The First War of Physics (2 page)

In Part III the book addresses the direct involvement of Allied scientists in the hunt for their German counterparts in war-torn Europe following the D-Day landings, the successful Trinity test at Alamogordo in New Mexico, the bombing of Hiroshima and Nagasaki, and the reactions of the captured German scientists on hearing of the Allied success.

Finally, Part IV describes the origins of the Cold War, the acceleration of the Soviet atomic programme, proliferation of weapons technology, the Venona project, the unmasking of Soviet spies, and the first successful Soviet test in August 1949. The book concludes with an extended epilogue which attempts to tie up many of the loose ends, describing the American and Soviet H-bomb programmes and the Cuban missile crisis which brought the world to the very edge of disaster.

For me, this book represents the end of a long journey. I suppose I can trace its beginning all the way back to my first classes in quantum mechanics, as an undergraduate student in Manchester, England, during the cold, damp winter of 1975–76. I probably didn’t fully realise it back then, but I was completely captivated. To anyone tutored in the language and the logic of classical physics, quantum mechanics is at once mathematically challenging, maddeningly bizarre and breathtakingly beautiful. I have spent a lifetime trying to understand it.

The physicists who forged this outrageous new theory left their fingerprints all over it, in the form of new laws, physical constants, principles and approximations. It is impossible to study quantum mechanics without tripping over their names. To study quantum mechanics, therefore,
is to study the physicists who made it. Many of these same physicists also played crucial roles in the development of the world’s first atomic bombs, and this juxtaposition has always fascinated me. To understand them is to understand the various roles they played in this development: the things that drove them, and the things that scared them.

I have drawn extensively on the published works of noted scholars and sources of historical documents that can be found online. I owe particular debts of gratitude to Kai Bird and Martin Sherwin, authors of
American Prometheus: the Triumph and Tragedy of J. Robert Oppenheimer
, Margaret Gowing, author of
Britain and Atomic Energy
and
Independence and Deterrence: Britain and Atomic Energy, 1945–1952;
David Holloway, author of
Stalin and the Bomb;
Richard Rhodes, author of
The Making of the Atomic Bomb
and
Dark Sun;
and Mark Walker, author of
German National Socialism and the Quest for Nuclear Power, 1939–1949
and
Nazi Science: Myth, Truth and the German Atomic Bomb.
I have happily climbed on the shoulders of their scholarship.

I owe a debt of thanks to Jeremy Bernstein, John Fricker, Martin Sherwin, Peter Tallack, Jon Turney and Mark Walker, who read and provided many comments on the first draft manuscript. I am, of course, more than happy to accept full responsibility for all the errors that remain. My thanks must also go to Simon Flynn, my editor at Icon, for being indulgent when the project ran on longer than anticipated, and for being ready to accept an ‘epilogue’ that surely does violence to the meaning of this term.

Prologue

LETTER FROM BERLIN

Christmas 1938–September 1939

I
t was something of a family tradition. Every year Otto Frisch would celebrate Christmas in Berlin with his aunt, Lise Meitner. But not this year. Not this Christmas.

Frisch had left Germany five years earlier, in October 1933. He was a young, personable and inventive physicist at the University of Hamburg. He was also an Austrian Jew, and he had fallen victim to the Law for the Reestablishment of the Career Civil Service, introduced in April that year by the new National Socialist government, the first of 400 such decrees. It provided a legal basis on which the Nazis could forbid Jews from holding positions in the civil service, including academic positions in German universities.

Like most academic physicists, he had until that time paid little attention to politics. His only short-lived political affiliation had been to a student organisation in Vienna, for which he had served on the entertainments committee, arranging dances. When he had taken part in political discussions as a student he had found them stiffly formal, and rather ridiculous. He had dismissed Adolf Hitler’s appointment as Chancellor of Germany earlier in 1933 with a shrug of the shoulders. He figured that Hitler could surely be no worse than his predecessors.

He was quickly proved wrong. Within a few short months came the stark realisation that he was about to lose his job. He had no alternative but to join the swelling ranks of displaced Jewish physicists, together accounting for a quarter of all the physicists in Germany, including many Nobel prize-winners. He had to rely on the small but close-knit international community to which he belonged, which now scrambled to find grants and positions for those displaced by Hitler’s anti-Semitism. He had moved from Hamburg first to Birkbeck College in London before being whisked off a year later to Copenhagen by the celebrated Danish Nobel laureate Niels Bohr.

Meitner had received reassurances from Carl Bosch, a director of the chemicals giant I.G. Farben and a principal sponsor of the prestigious Kaiser Wilhelm Institute for Chemistry, where she worked. She remained stubbornly optimistic for the future, and continued to work in Berlin for another five years before she too succumbed to the inevitable. Frisch’s ‘short, dark and bossy’ aunt was a pioneer of the study of radioactive substances. She had stoutly fought prejudice against women in science for most of her professional life.

Though rather shy and withdrawn, she had earned great respect. In 1919 she had become head of physics at the Kaiser Wilhelm Institute for Chemistry, where she worked with distinguished German chemist Otto Hahn, her collaborator of some 30 years. She had become a professor (a
Privatdozent)
at the University of Berlin in 1926, at the age of 48, the first female professor of physics in Germany. Albert Einstein had once called her a ‘German Madame Curie’.

But Meitner was not German. Like Frisch, she was Austrian. She was the third of eight children born into a Jewish family in Vienna. Her Austrian nationality had for five years spared her from the worst excesses of Nazi persecution, although her position and status had gradually and inexorably been eroded.

