Of Physics, Friendship and Nazi Germany's Atomic Bomb Efforts
and Particles on Broadway
By JAMES GLANZ
istorians and scientists are still
arguing over whether Werner Heisenberg, the Nobel Prize winner who was
Germany's leading scientist during World War II, told the truth about his
role in the failed attempt to build an atomic bomb for Hitler.
In the face of decades of accusations to the
contrary, Heisenberg always maintained that while he had understood the
principles of an atomic bomb, he never seriously considered building one
and had deliberately led the German program into concentrating on peaceful
uses of atomic energy, like reactors.
Bridget Besaw Gorman for The New York Times
|Michael Cumpsty, right, Philip Bosco and Blair
Brown rehearse a scene from "Copenhagen."
But did he?
Half a century later, that wrenching and still-unresolved question stalks
in ghostlike fashion through "Copenhagen," by the British playwright Michael
Frayn, that opens next month in New York.
The play revolves around Heisenberg's mysterious wartime meeting in
September 1941 with his fellow Nobel laureate and former mentor, the Danish
physicist Niels Bohr.
Little is known for certain about the meeting, beyond the fact that
Heisenberg talked with Bohr about the possible use of nuclear fission for
But was Heisenberg trying to extract from Bohr any information the Dane
might have had about Allied bomb efforts? Was he trying to assure Bohr
that the Germans had no hope of building their own atomic bomb during the
war, in hopes that Bohr would persuade American physicists not to develop
such a terrible weapon either? Or did he simply wish to ask his old mentor
whether physicists were morally justified in applying their knowledge to
Bohr, who died in 1962, said soon after the meeting that Heisenberg
had been trying to elicit information and had claimed that a German bomb
could be built. Heisenberg, who after the war openly opposed research on
atomic weapons, said he raised with Bohr the possibility that world's physicists
might refuse, even in wartime, to build such weapons, both because of their
enormous cost and their terrible power.
But many historians and scientists point out inconsistencies in his
story, particularly since it seems that he understood much less about bomb
physics during the war than he later claimed.
So, was Heisenberg stopped more by his ignorance of bomb physics than
by moral scruples? Uncertainty about the meeting in Copenhagen allows that
question to live on.
In response to interest raised by the play, a physicist, Dr. Brian Schwartz,
has organized a symposium, "Creating Copenhagen," for next Monday at the
Graduate Center of the City University of New York, where Dr. Schwartz
is vice president for research.
Along with Mr. Frayn and the play's director, Michael Blakemore, participants
at the symposium will include two survivors of the Manhattan Project: John
Wheeler, who wrote a crucial paper on uranium fission with Bohr in 1939
and is now an emeritus professor at Princeton, and Hans Bethe, a Nobel
Prize winner who has turned into a forceful advocate for arms control from
his office at Cornell.
As the physicist who all but created the field of theoretical nuclear
physics, Dr. Bethe gives some ammunition to both sides in the debate over
Heisenberg. On one hand, Dr. Bethe said, secretly recorded conversations
between Heisenberg and fellow German scientists show that his understanding
of bomb physics was "totally wrong."
But Dr. Bethe said that those scientific mistakes showed that Heisenberg
"had never thought how to make a bomb," rather than suggesting that he
had merely been stopped by incompetence.
"Then, to me, in 1948, he said his main intention had been to save a
few young physicists from going to the war by employing them in the uranium
project," Dr. Bethe said. "And indeed there were several promising young
German physicists whom he did save. So I believe that motive."
After Nazism's defeat, when the total failure of its bomb program was
exposed, Heisenberg himself began telling reporters that his team's theoretical
understanding of bomb physics had not been not far behind that of the Allies.
Because financing and industrial support for the
German atomic bomb program had been so weak, Heisenberg said, he and his
team abandoned the practical goal of actually building a bomb, deliberately
concentrating on nuclear reactors.
Implication Was Obvious'
In this excerpt from Michael Frayn's play "Copenhagen"
(courtesy Methuen), Werner Heisenberg, Niels Bohr and Bohr's wife, Margrethe,
try to recall exactly how the shocking topic of weapons based on nuclear
fission had come up in their conversation many years before.
MARGRETHE So what was this mysterious thing you
HEISENBERG There's no mystery about it. There never
was any mystery. I remember it absolutely clearly, because my life was
at stake, and I chose my words very carefully. I simply asked you if as
a physicist one had the moral right to work on the practical exploitation
of atomic energy. Yes?
BOHR I don't recall.
HEISENBERG You don't recall, no, because you immediately
became alarmed. You stopped dead in your tracks.
BOHR I was horrified.
HEISENBERG Horrified. Good, you remember that.
You stood there gazing at me, horrified.
