The Lord of the Atom
This year will mark the 75th anniversary of the death of Ernest Rutherford, who deserves some new reflections. He was the greatest experimental physicist of the 20th century, and one of the most creative and influential scientists of all time. During his lifetime, he was admired by his scientific peers and by the public as much as was Albert Einstein. Many historians of science think that his overall achievements were even more substantial than Einstein’s.
But Rutherford’s name has not kept the enduring mystique attached to Einstein’s, especially in the U. S. Few there objected, to a claim in a 1997 speech by Bill Clinton, that Americans had ‘split the atom’, although it was two of Rutherford’s students who first did that in Cambridge in 1932. His many biographers recognize the impressive scale of his laboratory triumphs, and the powerful personality of the living man; like Teddy Roosevelt, he was often described as a force of nature. But for the wider public, that force did not long outlive him.
He has remained a favourite for historically-informed scientists and historians of science, but not an Einstein-like cultural icon. This offers a lesson in the differences between history and myth. Rutherford virtually invented nuclear physics, and the particle physics that succeeded it, and was the most important single individual in shaping the practice and prestige of natural science in the first half of the 20th century. One reason this did not prevent later fading popular attention has been that, like his contemporary, Winston Churchill, Rutherford rose to fame when Britain and its Empire appeared to be at their height. Dying unexpectedly in 1937, he did not witness, as Churchill, Bertrand Russell, and other longer-living late-Victorian contemporaries did, the postwar decline of Britain and the rapid collapse of its Empire.
He thus also missed the arriving American domination in all fields of science that began in World War II, spectacularly and horrifyingly displayed at Hiroshima. He had frequently dismissed the likelihood of drawing energy from the atom – although he quietly warned British officials to ‘keep an eye’ on future possibilities. They did. Several of his brightest British students, and Nils Bohr, his Danish longtime colleague and friend, would play an important part in the multinational Manhattan Project. It had been Rutherford’s onetime student in 1905 Montreal, Otto Hahn, who made the crucial experiment demonstrating nuclear fission in Berlin in late 1938. The world’s then tiny group of nuclear scientists immediately realized that the Bomb would be possible, and that it might first be built by Nazi Germany. Hahn was not a Nazi, but other Germans were, including Hans Geiger, another former Rutherford student. Hahn, a British captive by August 1945, collapsed when he heard of Hiroshima, and spent the rest of his life as a passionate opponent of nuclear weapons. But it was Robert Oppenheimer, the complex, cultivated, leftist scientific head at Los Alamos, who became the tragic hero of the nuclear age, portrayed not just in histories and biographies, but in plays and movies.
Albert Einstein, whose famous letter to Roosevelt warning about the possible atomic bomb was actually written for him by two e’migre’ Hungarian nuclear scientists, had far less to do with nuclear physics or the creation of the Bomb than is commonly imagined. But as the century’s greatest theoretical physicist, Einstein was already acquiring his iconic status in the 1920s, after observations made during a 1919 eclipse of the sun provided powerful empirical support for his 1915 General Theory of Relativity. A worldwide poll in the 1920s found him one of the two most famous men in the world (the other was Charlie Chaplin). Other scientists shared ideas with him, but he did not establish his own distinct research tradition; he was not inaccurately seen as a solitary genius, persecuted as a Jew, and a welcome arrival and adornment in America.
Rutherford, a New Zealand Scot by origin,, an English graduate student, a temporary Canadian, eventually an English peer of the realm, was a British late Victorian above all, who sometimes reminded people of a sturdy and cheerful colonial farmer. But he was also the incarnation of a brief era in which a very small elite international community of laboratory physicists and chemists, mainly British and German and learning from each other, were the world’s leading discoverers. He used astonishingly simple and inexpensive laboratory equipment. He lived just long enough to recognize the increasing usefulness of his students with engineering background, and the larger and more powerful equipment they built for the Cavendish in the 1930s. But he never saw the full arrival of ‘Big Science’, financed by government and war. For him, until the rise of Stalin and Hitler, science had remained something of an idyllic arcadia, in which a few gifted researchers, many from aristocratic backgrounds who did not even need a university income, and in which even those who did – new professionals like Rutherford himself – were driven mainly by pure curiosity and the competitive drive for recognition.
