Ernest Rutherford

Ernest Rutherford was born on August 30, 1871, at Brightwater, near Nelson in New Zealand's South Island, the fourth of twelve children of James Rutherford, a flax miller and farmer of Scottish descent, and Martha Thompson, an English-born schoolteacher ^[1]. The family worked hard for modest means, and Ernest grew up milking cows, mending equipment, and learning the practical resourcefulness that would later mark his experimental style. He was fond of recalling in later life that the family motto might as well have been that there was no money, so they had to think.

His mother's teaching background gave the children an early grounding in books and arithmetic. Ernest attended Havelock School and then won a scholarship to Nelson College in 1887, where he excelled in nearly every subject and captained the rugby team ^[1]. A second scholarship carried him to Canterbury College in Christchurch, part of the University of New Zealand, in 1890.

At Canterbury he took degrees in mathematics and physical science, earning his BA in 1892 and MA in 1893 with first-class honours in both mathematics and physics ^[2]. For his early research he built a sensitive detector of radio waves, work on high-frequency magnetization of iron that was advanced for its time and place. In 1894 he added a BSc, and the following year he won an 1851 Exhibition scholarship that funded study abroad. The story told in many accounts of the Ernest Rutherford biography is that he was digging potatoes on the family farm when news of the award arrived, and declared it the last potato he would ever dig ^[3].

In 1895 Rutherford sailed for England to join the Cavendish Laboratory at Cambridge, becoming one of the first research students admitted under new university rules that allowed graduates of other institutions to work there ^[2]. His supervisor was J. J. Thomson, who would discover the electron in 1897. Rutherford at first continued his radio detection work, then turned with Thomson to the study of how X-rays ionized gases, a shift that set the direction of his whole career.

When Henri Becquerel discovered the strange emissions of uranium in 1896, Rutherford began probing this new radioactivity. By 1899 he had shown that uranium gave off at least two distinct kinds of rays, which he named alpha and beta for their differing powers of penetration ^[4]. The naming was characteristically plain, and it stuck.

In 1898, aged just twenty-seven, he accepted the chair of physics at McGill University in Montreal. The laboratory there was well funded, and Rutherford made the most of it. Working with the chemist Frederick Soddy from 1901, he established that radioactivity was not a mysterious glow but the actual transmutation of one element into another, with atoms of thorium and uranium disintegrating in a chain of steps at fixed statistical rates ^[4]. The pair introduced the concept of the half-life, which later allowed the radioactive dating of rocks and gave the first physical estimates of the Earth's great age. This work on the chemistry of radioactive substances earned Rutherford the 1908 Nobel Prize in Chemistry, a result he found amusing, since he regarded himself as a physicist and joked that his own transformation from physicist to chemist had been the fastest he had ever observed ^[3].

Anyone asking who was Ernest Rutherford usually meets his most famous result first: the nuclear atom. In 1907 he moved to the University of Manchester, and there, in 1909, his junior colleagues Hans Geiger and Ernest Marsden carried out an experiment at his suggestion, firing alpha particles at thin gold foil. Most passed straight through, but roughly one in eight thousand bounced back at large angles ^[5]. Rutherford later said the result was as surprising as if a fifteen-inch shell had rebounded from a sheet of tissue paper. In 1911 he published the explanation: nearly all of an atom's mass, and all of its positive charge, sit in a minute central nucleus, with electrons occupying the vast empty space around it ^[5].

The nuclear model overturned Thomson's picture of the atom and became the foundation on which Niels Bohr, who worked under Rutherford at Manchester in 1912, built his quantum theory of electron orbits. Among the many Ernest Rutherford achievements that followed, two stand out. In 1917 to 1919 he showed that alpha particles striking nitrogen gas knocked out hydrogen nuclei, converting nitrogen into oxygen. This was the first artificially induced nuclear reaction, popularly described as splitting the atom ^[6]. In 1920 he named the hydrogen nucleus the proton and predicted the existence of a neutral particle of similar mass, the neutron, which his student James Chadwick found in 1932 ^[6].

