by Sam Kean
In the Alps, Irène and her husband saw some mildly interesting trails appear, including some odd spirals. The particle that created them apparently weighed the same as an electron, but the trail twisted in the opposite direction, like the trail of a positive particle. Regardless, neutral neutrons wouldn’t leave such a trail, so after two fruitless months the couple dropped the project and returned to Paris with their child.
But that September, an announcement sent them racing back to their lab books. A physicist in California, also using cloud chambers, had found something called antimatter. Different combinations of the three fundamental particles—protons, neutrons, electrons—make up virtually everything around us, and we call this everyday stuff matter. But the universe also contains antimatter, which is basically matter’s photographic negative. (If matter and antimatter touch, they obliterate each other in a burst of energy.) Like the Joliot-Curies, the California scientist had noticed an electron-sized particle tracing out unusual swirls in his chamber. Unlike them, he realized the significance of this: that he’d captured the first proof that antimatter exists. In particular, he’d found a particle called the positron.
When Irène and Joliot dug up their old lab notes, they could only groan. They’d seen the same tracks, the same evidence—and for the second time in a few months had missed a fundamental discovery. This time, their scientific aria was one of heartbreak.
If 1932 couldn’t end fast enough for the Joliot-Curies, the next few years brought them some redemption. They resumed bombarding different sheets of metal with alpha particles, and they got a nice surprise when they tested aluminum in the autumn of 1933. Normally, a barrage of alphas produced only one type of secondary shrapnel, often neutrons. But bombarding aluminum foil produced both neutrons and positrons—a twofer. No one had ever seen double-barreled radioactivity like this, so the Joliot-Curies decided to prepare a report for a prestigious conference in Brussels in October. The attendees would include virtually every bigwig in nuclear physics—Bohr, Fermi, Dirac, Schrödinger, Rutherford, Pauli, Heisenberg.
The talk could have made their careers. Instead, it nearly ruined them. Because of their previous blunders the Joliot-Curies had gained a reputation as careless, and this new discovery—one that, conveniently, involved both new particles they’d missed before—seemed too good to be true. A brilliant Austrian physicist named Lise Meitner stood up after their talk and declared, with all the sternness of an Old Testament prophet, “That is not so.” She’d run similar experiments in Berlin, she claimed, and had never seen such a thing. It was a damning assessment, and given Meitner’s reputation, most scientists in attendance believed her.
Crushed, Irène and Joliot returned to Paris. Rather than hang their heads, however, they grew obsessed with proving their results valid. They thought about little else, discussing the experiments over every meal and late into the night. After weeks of tediously double-checking everything, Fortune’s wheel finally spun their way. One morning in January 1934 Joliot rolled up the sleeves on his white lab coat and tried rearranging their experimental setup, just to see what happened. He started by pulling the alpha source farther back from the aluminum foil. Then, for no real reason, he removed the alpha source altogether. To his confusion, the radioactivity detector kept recording pings of shrapnel. And not just for a second or two, but for several minutes. This made no sense: the alpha particles were necessary to knock the shrapnel loose, and removing them should have halted everything. So why was the detector still registering hits minutes later? As he often did when perplexed, he called for Irène.
They set to work, and after a day of frenzied activity—which left their lab uncharacteristically messy—they realized what was happening. In all other known experiments of this type, when an alpha particle struck the metal foil, it immediately knocked something loose. In this case, however, the aluminum was absorbing the alpha particle and becoming radioactive only later, after a delay. That was intriguing, because alpha particles, in a technical sense, are simply a bundle of protons and neutrons. A little ball, really, with two of each. So if an aluminum atom absorbed an alpha particle, it gained two protons in the process. Atoms are defined by the number of protons they have, so if aluminum (element 13) absorbed an alpha with two protons, it must be changing into phosphorus (element 15); the phosphorus then released radioactive shrapnel and disintegrated. In other words, Irène and Joliot had seemingly discovered a way to convert one element into another element via artificial means. It was artificial radioactivity—scientific alchemy.
