Kiwi country lad Ernest Rutherford described the structure of the atom and became “the father of nuclear physics”.
There, James Rutherford ran a spirited commentary on the scene in the sky, describing for his children what was sheet, what was fork, what was ball lightning, showing how, if they counted the interval between flash and thunderclap, they could tell whether the storm was approaching or moving away.
Great damage was done in the Brightwater area that night, but after the dead stock – both the beasts that had gone wild and galloped into fences, and those struck by lightning – had been replaced, the storm became for most people a fading memory. But not for one of the Rutherford boys, whose nine-year-old mind was given its direction for all time by the elemental fury he had witnessed. Naturally of a quiet disposition, he now became even more withdrawn and thoughtful, and sometimes at the table he would lay down his knife and fork and stare into vacancy, so that his family would chaff him, saying: “Look at Ern! Look at Ern!” So started, over a storm in Nelson, the chain of thoughts and actions that irrevocably led to the man-made storm that broke over Hiroshima some 65 years later with incalculable significance for mankind.
The story of Ernest Rutherford’s childhood in New Zealand is by and large too well known to bear repetition. He was a healthy, normal boy, dividing his energy evenly between physical activity and mental effort, thus exemplifying an ideal that has always been held up to generations of schoolchildren. He read voraciously, but no book would have kept him from joining his brothers in one of their favourite pursuits, bird-nesting on the banks of the Wai-iti River. The eldest Rutherford boy, George, used to sell the blown eggs to boys in Nelson to raise pocket-money for, among other things, “rubber rings for catapults, and string for kites”.
The last potato
The great influences on the young Rutherford were, in order, his mother, Nelson College, and later, Canterbury College. On Martha Rutherford devolved a great deal of the responsibility for training her children (she had 12), because James Rutherford was often away from home engaged in his flaxcutting and milling. Ernest Rutherford was to acknowledge this debt in a cable he sent to his mother in 1931: “Now Lord Rutherford. Honour more yours than mine …”
Another debt he acknowledged was to Nelson College, for one of the last sentences he spoke on his deathbed in 1937 was a request to Lady Rutherford to “see to” a £100 bequest to the school. It was there, under William Still Littlejohn, the mathematics and science master, that Rutherford first got his grounding in physics – often in a class by himself, as science was an optional subject, and the majority of students took French instead. But he was also encouraged in other subjects, so much so that, in 1889, he won the junior university scholarship at Canterbury College. But for this scholarship, he was to remark later in life, he would probably have been a farmer. He was in fact digging in the garden at Foxhill when the news came, and it is recorded that he threw the fork down and commented: “That is the last potato I shall ever dig.”
By 1892, when he was 21, Rutherford had graduated with a BA and had won a senior university scholarship in mathematics, which was then regarded as his strongest subject. A year later, he’d earned an MA with double first-class honours, in mathematics and physical science. Then followed a year of postgraduate research, when he worked in the famous “den”, experimenting with Hertzian waves. In 1895, he became the University of New Zealand’s first overseas scholar, and in September of that year – after borrowing his passage money – he set out for London and Cambridge. Prometheus was at last unchained.
In the early 1890s, in Britain and the US, it was a common remark that “all the major discoveries of science have been made”. But before the decade was out, JJ Thomson had proved the existence of particles lighter than the lightest known atom. He called these particles “corpuscles” – they are now known as electrons. Thomson made his announcement in 1897, and it was during this same year that Rutherford, working as a research student under Thomson in the Cavendish Laboratory, first began his own investigations into radioactivity. From then on, Rutherford’s primary work was in unravelling the complicated processes involved, and explaining them with a theory that was checked at all stages by careful experimentation.
Like Edison, Rutherford not only was interested in results as such, but also wanted to get them before anyone else. “I have to keep going,” he once wrote to his mother, “as there are always people on my track.” As Dr Albert Shaw, a one-time student of Rutherford’s at McGill University, Montreal, and later the director of its physics department, says, “Rutherford was always ready to take as much credit as was given to him.”
