Before the Fallout

by Diana Preston

  Failing to find a permanent academic post, in 1905 Einstein took a job as a patent examiner in the Swiss patent office in Bern. In his spare time he read Planck's work and found it a revelation. "It was," he later wrote, "as if the ground was pulled from under one." Realizing that quantum theory explained some hitherto inexplicable phenomena, he worked to confirm and extend it. In particular, he applied the theory to the "photoelectric effect"—the way that light colliding with certain metals expelled a shower of electrons. Just as Planck had found with heat, Einstein realized that his experimental findings could be explained if he assumed that light was not a smooth, wavelike phenomenon as previously thought but was emitted in tiny, discrete "energy quanta"—separate packages more akin to tiny bullets.*

  The year 1905 was a fertile one for the twenty-six-year-old Einstein in other ways. His facility for thinking the unthinkable had led him to not only uphold Planck's quantum theory but also to the discoveries on relativity for which he is best known. Since the days of Galileo and Newton, scientists had believed that objects at rest and objects moving straight and at constant speed behaved in the same way. However, James Clerk Maxwell's theories suggested that light was an exception to this principle, so that measurements of the velocity of light would vary depending on the effects of motion. Einstein, however, believed intuitively that the velocity of light did not vary. One morning he awoke feeling as if a tempest was raging in his mind but that somewhere in the maelstrom were the answers he had been seeking. As he later put it, "The solution came to me suddenly." It was nothing less than a revolutionary analysis of space and time.

  Einstein described his theory in one of five remarkable papers he published that year in the leading German physics journal, the Annalen der Physik. It was called "On the Electrodynamics of Moving Bodies." He postulated how light traveled from place to place with the same velocity regardless both of direction and of whether the source of light was moving relative to the person observing it. This was Einstein's "special relativity theory," which, as C. P. Snow wrote, "quietly amalgamated space, time and matter into one fundamental unity." It was the first step on the path to his "general theory of relativity."

  Einstein's three-page supplement to the paper, added as an afterthought, argued that if a body emits energy, then the mass of that body must decrease proportionately—in other words, that light transfers mass. He articulated the ideas that he would soon express in the world's most famous equation: E = mc2—energy is equal to mass times the speed of light squared. Einstein's groundbreaking insight was that energy and mass were not separate phenomena but interchangeable. Each could be converted into the other, and the speed of light was the conversion factor. Implicit in E = mc2 was the potential for enormous amounts of energy to be squeezed from tiny amounts of mass, given the enormous size of the conversion factor.† However, more than thirty years would pass before scientists would finally grasp how to access that energy.

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  Einstein, who privately nicknamed the 1911 Solvay Conference "a witches' sabbath," found it more enjoyable than he had anticipated. He wrote to a friend that he spent "much time" with Marie Curie and Paul Langevin. He was "just delighted with these people" and praised Marie's "passionateness" and "sparkling intelligence." As was about to emerge in a thundercloud of scandal, one reason for Marie's animation was that she and Langevin were in love. This did not, however, soften her insistence at the conference that the International Radium Standard she had prepared should remain chez moi—in other words, in her personal laboratory and under her sole control. When others argued that this was unacceptable, she retreated to her room, once again claiming nervous exhaustion and headaches. Critics claimed her ailments were psychosomatic, and even Rutherford's patience was wearing thin. He wrote that "Madame Curie is rather a difficult person to deal with. She has the advantages and at the same time the disadvantages of being a woman." He told her firmly that an international standard should not be "in the hands of a private person." Marie would later back down, personally sealing the radium standard in a glass tube and depositing it at the International Bureau of Weights and Measures at Sevres, near Paris.