When German forces marched into a welcoming Austria in the Anschluss of 12 March 1938, Meitner became a German Jew. That she considered herself a Protestant Christian who had withdrawn from the Jewish community and been baptised at the age of 30 held no sway with
German racial laws. Against the prejudices to which she was now fully exposed, there could be no victory, however small. The very next day she was denounced by a Nazi colleague and declared a danger to the Institute.

Hahn had tried to defend her, but lost his nerve. While he was not perceived by his colleagues as a Nazi or even a strong supporter of the National Socialists, he had never really questioned the legitimacy of the new regime. He had told a newspaper reporter in Toronto in 1933 that he believed that those whom the Nazis had jailed during their first months in power had been Communists who also just happened to be Jews. Like many middle-class Germans, Hahn was now learning that there was a significant price to be paid for his passive acceptance. He told Meitner on 20 March that she could no longer work at the Institute. She was stunned. Hahn had, in effect, thrown her out.

Meitner’s position had grown more perilous by the day. Jewish academics had previously been allowed to leave Germany with their families and their possessions. But new laws threatened to close all escape routes. In May 1938 she had applied to join Bohr in Copenhagen, where her nephew was working, but the Danish embassy had declared her Austrian passport invalid and refused to grant her a visa. In June she was refused a German passport. Heinrich Himmler, Reichsführer-SS, had declared it undesirable that well-known Jewish scientists be allowed to leave the country. She was at considerable risk of becoming trapped in Nazi Germany.

Bohr appealed to the scientific community on her behalf. Weeks of anxious waiting went by. Eventually, on 13 July 1938, Meitner left Germany for neighbouring Holland. She was taken to the railway station by fellow Austrian Paul Rosbaud, editor of the German scientific journal
Die Naturwissenschaften
and no friend of the Nazis. Hahn had helped her to pack, and had given her a valuable diamond ring to provide for her in an emergency.

Meitner crossed the border into Holland without incident. From Groningen she made her way first to Copenhagen, then to Stockholm, where a job awaited her as a guest researcher in Swedish physicist Manne Siegbahn’s research group. Professor Meitner from the prestigious University of Berlin and Kaiser Wilhelm Institute for Chemistry became an
ordinary researcher, with a salary that barely covered her living expenses. That she was able to continue her collaboration with Hahn by letter at least offered some small consolation.

She met with Hahn briefly in November 1938 at Bohr’s Institute for Theoretical Physics in Copenhagen, but it was not an auspicious meeting. Hahn arrived bearing news that Frisch’s father – Meitner’s brother-in-law – had been arrested in Vienna. She subsequently discovered that he had been taken to Dachau concentration camp in Bavaria.

As Christmas 1938 approached Frisch grew determined to honour what family traditions remained. Meitner was lonely and depressed, her poor relationship with Siegbahn preventing her from deriving any real pleasure from her work in Stockholm. She was in need of her faithful nephew. Frisch took a break from his work with Bohr in Copenhagen and joined his aunt in the small seaside village of Kungälv – King’s River – near Gothenburg, where she had been invited to spend Christmas with some Swedish friends.

For Frisch, this was to prove ‘the most momentous visit of my whole life’.

Secrets of the atom

The early decades of the twentieth century had witnessed a remarkable transformation in our understanding of the constitution of physical matter. The once indestructible and indivisible atoms of ancient Greek philosophy had given way to a new model of atoms with discrete internal structures. Atoms had become tiny positively-charged nuclei surrounded by mysterious negatively-charged electron ‘wave-particles’.

Attention turned inevitably to the atomic nucleus. With the discovery of the neutron in 1932, a picture emerged of atomic nuclei made up of positively-charged protons and electrically neutral neutrons. In this model, the number of protons in the nucleus determines the nature of the chemical element. Different elements, such as hydrogen, oxygen, sulphur, iron, uranium, and so on, all have different numbers of protons in their atomic nuclei. Atoms containing nuclei with the same numbers of protons
but different numbers of neutrons are called
isotopes.
They are chemically identical, and differ only in their relative atomic weight and stability.

New discoveries came thick and fast. It was found that by using powerful magnets and electric fields it was possible to accelerate charged particles such as protons to the kinds of high speeds, and hence high energies, required to smash nuclei apart. At the University of California in Berkeley, a district of San Francisco, Ernest Lawrence invented the
cyclotron
, a new type of particle accelerator, which was used to obtain evidence for artificially-induced nuclear reactions.
¹

But the discovery of the neutron had not only given physicists deeper insight into the structure of the nucleus, it had also provided them with another weapon with which to penetrate its secrets. As an electrically neutral sub-atomic particle, the neutron could be fired into a positively-charged nucleus without being diverted by the force of electrostatic repulsion.

Italian physicist Enrico Fermi and his research team in Rome began a systematic study of the effects of bombarding nuclei with neutrons, starting with the lightest-known elements and working their way through the entire periodic table. When in 1934 they fired neutrons at the heaviest known atomic nuclei – those of uranium – the Italian physicists presumed they had created even heavier elements that did not occur in nature, called
transuranic
elements. This discovery made headline news and was greeted as a triumph for Italian science.

It was a discovery that had caught Hahn’s attention in Berlin, and he and Meitner had set about repeating Fermi’s experiments and conducting their own, much more detailed, chemical investigations.

All the scientists involved in this work assumed that while neutron bombardment would transform elements, it would do so only in small, incremental amounts. Absorbing a neutron was expected to yield products that differed from the original target nucleus by no more than a couple of protons or neutrons. In other words, the products were expected to be found no more than one or two places higher or lower in the periodic table of the elements.

Hahn and his assistant Fritz Strassman carefully repeated work on the neutron bombardment of uranium. The German chemists initially believed that they were producing the highly radioactive element radium, somewhat lighter than uranium. They could find no evidence for transuranic elements.