BOHR Because the implication was obvious. That
you were working on it.
HEISENBERG And you jumped to the conclusion that
I was trying to provide Hitler with nuclear weapons.
BOHR And you were!
HEISENBERG No! A reactor! That's what we were trying
to build! A machine to produce power! To generate electricity, to drive
BOHR You didn't say anything about a reactor.
HEISENBERG I didn't say anything about anything!
Not in so many words. I couldn't. I'd no idea how much could be overheard.
How much you'd repeat to others.
BOHR But then I asked you if you actually thought
that uranium fission could be used for the construction of weapons.
HEISENBERG Ah! It's coming back!
BOHR And I clearly remember what you replied.
HEISENBERG I said I now knew that it could be.
BOHR This is what really horrified me.
But some Allied scientists, notably Dr. Samuel A. Goudsmit, a Dutch-American
physicist, took great exception to articles in The New York Times in which
Heisenberg aired his views. Goudsmit and other critics said those statements
were a whitewash of an active bomb program stymied only by Heisenberg's
misunderstanding of some basic physics of bombs.
Dr. Goudsmit, the discoverer of the electron's so-called spin and the
founder of the world's most prestigious physics journal, Physical Review
Letters, had been the scientific director of the wartime effort by the
Allies to learn about Germany's bomb program. His parents had died at Auschwitz.
The possibility that an explanation more like Dr. Goudsmit's was correct
made Heisenberg's increasingly frequent statements of concern about the
morality of nuclear weapons harder to accept by some Allied scientists.
"I pray that the politicians will be clever enough to save us from the
evil misuse of science," Heisenberg, who returned to prominence in German
science after the war, told The Associated Press in February 1947.
In later years, "a subtle escalation was introduced," Dr. Jeremy Bernstein
in "Hitler's Uranium Club" (AIP Press, 1996) , wrote skeptically. "Not
only did they work only on the 'peaceful' reactor, but they actually 'prevented'
the atomic bomb from falling into Hitler's hands."
Over the decades, some authors -- most persuasively, Thomas Powers in
"Heisenberg's War" (Knopf, 1993) -- would argue that Heisenberg knew more
about bomb physics than he let on, but deliberately killed the project.
But even if the incompetence argument could be defeated, there remains
little evidence of Heisenberg's wartime concern with the morality of atomic
weapons -- except, possibly, for Copenhagen.
When Heisenberg later wrote that he had intended to warn Bohr of the
enormous technical challenges that stood in the way of building a bomb,
implying that Allied scientists could safely refuse to build one too, was
he being truthful? By extension, was he truthful about his intentions in
the German bomb program itself?
Mr. Frayn, who said he was inspired to write his play after reading
Mr. Powers's book, said in an interview that he believed that Heisenberg
did have at least some intention to alert Bohr that Germany had little
chance of building a bomb then.
"But he's very inhibited about saying it, because the only way he can
say it is to commit treason," he said.
Mr. Frayn suggested that after the war, Heisenberg had to be "extremely
guarded in what he said," further clouding the historical record. "He didn't
want to say, 'I was just incompetent,' or on the other hand, 'I could have
done it and I didn't, so I've lost the war for all these other Germans.'
The play itself offers an imagined version -- actually several versions
-- of what might have happened on that night in Copenhagen. Somewhat like
particles in the quantum mechanical world that Bohr and Heisenberg did
so much to illuminate, the characters seem to exist in many different states
of interaction at once.
So each version remains suspended in a state of possibility, unproved
Mr. Frayn said he was particularly interested in
Heisenberg's celebrated uncertainty principle, which states that an irreducible
quantum fuzziness, caused by the wavelike nature of matter on small scales,
makes it impossible to know simultaneously both a particle's position and
its momentum. Human intentions have their own irreducible fuzziness, he
Abstruse Topic Saved His Life
World War II, the Allies so feared the possibility of a German bomb that
they sent Moe Berg, a baseballcatcher, linguist and spy, to attend a scientific
lecture that the Nazi government allowed the physicist Werner Heisenberg
to give in Zurich in 1944.
Berg was instructed to carry a pistol and shoot Heisenberg
dead if he gave any hint that he was working on an atomic bomb.
Heisenberg restricted his talk to an abstruse topic called
S-matrix theory, David C. Cassidy writes in his book "Uncertainty" (W.
H. Freeman, 1992). But at dinner, in response to a barbed assertion from
a Swiss physicist that Germany had all but lost the war, Heisenberg retorted,
"It would have been so beautiful if we had won."
Years later, Heisenberg learned of Berg's mission and
quipped that he owed his survival to the difficulty of his topic that day.