Rutherford had also, at McGill and Manchester, proved that the alpha particle was a helium nucleus, devised with Geiger the electrical counting of single particles that led to the Geiger counter, and, with Bertram Boltwood and others, laid the groundwork for radiometric dating ^[4]. During the First World War he worked on acoustic methods for detecting submarines, and famously excused a late arrival at a defence committee by saying that he had been engaged in experiments suggesting the atom could be artificially disintegrated, which mattered more than the war ^[3].

Rutherford married Mary Georgina Newton in Christchurch in 1900, having met her while boarding with her mother during his student years at Canterbury College ^[1]. Their only child, Eileen, was born in 1901. Eileen married the physicist Ralph Fowler, and her death in 1930, shortly after the birth of her fourth child, was a heavy private blow to her parents ^[2].

Colleagues remembered Rutherford as loud, direct, and warm, a big man with a booming voice who sang badly and cheerfully in the laboratory. He had little patience for pretension and a strong instinct for simple apparatus and decisive experiments, preferring sealing wax and string to elaborate machinery. Students found him demanding but generous with credit and ideas, and an unusual number of them went on to Nobel Prizes, among them Chadwick, Bohr, Otto Hahn, Patrick Blackett, and John Cockcroft ^[7].

Honours accumulated steadily. He was knighted in 1914, appointed to the Order of Merit in 1925, served as president of the Royal Society from 1925 to 1930, and in 1931 was created Baron Rutherford of Nelson, a title that pointed straight back to his New Zealand origins ^[2]. He chose for his coat of arms a kiwi and a Māori warrior, alongside curves representing radioactive decay.

In 1919 Rutherford succeeded J. J. Thomson as Cavendish Professor of Experimental Physics at Cambridge, directing the world's most productive physics laboratory through its golden decade ^[2]. Under his leadership the Cavendish delivered a run of landmark results in 1932 alone: Chadwick's discovery of the neutron, and the first splitting of the lithium nucleus by artificially accelerated protons, achieved by Cockcroft and Ernest Walton with a machine Rutherford had pressed them to build ^[6].

He remained sceptical that the energy locked in the nucleus could be harnessed on a practical scale, remarking in 1933 that anyone who expected power from the transformation of atoms was talking moonshine ^[7]. The physicist Leo Szilard, irritated by the claim, conceived the idea of the nuclear chain reaction shortly afterwards. Rutherford did not live to see fission discovered in 1938 or the atomic age that followed.

In his final years he also served as president of the Academic Assistance Council, helping scholars who had fled Nazi Germany find posts in Britain ^[7]. He died in Cambridge on October 19, 1937, at the age of sixty-six, from complications following surgery for a strangulated hernia. His ashes were buried in Westminster Abbey, near the graves of Isaac Newton and Lord Kelvin ^[2].

Rutherford is widely described as the father of nuclear physics, and the description is earned rather than honorific. He identified the main forms of radioactive emission, explained radioactive decay as elemental transmutation, discovered the nucleus, achieved the first artificial nuclear reaction, and named the proton ^[5]. Almost every later development in nuclear science, from the neutron to fission to particle accelerators, grew from questions he framed or from people he trained.

His name is fixed in the vocabulary of science. Element 104 was named rutherfordium in his honour in 1997, and the SI unit of radioactive decay rate was once called the rutherford ^[8]. Craters on the Moon and Mars carry his name, as do laboratories, buildings, and scholarships across Britain, Canada, and New Zealand, including the Rutherford Appleton Laboratory in Oxfordshire.

New Zealand claims him with particular pride. His portrait appeared on the country's 100 dollar note, his birthplace at Brightwater is preserved as a memorial site, and Nelson College still houses relics of its most famous pupil ^[1]. Among the plainest Ernest Rutherford facts is this: a boy from a remote colonial farm, working with equipment he often built himself, changed the picture of matter more thoroughly than anyone since Dalton, and did it chiefly by asking simple questions and trusting what his experiments told him.