Before the Fallout

by Diana Preston

  They began work in October 1901 and soon proved that the emanation was not merely the result of some disturbance of the air caused by the radioactivity in thorium. The emanation was an inert gas—one without active chemical properties—which would not react or combine with anything. The evidence suggested it was another element, and this moment of discovery was awesome. Soddy, "standing there transfixed as though stunned by the colossal import of the thing," turned to his companion and said: "Rutherford, this is transmutation: the thorium is disintegrating and transmuting itself into an argon gas." Rutherford "shouted to me, in his breezy manner, 'For Mike's sake, Soddy, don't call it transmutation. They'll have our heads off as alchemists. You know what they are.' After which he went waltzing round the laboratory, his huge voice booming, 'Onward Christian so-ho-hojers [soldiers]' which was more recognizable by the words than by the tune." Rutherford urged Soddy to call their discovery not transmutation but transformation. They checked and rechecked, but their results held good. Their discovery, which was indeed akin to alchemy, suggested that radioactive elements disintegrate spontaneously and unstoppably, forming different "daughter" elements in the process. They contain unstable atoms which decay over time, shedding radiation in the form of alpha or beta particles in an attempt to reach stability.

  However logical it might have seemed in the laboratory, Rutherford and Soddy knew that their "disintegration theory" contradicted another basic law: the immutability and indestructibility of chemical elements. As they expected, their work provoked skepticism and hostility. Alarmed colleagues warned they would bring discredit on McGill University and urged them to delay publishing their findings. The British chemist Henry Edward Armstrong demanded to know why atoms should indulge in an "incurable suicide mania." But Rutherford and Soddy refused to be browbeaten, facing down their opponents with confidence and hard evidence.

  They were helped by J. J. Thomson in England, who steered them through these potentially damaging and difficult times, ensuring early publication of their papers and lending his authority to their findings. By 1903 they had published a series of papers they considered conclusive. The final paragraph of their final paper stated, "All these considerations point to the conclusion that the energy latent in the atom must be enormous." Around this time Rutherford made a "playful suggestion" that if a proper detonator could be found, it was conceivable that "a wave of atomic disintegration might be started through matter, which would indeed make this old world vanish in smoke."

  The Curies were among the skeptics. In the generous, collaborative spirit of the time, they had loaned Rutherford a sufficiently powerful radioactive source to allow him to conduct his research, and they were keenly interested in the findings. As early as 1900 Marie Curie had written that the idea of some kind of transformation was very seductive and explained the phenomena of radioactivity very well, but despite her belief that radioactivity was an atomic phenomenon, she had shied away. Transformation seemed too revolutionary, too alien to the laws of chemistry. The Curies wondered whether Rutherford and Soddy were rushing to unjustified conclusions based too narrowly on findings from thorium. They also worried that the transmutation theory threatened the status of their discoveries, radium and polonium, by redefining them as transitional entities rather than new elements.

  In fact, as the theory developed, the reverse would prove true. The theory would explain where radium and polonium fitted in despite their instability. Uranium slowly but inexorably decays, transmuting through a series of radioactive elements, all present in uranium ores. The chain ends when uranium finally transforms into stable, unradioactive lead. Radium is the fifth element in the chain descending from uranium to lead, and polonium is the penultimate link in the chain before lead. The fact that uranium is still present in the Earth's crust—created some 4.5 billion years ago—shows just how slowly uranium decays.

  The Curies' perplexity was heightened by Pierre's discovery in 1903 that radium released an astonishing amount of heat. Just 1 gram of radium could heat around 1.3 grams of water from freezing point (o°C) to boiling (ioo°C) in an hour. These seemingly bizarre findings contradicted the nineteenth-century law of conservation of energy, which stated that although energy might change from one form to another (for example, from heat to motion), it could not be conjured out of nowhere. The Curies speculated whether some sort of external energy might be responsible. Others wondered whether gravitational energy might have something to do with it. Nevertheless, the Curies were uncomfortably aware that the transformation theory offered an explanation—that the energy was being conjured from within the atom. Eventually, they would come to accept it.

