by P. D. Smith
Einstein had long suffered from anti-Semitic attacks in Germany. Hitler had ranted about what he saw as the malign influence of ‘Hebrew’ science on the German ‘soul’. Within the physics community, anti-Semites such as Nobel prizewinning physicist Philipp Lenard began opposing what they called ‘Jewish physics’ and promoting their own ‘Aryan physics’. Soon, nationalists gathered outside Einstein’s Berlin home to shout insults against him and relativity. At one point a reward was offered to anyone who killed Einstein. When the Jewish foreign minister Walther Rathenau was assassinated near Dahlem in 1922 by a reactionary gang, Einstein was thought to be next in line. Rathenau, whose father had founded AEG, was a close friend of Einstein’s. After his murder the physicist seriously considered leaving Germany. Fritz Haber managed to convince him to remain.
When Hitler came to power in 1933, many of Germany’s greatest physicists would be expelled from their positions under new racial laws. By then the Hungarian Quartet had all fled their new country. America would be their final destination. With them they took the knowledge that could have given the Third Reich the key to absolute power – the superweapon.
10
Faust and the Physicists
You see things; and you say, ‘Why?’
But I dream things that never were; and I say, ‘Why not?’
The Serpent in George Bernard Shaw’s Back to Methuselah (1921)
On Christmas Day 1931, the passengers of the SS Leviathan crowded on deck to watch as their ship approached Manhattan Island, the gateway to the New World. Six months earlier, the world’s tallest building had been officially opened here – the Empire State Building, a towering monument to the technological age and an anticipation of tomorrow’s cities. In the future, as Fritz Lang’s 1926 film Metropolis had shown, architecture would touch the skies.
But in 1931 most people still had their feet firmly on the ground. In the aftermath of the Depression that had followed the Wall Street Crash, the immediate future was a long way from utopia. Little of the new skyscraper’s two million square feet of office space had been rented, and New Yorkers quickly renamed it the Empty State Building.
The Leviathan had left England on 19 December with Leo Szilard on board. He was supposed to be giving lecture courses in Berlin – one on atomic physics with Lise Meitner and the other on new work in theoretical physics with Erwin Schrödinger. But the chance to spend a year working on mathematical physics at Princeton University had been too good to miss. The offer had come from Eugene Wigner, who along with John von Neumann had accepted a post at Princeton the year before. A personal letter from Albert Einstein had secured Szilard a visa, and as the cancer of fascism spread across Europe he was seriously considering whether he should move permanently to the land of the free.
No one who approaches New York from the sea can fail to be moved by the city’s breathtaking skyline. It is a sight that seems quintessentially modern – the city of the twentieth century. Typically, though, Leo Szilard also sensed the vulnerability of the great metropolis:
As the boat approached the harbour, I stood on deck watching the skyline of New York. It seemed unreal, and I asked myself, ‘Is this here to stay? Is it likely that it will still be here a hundred years from now?’ Somehow I had the strong conviction that it wouldn’t be there. ‘What could possibly make it disappear?’ I asked myself… and found no answer. And yet the feeling persisted that it was not here to stay.1
When he wrote these words, two decades later at the height of the cold war, with America and the Soviet Union preparing to test their new hydrogen superbombs, every schoolchild knew what could make New York or any other city disappear. But at the end of 1931, Szilard seemed to have few grounds for his doomsday fears. Perhaps it was his sixth sense for the ‘tragedy of mankind’ that warned Szilard that an extraordinary year was about to dawn in atomic physics, comparable in its impact to 1895, when Wilhelm Röntgen saw the bones in his hand revealed by mysterious rays.2 For, as Hans Bethe has said, 1932 was the year in which atomic physics was born.
