On a spring morning in May 1932, readers across England picked up their Sunday copies of the popular Reynolds’s Illustrated News to find themselves confronted by astounding news. There, on the front page, underneath an advertisement touting custom for professor Conti, astrologist, and eclipsing reports of a “Peeress Robbed on Road” and an “Actress Killed at ‘Cavalcade”’, the newspaper trumpeted, in headlines splashed across all five columns: “SCIENCE’S GREATEST DISCOVERY”.
Subheaded “The atom split at 100,000 volts”, the story breathlessly told of an earth-shattering breakthrough down in sleepy Cambridge. “A dream of scientists has been realised,” declared the paper.
The atom has been split, and the limitless energy thus released may transform civilisation. On the authority of Lord Rutherford, the world-famous scientist, Reynolds’s is able to announce exclusively that years of patient experiment at the Cavendish Laboratory at Cambridge have at last been successful. The effect of the splitting of the atom is that the electrical power now available to mankind may be multiplied 160 times.
As if unsure that even this was doing justice to such weighty tidings, the paper then felt stirred to repeat its claim that it was reporting “the greatest scientific discovery of the age”.
New Zealander Ernest Rutherford and his colleagues at the prestigious Cavendish Laboratory no doubt would have preferred a more sober vehicle than Reynolds’s to convey this triumph of British physics to the world at large.
For years they had availed themselves of James Crowther, the capable and sympathetic Manchester Guardian journalist who, in Britain at least, had almost single-handedly created the role of science correspondent. But on May 1, 1932, when the extraordinary news broke, Crowther was abroad, attending a scientific gathering in Copenhagen and looking at the state of Danish agriculture. So Rutherford, director of the Cavendish—and a man who since the turn of the century had been obsessed with unlocking the mysteries of the atom—was condemned to see his news bathed in the lurid light of a sensationalist press.
He had announced the scientific breakthrough several days earlier, at a meeting of the Royal Society, and had spelled it out in a letter to the august journal Nature, which appeared that same weekend. Acting on a tip-off, however, Reynolds’s had cornered Rutherford before Nature hit the news-stands, and the doyen of atomic physics had gruffly admitted that the experiment had occurred and that the reporter’s conclusions were “fairly correct”.
Other newspapers scrambled to catch up. Cobbling together its own version of events the Sunday Express tried to reassure its readers with the headline: “The Atom Split, But World Still Safe”. The Daily Mirror was less restrained. “Let it be split so long as it does not explode”.
The collective nod of the popular press in the direction of safety was understandable given the disturbing notion of men in white smashing a tiny atom asunder to let loose who knew what unbridled power.
A play just then opening in London ensured that nerves were already on edge at the prospect. Wings Over Europe told the story of a young scientist who stumbles on the key to the energy bound up in atoms, endearingly demonstrating his skill by detonating a lump of sugar and carving out a crater the size of Vesuvius. When the British government fails to arrange for international control and the peaceful development of this powerful technology, the scientist threatens to reduce England to a “whirlpool of disintegrating atoms”.
This scenario, by playwrights Robert Nichols and Maurice Browne, took its cue from the master of cataclysm, H.G. Wells. Years earlier, at the outbreak of World War I, Wells had written of a devastating nuclear war to come. The misleadingly titled The World Set Free had unforgettably pictured humanity, in its fascination with atomic power, as “a sleeper who handles matches in his sleep and wakes to find himself ablaze”.
Meeting the Cambridge boffins celebrated on the front page of Reynolds’s, however, would have reassured all but the most profound pessimist that both the sugar and the matches were safe—at least for the time being. The two researchers who, under Rutherford’s guidance, had fired protons at lithium with such effect were a rather self-effacing duo. Yorkshireman John Cockcroft and Ernest Walton, the son of an itinerant Irish clergyman, had gone about the business of deconstructing the unimaginably small atomic nucleus with patience (it took them five years to build a machine that worked), forbearance and a great deal of inspired improvisation.
A photograph of them outside the laboratory the day after the momentous news broke, posing with a rather avuncular Rutherford (who smiles genially from under his Homburg hat), reveals two likeable young men—Walton, rather sheepish behind his Harry Potter glasses, and Cockcroft, hand in pocket and quietly satisfied but looking in need of a long kip.
Exhilarating though it was, the breakthrough had not come out of nowhere. It was the climax—or, rather, a climax—of decades of extraordinary discoveries that had set staid old classical physics, the common-sense physics of Isaac Newton, on its head.
For two hundred years or more—since the publication in 1687 of Newton’s Principia, that great distillation of the physical laws—scientists had adhered to a central tenet: that all phenomena in the material universe would eventually be explicable in terms of large particles moving under the influence of forces. It was assumed that Newton’s laws would also hold good in the nano-world of minute distances and extraordinary velocities, and that Newtonian mechanics was the right tool for describing even the motion of atoms (should they be proved to exist).
It should be said that almost everyone by the 1880s was an “atomist”. They knew something of how fine-grained the realm was that they were dealing with—for instance, that if all the molecules of air in an empty cabin trunk were joined one to another in a straight line, that line would stretch to the nearest star, four light years away. Nevertheless, they believed, with something approaching religious conviction, that with Newton’s help all would be revealed.
Then came the body blows. First Hertz’s electromagnetic waves; then, in Würzburg in 1895, Wilhelm Röntgen chanced upon X-rays. A short while later Marie Curie isolated the radioactive metal radium. Then, in 1905, as if to underscore how different the new mental landscape was, how irrevocable the new path, theoretical papers of an entirely new kind began to appear, written by a patent clerk in Berne, which spoke of “relativity” and something called “quantum physics”.
Each advance enlarged the horizon and pushed further the boundaries of human understanding, creating a momentum, a vortex, that drew in the keenest minds in theoretical and experimental physics. It was Rutherford’s fortune, his genius, not only to embrace physics at such an epoch-making time, but to be at its forefront. Indeed, one experiment he carried out at Manchester University in 1909, in which he fired fast particles at thin gold leaf and by noting the surprising results got a glimpse of the very architecture of the atom, can be said to have set in train the entire heady enterprise that has come to be called nuclear physics.
To understand how that happened, to get a sense of why the task fell to Ernest Rutherford—the first true alchemist, the Nobel laureate, the man described as the greatest experimental scientist since Michael Faraday—it is necessary to wind back the clock well into the 19th century and to spin the globe to Europe’s antipodes.
Rutherford was born at Spring Grove, in the rural hinterland of Nelson, New Zealand, on August 30, 1871, the second son and fourth child of a Scottish immigrant, James, and his English wife, Martha. Like many early settlers in the rough-hewn colony, James turned to the land to support his growing family—there were to be 12 children—milling flax and, when business slowed, trying his hand as a mechanic and wheelwright. The family moved several times in search of work, first to Foxhill, then to Havelock, and finally, in 1888, to Taranaki.
Both Martha, who was a teacher, and James valued education, and they made the most of what limited schooling opportunities were available to their children. Throughout the country the situation for all but the wealthy was bleak, with almost half of all pupils leaving school by the age of 13. Only one in 50 enrolled at secondary schools, which were private and fee-charging.
Like most students, Rutherford needed financial backing to stay at school beyond the age of 15, when free education ended. This he managed to secure, narrowly. In 1887, on his second attempt, he won a scholarship to Nelson College, which paid board and tuition fees.
If his chief rival for the scholarship—a younger lad called Edward Pasley—had been better at English, Rutherford may have failed a second time and been railroaded into an entirely different future. As it was, he ended up at Nelson College, the sole provider of secondary-school education in the upper South Island. It was a mark of how thin on the ground 19th century education in the colony was that the nearest alternatives were Wellington College, across Cook Strait to the north, and several schools in Christchurch, 350 km to the south.
Rutherford did well enough at Nelson, becoming head boy in his second year, despite playing indifferent rugby. He proved diligent and adaptable, gaining prizes for classics, French and Latin as well as mathematics. He also began to demonstrate the single-mindedness and drive that were to become the hallmarks of his life in physics.
A school photograph shows him wearing a boater and standing amid 60 or so schoolmates outside an imposing two-storeyed wooden building bordered by a picket fence and some unruly trees. The intended suggestion was of a flourishing Eton of the south. In reality, the photograph stands as eloquent testimony to how few boys from Marlborough, Nelson and the West Coast got as far as secondary school.
