Ernest Rutherford: The New Zealander Who Split the Atom
Ernest Rutherford is on the New Zealand $100 note for a simple reason: no scientist the country has produced — and few any country has produced — changed our picture of the physical world so completely. Born on a flax-farm at Brightwater near Nelson in 1871, the fourth of twelve children, he ended as Lord Rutherford of Nelson, Nobel laureate, President of the Royal Society, and the father of nuclear physics.
Three discoveries would each alone have secured his reputation: the laws of radioactive decay, the nuclear model of the atom, and the first artificial splitting of the atomic nucleus. He made all three.
Born |
30 August 1871, Brightwater, near Nelson |
Education |
Nelson College; Canterbury College, Christchurch; Cambridge |
Nobel Prize |
Chemistry, 1908 — for work on radioactive decay |
Greatest discovery |
The atomic nucleus (1911, Manchester) |
First to |
Split the atom — artificially disintegrate a nucleus (1917–19) |
Died |
19 October 1937; ashes in Westminster Abbey |
From Brightwater to Cambridge
Rutherford's path out of rural Nelson ran through scholarships — to Nelson College, then Canterbury College in Christchurch, where he completed three degrees and built, in a cold basement den, some of the most sensitive radio-wave detectors then in existence. In 1895 an 1851 Exhibition scholarship carried him to the Cavendish Laboratory at Cambridge, reportedly greeted while digging potatoes on the family farm with the words: "That's the last potato I'll ever dig."
At the Cavendish under J.J. Thomson he set aside radio — leaving that field to Marconi — and turned to the brand-new mystery of radioactivity. It was the decisive turn of his life.
Radioactivity and the Nobel Prize
At McGill University in Montreal (1898–1907), Rutherford and the chemist Frederick Soddy established that radioactivity was the spontaneous transmutation of one element into another — alchemy made real, and heresy to much of chemistry at the time. He named alpha and beta radiation, formulated the concept of half-life, and with Bertram Boltwood pioneered radiometric dating, which would eventually give geology and archaeology their clocks.
The work earned him the 1908 Nobel Prize — in chemistry, to the lasting amusement of a man who liked to say that all science was either physics or stamp collecting. He observed at the ceremony that he had witnessed many transformations in his laboratory, but none so rapid as his own from physicist to chemist.
The Nucleus, and Splitting the Atom
At Manchester in 1909, Rutherford set Hans Geiger and Ernest Marsden to fire alpha particles at gold foil. A tiny fraction bounced straight back — "as incredible," he said, "as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you." His 1911 explanation: virtually all of an atom's mass sits in a minute, charged core. The nuclear atom — the model every schoolchild now draws — dates from that paper.
In experiments completed by 1919 he went further, using alpha particles to knock protons out of nitrogen nuclei: the first artificially induced nuclear reaction — "splitting the atom" in the popular phrase. That same year he returned to Cambridge as Director of the Cavendish, where his students went on to detect the neutron (Chadwick, 1932) and split lithium nuclei with a purpose-built accelerator (Cockcroft and Walton, 1932). Eleven Nobel laureates trained under him.
Rutherford died suddenly in 1937 after surgery, and his ashes were buried in Westminster Abbey near Newton and Kelvin. He famously dismissed talk of atomic energy as "moonshine" — yet the physics he founded reshaped the century, and element 104, rutherfordium, carries the Brightwater farm boy's name into the periodic table.