Poignantly, the very magnitude of this discovery made the Joliot-Curies hesitate. They couldn’t quite trust themselves anymore, not after stumbling twice already. What if their detector was defective? What if they were misinterpreting their results again? What if, what if? Alas, they had an important dinner to attend that night and couldn’t keep working. But they left instructions for a young German assistant in the lab—Joliot’s cigarette buddy—to check every millimeter of their detector for shorts or other flaws.
The German worked all night running various tests, then left a note for Irène and Joliot. They rushed back to lab the next morning, as anxious as teenagers after a big exam. The counter, the German assured them, worked perfectly.
This convinced the flighty Joliot, who was ready to celebrate their discovery. Irène reserved judgment. Chemists are more tactile than physicists, and she needed to see that newly created phosphorus for herself, hold it in a vial. So she devised a plan. They pushed the clutter of the previous night aside and bombarded another sheet of aluminum foil for a few minutes. Instead of placing it in front of a detector, however, this time Irène plopped the foil into a beaker of acid, which began to bubble and hiss, releasing a gas.
If they really had created phosphorus, then that gas was phosphine (PH3). Identifying phosphine was straightforward, but the nature of this setup complicated things, since the P in the PH3 was itself radioactive and was disappearing at a rapid clip. So Irène had to work fast, collecting the gas and carrying out her entire analysis in just three minutes. A lesser chemist would have stumbled under the pressure. Irène didn’t, and found definitive evidence of phosphorus. Alchemy was real.
At this point, watching his wife finish up, Joliot all but burst into song. He began running around the lab, leaping with joy. “With the neutron we were too late!” he shouted. “With the positron we were too late! Now we are in time!”
Still, within the Joliot-Curie family, no discovery counted until the big Curie, Marie, had weighed in. By early 1934, after years of exposing herself to radioactive substances, Curie was suffering from anemia and rarely visited the lab. That afternoon, however, upon hearing what her daughter and the man who’d married her daughter had discovered, the old lioness roused herself and barged into the lab. (She was accompanied, oddly enough, by her former lover, Paul Langevin, who’d since divorced his wife and remained a family friend.) Irène coolly reran the experiment for her mother, dissolving the foil in acid and collecting the gas. As Marie clutched the vial with the phosphorus inside, her daughter could see cracks and ulcers on her fingers from radiation damage. The old woman’s eyes had clouded with cataracts as well, and she had to hold the Geiger counter close to hear the clicks of radioactivity. But when she did, she smiled a smile that could only be described as phosphorescent. Joliot later said, “It was without a doubt the last great satisfaction of her life.”
Marie died a few months later. But in autumn 1935, the Joliot-Curies won the Nobel Prize in Chemistry for their work on artificial radioactivity. Remembering the media swarm that had engulfed her parents, Irène fled her home on the afternoon of the announcement and dragged her husband out to shop for a tablecloth. Still, she attended the ceremony in Stockholm that December and received her Nobel from the same king, Gustave V, who’d twice hung the medal around her mother’s neck.
Fittingly, she and Joliot shared the Nobel stage that year with the man whose discovery of the neutron had so tormented them, newly minte
d physics laureate James Chadwick. But it was another winner that year—biologist Hans Spemann—whom most attendees would recall in later years, albeit with a shiver. Spemann was German, and at the end of his acceptance speech, he threw out a bizarre salute to the audience—his palm flat and arm extended at the shoulder. The world would soon know it as the Sieg Heil.
As with most relationship milestones, winning the Nobel Prize together changed things for the Joliot-Curies, especially for Frédéric. A colleague once dubbed him “the most ambitious man since Richard Wagner,” and as soon as he returned from Stockholm he began sketching out plans to build what was then the most ambitious piece of scientific apparatus in the world, a cyclotron. These particle accelerators allowed scientists to study the subatomic world by smashing atoms together. Cyclotrons were also the best way to mass-produce radioactive isotopes.