Hence his career was filled with ironies, some not even requiring post-Hiroshima hindsight. For example, it has now long been taken for granted that physics is the ‘paradigmatic’ science, assumed to have a predominance going back to Galileo and Newton. That was not the way things looked when Rutherford began his career at McGill in 1898. What is now identified as ‘physics’ was in the 19th century still thought of as either ‘natural philosophy’ or as chemistry. Even the word ‘physicist’, the ‘-ist’ implying a paid professional occupation, had only been invented a few years earlier (and was detested by Michael Faraday). Encyclopedias of the early 1900s devoted dozens of pages to chemistry, only a couple to physics. However, the last years of the 19th century had also seen engineering education moved from expensive apprenticeships to comparatively cheap university programs, which offered guaranteed work for mathematically-expert young men, teaching calculus to undergraduates forever after. Rutherford and many other of the most famous physicists of the early 20th century, while well-trained in higher mathematics, otherwise took their undergraduate education in liberal arts.
He arrived at McGill with distinguished Cavendish credentials, but still as a young unknown. In 1901, a fateful encounter with an even younger Oxford chemist, Frederick Soddy, led to an outstandingly successful collaboration. Studying particles emitted from uranium, they introduced the concept that radioactivity was the product of atomic disintegration. That brought Rutherford a Nobel Prize in 1908, but to his amusement, it was in chemistry rather than physics. Otto Hahn was a chemist as well, a very German and patient one; his skill in making ultra-microscopic titrations helps explain why it was he, rather than any of the 1930s physicists of Germany, Italy, Britain, or America who first accurately explained nuclear fission.
Rutherford was irresistibly drawn back to England in 1907, with a chair at Manchester. By then collaborating with other great talents like Bohr and Geiger, he essentially created modern physics, still closely allied with chemistry. His most gifted Manchester student H. G. J. Moseley – another chemist – killed in 1915 at Gallipoli – first worked out the table of elements based on atomic number, and Rutherford also caught the public imagination as an ‘alchemist’, as he ‘transmuted’ nitrogen, by alpha particle bombardment, into an isotope of oxygen.
In 1919, he replaced J. J. Thomson as Cavendish Director, and felt somewhat stalled in the 1920s, observing with annoyance that the theoretical physicists ‘have got their tails up again’. But in the 1930s, now acting mainly as a guide and inspiration to his younger colleagues, he entered another brilliant decade. His wife, a puritanical prohibitionist, grew rather shrewish with age, and both of them were devastated by the early death of their daughter and only child in 1930. But he still found joy in the laboratory, booming out that they were living ‘in the heroic age of physics’, greeting each new experimental triumph with loud choruses of ‘Onward, Christian soldiers.’ The almost entirely British scientists who studied with him won Nobel Prizes galore in the 1930s and 1940s, even as decisive overall leadership in science was passing to the United States.
Becoming Lord Rutherford of Nelson in 1931, he soon also became a friend and adviser of Prime Minister Stanley Baldwin. In the laboratory, as teacher and mentor, he constantly drove students back to experiment and observation. Highly skilled in mathematics, he would deliberately conceal his expertise from his students, and regularly warn them about the seductive dangers of purely mathematical reasoning, quickly flying too far from the world of experience. Teasingly irreverent even about chemistry, he would probably have been even more derisory about arriving ‘social sciences’, heavily dependent on theory, neologisms, and statistics. ‘All science,’ he would only half-jokingly proclaim, ‘is physics or stamp collecting’.
More surprisingly, he several times turned down financial bequests to the Cavendish. He believed that too much money actually stifled imagination and creativity; that an absence of resources compelled young men to think harder. Some of his lessons could be well worth re-learning today, with theoretical physics stalled for two decades in mathematical string theory abstraction, and with granthunting and university bureaucracy frequently stifling original thought – and money visibly having he bad effects he feared. Today’s professors and students – and not just in the sciences – could still learn a lot from him.