All roads led to Blegdamsvej 15 if you were a physicist in the 1920s and 30s. This was Niels Bohr’s Institute for Theoretical Physics in Copenhagen. The brilliant Ukrainian physicist George Gamow recalled that ‘the Institute buzzed with young theoretical physicists and new ideas about atoms, atomic nuclei, and the quantum theory in general’.3
Niels Bohr was a superb footballer and as a young man had played for a top Danish club. But in physics, the tall, softly spoken Bohr was in a league of his own. He was the ‘deepest thinker I ever met’, said Paul Dirac, the English physicist who in 1928 correctly predicted the existence of antimatter.4 ‘I have seen a physicist for the first time,’ said the German physicist Carl Friedrich von Weizsäcker after meeting Bohr. ‘He suffers as he thinks.’5 Together with Ernest Rutherford, Bohr had mapped the basic structure of the atom, and later, in the 1920s, he helped to shape the quantum revolution – despite strong resistance from its founder, the former patent officer from Berne. Indeed, he had as profound an influence on the course of twentieth-century physics as did Einstein himself. After they met for the first time in Berlin, Einstein wrote to Bohr that ‘not often in life has a person, by his mere presence, given me such joy as you’.6
Einstein’s debates in the late 1920s with Bohr on quantum theory were like a scientific clash of the Titans. Einstein could never accept the indeterministic quantum mechanics of the 1920s that grew out of his own 1905 paper on the photoelectric effect. In it he used Max Planck’s notion of quantized energy and argued that light was not a wave but a stream of particles – photons. Einstein was right to describe his own paper as ‘very revolutionary’.7 In fact it was this rather than his more famous paper on relativity that won him his Nobel prize in 1921. But as a new generation of physicists carried the red banner of quantum revolution into ever stranger territory, Einstein clung doggedly to what he called ‘objective reality’. As he told his friend Max Born in 1926, God does not play dice.8 If an electron could choose its direction ‘of its own free will’, he said, ‘I would rather be a cobbler, or even an employee in a gaming house, than a physicist’.9
From the mid-1920s, while he was collaborating with Leo Szilard on refrigerator designs, Einstein began to plough a long and lonely intellectual furrow in theoretical physics. His goal was what he called a unified field theory. He believed until his dying day that this would bring relativity and the quantum realm together in one theory describing the movement of planets as well as subatomic particles. His quest isolated Einstein from the new generation of nuclear physicists, who with their increasingly counter-intuitive ideas about the subatomic realm challenged the very foundations of classical physics and provided the conceptual tools to build the atomic bomb. These new, revolutionary physicists – people such as Walther Bothe, James Chadwick and Frédéric Joliot-Curie (Marie Curie’s son-in-law) – were Einstein’s intellectual children. When he disowned them, the former footballer Niels Bohr became their father figure.
Bohr’s annual conference, to which he invited about thirty physicists, was the highlight of the physics year. In 1932, from 3 to 13 April the brightest minds in physics gathered together in Copenhagen. In a few years’ time, many of them would be working on the atomic bomb. But for now they still had time for a little light-hearted play-acting. Each year the conference ended with what George Gamow called a ‘stunt pertaining to recent developments in physics’.10 The year before, Gamow had rounded up proceedings with a cartoon history of quantum mechanics, starring Mickey Mouse in the lead role.11 This year marked the centenary of Goethe’s death, so they decided to stage a version of the German writer’s greatest play, Faust.
Scientists attending the 1932 conference at Niels Bohr’s Institute for Theoretical Physics in Copenhagen. Among those pictured are Werner Heisenberg, Max Delbrück, Lise Meitner, Paul Ehrenfest, Carl Friedrich von Weizsäcker and Paul Dirac.
Written when the industrial revolution was transforming Europe, Faust draws on the story of
a sixteenth-century alchemist to ask what is the purpose of knowledge and how we can have progress without increasing human suffering. It is a remarkable work, one that acknowledges the indebtedness of science to its earlier, hermetic roots in alchemy while looking forward to the scientific world of the future. By chance, the final part of Faust was published in the year the word ‘scientist’ was coined. Goethe’s Faust is a proto-scientist whose desire to know nature’s deepest secrets leads him to strike a fateful bargain with Mephistopheles, the fallen angel who is the Devil’s representative on earth. By usurping the authority of God, Faust becomes an iconic figure of human hubris, like Dr Frankenstein.
In the sixteenth century, the story of Faust – a disreputable dabbler in alchemy and the occult, who came to a sticky end in an explosive experiment – was used by the Church to frighten people about the dangers of non-Christian knowledge. Goethe’s play reworks the classic theme for the modern age. His Faust is not a mad scientist, as the Church had once tried to portray him. Instead, Goethe celebrates the spirit of inquiry while highlighting the dangers of misapplied knowledge. True scientific understanding is life-affirming and creative, not destructive and exploitative, Goethe suggests.
At the beginning of the play, Faust longs to know ‘the inmost force / That bonds the very universe’.12 It is a scientific and philosophical goal he pursues tirelessly throughout his life, regardless of the cost to himself or others around him. True to the scientific spirit of the age in which it was written, Goethe’s Faust does not question the value of such knowledge.
Goethe’s portrait of the unsatisfied searcher for knowledge is tragic not because Faust loses his eternal soul, as happens in the original sixteenth-century tale. Instead, the quest of the modern Faust is tragic because, until the final moments of his life, this brilliant man does not truly understand himself. What is the point of knowing nature’s deepest secrets, Goethe asks, if humankind never attains self-knowledge? The Faustian scientist might control the forces of nature but he does not understand, let alone control, himself. The implications were not lost on the atomic physicists gathered at Bohr’s Institute in spring 1932.
The physicists’ Faust was written by the younger scientists present, their literary skills no doubt boosted by the products of Copenhagen’s other claim to fame – the Carlsberg Brewery, which also happened to be one of Danish science’s most generous benefactors. Max Delbrück, a friend of Szilard’s from Dahlem who would later be a central figure in the post-war revolution in molecular biology, did most of the writing. Goethe’s characters were replaced with the great physicists of the day, their younger colleagues donning masks to play them. Mephistopheles became the irascible Austrian Wolfgang Pauli, while Faust became Paul Ehrenfest, a close friend of Einstein. The role of God was reserved, appropriately enough, for their gentlemanly host, Niels Bohr.
The play parodied Goethe’s masterpiece and allowed the next generation of physicists to poke fun at their esteemed elders, who were sitting in the audience. Wolfgang Pauli’s rudeness was legendary. In the play he bluntly tells the painfully polite Niels Bohr (God) that his latest theory is ‘crap’.13 But Bohr is also gently mocked. His almost pathological fear of being too critical becomes the motto of the play, emblazoned on the text’s cover: Nicht um zu kritisieren (Not to criticize).14 Even Einstein doesn’t escape unscathed. His flawed unified field theory, which created a media storm when it was published in 1929, is lampooned as the son of a flea.
Cover of the script for the 1932 Copenhagen performance of Faust, designed by the Danish scientist and poet Piet Hein.
At times the play is anarchic, even Dadaist, in its celebration of the bizarre world of quantum theory. But the new physics was full of weird and wonderful notions. Niels Bohr once greeted one of Pauli’s theories with the comment: ‘We are all agreed that your theory is crazy. The question, which divides us, is whether it is crazy enough to have a chance of being correct. My own feeling is that it is not crazy enough.’15
The audience of the physicists’ Faust were not surprised, therefore, when ‘The Group Dragon’ and ‘Donkey-Electrons’ appeared on stage in the Quantum Mechanical Walpurgis Night scene. As Dirac says in the play, ‘our theories, gentlemen, have run amuck’.16 The physicists transformed Faust’s death scene at the end of the play into a moment of supreme bathos. Paul Ehrenfest utters Faust’s famous dying words just as he is about to be immortalized by a throng of press photographers: ‘To this moment I want to say: / Do stay, you are so beautiful!’17
In the physicists’ Faust this becomes a wonderfully witty moment, although humour was the last thing in Goethe’s mind as he penned this poignant scene. The physicists are making fun of their colleagues’ vanity and self-importance. By highlighting the theme of fame, they were making an important point. In the coming years, nuclear physicists would indeed feature ever more frequently in the media. A new age of science was dawning. As actors on the world’s stage, scientists would be increasingly forced to drop the mask of the saviour. Instead, as they were drawn ever closer to government and the military, they began to be feared by the public and viewed as Strangelovean mad scientists. This would be the price of their Faustian bargain.