There was just one problem. Cyclotrons were big, expensive machines, and Joliot and Irène’s institute had no room to house one. As a result, Joliot had to transfer to a new lab in an abandoned power station a few miles away. And with this move, things changed between Irène and Frédéric. As one biographer wrote, they were “only a short walk from one another, but it wasn’t the same as being in the same room, with their heads stuck together over a single experiment.” The Joliot-Curies would be working apart for the first time in their professional lives, breaking up one of the world’s most productive scientific teams.
Far from regretting this schism, however, Joliot pushed for it. As husband and wife, he and Irène were still on good terms, still much in love. Scientifically, though, he was tired of being Irène’s gigolo. He wanted to break free from the Curie matriarchy, to become his own man. They could have their grams of radium and their family cottage—he’d have his cyclotron. He had no idea how badly this decision would burn him.
CHAPTER 3
Fast and Slow
During his Nobel Prize acceptance speech, Frédéric Joliot made a sobering prediction. Artificial radioactivity, he warned, could someday lead to “transmutations of an explosive character,” using something called a “chain reaction.” No one had ever applied that term to a nuclear process before, and Joliot no doubt assumed that the danger lay far in the future. But within a few years, those two words were on the lips of every nuclear scientist in the world, thanks largely to a group of high-spirited physicists in Rome.
Like the Joliot-Curies, the Italian team bombarded samples of various elements with radioactive shrapnel. The difference was that they used neutrons instead of alpha particles. The Italians were also more systematic, starting with samples of the lightest elements on the periodic table and working their way down.
It would have been an ingenious setup, except for one flaw: due to space constraints, all the equipment to irradiate the samples lay at one end of a long hallway, while all the detection equipment lay at the opposite end. Worse, many of their artificially radioactive samples decayed in mere seconds, far longer than it took to walk down the hallway. So, making the best of a bad situation, the leader of the lab, Enrico Fermi, made each experiment a game, challenging his assistants to footraces to see who could get the samples to the detectors the fastest. (Colleagues wandering the hall quickly learned to yield the right-of-way.) The races kept morale high, and each scientist swore he was the fastest physicist in Italy.
One morning in October 1934, when the team was halfway through the periodic table, one of Fermi’s assistants, Edoardo Amaldi, noticed something strange while bombarding a piece of silver. If he performed the experiment on a marble shelf, the silver sample he sprinted down the hallway produced only a few radioactive pings. But if he performed the experiment on a wooden table, the number of pings increased a hundredfold. This made no sense to him. Why would the table matter? He called in Fermi to show him. On a whim, Fermi placed the silver inside a block of paraffin and irradiated it again. When they took off sprinting this time, the detector down the hallway went mad, clicking almost too fast to count all the activity. It seemed, one of them remembered, like “black magic.”
Baffled, the team broke for lunch. But while the other scientists concentrated on filling their bellies, Fermi kept chewing over the odd result. Foot speed aside, he was considered the fleetest thinker in science, and sure enough, by the time everyone reconvened in the lab, Fermi had solved the mystery. (Granted, a typical Italian lunch did last several hours.) The key, he announced, was neutron speed.
When neutrons slammed into a target, one of two things could happen. They could ricochet off, or they could be absorbed by the atoms of the target. And it was the speed of the neutrons, Fermi argued, that determined their fate. Neutrons normally move at incredible speeds (10,000 miles per second), and some elements were simply good catchers; like Moe Berg, they could snag anything thrown at them. But perhaps elements like silver were clumsier, and couldn’t handle heaters. Perhaps they preferred neutrons traveling at more modest speeds (maybe 1 mile per second). Fermi used more sophisticated arguments, naturally, but the overall point was simple: each version of an element preferred neutrons of a certain speed, and when it’s bombarded with neutrons of that speed, it readily absorbs them and turns radioactive. Otherwise, it struggles.
But how, his assistants asked, did that explain the difference between the marble countertop and wooden table? Easy, Fermi responded. Imagine a neutron flying along. Perhaps it doesn’t hit the target directly but rebounds off a nearby surface first. If the material that makes up the surface contains mostly heavy atoms, the neutron will bounce off without losing much momentum—just like a cue ball bounces off the cushions of a much heavier pool table without losing much speed. But if the material that makes up the surface contains lighter elements, then the neutron will lose momentum, just like a cue ball loses speed when it strikes another, similar-sized billiard ball. The key point is that wood and paraffin contain a much higher percentage of light elements, especially hydrogen, than marble does. So when silver was surrounded by those materials, the neutrons ricocheting around got slowed down quite nicely, allowing silver to catch them.
It was a virtuoso performance. Fermi had basically discovered a new law of physics over antipasto. But he wasn’t done. According to his reasoning, a substance with an even higher percentage of hydrogen—say, H2O—should slow down neutrons even more effectively. So the Italians decided to grab some water and test this theory. Why they didn’t fill up a bucket in the nearest sink, no one knows. Instead, Fermi and Amaldi and the others dashed down the steps that afternoon like boys after the last school bell and made for the pond behind the institute. Normally they caught salamanders and raced toy boats there, but today they splashed right in, skimming off the pond scum and scooping up some water.
Back in the lab, Fermi proved right, as always: water slowed down neutrons brilliantly. And although they didn’t yet realize it, this discovery would vastly expand the power of artificial radioactivity. The Joliot-Curies had showed how to turn a few elements radioactive. But with the discovery of fast and slow neutrons, Fermi could now make almost any element radioactive—a skill the world would soon curse.
CHAPTER 4
Crimea to Hollywood
The mob at the wharf was getting desperate. Hordes of murderous Bolsheviks were about to overrun the city of Theodosia, on the coast of Crimea. The ships moored there offered the only means of escape now, and thousands upon thousands of refugees were clamoring to get aboard. Only the barbed-wire barricades surrounding the wharf prevented a full-on riot.
A handful of Red Cross relief workers in Theodosia, including Boris Pashkovsky, spent the afternoon of November 12, 1920, loading supplies onto their ship and preparing to evacuate. Just as they were finishing up, a few rogue soldiers with sabers attacked them, desperate to steal the supplies for themselves. Pashkovsky’s crew beat them back, but duty compelled him to stand guard and prevent looting. He left his post only once, with armed escorts, to bolt down a meal at the Red Cross compound in the city. While there, he kissed his new bride,
Lydia, and warned her to stay put at their villa until the Red Cross trucks brought her down to the wharf for evacuation the next day.
Refugees, meanwhile, kept pouring into the city, many of them carrying their entire lives in filthy bundles in their arms. They could hear Bolshevik rifles firing in the distance; later, an ammunition dump exploded with a series of booms. As the mob at the dock grew and grew, Pashkovsky stood guard through it all that night and much of the next day. He never allowed himself to relax until the Red Cross trucks finally rolled through the dockyard gate, bringing dozens of relief workers to safety.
But when the truck doors opened, Lydia was nowhere to be seen. Not panicking quite yet, Pashkovsky ran up and asked where she was, yelling over the noise of the crowd. Was she hurt? Lost? His colleagues wouldn’t meet his eyes. Dead?
Finally the captain of their evacuation ship, the SS Faraby, leveled with Pashkovsky. Lydia was missing. “That damn fool wanted to say goodbye to some friend,” he said, and had run off to the woman’s house. Several hours later she still hadn’t returned, so they’d left her behind.
Pashkovsky immediately declared that he was going after her. Now the captain called him a damn fool: “You’ll never find her. The people are crazy out there.” He pointed to the barbed-wire barricade, to the snarling mob. Pashkovsky could see that there was little chance of fighting his way out, much less of getting back in time. He hesitated, and the captain warned him, “We cannot wait.”
Pashkovsky looked again. Why the hell hadn’t she stayed put?