Ernest Rutherford

Ernest Rutherford was born in 1871 at Spring Grove near Brightwater, New Zealand, the fourth of twelve children of a wheelwright who also farmed. Money was scarce but books were not, and a boy who won a scholarship to Canterbury College kept winning them — in 1895 one carried him across the world to the Cavendish Laboratory in Cambridge, where he joined J.J. Thomson among the very first research students the laboratory had ever admitted from outside Cambridge.

In 1898, not yet thirty, he was appointed professor at McGill University in Montreal, whose well-equipped laboratory let him chase the mystery of uranium’s rays. He showed that the radiation came in two kinds, which he named alpha and beta — and proved that the alpha was simply a bare helium nucleus. With the young chemist Frederick Soddy he demonstrated that radioactivity is one element changing into another: the seed from which nuclear physics grew. The work earned him the 1908 Nobel Prize — in chemistry, of all subjects — and he joked that in all his researches he had never witnessed a transformation as quick as his own, from physicist to chemist.

From 1907, at Manchester, he handed his students Hans Geiger and Ernest Marsden a question that should have been routine: fire alpha particles at thin gold foil and record how they scatter. Most sailed straight through, but to universal astonishment a few came almost straight back — “as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you”, Rutherford said. Only one explanation survived: the atom’s positive charge and nearly all its mass are packed into a tiny nucleus — the nuclear atom of 1911. In 1919 he bombarded nitrogen with alpha particles, turning it into oxygen and knocking out hydrogen nuclei: the first artificial transmutation, and the particle he would soon name the proton. That same year he succeeded Thomson as head of the Cavendish, directing a golden generation — Chadwick, Cockcroft, Blackett among them — and predicting the neutron’s existence. When he died in 1937, his ashes were interred in Westminster Abbey near the grave of Isaac Newton.