Griffin, the megalomaniac scientist in the film of The Invisible Man (1933), knows the temptation of such power and pays the ultimate price for hubris: ‘I wanted to do something tremendous, to achieve what men of science have dreamt of since the world began, to gain wealth and fame and honour, to write my name above the greatest scientists of all time.’18 Indeed, one physicist featured in the play would, after Hiroshima and Nagasaki, rival even Einstein’s fame: Robert Oppenheimer.
Another physicist who would enter the media spotlight this year made a brief appearance at the end of the play as Faust’s overambitious assistant, Wagner. James Chadwick is portrayed by his fellow physicists as ‘the personification of the ideal experimentalist’. In the play’s manuscript there is a sketch of him looking very serious and wearing the scientist’s trademark white lab coat. He walks on stage after Faust’s death scene, balancing a black ball on one finger. ‘The neutron has come to be,’ declares Chadwick’s character. ‘Loaded with Mass is he, / Of Charge, forever free.’19 This rather sinister figure at the end of the play was announcing an extraordinary discovery, one of which Faust himself would have been proud. James Chadwick had found one of the basic constituents of matter – the third elementary particle.
Ernest Rutherford and Niels Bohr’s planetary model of the atom – a nucleus orbited by electrons – was widely accepted. But the structure of the nucleus remained unknown. In 1919, Rutherford had found that nitrogen atoms under bombardment disintegrated to produce hydrogen nuclei. He coined the term ‘proton’ for these particles, after British chemist William Prout’s term for elementary hydrogen atoms, ‘protyle’. Rutherford then suggested that the core of the atom consisted of alpha particles together with protons and electrons. Significantly, in 1920 he speculated that protons and electrons might join together, forming what he called ‘neutral doublets’.20 The search had begun for the neutron.
James Chadwick had spent World War I interned in Germany, where his scientific activities were limited to experiments with radioactive toothpaste. A tall and rather aloof man, Chadwick became assistant director of Rutherford’s Cavendish Laboratory at Cambridge in 1923. Chadwick set himself the task of tracking down the hypothetical neutron. The first major clue came in 1930. Two German scientists, Walther Bothe and Herbert Becker, found that a light, silvery metal called beryllium could be made to emit radiation when bombarded with alpha particles from polonium. But this was no ordinary radiation – it was more powerful than anything so far detected from natural radioactivity or artificial transmutations, such as Rutherford’s. It could penetrate eight inches of lead.21
Marie Curie’s daughter, Iréne, and her husband Frédéric Joliot, working at the Radium Institute in Paris, claimed that this was gamma radiation. What’s more, they said they had used this strong radiation to punch
protons out of hydrogen-containing materials, such as paraffin wax. This was an extraordinary claim. Gamma radiation is essentially a highly energetic form of light, and although photons – particles of light – had been known to knock electrons out of the way, the idea that they could dislodge a particle two thousand times as massive, such as a proton, seemed fantastic. So Chadwick thought, when he read the Curies’ paper in January 1932.
Primed by Rutherford’s theory that the atomic nucleus is made up of protons and neutral particles, Chadwick realized that this was the chance he had been waiting for. After three weeks of intense work using equipment which resembled ‘a piece of discarded plumbing’, Chadwick announced that Bothe and Becker’s powerful radiation was not gamma rays, but neutrons.22
The mysterious radiation detected by the two German physicists was now explained. Beryllium was emitting a particle as solid as a proton, but with one vital difference. The neutron, as its name suggests, has mass but no electrical charge. And because it is electrically neutral, the neutron can penetrate right into the heart of the atomic nucleus – unlike the positive protons and alpha particles, which are repelled. The neutron was what the atomic scientists had been waiting for: an ideal tool to probe the dark heart of matter.
James Chadwick mailed a hurried announcement of his discovery to a scientific journal on 17 February 1932. A few evenings later, he told a rapt group of his Cambridge colleagues, including novelist and physicist C. P. Snow, how he had made his remarkable discovery. At the end of his talk he sat down and (as Snow recalled) said, ‘now I want to be chloroformed and put to bed for a fortnight’.23