While at the college, and again only on his second attempt, Rutherford won a university scholarship—one of just 10 offered countrywide. To gain the scholarship, he fought through such obstacles as this question, in an exam paper on light and sound:
Show that the velocity of sound in air is not affected by variations of pressure, but that it is affected by variations of temperature. If the velocity in air be 360 mps, find the velocity at the same temperature in hydrogen gas, which is 14 1/2 times lighter than air.
Rutherford decided to enrol at Canterbury College, and arrived in Christchurch in 1890. The college—one of the affiliates of the national examining body, the University of New Zealand—had been planned as a transplanted Old World university, but the practicalities of colonial life soon forced a rethink. The government’s introduction in 1877 of free, compulsory and secular primary education created a demand for trained teachers, and Canterbury College became their “finishing school” and a nursery for future headmasters and headmistresses.
The college didn’t come close to being a research institution—students lacked the necessary libraries, laboratories and even the leisure to undertake original research. Thanks to its meagre resources, it couldn’t even offer comprehensive professional training, except in engineering. In any case, its strength was in the liberal arts.
The ardent and unrelenting taskmaster at Canterbury, John Macmillan Brown, classics professor and college dynamo, compared the heroic efforts of his colonial students favourably with those from his Scottish homeland, claiming approvingly that half supported themselves financially “by daily toil”.
Despite such hardships, the students managed to hold their own in exam results against rivals at other University of New Zealand outposts, and achieved an air of academic respectability by wearing caps and gowns. (Canterbury College was the only university institution in the country to adopt this practice.)
The college also showed a praiseworthy receptiveness toward women, becoming, with the enrolment of Helen Connon in 1876, the first co-educational university in the British Empire. Indeed, so receptive toward women was it, that Professor Macmillan Brown discreetly courted and eventually married Ms Connon. By 1893, the college had 176 women students, and a higher ratio of women to men than almost any other co-educational university in the world.
The benefits to Rutherford of attending such a liberal and inclusive institution outweighed any technical deficits it might have had. For one thing, the course of study fuelled his literary interests and fostered the humanity so evident in his letters. Historian W.J. Gardner has made an even bigger claim, suggesting that “his years at Canterbury College equipped him in non-scientific ways that helped to make him a better scientist”.
Undoubtedly the most fortunate circumstance for Rutherford, however, was the calibre of his teachers. Canterbury College, in its “golden age”, was under the sway of a talented if unlikely triumvirate of founding professors. Macmillan Brown, the head of English and a graduate of Balliol College, Oxford, was joined by Alexander Bickerton, professor of chemistry—a firecracker of a man and one who never seemed able to stray far from controversy—and Charles Cook, professor of mathematics and natural philosophy.
Cook, an advocate of education for women and a keen cricketer, ranked high in Rutherford’s affections. It was he who Rutherford mentioned first on being awarded a Nobel Prize in 1908. Cook cultivated Rutherford’s strong suit, mathematics, and instilled in him the habits of careful scientific calculation.
There could be no greater contrast than that between Cook, the traditionalist, and Rutherford’s other great mentor, Bickerton. A charismatic science populariser with a flair for theatre, Bickerton had chalked up an outstanding record at the Royal School of Mines, in London, and he came to Canterbury as something of a one-man science faculty. The emphasis on chemistry was natural, given the colony’s agricultural needs, but Bickerton was also charged with teaching pure mineralogy and electricity and its applications.
The genial, stocky, luxuriously bearded Bickerton, “like some gnome out of an underground cavern of science” according to one biographer, exercised a strong influence on Rutherford. His practicality and his success in winning over everyone from working-class audiences to honours students, combined with his kindness and warmth of personality, helped the “rather shy and rather vague” Rutherford to gain confidence socially. Bickerton’s championing of research was not lost on his student either, and he had the good sense, once Rutherford had launched himself on a project, to leave him alone.
Years later, Rutherford was to come to the chemistry professor’s defence when he was attacked, and eventually dismissed, over erratic teaching, theoretical obsessions and unsatisfactory management. While it is true that Bickerton’s reputation suffered as a result of his outside interests and his unswerving advocacy of the unorthodox cosmological theory of “partial impact”—which he managed to introduce in the unlikeliest of contexts—his friends were undoubtedly right to see his unconventional views on religion, society and government as the root cause of the hostility towards him.
