However, no simple relationship governed differences between atomic weights in Mendeleyev's table, whereas Moseley's new classification—"the law of Moseley," as Rutherford later called it—provided a ladder with ninety-two regular rungs. It was beautifully simple and has provided the basis for physical and chemical analysis of atomic structure ever since.* At the end of his work, Moseley had no remaining doubt that his findings supported Bohr's theories and said so firmly in the papers he published.
By identifying that there were gaps in his table, Mendeleyev had turned it into a tool for the prediction of new elements. By 1886, three with the chemical properties he had identified—scandium, gallium, and germanium—had been discovered. Moseley's "law" suggested that between hydrogen at number one and uranium at ninety-two, there were still seven elements (whose characteristics were predicted) as yet undiscovered. Moreover, Moseley's classification placed several element-pairs in their correct order in the periodic table, whereas Mendeleyev, in order to get the chemical properties to fit, had had to place them out of sequence in his ranking by atomic weights.
At the same time, however, there was a difficulty. Moseley's tabulation left no room at the upper, heavier end of the range for the recently identified products resulting from radioactive decay, like some discharges from radium and thorium. While working at McGill, Rutherford and Soddy had argued that such products were elements in their own right. If so, it had to be possible to fit them into the table.
The anomaly was resolved by Frederick Soddy, who identified the "Law of Radioactive Displacements" revealing the existence of "isotopes." Soddy deduced that elements could exist in several forms, identical in their chemical and most of their physical properties but differing in their atomic weight. To name them, he borrowed two words from ancient Greek—isos, meaning "the same," and topos, meaning "place"—to signify that isotopes of the same element occupied the same place in the table of chemical elements. Others had also been moving toward the same conclusions, which were an integral part of the jigsaw puzzle of the atom being assembled with such rapidity.
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The Rutherford-Bohr atomic model
In the spring of 1914 Rutherford, convinced by the accumulating weight of evidence, put his own considerable weight firmly behind the Rutherford-Bohr model of the atom. This was also the year when, on 12 February, the forty-two-year-old Rutherford was knighted by the king. Sir Ernest reacted to the honor with due modesty but was plainly delighted, reveling in his costume of velvet breeches, cocked hat, sword, and silver buckles. Former pupils from around the world wrote to congratulate him. One of them was the German chemist Otto Hahn, who had studied under Rutherford at McGill and would one day play a critical part in the discovery of nuclear fission.
Hahn was born in Frankfurt in 1 879, the son of a prosperous artisan. Rejecting his father's suggestion that he become an architect, he instead studied organic chemistry. He was, by his own admission, a "slightly superficial, easygoing" young man, not a hard worker. In his final school report, two of his three top marks were for gymnastics and singing. At Marburg University, he enjoyed "beery days" and once dueled with sabers. However, in 1904, a chance event changed his life. As preparation for working in industry, Hahn went to London to learn English. By sheer good fortune, he managed to get a place at University College, in the laboratory of Sir William Ramsay.
Hahn at this time knew nothing of radioactive substances, but Ramsay set him to extracting radium from barium salt. Somewhat to Hahn's surprise, this task led him to the discoverv of a radioactive substance, radiothorium. He watched the material glowing in his darkroom, where he was sometimes distracted by a female assistant who found excuses to join the personable young man in the gloom, though, as he later wrote, "I never dared to kiss her." He was very fond of women, but his English sometimes let him down in the chase. Once, while dancing the fashionable two-step at a university ball, he whispered conversationally in his partner's ear: "You, here in England, you dance on the carpet. We in our country prefer to dance on the naked bottom." The girl left the dance floor.
Fascinated by his new area of work, Hahn abandoned thoughts of industry. Instead, he wrote to Rutherford, then in Montreal, believing him to be "the only person who had real grasp" of the new science. Rutherford agreed to take Hahn for six months. He enjoyed life in the "New World," although the discovery that the Rutherford household was teetotal was a shock. He sought solace in his pipe, lending his "much-chewed specimens" to Rutherford, who frequently mislaid his own. Hahn admired Rutherford's directness, even his simple way of dressing. When a photographer arrived to take Rutherford's photograph, Hahn had to lend him some detachable cuffs because he had not bothered to put any on. More than anything, though, Hahn had found his vocation.
