Keith Huxen - The Mysterious Meeting between Niels Bohr and Werner Heisenberg
In the fall of 1941, the course of history
in the Second World War took a different pathway based upon a mere conversation
between two men. At first glance, it would appear unlikely such an event could
have such an effect, particularly since both men were intentionally vague with
each other, each later maintained misunderstandings of the other’s intention,
and to this day the conversation remains shrouded in mystery. The two men were
civilians, not soldiers; they were scientists, not politicians; they met in
Nazi-occupied territory, not in free lands where they could speak frankly.
Lastly and most importantly, they were thinkers dedicated to the discovery of
knowledge of the natural world, not the mass destruction of human life.
But when the participants in this uncertain
conversation were Niels Bohr and Werner Heisenberg, then the import of the
event becomes clearer. On the surface, the Dane of Jewish descent and the
German Lutheran, separated in age by sixteen years, did not have much in
common. But their lives were deeply intertwined with each other on personal,
intellectual, and professional levels. They began as an internationally
recognized physics professor and gifted student when they first met in 1922,
the year Bohr became a Nobel laureate. But they became much more than that.
Personally, Heisenberg virtually became another of Bohr’s sons and shared the
intimacy of his family life. Intellectually, Bohr’s manner of thinking about
physical problems in which he attempted to comprehend phenomena as a whole
found balance, advancement and authenticity through collaboration with
Heisenberg, whose fascination with and ability to find the music of mathematics
located within physical events led to great scientific breakthroughs.
Professionally, the two men mapped and
explored the quantum universe inside the atom. In 1927, Heisenberg staked his
own claim to great scientific achievement when he published his “Uncertainty
Principle,” which stated that the exact position of an electron within an
atomic nucleus at a given time could not be known with certainty, but only
statistically calculated within a probability. By that same year Bohr had
developed his ideas on “complementarity” in physics, through which he
incorporated Heisenberg’s physics within his own, and proposed that the seeming
chaos of the quantum world and the order of the universe based upon classic
physics did not refute each other, but complemented each other in a manner
which we had yet to comprehend and explain. The two men were the fathers of
quantum mechanics, and together they had carried out a revolution in the
physics world during the 1920s. In 1932, Heisenberg joined Bohr as a Nobel
laureate.
Science was
traditionally seen by its practitioners as an international fraternity at the
beginning of the twentieth century. Information, news of discoveries, papers
and ideas flowed freely across national boundaries between scientists intent
upon expanding the frontiers of knowledge. This was an idealized era in
science; while not free of individual rivalries, nonetheless the atmosphere was
not romanticized. Scientists viewed themselves as colleagues in the craft of
pursuing higher truths, not as national rivals. This was the atmosphere of
Ernest Rutherford, Max Planck, and above all, Albert Einstein. Niels Bohr also
entered this idyllic prewar scientific atmosphere. In 1913, he published “On
the Constitution of Atoms and Molecules,” a paper which brought him reputation
and fame when he described how electrons jumped between orbits within the nucleus.
However, the
instabilities of the international political system began to change this
idyllic scientific atmosphere after 1914. The Great War saw scientists mobilize
on behalf of their national governments to use science as a new offensive
weapon, creating new and more devastating ways to kill. The Great War did not
kill off this atmosphere of scientific cooperation. The German-born Einstein
completed his General Theory of Relativity while employed at the University of
Berlin in 1915; copies of his paper were smuggled to Allied scientists, and the
British astronomer Arthur Eddington successfully arranged financing from his
government during wartime to photograph a solar eclipse in 1919 to prove
Einstein’s theory. Nonetheless, nationalist politics showed itself as the
greatest threat to the idealized world of free inquiry and knowledge which
scientists held dear.
Bohr and Heisenberg
had inherited the benefits of this atmosphere in the 1920s, when together they
explored the quantum revolution. However, the rise of the arch-nationalist,
Adolf Hitler in Germany, ushered in a new and shocking suppression of
scientific inquiry and knowledge. Even before Hitler achieved power in Germany,
Heisenberg personally experienced opposition to the “new physics” by hostile
German scientists who demanded a German or “Aryan Physics” which applied to
natural Germans (supporters of this “Deutsch Physik” included Nobel laureates
such as Johannes Stark). The revolutionary physics of relativity and
uncertainty, led by Einstein, Bohr, and Heisenberg, was tied to impurity,
deformity and Judaism by the Nazis in a manner similar to how they dealt with
the modern art of cubism and Picasso. It should be noted that the new physics
(along with Freudian psychology) had been condemned in the Soviet Union as well
in the early 1920s for not conforming to the precepts of Marxist-Leninist
ideology. But where Russia was seen as scientifically and technologically
backward, Germany was the most advanced educational, scientific, and technological
power in Europe.