The mystery of Heisenberg's role in the German atomic
program has provided grist for several books, including these:
"Uncertainty," David C. Cassidy, W. H. Freeman and Company,
"Heisenberg's War," Thomas Powers, Alfred A. Knopf, 1993.
"Hitler's Uranium Club," Jeremy Bernstein, The American
Institute of Physics, 1996.
"Neils Bohr's Times," Abraham Pais, Oxford University
In his research for the play, Mr. Frayn read Heisenberg's original 1927
paper on this Unbestimmtheit -- indeterminacy or uncertainty. Mr.
Frayn, 66, who read philosophy at Cambridge but has no formal training
in science, said he was "very struck" by how "extremely clear" that original
Six years old and living in the outer suburbs of London when the war
broke out, he remembers watching dogfights and German bombing runs while
standing in his garden with his father.
"The war for me was delightful entertainment," he said, recalling with
particular fondness the impact one of the German pilotless planes, called
V-1's, made when it fell with its explosive charge near his house. "It
was a nightmare for my parents," he said. "But I thought, suddenly the
house was transformed -- suddenly no boring glass on the windows. We had
plaster dust and broken glass everywhere."
But even the young Mr. Frayn became frightened when Werner von Braun's
much more effective V-2 rockets began falling. Somehow their great explosions,
followed only afterward by the sound of the approaching rocket, unnerved
him, he said.
If Heisenberg's program had been as successful as von Braun's, of course,
an atomic bomb would have arrived with much more deadly efficiency from
the skies above London. Uncertainty about whether the Germans were developing
a bomb infused the Manhattan Project with a frenzied urgency.
Despite his acknowledged patriotism, Heisenberg was no great supporter
of the Nazis, having defied their attacks on what they called "Jewish science"
by continuing to teach Einstein's theory of relativity and by occasionally
helping scientists persecuted by the Reich. But as Germany crumbled in
the spring of 1945, Allied agents, led by Dr. Goudsmit, were desperate
to learn how close Heisenberg and his program had come to making a bomb
and, in particular, to keep the scientists and their data out of Russian
Heisenberg and others were quickly rounded up, questioned and finally
sequestered for six months at a country manor in Britain called Farm Hall,
where microphones secretly recorded many of their conversations. Judging
from these, war's end found the German program almost pathetically far
behind the Manhattan Project. The German scientists had not even produced
the contained nuclear chain-reaction that Enrico Fermi had achieved at
the University of Chicago in December 1942, a critical step in the bomb's
But until the news came that the Allies had dropped an atomic bomb on
Hiroshima, Heisenberg confidently assumed that if German scientists could
not build such a weapon, nobody could.
"The reasoning was not bad," Heisenberg later told Waldemar Kaempffert,
a science writer at The Times. "After all, it took the United States several
years to produce atomic bombs, and the war in Europe was won without their
In fact, the German scientists at Farm Hall initially refused to believe
the news; Heisenberg speculated aloud that the Hiroshima weapon was really
a juiced-up chemical explosive.
But he finally had to accept how thoroughly the German program had been
bested. And in an astonishing recorded conversation with a fellow Farm
Hall inmate, the physicist Otto Hahn, Heisenberg confessed he had never
even taken the trouble to calculate the minimum amount of uranium-235 one
would need to fuel a bomb -- the so-called critical mass. "Quite honestly,
I have never worked it out," Heisenberg said, "as I never believed one
could get pure 235."
Like Dr. Bethe, Mr. Frayn takes this admission as further evidence that
Heisenberg never intended to build a bomb. Others suggest that it merely
shows what a hash Heisenberg had made of a project he supported.
By 1947, Dr. Goudsmit was vigorously disputing Mr. Kaempffert's articles
on Heisenberg. Mr. Kaempffert, who had covered Heisenberg's original breakthroughs
in quantum mechanics 20 years earlier, replied in print that "liars do
not win the Nobel Prize," and criticized Dr. Goudsmit's accounts as hot-headed
and biased. Mr. Kaempffert added that the "scientific reasoning of Heisenberg
and his colleagues was exactly like that of the Americans."
More than 50 years later, the record provides evidence in support of
Monday's symposium will bring together Dr. Wheeler, 89, and Dr. Bethe,
93, and a number of other physicists and historians, including Dr. Gerald
Holton of Harvard and David C.
Cassidy, author of "Uncertainty" (W. H. Freeman, 1992).
"I think both of them are anxious to give a very personal view," Dr.
Schwartz said of Dr. Wheeler and Dr. Bethe.
Dr. Schwartz, however, is not sure exactly where the panel members will
agree and disagree, except to say that it is unlikely that they will clear
up all the remaining questions on what Heisenberg was up to during the
war. The uncertainty about Heisenberg may be eternal.