  Rutherford's knowledge of the Curies' work had made him eager to meet them. In 1903 the opportunity came. While visiting England from McGill to defend his heretical transformation theory, Rutherford, accompanied by Mary, took a trip to the Continent. Reaching Paris on a hot June day, he was alerted by a postcard from Soddy that Marie Curie wished him to call. He hastened to her ramshackle workplace to find it locked. It was, in fact, the very day she was being examined on her triumphal doctoral thesis, "Researches on Radioactive Substances," reporting her work on isolating radium. However, he managed to track down Paul Langevin, whom he had met during his Cavendish days, and Langevin invited the Rutherfords to the celebration that night, at which Pierre Curie brandished his tube of glowing radium in his damaged hands.

  It was, by all accounts, a lively evening, unmarred by any differences of opinion. Rutherford admired Marie Curie's intellect, "no-nonsense" style, and directness. She, in turn, appreciated that he treated her as an equal. This was to be the first of many meetings between them, but, sadly, it was the one and only time he would talk with Pierre Curie. Just three years later on a wet, windy, overcast Paris afternoon, Pierre absentmindedly stepped out in front of a horse-drawn wagon in the Rue Dauphine. Too late he tried to scramble out of the way, slipped, and fell. The wagon's iron-rimmed rear left wheel crushed his skull, spilling his brains on the wet boulevard. He was only forty-six.

  Marie was left a widow at thirty-eight, with Irene as well as her second daughter, Eve, born in 1904, to care for. The University of Paris decided to maintain its chair of physics, created for Pierre two years earlier, and invited Marie to assume his duties but did not award her the professorship. It was, nevertheless, the first time in France that such an appointment had been given to a woman, and she accepted. Her first lecture, delivered fifteen years to the day since she had first entered the Sorbonne to register as a student, was a highlight of the social calendar. The fashionable and curious craned their necks for a good look at the first woman to lecture at the Sorbonne. She walked into the lecture room quietly with downcast eyes and commenced her course at the exact point at which death had halted Pierre's. Newspapers hailed her performance as "a victory for feminism."

  Marie rejected a government proposal to build her a laboratory. Pierre had been haunted by the lack of proper facilities, and she was bitter that it had taken his death to induce the authorities to provide them. Single-mindedly, at times obsessively, she immersed herself in her work, shunning celebrity. Her greatest dread, as Eve Curie later recalled, remained the "crushing, mortal boredom which dragged her down when people rambled on about her discovery and her genius." Her response, repeated like a mantra over the years to come, was "In science we must be interested in things, not in persons." Rutherford would prove one of her greatest allies in some difficult personal times ahead.

  Rutherford's findings on radioactivity had established his international reputation as one of the leading experimental physicists of the day. Universities courted him eagerly, and in May 1907 he returned to England as professor of physics and director of the Manchester University Laboratory. The laboratory was only seven years old and, unlike the Cavendish with its "sealing wax and string," was magnificently equipped. The only drawback was that it possessed almost no radioactive materials. Since Rutherford's primary interest was to follow up his work with Soddy and unrav
el the sequence of elements generated through radioactive decay, this deficiency had to be remedied. A generous loan of some five hundred milligrams of radium bromide from Professor Stefan Meyer of the Radium Institute in Vienna, who had access to the same Bohemian mines that had furnished Marie Curie's pitchblende, solved the problem.