He returned to Germany in 1906 to the Institute of Chemistry in Berlin and began working on the sample of radiothorium Ramsay had given him as a parting gift. He was joined the following year by a slight, dark-haired theoretical physicist from Vienna, Lise Meitner, who would earn from Einstein the accolade of "the German Marie Curie." She had arrived in Berlin to research under Max Planck and been immediately drawn to the confident, energetic, easygoing Hahn. They decided to work together on radiation experiments, but the institute's director, Emil Fischer, had barred women from the premises. His pretext, after an incident involving a wild-haired Russian student and a Bunsen burner, was that he feared they would set their hair alight. However, he allowed Lise Meitner to work with Hahn in a room that had formerly been the carpenter's workshop and had its own entrance from the street. When she needed to use the toilet, she had to visit a nearby restaurant.
Lise Meitner's difficulties reveal how extraordinary Marie Curie's achievements had been and the scale of the problems then facing women scientists. Meitner was one of just thirty women working in the new field of radioactivity between 1900 and 1910. She was such a rarity that even Rutherford, who encouraged women in his own laboratories, committed a gaffe. Passing through Berlin in 1908 after receiving his Nobel Prize, he was introduced to the thirty-year-old Lise Meitner. He had seen her name in publications, but even "Lise" had failed to alert him. He exclaimed, "in great astonishment: 'Oh, I thought you were a man!'"
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In the period leading up to the First World War, Rutherford's ability and personality had made him the hub of the international scientific community. When hostilities began in the summer of 1914, he was shocked and depressed. Believing that science should know no boundaries, he did his best to maintain contacts with colleagues overseas. He also worried about what would happen to his "boys," as he called his current and former students, whether foreign, like Hans Geiger, by then back in Germany, or British, like James Chadwick, whom the outbreak of war left stranded in Berlin.
Chadwick had arrived in Rutherford's physics department at the age of eighteen, having won a scholarship to Manchester University. He was from a poor working-class background, shy, and, as he later confessed, "very definitely afraid" of Rutherford, who did not immediately take to the tall, thin, nervous, birdlike young man. However, he was soon convinced of Chadwick's rare gifts and backed his nomination for an 1 851 Exhibition Science Research Scholarship—the same award that had enabled him to fling down his spade in New Zealand and renounce digging potatoes forever.
Chadwick had arrived in Berlin in 1913 to take up his scholarship working with Hans Geiger. When war came the following year, Chadwick and a German friend were denounced and thrown into prison for, in Chadwick's words, "having said something we hadn't said." Chadwick was held for ten days on a diet of coffee and moldy bread and then released, but not for long. Several weeks later he was rounded up and interned with four thousand others—including "an Earl . . . musicians, painters, a few race-horse trainers, a few jockeys," and around one thousand merchant seamen—in an improvised prison camp at the racecourse at Ruhleben, near Spandau. He was barely twenty-three and remembered the experience as the time "when I really began to grow up."
/> To preserve his sanity and distract him from the miserable living conditions like rations of kriegswurst—"war sausage made from bread soaked in blood and fat," from which his digestion would never fully recover—and "the agony when my feet began to thaw out about 11 o'clock in the morning" in unheated stables in the winter, Chadwick gave lectures. He also set up a makeshift physics laboratory in a condemned barracks. Geiger and other German scientists supplied him with bits and pieces of spare equipment. Chadwick also managed guilefully to acquire some radioactive material. Hoping to cash in on the public's passion for radium, the Berlin Auer company was manufacturing toothpaste containing thorium, promising its customers that it would whiten their teeth and give them a radiant smile. Chadwick used it as a radioactive source in experiments. He also acquired a copy of a new paper by Einstein, published in Germany in November 191 £, expanding his work on relativity into a new theory which he called "general relativity." And so, as Chadwick later described, he became "probably one of the first English people to know about it." He could not follow the mathematics but found another internee who could explain it to him.
