard he tried, Hahn couldn’t make element 93; instead, he was producing barium, element 56, best known today for its use in enemas. The only way it could have been made was if he had somehow split a uranium atom in two.
Unlike many of his colleagues, Hahn was not a Nazi. A few months earlier he had helped his old lab partner, Lise Meitner, escape the country, going so far as to give her his mother’s diamond ring in case she needed to bribe the border guards. Convinced he was going wrong somewhere and stuck for an answer, Hahn wrote to Meitner: ‘Perhaps you can suggest some fantastic explanation … we understand that it really can’t break up into barium.’
Meitner was in Kungälv, Sweden with her nephew, the physicist Otto Frisch. Both Jewish, the duo had been displaced by the Nazi regime (Frisch’s father was impriso
ned in a concentration camp), and friends had invited the lonely scientists to stay for Christmas. Figuring that atomic physics was more fun than charades, they decided to work on Hahn’s problem together.
The pair of exiles soon had an answer. By the late 1930s the nucleus wasn’t viewed like a brittle core that could be cracked and split – it was imagined as a high-density drop of liquid. Adding a neutron made the liquid shake. Meitner took a pencil and started drawing. What if the energy made the liquid turn into a dumb-bell shape? At some point, the forces binding the nucleus together and the electrostatic repulsion trying to pull it apart would cancel each other out. The droplet would goop, split and create smaller droplets.
Ida Noddack, the chemist who had doubted Fermi’s discoveries, had been right all along. Creating an element was walking a tightrope: you needed energy to push past the Coulomb barrier in the first place, but if you used too much energy the nucleus would literally shake itself apart. In other words, the nucleus acted like a fuse box: too much energy and the fuse blew. Meitner wrote back to Hahn. They called the discovery ‘nuclear fission’.
It was the biggest discovery since the neutron: something that Fermi, the British, the Americans, everyone, had missed completely. Overnight, Fermi’s elements 93 and 94 vanished as the scientific world woke to the consequences of Meitner and Hahn’s discovery. By breaking apart the nucleus of the atom, some of the massive energy that bound it together was released. A single atom undergoing fission wouldn’t do much. But if you could get a lot of atoms to fission at once, one after each other in an irresistible chain reaction, the power would be immense. If you could control it, the energy could light a city … or flatten one.
Fermi’s experiments had spurred a competition to create and understand new elements. Meitner and Hahn’s discovery meant nuclear science was no longer a matter of academic curiosity. It was a race to make the first atomic bomb.
Notes
1 Lavoisier also married a 13-year-old and was executed during the French Revolution for upsetting tobacconists, but such was the life of an aristocrat in eighteenth-century France.
2 Electrons were discovered earlier, in 1897, by Ernest Rutherford’s mentor J. J. Thomson. Thomson thought atoms were like plum puddings, with electrons as the raisins.
3 A classic Fermi problem is ‘How many piano tuners are there in Chicago?’ By approximating the number of households that had pianos and how often they would need tuning, Fermi was able to come up with a rough estimate of the number of piano tuners the city could support (about 225, for those wondering).
4 Strictly speaking, this is beta minus radiation, but that’s not really important for our story. Nor is the third main type of radiation, gamma.
5 Element 85, astatine, hadn’t been discovered at the time, but Fermi knew it couldn’t have been produced by uranium, as alpha decay loses two places at a time, so would have skipped over it.
6 Fermi could also have won for the paper on beta radiation Nature had rejected: it described the possibility of a ‘baby neutron’ – or, in Italian, neutrino. This was eventually found in the 1950s, and gets name-checked in pretty much every episode of Star Trek.
CHAPTER TWO
The Secret of Gilman Hall
Luis Alvarez needed a haircut. Taking a mid-morning walk across the hilly rise of the Berkeley campus, the 27-year-old physicist, blond locks tousled in the breeze, admired the view out across the San Francisco Bay. In the distance he could see the new federal prison on Alcatraz; past that, the recently constructed suspension bridge across the Golden Gate, the longest and tallest bridge in the world. Reaching the barber, he settled into the chair and pulled up the morning’s San Francisco Chronicle with immense satisfaction. It was Tuesday, 31 January 1939.
Alvarez stared at the page in shock. The Chronicle had picked up Hahn and Meitner’s discovery of nuclear fission from a wire service. Stopping the barber mid-cut, Alvarez snatched the page, leaped from the chair and sprinted back to the Radiation Laboratory. This was at the heart of the campus, a small, ugly wooden hut sandwiched between the grand, Beaux-Arts colonnades of LeConte Hall and the rising needle of the campus clock tower, modelled after the Campanile of San Marco in Venice. Inside, the Rad Lab was a chaotic mess, full of cages of mice for biomedical experiments, blackboards chalked with equations and giant magnets for the ‘proton merry-go-round’ that was the Berkeley particle accelerator. It was probably the most advanced laboratory in the world.
Skidding through the door, Alvarez hurried to his assistant, Phil Abelson, to tell him the news. ‘I have something terribly important to tell you,’ Alvarez relayed. ‘I think you should lie down on the table.’ Abelson was game and, grinning, climbed up on the workbench, spreading himself out among the chemical reagents and machine tools. Fission! Atoms can split apart! Abelson went numb; he’d been experimenting with uranium, had noticed similar results to Hahn’s and was probably moments away from making the discovery himself.
Alvarez didn’t stop, rushing around to tell everyone, not caring that he had accidentally invented the mullet. He started herding anyone nearby, including future Manhattan Project leader Robert Oppenheimer, to show them the fission energy ‘kicks’ coming off the lab’s own machines. For years, the ‘atom smashers’ had been picking up strange radioactive noise, but it was always dismissed as a quirk of the machine. The Berkeley team had all missed the discovery of the century – and it had been staring them right in the face.
By nightfall, news of the breakthrough had reached the journal club, where a 26-year-old researcher called Glenn Seaborg heard the tale. ‘I walked the streets of Berkeley for hours,’ Seaborg later recalled in his autobiography, Adventures in the Atomic Age. ‘My mood alternated between exhilaration at the exciting discovery and consternation that I’d been studying the field for years and had completely overlooked the possibility.’
Seaborg was a chemist who had been adopted by the physics set. Immensely tall and lean, with a wide grin and pocked cheeks, the young man hailed from Ishpeming, an icy backwater in the wilds of north Michigan, not far from the Canadian border. His family as far back as his great-grandfather were machinists from Sweden and were hardy stock used to rolling up their sleeves. When his grandfather had passed through Ellis Island in 1867, an immigration official had Anglicised ‘Sjöberg’ to ‘Seaborg’ with a wave of his pen. There was no way the official could realise that his invented surname would, 130 years later, be inked indelibly into human history.
Seaborg had grown up speaking Swedish at home, scraping out a life in a town whose ‘unpaved streets were tinged red from iron ore’. It was a hard upbringing; Ishpeming’s only claim to fame was hosting the first away game for the newly formed Green Bay Packers American football team (the Michigan men had sent three of the Packers off with broken bones in the first three plays). When he was 11, the family had moved to Los Angeles, where the young Seaborg’s world had suddenly expanded into technicolour. In Ishpeming he’d never heard a radio or seen a building more than a few storeys tall; in the City of Angels he’d found his world filled with lights, cars and oil riches. Inspired by the glitz and glamour of Hollywoodland at his doorstep, the young Glen had added an extra n to his name – it just looked cool – and had gone to find his fortune in science.
Science isn’t made for fortune hunters. Seaborg had struggled, paying his way through the University of California, Los Angeles first by working at factories and as a lab assistant, then by borrowing money from high school friends. Eventually, he had ended up at Berkeley. In 1937, in one of those quirky moments of luck that change history, he’d been strolling about campus when one of the Radiation Laboratory team had asked him to help with the tricky task of separating out different elements in a solution – he was literally the first chemist they could find. After that, he had been as much a part of the lab as any of them, covering the chemistry while the physicists created new radioactive isotopes of tin, cobalt, iron and Emilio Segrè’s element 43 (later called technetium). Many of thes
e isotopes, such as technetium-99m and cobalt-60, were to become the cornerstone of modern radioactive medicine; today they are still used in millions of cancer treatments and diagnostic tests around the world.
The secret to the Berkeley Radiation Laboratory’s success was its revolutionary approach. The opposite of the Via Panisperna Boys’ homespun charm, the Americans were all about ‘Big Science’: big teams using big equipment from sponsors with big pockets. It was the brainchild of Ernest Lawrence, the grandson of Norwegian immigrants from South Dakota, who had broken through the stuffy, elitist physics department at Yale before moving west to make his name. Under his guiding hand as director, the Rad Lab had become a template for modern research. Rather than each scientist working on their own experiments, laboriously blowing their own glass tubes, making their own circuits and testing their own reactions, Lawrence expected everyone to work together. Berkeley was an epicentre of large-scale partnerships, teams working in shifts and each member focusing on their own area of expertise.
Figure 2 The Berkeley 60-inch cyclotron, a particle accelerator designed by Ernest Lawrence.
Throughout the 1930s, Lawrence had pioneered the construction of compact particle accelerators called cyclotrons, the most powerful research machines in the world. It was the spare parts from one of these behemoths that Segrè had cheekily borrowed to discover technetium. Unbeknown to their operators, the machines had already produced another element too.
Its discovery came hot on the heels of Alvarez’s barbershop dash. Edwin McMillan was a California native who had made it as far as Princeton before being lured back to his home state by Lawrence. Still in his early thirties, Ed was one of the cyclotron’s best operators and possessed a keen experimentalist mind that wouldn’t rest until it had answers.