One time when he didn’t, says Shaw, and it was in a “case when it really mattered”, was when Rutherford gave more credit to his co-worker, Frederick Soddy, for his accomplishments on their famous theory of the disintegration of matter, than Soddy claimed for himself.
Rutherford was also capable of glee over the discomfiture of rival researchers, as shown by his comment on his 1911 theory of the nuclear atom: “I know some people who would give a thousand pounds to prove me wrong.”
The 1902 theory of the disintegration of matter – the climax of the brilliant researches Rutherford undertook when he went to McGill as research professor in physics in 1898 – was put forward under some opposition. He and Soddy had been working on thorium emanations, to discover their chemical nature, and through this work Rutherford first began to understand the mechanism of radioactivity. He claimed that atoms of thorium spontaneously disintegrate, shooting out a part of themselves in the form of alpha-particles, and in the process are transformed into a new kind of atom.
This idea – of atoms exploding spontaneously – was so revolutionary that some of Rutherford’s colleagues at McGill objected that its publication might bring discredit on the university. Professor Norman Shaw, who was at the meeting where this objection was voiced, later recalled how Professor John Cox, then director of the physics department, rose to support Rutherford, and to predict that not very long in the future Rutherford would be rated as rivalling [Michael] Faraday as an experimental physicist.
Describing the structure of atoms
The theory was published, and did indeed meet with widespread incredulity and criticism. In particular, Lord Kelvin, one of the creators of 19th-century physical science, found the idea of exploding atoms unbelievable. He suggested that the vast amount of energy given out by radioactive substances originated not by atomic disintegration, but by the absorption of “aetherial” waves.
Rutherford, with this theory, made an important step towards describing the structure of atoms. It was this work with Soddy, and later studies in his remaining years at Montreal on the chemistry of the naturally radioactive elements, that brought him, in 1908, the Nobel Prize for Chemistry.
Rutherford left McGill in 1907 to become professor of physics at Manchester University. There, he had Hans Geiger for his colleague, and Ernest Marsden – later Sir Ernest, and secretary of the New Zealand Department of Scientific and Industrial Research – as one of his associates. At Manchester, Rutherford continued with his studies of alpha particles. (He and Geiger, incidentally, developed an electrical method of detecting these and this instrument was the forerunner of the present Geiger counter.)
In 1911, four years after going to Manchester, he announced the revolutionary thesis that the atom had a “small but massive” positively charged nucleus, with negative electrons circling around it – a sort of miniature solar system.
His next step, once it was clear that the nucleus of an atom was composed of particles, was to experiment with the possibility of knocking out one or more of these particles. Since each of the elements takes its chemical nature from its atomic number – that is, the number of particles in the nucleus and the number of planetary electrons revolving around it – successful bombardment could be the key to what Rutherford called the “newer alchemy” – the transmutation of elements.
The key to the atomic age
The rest of the story has often been told: how in 1919 he succeeded in disintegrating a nitrogen atom and converted it to oxygen. His account of this momentous experiment – the first successful attempt by man deliberately to transform matter – was humbly entitled “An Anomalous Effect in Nitrogen”.
That same year, Rutherford took over from his old chief, Thomson, as Cavendish professor of experimental physics at Cambridge. It was in the Cavendish Laboratory, in 1932, that John Cockcroft and Ernest Walton conducted what has become perhaps the most publicised experiment of that century, by splitting an atom of lithium.
Earlier that same year, a perhaps more important achievement was James Chadwick’s discovery of the particle whose existence Rutherford had predicted in 1920 – the neutron – which was to provide the key to the atomic age. And, six years later, in 1938, Otto Hahn, who had been a pupil of Rutherford’s at McGill, accomplished the fission of uranium by neutron bombardment.
Rutherford did not live to see Hahn’s success. He died in 1937, after a short illness following a surgical accident, and was buried in Westminster Abbey. He had lived only 66 years, and perhaps could have gone on to even greater heights had he lived. But his achievements as the father of nuclear physics remain great and unassailable. As Nobel laureate Sir Henry Dale has said, he is “among the few great ones, in all the long history of man’s effort to understand the material universe in which he has his being”.
This article was first published in the September 9, 1961 issue of the New Zealand Listener.