  At the conference, though, such squabbles were pushed aside as the sensational "Affaire Langevin" broke in the press. The Paris newspaper Le fournal reported that Paul Langevin's wife, Jeanne, was accusing him of having an affair with the forty-three-year-old Marie Curie and intended to divorce him. Newspapermen ambushed Marie in Brussels, thrusting copies of Le fournal at her. At first she refused to comment; then, in a handwritten note to the Brussels correspondent of the Paris Le Temps, she rebutted the accusations as "pure fantasy." However, other papers enthusiastically took up the story. Le Petit four­nal titillated its readers with a story headlined "A Laboratory Romance—The Adventure of Mme. Curie and M. Langevin." It included an interview with Jeanne Langevin in which she claimed that the affair had been going on for several years. She had kept quiet about it, hoping for a reconciliation, but her husband's recent behavior—including slapping her face for spoiling a fruit compote—had forced her to speak out.

  The story broadened. Some suggested that the affair might have started before Pierre Curie's death, even that it had prompted him to commit suicide. One journalist used the scandal to attack not just Marie's morals but her credibility as a scientist, querying whether women were capable of creative, independent research. He quoted an eminent but conveniently unnamed scientist, who claimed she was a mere "plodder" and that a woman could only shine in science when "working under the guidance and inspiration of a profoundly imaginative man" with whom she was in love.

  Returning to Paris, Marie Curie continued to deny the affair, seeking refuge from the press with friends. However, the allegations were almost certainly true. In mid-July 191 o Langevin is known to have rented an apartment near the Sorbonne under an assumed name. He and Marie Curie were observed meeting there almost daily. In early 1911 friends had noticed how Marie had suddenly appeared dressed in white with a rose at her waist, rather than in her usual somber hues. One wrote that "something signified her resurrection like the spring, following a frozen winter." Paul Langevin was five years her junior, handsome, charismatic, and an acknowledged ladies' man. He would later father a child by one of Marie Curie's pupils. He had married very young, and the relationship had soured early. He had turned for advice and solace to Marie. An old friend, she considered Langevin a genius, but weak and in need of affection. She feared his wife would force him to desert science in favor of going into industry to make money.

  Letters between Marie Curie and Paul Langevin were stolen, probably by Langevin's brother-in-law, Henry Bourgeois, who pried open a drawer in Langevin's marital home. There is evidence that Langevin paid blackmail money—given him by Marie—to try and prevent the letters' disclosure. Marie lent Langevin a total of five thousand francs—more than a tenth of her salary—over this period, and Langevin made "loans," never recorded in writing, to his brother-in-law. Marie's friend Jean Perrin wrote angrily of "odious blackmail."

  In November 1911, while the scandal still raged, came news that Marie Curie had been awarded a second Nobel Prize—this time for chemistry—for her original isolation of pure radium. It was an unprecedented honor, but the press attacks continued. Some contained darker undercurrents than mere simulated moral outrage. Only five years after the end of the Dreyfus Affair,* they reminded readers that Marie was a foreigner and suggested incorrectly that she was probably a Jew. They demanded she resign from the Sorbonne and return to Poland. Matters finally came to a head when Gustave Tery, editor of the weekly L'Oeuvre, published extracts from the Curie-Langevin letters and derided "the Vestal Virgin of radium" as "an ambitious Pole who had ridden to glory on Curie's coat-tails and was now trying to latch onto Langevin's."

  Langevin challenged Tery to a duel. He told a friend, "It's idiotic, but I must do it." It proved more farcical than dramatic. Dressed in black and wearing bowler hats, the duelists met at the Pare des Princes Bicycle Stadi
um. Tery, as the man who had been challenged, was entitled to raise his weapon first but kept his gun pointed to the ground while he gazed up at the sky. Unable to shoot a man who had not discharged his weapon, Langevin also lowered his. They left the field, honor satisfied. Tery wrote piously, "The defence of Mme. Langevin does not oblige me . . . to kill her husband. . . . I could not deprive French science of so precious a brain." With this ridiculous encounter, public interest waned, although the Affaire Langevin provoked at least four further duels between defenders and detractors of Madame Curie.