While Chadwick tried to make the best of things, Rutherford's other star protege, twenty-seven-year-old Harry Moseley, lost his life. A patriot from a patrician family, he had seen it as his duty to enlist at once. He was killed in hand-to-hand fighting with the Turks on 10 August 1915 in the battle for Gal-lipoli, where he was serving as brigade signal officer. Rutherford, who had tried hard behind the scenes to have Moseley reassigned to scientific work, wrote sadly that "his services would have been far more useful to his country in one of the numerous fields of scientific enquiry rendered necessary by the war than by exposure to the chances of a Turkish bullet."
The field "rendered necessary by the war" to which Rutherford turned his own talents was antisubmarine tactics. In early 1915 Germany, in an effort to break the deadlock on the western front, had declared unrestricted submarine warfare, under which, contrary to international law, merchant shipping could be torpedoed on sight, without first being stopped and searched. On 7 May 191£, the German submarine U-20 torpedoed the Cu-nard passenger liner Lusitania off the coast of Ireland with the loss of 1,200 lives, including 1 28 citizens of the then neutral United States. The Admiralty realized that Britain needed better ways of locating and destroying U-boats, and Rutherford threw himself with his natural energy into a program for developing underwater listening devices. The result was an early forerunner of sonar, known by the acronym ASDIC (Anti-Submarine Detection Investigation Committee).
Marie Curie also plunged into war work. She scoured laboratories and hospitals for x-ray equipment, solving the problem of how to move it to where it was most needed by converting vehicles into "radiological cars." French aristocrats put their limousines at her disposal and she equipped twenty vehicles, nicknamed "little Curies." The x-ray machines themselves were driven by dynamos powered by the car engines. Her own radiological car was a flat-nosed Renault, painted regulation gray with a red cross on the side, in which she dashed from place to place just behind the front lines. She found it distressing work, later writing, "To hate the very idea of war, it ought to be sufficient to see once what I have seen so many times . . . men and boys . . . in a mixture of mud and blood." As the war progressed she was joined by her elder daughter, Irene. Marie also set up two hundred radiological units in field hospitals and trained hundreds of technicians to operate them. Over the course of the war, the units assisted the treatment of more than a million wounded.
Mobile radiological ambulances known as "little Curies"
First, though, on the instructions of the French government, she had taken steps to protect her precious gram of radium. In the opening weeks of the conflict, when it seemed that the Germans would soon be in Paris, she took the radium, packed into tiny tubes shielded by lead in a case weighing forty-four pounds, by train to Bordeaux, where she deposited it in a bank vault. The following year, 191c, when conditions seemed safer, she retrieved it and began "milking" its radioactive emanation for use in radiotherapy to treat cancers and other diseases.
Elsewhere, science and technology were being applied as never before to the art of war. In November 1911, less than eight years after the first flight by Orville Wright and during his country's colonial war in Libya, the Italian lieutenant Giulio Gavotti had dropped the first aerial bombs from his flimsy Et-rich monoplane. Less than a month after the sinking of the Lusitania, a German zeppelin had dropped the first bombs on London, bringing home to its inhabitants that neither Britain's status as an island nor their own as civilians any longer provided protection.
On the evening of 22 April 191 £, Germany launched the wrorld's first poison gas attack, releasing 168 tons of chlorine over the French and Canadian lines on the western front. The German-Jewish chemist Fritz Haber had, from the early stages of the war, been pioneering chemical warfare—the use of poison gases, starting with chlorine—to kill the enemy or to drive them from their trenches. Otto Hahn was summoned to join Haber's unit, together with fellow scientists such as the physicist James Franck. After discharging gas over Russian trenches, Hahn came across some of the victims. They were lying or crouching "in a pitiable position." The sight left him "profoundly ashamed and perturbed," but as the war progressed he and his colleagues became "so numbed that we no longer had any scruples about the whole thing." As Hahn later recalled, Fritz Haber justified the use of gas by stating, "It was a way of saving countless lives, if it meant that the war could be brought to an end sooner." Even after the war, Haber argued that the use of gas was "a higher form of killing," the use of which would be essential in future wars. Haber's wife, Clara, also a chemist, did not agree. After pleading unsuccessfully with her husband to give up his work, she killed herself in despair the very night in 191£ he returned to the front to prepare for further attacks. Although Britain, France, and the United States initially condemned gas attacks, by the armistice Allied production of chemical weapons outstripped Germany's.
The First World War had exposed, as never before, the conflicts and ambiguities between expediency and morality in warfare. At its end, the British Air Ministry opposed the trial as war criminals of German bomber pilots such as those of the Gotha bombers who had killed 162 civilians in air raids on London in June 1917, including 18 children whose school took a direct hit. The officials' reasoning was that "to do so would be placing a noose round the necks of our airmen in future wars." They were reluctant to deny Britain the possibility of carrying out bombing acts, which, when undertaken by others, they called war crimes. Indeed, in 1920, in Mesopotamia, as Iraq was then known, Britain would become the first power to attempt "to control without occupation" a country from the air. *
*His discoveries about the properties of light would eventually lead to the development of television.
†The speed of light is 670 million miles per hour, and the huge factor obtained by squaring it means that just a single pound of matter, if wholly converted to energy, would be equivalent to burning over a million tons of coal.
*The Dreyfus Affair was a notorious French miscarriage of justice in which anti-Semitism played a major part. Jewish army officer Alfred Dreyfus was wrongly convicted of passing military secrets to Germany and imprisoned on Devil's Island. His conviction was eventually overturned after a long campaign led by writer Emile Zola.
*Hydrogen, the smallest atom with its one orbiting electron and a charge of one on the nucleus, occupies the first place, helium with its doubly charged nucleus and two, orbiting electrons is in place number two and so on until uranium with its ninety-two whizzing electrons.
*The British army would withdraw, leaving the task to the Royal Air Force. However, the use of air-power alone would, in this instance, fail; many civilians were killed in ill-directed bombing raids or machine-gunned when mistaken for hostile forces, thus promoting increased resistance.
FOUR
"MAKE PHYSICS BOOM"
THE WORRIES AND DISTRACTIONS of war did not
divert Rutherford from yet another major discovery: how to split the atom. In 1914 Ernest Marsden had been bombarding hydrogen gas with alpha particles. To his surprise he found that this produced far more "H-partides"—the fast-moving nuclei of hydrogen atoms—than he could account for. His departure to become professor of physics at Victoria College in Wellington, New-Zealand, prevented him from investigating further, leaving the anomaly for Rutherford. Systematically eliminating all other possibilities, such as the contamination of Marsden's equipment by hydrogen, Rutherford proved that the mysteriously prolific H-particles were fragments chipped off the nuclei of nitrogen atoms in the air surrounding the experiment. He showed that the bombarding alpha particles had forced the nitrogen atoms in the atmosphere to release hydrogen nuclei—the simplest, lightest nuclei consisting solely of what Rutherford would soon term protons.
This was the first time that human action had split the atom. Rutherford had sensed all along that he was on the brink of something major. He defended his absence from a submarine warfare meeting with the statement: "If, as I have reason to believe, I have disintegrated the nucleus of the atom, this is of greater significance than the war." By early 1919 his paper announcing the splitting of the atom was on its way to the printers. He had shown that humans could deliberately manipulate and transmute the elements and that, as C. P. Snow put it, "man could get inside the atomic nucleus and play with it if he could find the right projectiles." The only snag was that although it was a simple matter to aim alpha particles at nitrogen nuclei, there was no certainty of hitting them. In fact, most missed, passing by like spent bullets. It was, as Einstein characteristically put it, "like shooting sparrows in the dark."
Before the Fallout Page 7