The chemistry professor was a free-thinker with the zeal of a reforming socialist. The only academic to be president of the Tailoress and Pressers Union, he also served briefly as a city councillor. However, his vigour in that post was not rewarded; despite advancing many enlightened motions, his only achievement was a bylaw limiting horse traffic to a walking pace at the junction of Hereford and Colombo Streets.
It was his social experiments that caused the greatest ire. These reached a climax in 1899—long after Rutherford had left Canterbury College—when he set up a “federative home” by the sea at Wainoni. For Bickerton, who disapproved of the institution of marriage, this essay in communistic life, in which some 30 people lived in shared domesticity, was an attempt to make concrete the utopian dream.
Despite the many feathers he ruffled, to Rutherford, the student of science, Bickerton was a godsend. Rutherford’s studies in physics and his experiments concerning electricity were all done under Bickerton’s watchful eye. Rutherford embarked on a practical physics course—his initiation into the world of experimental science—in 1891. Bickerton’s “Tin Shed”, built originally as a chemistry lab, was the unsatisfactory venue, along with makeshift space in a lecture theatre and two preparation rooms.
Despite—or, perhaps, because of—the dire conditions, Rutherford thrived. In 1893 he obtained his BA degree, and by winning the only available senior scholarship in mathematics he became one of just 14 postgraduate students in the country.
For his honours research project, he decided to determine whether iron was magnetic at high frequencies of magnetising current, having been inspired by the American physicist Nikola Tesla, who used a high frequency coil of his own design to transmit electricity without wires.
The results of Rutherford’s experiment are less significant than the ingenuity of the equipment he developed, which, with its elegant simplicity, was a hint of things to come. The first item was a “time apparatus” for switching two electrical circuits, which in essence involved a falling weight striking the end of a copper rod and breaking a circuit. By the use of threaded screws, the time interval could be adjusted to an impressive hundred-thousandth of a second. The second device was a magnetic detector for revealing fast current pulses.
Other experiments involved measurements using a contraption known as a ballistic galvanometer. Rutherford had, at one time or another, set up shop in various parts of the Tin Shed—even in the attic storeroom—but the sensitivity of the galvanometer to vibration called for something new. Bickerton provided the solution, addressing to the board of governors a letter that began: “I have the honour to ask for the use of the cloak room under the Modern Language room for a time during the vacation…”
The small room, with its concrete floor, was ideal for such experiments as Rutherford was bent on, if not for the experimenters (Rutherford shared the space with a fellow student, Jack Erskine).
By 1894 Rutherford had a double first-class honours degree in physical science and mathematics but little prospect of work. Having failed to get a teaching job at Christchurch Boys High School (mercifully, given what lay ahead), he returned to Canterbury College for another spell of research in electrical science with the hope of winning an international scholarship.
Fortuitously, such a thing had been established in England three years earlier, in the form of the Exhibition of 1851 Scholarship. Named after the hugely successful celebration of British industry and science held mid-century in a vast iron and glass pavilion, the 1851 Scholarships were funded by exhibition profits. They were designed to help outstanding graduate students in the British Empire undertake original research anywhere in the world in fields of importance to national industries.
With the scholarship in his sights Rutherford enrolled in geology and chemistry for a BSc and began conducting electrical researches in the gown room below the mathematics lecture hall. Using such devices as Leyden jars, a Voss machine and, later, a Ruhmkorff coil, Rutherford tinkered with magnetism in high-frequency fields. He magnetised a steel needle by surrounding it with a wire loop and subjecting it to an electric current with frequencies as high as 500 million per second.
By the ingenious stratagem of gradually dissolving the needle in dilute nitric acid and measuring changes in deflection, he then showed that only the thin surface layer of the needle was magnetised. Surprisingly, he was able not only to determine the thickness of the magnetised layer—0.25 mm—but also to prove that it consisted of a thin outer layer magnetised in one direction, and a thicker inner layer with reverse magnetism.
Bickerton was impressed, declaring that the research would be considered “a classic one of extraordinary ability”.
Rutherford published his findings in two papers in the Transactions of the New Zealand Institute. Totalling some 55 pages, these represented the most substantial physical research yet to appear in the journal and established their au‑thor at the leading edge of electrical technology.
In the spring, Rutherford took on some temporary teaching, at which he cannot be said to have shone. One former pupil recalled that “disorder prevailed in his classes, not quite so overt as the Auckland riots, but far more continuous”.
He was digging potatoes at the family home in Pungarehu [just inland from Cape Egmont] when news of his scholarship success came through. Thirteen days later he was aboard a steamer bound for Christchurch and London.
On arrival in England in 1895, Rutherford wasted no time making for Cambridge University’s Cavendish Laboratory and its 37 year-old director, Joseph John (“JJ”) Thomson. There were good reasons for the New Zealander’s choice of institution. Thomson had built a fine reputation there as an experimental physicist (he was soon to discover the first subatomic particle, the electron), as had his predecessor, James Clerk Maxwell. In fact, Thomson had edited the third edition of Maxwell’s Treatise, a book that had profoundly influenced Rutherford.
It helped that Cambridge had, that very year, decided to follow the lead of German universities and grant degrees for research. Rutherford was to be the first outsider to take advantage of the fact.
At the Cavendish he quickly settled down to tidy up unfinished business from Canterbury College days, working on Hertzian waves and in the process increasing the range of his transmissions, until finally they extended from the laboratory out across streets and houses to the lodgings of an assistant. Though it signified little to Rutherford, for a time he held the world record for long-distance transmission.
Then, as if scenting something more promising, Rutherford closed the gate on the incipient world of wireless telegraphy, leaving its exploration and eventual commercialisation to the young Italian researcher Guglielmo Marconi, and instead joined Thomson in studying the electrical conduction of gases.
The switch coincided with the spectacular arrival on the world stage of Röntgen’s rays—mysterious emanations that seemingly could penetrate deep into matter, producing grisly photographic images of the bones concealed within human flesh. Within weeks, Cavendish experimenters had turned their attention to the new phenomenon, and over the coming months learned societies around the world were inundated with communications on the subject. Rutherford himself soon harnessed the increasingly popular X-rays to trigger electrical conduction in gases.
Later that year, 1896, while investigating the new rays, the French physicist Henri Becquerel stumbled on something equally surprising. On developing several photographic glass plates that had lain in a desk drawer alongside a compound of potassium and uranium, he saw that, despite being in darkness, a strong photographic impression had been made on the plates.
In the face of a widespread fascination with X-rays, Becquerel’s discovery went largely unnoticed for almost a year. Rutherford was the first to take up the study of what, in a notebook, he called the “electrical effects of uranium potassium sulphate”. It was a turning point. From this time on, almost without a break, his working life revolved around a field that he was to make his own—the study of what came to be called radioactivity.
Fortune had favoured Rutherford. He had been at the Cavendish when three of the most important discoveries in nuclear physics had been made: X-rays, radioactivity and, closer to home, the isolation of the electron.
Thomson’s work with the electron was particularly noteworthy in that it can be said to have heralded the age of subatomic particles. Even Thomson seemed taken aback by the implications of what he had found, remarking that “the assumption of a state of matter more finely subdivided than the atom of an element is a somewhat startling one…”
Chemists, who had built their world around the readily understandable and somewhat tribal behaviour of atoms and molecules, grew uncomfortable at the prospect of such a nether world. Rutherford had no difficulty embracing the idea, however, and sensed questions enough for a lifetime.
“He is quite in the first rank of physicists…I am sure such a proceeding would tend greatly to the advancement of Physical Science,” Thomson wrote shortly afterwards in support of a renewal of Rutherford’s scholarship for a third year. The commissioners did as they were asked, and Rutherford rewarded their sound judgement by identifying two distinct emissions from radioactive atoms, which he named alpha and beta radiation. Beta rays were soon shown to be high-speed electrons, and alpha ray particles 7000 times as massive and oppositely charged.
The incandescent bloom of Rutherford’s genius, however, had to wait for a colder climate. Daily life as he knew it in Cambridge—working in the lab on weekdays and cycling or walking at the weekends—came to an end perfunctorily in 1898. With no immediate prospect of advancing further at the Cavendish, he accepted a job as professor of physics at McGill University in Montreal, Canada. In September, he took down the photographs of home and of his old college that had decorated the walls of his student digs, placed an order for thorium and uranium salts to continue his experiments, and boarded a steamer for North America.
The professorial salary was modest compared with the vast amounts invested in McGill’s laboratories, but then McGill was unusual. In a letter home, Rutherford explained that the imbalance was largely due to the university’s idiosyncratic benefactor, Sir William Macdonald, a non-smoking tobacco magnate. “He lives on £250 a year, so he reckons a professor should live on £500.” In any case, the clear-headed Rutherford was there for the physics laboratory, which was then the best of its kind in the world, and he eventually frightened McGill into improving his salary by the stratagem of taking an interest in jobs elsewhere.
Rutherford’s years in Canada were highly productive. With research assistant Harriet Brookes, he quickly discovered the chemically inert, but radioactive, gas radon and later an isotope of radon, the gas thoron. Then, having initially felt scientifically isolated (“the great drawback to colonial appointments”), he joined forces with the young Oxford chemist Frederick Soddy to examine the cause and origin of radiation. The effectiveness of this heavyweight coupling can be gauged by the published results—eight papers totalling 150 pages in two years. Over the same period, with other collaborators, Rutherford produced a further five papers and 87 pages.
He sought answers to some fundamental questions: What was the connection between radioactivity and the production of new types of matter? Were temporarily radioactive substances and ones that were permanently radioactive different in kind or just in degree? And, most troubling of all, did not the idea of radioactivity directly contradict the cornerstone principle of the conservation of energy: the notion that energy can be changed from one kind to another—from stored to active energy, for example—but can never be created from nothing or cease to exist?
Rutherford and Soddy welded their findings into an elegant theory, which they set down in a paper called Radioactive Change, published in 1903. Their unmistakable conclusion: radioactivity is the spontaneous disintegration of atoms.
The implication was clear. The centuries-old quest of alchemy, the transmutation of matter, had been occurring naturally all the time as, without any human intervention, atoms of one heavy element “fell apart” and decayed into atoms of another, lighter, element.
Once he knew that lead was the end product of uranium decay, it occurred to Rutherford that measuring the relative proportions of the two elements and knowing the rate of decay of uranium would allow the ages of minerals to be determined and the age of the earth to be estimated. The resulting technique of radioactive dating is a foundation of modern geology.
Endlessly drawn to the problematic zone between matter and energy, Rutherford accumulated a growing understanding of microcosmic forces. He discovered that alpha particles travelled at an incredible 30,000 kilometres per second (one tenth the speed of light) and, from experiments by Pierre Curie, deduced that each gram of radium gave off enough energy in its lifetime to lift 500 tonnes more than a kilometre.
Anticipating playwrights Nichols and Browne, he playfully suggested to one writer that “could a proper detonator be discovered, an explosive wave of atomic disintegration might be started through all matter which would transmute the whole mass of the globe, and leave but a wrack of helium behind”.
Rutherford’s star continued to rise. In 1904 the book Radio-activity, his thorough summary of where things stood, was published by the Cambridge University Press. He was elected to the Royal Society, which also awarded him the prestigious Rumford Medal. Honorary degrees were heaped on him.
Professor Morin, a good friend to Rutherford in Montreal (he often translated the Curies’ publications for him), remembered him as tall, slim and having an awkward gait. “He seemed to look fixedly, with large blue eyes; a well shaped long nose, a good crop of fair hair, light complexion, a man of ready speech, a sonorous deep voice, bursting often into loud laughter; a more amiable and accommodating man, we never had met before.” Morin added that Rutherford ate sparingly, smoked like a train, and often got up in the night and headed for his laboratory.
Yale University, the Smithsonian Institute and others queued to tempt him away from McGill, but for Rutherford the gravitational pull was toward Britain and the European centres of science. Nevertheless, only when a job came up at Manchester University in 1907 did he heed the call. While at McGill he had returned briefly to New Zealand to marry and bring back his fiancée, Mary (May) Georgina Newton, who he had known since his undergraduate days at Canterbury College. Together the couple now left Canada for England.
Such was the speed of Rutherford’s scientific ascent that when, shortly after his arrival in London, the 37-year-old physicist was introduced to Baron Kikuchi, the Japanese minister of education is said to have asked: “Rutherford? Would that be a son of the famous Professor Rutherford?”
Manchester was a high-water mark. There, instead of the individualistic approach commonly followed at McGill, Rutherford oversaw teams of researchers. For 10 years he laboured to understand the alpha particle (later shown to be a helium atom stripped of its electrons), which is 7000 times heavier than an electron but nevertheless able to penetrate metal foil. He told Hans Geiger to investigate this phenomenon further, and the German physicist found something startling—or, rather, his research student Ernest Marsden did.