  In 1908—the same year that Kenneth Grahame wrote Wind in the Willows and Jack Johnson became the first black man to win the world heavyweight boxing championship—Rutherford received the Nobel Prize for Chemistry for his investigations into the disintegration of the elements, and the chemistry of radioactive substances. He was amused that the prize was for chemistry, not physics, joking about his instantaneous transmutation from physicist to chemist. Students from around the world flocked to Manchester to study under the Nobel laureate. They found Rutherford an inspirational but taxing taskmaster with a facility to concentrate on a problem for long periods at a stretch without getting tired or bored. A young Japanese scientist named Ki-noshita from Tokyo Imperial University, who studied briefly under Rutherford in 1909, wrote wistfully from Japan, "I wish I could go back again to your lab so that I shall be able to do some decent work." The visiting Japanese minister of education, Baron Kikuchi, was so impressed by Rutherford's vitality as well as his intellect that he remarked—no doubt tongue in cheek—that he must be the son of the famous Professor Rutherford.

  The matter now absorbing Rutherford, and which would lead to the dissection of the atom, was the nature and behavior of alpha rays—the least penetrating form of radiation. While still at Montreal he had begun to think that helium found in the atmosphere was probably the product of radioactive decay. Studies by Soddy, by then in London and working with the chemist Sir William Ramsay, the discoverer of the inert gases, suggested he was right. Soddy demonstrated that, as it disintegrated, radium emitted streams of helium atoms, traveling at tremendous velocity. Rutherford suspected that these were the same as the alpha rays or particles emitted by radioactive materials and began investigating them.

  Together with one of his research students, the German Hans Geiger, Rutherford invented an electrical instrument capable of counting individual alpha particles.* However, Rutherford abandoned this method in favor of one capable of actually making alpha particles visible using a plate coated with zinc sulphide. When the plate was hit, or "bombarded," with alpha particles, tiny flashes of light occurred at each impact.† The method—called "scintillation" from the Greek word for spark—was time-consuming and hard on eyes straining to count every flash, but reliable. Hans Geiger recalled the atmosphere: "I see the gloomy cellar in which he had fitted up his delicate apparatus for the study of the alpha rays. Rutherford loved this room. One went down two steps and then heard from the darkness Rutherford's voice. . . . Then finally in the feeble light one saw the great man himself seated at his apparatus."

  Rutherford's next eureka moment resulted from a routine experiment which he had instructed Geiger and another researcher, Ernest Marsden—by his own account a callow youth from Blackburn—to conduct using the scintillation method. Their task was to see what happened when alpha particles were fired at metal foils, so they positioned a source of alpha particles near a thin gold foil. Most of the particles passed through with little deflection as they expected, given the particles' weight and velocity. However, a few—one in eight thousand—came bouncing straight back. To Rutherford this was "almost as incredible as if you had fired a 15 inch shell at a piece of tissue paper and it came back and hit you." It suggested the presence of incredibly strong forces in the atoms of gold.

  Rutherford meditated over these results, which he simply could not understand. He followed his own advice to his students, "Go home and think, my boy," and over a period of eighteen months by logic and intuition found an explanation for his experimental findings and so solved the puzzle. In December 191 o Rutherford, "obviously in the best of spirits," burst into Geiger's room and, as Geiger recalled, excitedly announced that "he now knew what the atom looked like." He had worked out that it was not the solid structure studded with electrons like plums in a pudding as suggested by J. J. Thomson and others. The atom Rutherford visualized was almost empty. Nearly all its mass was concentrated in a powerfully charged but tiny nucleus, the size, comparatively, of a pin's head in St. Paul's Cathedral. The reason why most of Geiger's and Marsden's alpha particles had barely been knocked off their trajectory as they passed through the gold atoms was that, like ships skimming a great, empty ocean with no other vessels for thousands of miles, they had passed too far from the tiny nucleus to be affected. However, occasionally and randomly, a particle had skimmed close enough to the nucleus to be violently repulsed by an electrical force so enormous that it had virtually been flung back on itself.

  Rutherford's interpretation of what had happened was revolutionary. Not only had he established the planetary model of the atom, whereby electrons orbit a tiny nucleus, but he had changed forever the way in which people would think of the world around them. He had revealed that the stability and solidity of everyday objects—tables, cups, spoons—are an illusion. At the most minute level human beings and everything around them consist almost entirely of voids with insubstantial boundaries defined by whirling particles.