  A subdued and frail Marie Curie went to Stockholm to claim her Nobel Prize. She collapsed on her return to Paris with fever and kidney problems, but her health picked up when she learned that Madame Langevin's writ formally seeking separation from her husband did not name her. However, henceforth her relationship with Langevin could, sensibly, be only professional. Einstein, who had remarked on Marie's passion in 1911, observed a change while hiking with her in 1913. He wrote that "Madame Curie is highly intelligent but has the soul of a herring, which means that she is poor when it comes to the art of either joy or pain. Almost the only time she shows emotion is when she's grumbling about things she doesn't like."

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  Rutherford had loyally supported Marie Curie throughout the brouhaha. He was by then deeply involved in further attempts to dissect the atom, in the aftermath of his finding of the nucleus. Shortly after his return from the Solvay Conference, a twenty-six-year-old Danish physicist had joined his team at Manchester. Niels Bohr was about to bring quantum theory to the heart of the understanding of the atom. Bohr was an athletic, strong-jawed, huge-handed man with an enormous domed forehead. He spoke in long, complex sentences studded with subclauses in a voice that was usually soft and trailed off into a whisper when he came to a crucial point. He belonged to a distinguished family—his father was professor of physiology at the University of Copenhagen. Like Rutherford, Bohr showed an early interest in understanding how things worked, and one of his boyhood pleasures was repairing clocks. Also like Rutherford, he was a lateral thinker, quick to spot connections. He was gentle but intellectually tenacious and unfraid to challenge anyone, however high their reputation.

  Albert Einstein and Madame Curie

  Bohr studied at the University of Copenhagen, where physics became his passion. He was intrigued by the new discoveries: Rontgen's x-rays, Bec-querel's rays, the discovery of radioactivity, Thomson's electron, and Rutherford's identification of alpha and beta radiation. For his doctoral thesis he explored the behavior of electrons in metals. His findings were so new and unusual that, as with Marie Curie when she was examined on her thesis, no one was equipped to question them. Bohr then decided he wished to study with J. J. Thomson at the Cavendish Laboratory and arrived in Cambridge in the autumn of 1911. However, shortly before Christmas he heard Rutherford speak at the annual Cavendish dinner about his discovery of the nucleus. Bohr was mesmerized and the following April moved to Manchester University.

  Bohr found the atmosphere there exhilarating. Rutherford encouraged his young scientists to gather every afternoon for tea. Perched on a stool, his great voice booming out, he urged everyone to speak up, provided they "made sense" and avoided "pompous talk." One of the subjects most eagerly debated was the structure of the atom. Bohr accepted Rutherford's model of the atom as a miniature solar system, with electrons orbiting around the nucleus like planets around the sun, but recognized an inherent flaw. According to Newtonian physics, which saw the world in mechanical terms, the whirling negatively charged electrons should have gradually dissipated their energy through their movement. As a result, they should have collapsed into the positively charged nucleus in the heart of the atom that was pulling them to their doom, gradually shrinking anything and everything. Yet clearly this did not happen. It was a mystery because, as Rutherford acknowledged, not enough was yet known about either the orbiting electrons and their paths or the nucleus.

  Bohr reasoned that, if Rutherford's model was correct, some kind of stabilizing or balancing effect must be at work within the atom. Over the next eighteen months he set out to prove this, turning to the quantum theories of Planck and Einstein. Unlike Planck, who was at the time developing his theory further and even coming around to believing in it himself, Bohr did not worry that the theory could not be properly explained. What mattered was applying it. His guiding principles were that science needed paradoxes to progress, and that, provided they were well-founded, seemingly contradictory ideas should not be changed but reconciled. A story frequently related by Bohr exemplified his mental flexibility. A visitor, surprised to see a horseshoe above the entrance to Bohr's house, asked whether Bohr really believed it would bring good luck. "Of course not," Bohr replied, "but I am told it works, even if you don't believe in it."

  Bohr instinctively accepted the existence of quanta and looked for ways to fit a theoretical structure to observed experience of atomic behavior. By late June 191 2, less than three months after arriving in Manchester, he had developed an initial version of what would become known as the "Rutherford-Bohr" model of the atom and which, once accepted, would be used by scientists ever after. Over the next eighteen months, during which he returned to Denmark and married, Bohr refined and developed his ideas further for publication in a trilogy of papers on the "Constitution of Atoms and Molecules." He applied quantum theory to matter as well as energy. The heart of Bohr's insight was that the orbits in which electrons travel around the nucleus are specified by quantum rules that provide each orbit with a defined level of energy. While orbiting, an electron suffers no energy loss. Building on this, Bohr envisioned successive layers of electrons "binding" into a structure around the nucleus until a stabilizing electrical neutrality was achieved. By a "quantum leap," electrons could switch orbits within an atom, emitting or absorbing energy in bursts.

  Niels and Margrethe Bohr (right), Ernest Rutherford (left) and Mary Rutherford (seated far left)

  Bohr's theories not only offered a solution to the problem of the stability of the atom. He was also nudging toward the conclusion that the structure of the rings of orbiting electrons, and how these built up, held the key to understanding the hierarchy of elements and how and why they could combine to form new ones.

  Rutherford, who initially found Bohr's ideas ingenious if hard to visualize, was his mentor throughout. He regarded the Dane as "the most intelligent chap I've ever met" and admired his disregard for the old orthodoxies. He welcomed his theory of electrons, without yet giving it his formal endorsement. As a confirmed experimentalist, he warned Bohr against placing too much credence on theory alone. He also warned him not to be long-winded when he published his findings: "It is the custom in England to put things shortly and tersely in contrast to the Germanic method where it appears to be a virtue to be as long-winded as possible." Bohr dug in his heels. Rutherford offered to edit Bohr's work for publication. The Dane hurried to Manchester to defend his work not just paragraph by paragraph but right down to the complex structure of his extensive sentences, which, he insisted, were essential to the detailed logic of his case, even if initially confusing. It was one of the few battles Rutherford ever lost. He submitted with good grace, telling his protege he never thought he would prove so obstinate.

  The scientific community responded to Bohr's theories with everything from enthusiasm to incredulity. According to a letter from the Hungarian scientist Georg Hevesy to Rutherford, when Einstein learned of them his "big eyes . . . looked bigger still, and he told me 'Then it is one of the greatest discoveries.' " Others were openly skeptical, including Thomson, who was developing his own, different model of the atom. In Germany a number of physicists swore "to give up physics if that nonsense was true. "Yet supporting evidence was emerging all the time. Some of it was provided by another of Rutherford's students, the obsessively hardworking, Eton-educated Harry Moseley, who had arrived in Manchester in September 191 o.

  Moseley was using x-rays, the penetrating radiation dis
covered by Rontgen about whose nature scientists were still arguing, to explore variations between elements. To do this, he built an ingenious piece of equipment resembling a toy train with a number of wagons. On each of these he placed a specimen of the element he wanted to examine and then, by winding silk cords on brass bobbins, moved his "train" along a pair of rails inserted inside an x-ray tube so that each of his elements, in turn, was bombarded bv cathode rays. When he examined the spectra his specimens produced, Moseley found that they differed according to a regular pattern. The difference between elements seemed to depend on a "something" which Moseley interpreted as a difference of one unit charge on the nucleus—in other words, a difference of one in the number of electrons possessed by the atom. He knew this would support Bohr's theory of the atom and the Dane's intuition that it was the number of electrons that determined the chemical and physical characteristics of matter.

  In late 1913 Moseley left for Oxford University to continue his research there but kept Rutherford and Bohr abreast of his findings. He worked through the naturally occurring elements, from the lightest, hydrogen, to the heaviest, uranium, arranging them in the light of his experimental findings in a revised periodic table. Until this time elements had been ranked bv their atomic weight. This practice went back to the days of the scientist John Dalton, who, in the early nineteenth century, had developed a theory attaching experimentally determined weights to chemical elements. The idea of a periodic table had been introduced in 1869 bv the Russian Dmitrv Mendelevev, who had noticed that when the elements were arranged in order of their atomic weights, they could be grouped according to their chemical behavior.