Sitting in darkness, peering through the cork-cushioned eyepiece of his microscope at a scintillation screen, Marsden studied the flashes that signalled events taking place before him on a scale smaller than that of atoms. Those flashes told him that some in the stream of alpha particles he was directing at a thin sheet of gold foil were being deflected and that, occasionally, one was thrown well off course.
The result was so unexpected that Marsden kept the news to himself for a week while he re-examined his working method to see if he might discover some flaw. There was none. At last he sought out Rutherford and told him what had happened.
Rutherford was almost speechless. Looking back many years later, he called it “quite the most incredible event that ever happened to me in my life”. It was, he said, “as if you had fired a fifteen-inch shell at a piece of tissue-paper and it came back and hit you”.
Over the years there had been a great deal of debate about the structure of atoms, with Rutherford’s old Cavendish boss J.J. Thomson envisaging a uniform sphere of positive electricity studded with an equal amount of negative electricity in the form of electrons. Rutherford pondered the implications of Marsden’s work for more than a year before making a daring and radical suggestion: what if atoms were mostly empty space, with most of their mass clustered in a tiny nucleus and with the electrons forming an energetic outer cloud. A straightforward calculation, based on the known potential and kinetic energy of alpha particles, showed the distance of closest approach by an alpha particle to the nucleus of an atom of gold leaf to be 10,000 times less than the radius of the atom. In other words, if the nucleus of an atom were enlarged to the width of the page you are reading, the atom’s outer margins would be over a kilometre away. To change the metaphor, in terms of size the nucleus within the atom resembles a fly in a cathedral.
A Danish colleague at Manchester, Neils Bohr, added the key notion of stable electrons surrounding the nucleus as planets circle the sun, and the now familiar Rutherford Bohr model of the atom—perhaps the emblem of the 20th century—was born.
In 1919 Rutherford returned to the hallowed brick of the Cavendish, this time as its director. He was by now an international celebrity and the undisputed authority in nuclear physics. Eleven years earlier he had been awarded a Nobel Prize—not, as expected, in physics, but in the less crowded field of chemistry, for his work on atomic disintegration and the chemistry of radioactive substances. The word in his ear was that soon enough another Nobel, this time in physics, would be his. Given Rutherford’s interests, it was not surprising that the Cavendish—which numbered three Nobel laureates among its staff—should, after World War I, have developed a near-monopoly on nuclear-physics research.
Over his students Rutherford exercised a paternalistic dominion. With his big frame, a booming voice and the air of a colonial farmer, the straight-talking New Zealander was difficult to ignore. When things went wrong he wasn’t slow to vent his frustration at anyone within earshot. But such storms quickly passed and Rutherford would then lapse into dignified contrition.
The young Australian physicist Mark Oliphant recorded his first meeting with the Cavendish head:
I entered a small office littered with books and papers, the desk cluttered in a manner which I had been taught at school indicated an untidy and inefficient mind. It was raining and drops of water ran reluctantly down the grime-covered glass of the uncurtained window. I was received genially by a large, rather florid man, with thinning fair hair and a large moustache, who reminded me forcibly of the keeper of the general store and post office…Rutherford made me feel welcome and at ease at once. He spluttered a little as he talked, from time to time holding a match to a pipe which produced smoke and ash like a volcano.
Rutherford joked that he smoked in order to stop thinking or working too much. In truth, he was one of the most focused, single-minded men alive. He wrestled daily to divine the meaning of abstruse experimental results, devoured scientific journals late into the night, and directed the full resources of the Cavendish Laboratory at unravelling the mysteries of the nucleus. For relaxation he stumped around golf courses or motored somewhere with May (his first car, a 1910 Wolseley-Siddeley, had been bought with Nobel Prize money).
James Chadwick, who worked alongside Rutherford for more than 20 years, was once asked whether the famous nuclear physicist had an “acute” mind. On reflection, Chadwick thought not. “His mind was like the bow of a battleship. There was so much weight behind it, it had no need to be sharp as a razor.”
The French physicist Paul Langevin, who knew Rutherford years earlier, when the New Zealander first arrived in England, called him simply “a force of nature”. He was, nevertheless, a benign force. An inspiring leader, he steered several colleagues to Nobel glory, including Chadwick and the atom-smashers Cockcroft and Walton, while taking little credit himself.
Rutherford did, however, have one irritating trait. As a young man at Canterbury College, he had of necessity made do with poor equipment and few resources, afterwards attributing some of his success to those primitive experimental conditions he’d endured. At the Cavendish, he saw little reason to change this belief in the benefits of austerity, insisting on scientific rigour while keeping the purse strings tightly drawn. Students who balked at the strictures were told that he himself could do research at the North Pole if necessary.
The frugality of the Cavendish was notoriously embodied in the person of a retainer named Lincoln, who dispensed the stores. In the words of science journalist Brian Cathcart: “If a researcher asked for six brass screws he would be given four steel ones; if he sought mahogany he would be given some lesser timber lopped off a piece of broken furniture; if he wanted copper wire it would be carefully measured to half the length he requested”.
One student, in need of a short piece of metal tubing, is said to have been directed by Lincoln to the courtyard and told to saw something off a bicycle.
The makeshift laboratory in Lecture Room D where Walton and Cockcroft were labouring away in the spring of 1932 with high voltages to crack the atom would not have disgraced the set of Frankenstein. An ungainly tower of glass cylinders stood alongside an acceleration tube, condensers, rectifiers and spark gap spheres. Atop a porcelain column sat a separate transformer for the proton source, shielded in metal and connected by a rope loop to a motor on the floor. In the centre of the room was a curtained, lead-covered wooden hut slightly larger than a tea chest in which to observe an experimental chamber. From a crude but grandly named “control table”, laden with switches and toggles, wires snaked out across the floor to the 800,000 volt apparatus.
With its appropriated oddments, its plasticine, oil and grease, and the DIY ingenuity of its creators, it was to be the last great triumph of “Heath Robinson” physics.
When Rutherford had arrived at the Cavendish as a young man, the age of the gentleman scientist had been coming to an end, to be replaced by the era of institutionalised research. Having returned to the Cavendish in middle age, he was to witness the eclipse of hand-made apparatus and the rise of the big machines. The rudimentary device now before him—the world’s first true particle accelerator—was all but obsolete even as Walton powered it up on that historic day. Weeks after the event, the distinguished visitor Albert Einstein would write of “astonishment and admiration” on standing in the room where the first irrefutable proof was displayed of his equation E = mc2. But elsewhere, much larger and more sophisticated machines were already being assembled.
In a failed attempt to beat Rutherford’s team at splitting the atom, the University of California had built an 83 t cyclotron. Soon it had one weighing 4900 t and capable of generating 100 million volts. Experiments in nuclear physics were on their way to requiring teams of a hundred or more scientists and technicians and taking a decade or more to plan. “When I look back on my activities as a scientist for more than thirty years,” Rutherford was to write, “I know that I am always longing for a breathing space, in which no important advances were made for several years.” That moment never came.
Rutherford died on October 19, 1937, aged 66, of a treatable strangulated hernia. He was, by then, a peer of the realm—Ernest Lord Rutherford of Nelson (motto: Primordia Quaerere Rerum—“To seek the nature of things”). Having a lord treated by a local doctor was unthinkable, and delays in the arrival of the obligatory Harley Street specialist later prompted the claim that Rutherford “died of fame”.
After his death, others persevered with nuclear research; one of Rutherford’s former students, Otto Hahn, was even then in Berlin working to harness atomic energy. New, lab-created elements appeared, including neptunium, plutonium and curium. Then came the Manhattan Project and the birth of the atomic bomb.
But Rutherford, who through his life had played down the likelihood or desirability of such a thing, left a far nobler legacy. He combined an unsurpassed spirit of enquiry with a statesmanlike involvement in public life. He fought against state censorship, championed the rights of women students at Cambridge and called for an international ban on the use of aircraft in war. When the Nazi Party came to power in Germany, he helped found, and was president of, the Academic Assistance Council, a body that helped many scientists escape the growing tyranny in Europe.
In its 1937 obituary, the New York Times declared: “It is given to but few men to achieve immortality, still less to achieve Olympian rank, during their own lifetime. Lord Rutherford achieved both.”
Fittingly, he was buried in Westminster Abbey, in company with that other great reshaper of worlds, Isaac Newton.