  Rutherford conducted a final suite of alpha-particle-scattering experiments to check his hypotheses and then, in early 1911, announced to his startled colleagues his discovery of the atomic nucleus. It was, as one later recalled, a "most shattering" revelation.

  *The ancient Greeks had two theories about the nature of matter. Some, like Aristotle, believed matter was infinite and continuous and so could be infinitely subdivided. Others, like Democritus and Epicurus, thought that matter consisted of minute and indivisible particles.

  *Hans Geiger would later develop this device into the Geiger counter, still used in radiation laboratories.

  †The scientists used the military term bombard to describe how they placed a source of radioactivity near an experimental subject—for which they again used a military term, the target—to determine the effect of the radioactivity released upon the target.

  THREE

  FORCES OF NATURE

  IF 1911 was a triumphant year for Rutherford, it was an annus horribilis for Marie Curie. Since her husband's death in 1906, she had scored two notable coups. In 1908 she was finally given the full rank of professor of physics at the Sorbonne. That same year, she coaxed and bullied the university and the Pasteur Institute into cofounding a radium institute, which comprised a laboratory of radioactivity (under her direction) and a laboratory of biological research and Curietherapy (the use of radium to treat cancer and other diseases). Yet she remained a retiring individual who flinched from the limelight. When she learned that the International Congress on Radiology was to meet in Brussels in the autumn of 191 o to establish an International Radium Standard—a physical benchmark specimen against which radium to be used in industry, medicine, and research could be measured—she was reluctant to go. She consulted Rutherford, who sensibly advised that, as the figurehead for radium, she had to be there.

  The congress endorsed Marie's unique authority by agreeing that she should prepare the standard and that the unit in which measurements were to be made against the standard should be named the "curie." However, arguments broke out over the definition of the unit. An angry Marie believed that she, and she alone, should decide the parameters. A female Swedish scientist had been correct in observing that Marie Curie regarded radioactivity as her "child" that she had "nourished and educated." She resented the interference of others. When Marie failed to get her way, she claimed she was too unwell to continue debating and withdrew. Finally she prevailed, but her stubbornness had roused considerable and lasting resentment. Rutherford, who considered her genuinely frail and "very wan and tired and much older than her age . . . a very pathetic figure," was one of her few defenders.

  Rutherford would meet Marie Curie again the following year, when the Belgian industrialist and entreprene
ur Ernest Solvay invited thirty leading physicists to the first Solvay Conference, held in Brussels. The conference's primary purpose was to debate a revolutionary scientific idea: quantum theory.

  · · ·

  The theory's rather apologetic creator was the German physicist Max Planck. This melancholy-eyed scientist had been investigating how hot solids radiate heat since 1897. He realized that he could make sense of his experimental findings only if he assumed that heat was emitted in "energy parcels," or separate "quanta," as he called them, from the Latin meaning "how much." The conservative Planck cautiously called his findings a "hypothesis" rather than a "theory" when he first published them in 1900. His problem was that, while on the one hand his hypothesis worked, on the other it conflicted with the established laws of physics, which decreed that energy was emitted in an uninterrupted flow, not discrete packets. Planck was in the paradoxical, but not unique, position of having discovered something intuitively that he did not understand fully in logic.

  Albert Einstein had the visionary brilliance to grasp what Planck could not. Challenging, analyzing, and stepping outside the conventional bounds of life and thought came naturally to him. Brought up in a secular, free-thinking Jewish family in Germany, the son of an engineer, he had quickly rejected what he considered the militaristic character of German education, where children marched and drilled like small soldiers. He completed his education at the Zurich Polytechnic Institute, where he studied mathematics and natural sciences. With his thick dark hair and shining dark brown eyes he exuded both energy and a potent sensuality. In 1903 he married Mileva Marie, a Serbian also studying at the institute. She was four years older and apparently walked with a limp. A daughter, Lieserl, born to them the previous year and whose existence came to light only in 1987, either died in infancy or was adopted.