After Hitler assumed
the Chancellorship in January 1933, the Nazis soon banned all Jews from working
for the German state or in professional capacities such as university
professors. This meant that better than a hundred German physicists of Jewish
descent, including Einstein, were soon displaced. An exodus of the world’s
greatest scientific talent began to emigrate from Germany to receptive western
nations. From his Institute of Physics attached to the University of Copenhagen
in Denmark, Niels Bohr tried to assist many colleagues in finding new lives and
employment.
Werner Heisenberg was not an anti-Semitic; indeed, he even tried to hire a Jewish colleague into an open position at his University of Leipzig in the 1930s. He did not join the Nazi party. However, he was a dedicated German nationalist. He participated in the military drills of his reserve unit. Most distressing to his international colleagues, he refused to follow the example of Einstein and leave Germany as a symbolic protest against the Nazi regime and its attitude towards scientific inquiry.
Werner Heisenberg was not an anti-Semitic; indeed, he even tried to hire a Jewish colleague into an open position at his University of Leipzig in the 1930s. He did not join the Nazi party. However, he was a dedicated German nationalist. He participated in the military drills of his reserve unit. Most distressing to his international colleagues, he refused to follow the example of Einstein and leave Germany as a symbolic protest against the Nazi regime and its attitude towards scientific inquiry.
But advancements in
the physics and political worlds were on a collision course. One of those
forced to flee Germany due to Hitler’s policies was Lise Meitner, an Austrian
Jewess formerly employed at the Kaiser Wilhelm Institute where she had
collaborated with the chemist Otto Hahn. After her departure, Hahn continued to
send to Meitner information on experiments he had conducted upon the element
uranium. On a skiing holiday, while seated under Kungalv castle in Sweden on
Christmas Eve 1938, Meitner and her nephew Otto Frisch successfully diagnosed
and calculated that nuclear fission had taken place. Within two weeks, they had
delivered to Niels Bohr their preliminary paper which he took with him to
America. In January 1939, the news was made public at a physics conference at
George Washington University. To leading physicists, the possibility of
splitting the atom and releasing untold amounts of energy through nuclear
fission was now within reach, along with the understanding that it was now
theoretically possible to build an atomic bomb.
In April 1939 the first
“Uranverein,” or German “Uranium Club” was established. This was a relatively
small group of forty or fifty German scientists assigned to work upon the
problem of nuclear energy. This was the situation in September 1, 1939 when war
came to Europe. On the day that Germany launched the invasion of Poland, the
German Army Ordnance Office took over the German nuclear energy project to explore
potential military applications. This second Uranverein was a military and
state secret. From his posts as a professor at the University of Leipzig and
Acting Director of the Kaiser Wilhelm Institute for Physics in Berlin,
Heisenberg became the lead theoretician of the Uranverein, cooperating with
professors spread across Germany to study and develop nuclear fission.
Initially, physicists
across the globe calculated that any proposed atomic bomb project would be
years in the making due to the tremendous technical difficulties, scientific
problems, labor commitments, and financial resources required of the
undertaking. In the meantime, however, the war moved quickly. Hitler and the
Germans had invaded Norway, Denmark, Holland, Belgium, and France by the summer
of 1940; from his physics institute in Copenhagen, Niels Bohr found himself
living under the Nazi occupation. Only Britain fought on alone against Hitler
for over a year, until in June 1941 Hitler double-crossed his ally Stalin. The
German invasion of the Soviet Union was initially very successful, as Operation
Barbarossa saw deep German penetration of Soviet territories. By September 1,
1941, Leningrad was completely cut off from the rest of the Soviet Union except
by Lake Ladoga; the Soviet military teetered under the terrific German
onslaught, and it appeared the Germans might take Moscow before Christmas. The
United States officially remained a neutral nation. And the Uranverein had
recently conducted experiments which hinted at the pathway to develop a
self-sustaining nuclear fission reaction. The ability to create an atomic bomb
appeared to be a key that might guarantee ultimate victory to whoever developed
it first, with Hitlerite Germany in the lead.
It is against this
historical backdrop of what appeared to be impending German victory and
potential German bomb that Werner Heisenberg, Nobel Laureate, chose to arrange
travel to attend a German-sponsored conference in Copenhagen in September,
1941. Bohr would not attend the conference as a protest against the Germans,
but he was willing to personally see Heisenberg. Heisenberg’s purpose was to
query his great mentor and friend, Niels Bohr, on a major issue troubling his
mind: namely, should a physicist help build an atomic bomb for his country in
wartime?
It is difficult for
historians to reconstruct exactly what was said between the two men. Heisenberg
was so eager he arrived four days early for the conference, but neither man
could remember the exact date or place of the conversation. In later years
Heisenberg recalled the conversation taking place on a long walk around the
harbor in Copenhagen; Bohr recalled that it took place in his study. Heisenberg
was a leader in a secret German nuclear program. To merely reveal the existence
of such a program was treason, and within Hitler’s state Heisenberg would
almost certainly lose his life. But for Bohr, this was countered by the fact
that Heisenberg was a loyal German national, and thus working for the victory
of the Nazi state… read more:
