FAUST
IN COPENHAGEN
 In
April 1932 seven physicists, six men and one woman,
attended a small annual gathering in Copenhagen.
To be honest, only six of them were actually there. The seventh,
Wolfgang Pauli, had originally intended to go, as he had in earlier
years and would do so again, but he decided that spring instead
to take a vacation. He was there in spirit, as you will see.
Four
of the seven—Niels Bohr, Paul Dirac, Werner Heisenberg,
and
Wolfgang Pauli—would be placed in most physicists' selection
of the
century's top ten physicists. Lise Meitner, the only woman
in the group,
ranks high on anyone's list of the century's most important
experimentalists.
Another of the seven, Max Delbrück, changed fields soon after
the meeting, though he never stopped defining himself as a physicist.
He
went on to become one of the founding fathers of modern molecular
biology and ranks as one of that discipline's top ten. All
of them taught
and mentored a generation of future scientists. The last of the
seven,
Paul Ehrenfest, was perhaps the greatest teacher of them all.
Physics
was fortunate to have at one moment a remarkable number of individuals
to help create and shape the great revolution in science
called quantum mechanics. Indeed, one could say that the revolution
occurred because of them. It developed very differently from relativity,
the twentieth century's other major departure from physics' past.
Relativity,
in the special theory of 1905 and the general theory of 1916, was
the
work of a single individual, Albert Einstein. Both the special
theory and
the general theory were essentially complete in Einstein's
initial formulations, requiring no revisions or subsequent interpretations.
Quantum
mechanics, on the other hand, emerged in 1925–26 only after
a long
buildup. Its details evolved over time, and its meaning continued
to be
debated for years. Unlike relativity, it was the work of many who
struggled
together, often arguing with one another as they hammered out the
theory's conclusions. Its final version, the so-called Copenhagen
interpretation, was contested even by some of the creators of the
revolution.
The questioning has not ceased.
Together Pauli, Heisenberg, Dirac, and the others created something
remarkable, something that has changed all our lives in a practical
sense more than any other twentieth-century scientific upheaval
has.
The inventions it led to, such as the transistor and the laser,
are both
implements that affect our daily activities and tools for future
research.
Considering the
human side of science, there's
no single answer to the question of what these seven physicists
were like, since physicists
are as different from one another as any other group. Among them
we
find the gregarious and the withdrawn, the philanderers and the
faithful,
the rooted and the wanderers. Some were abstemious and others drank
too much. There were perhaps a disproportionate number of music
lovers
and mountain climbers among them, but that may be because they
had been told these are things physicists do. Their working habits
differed:
some preferred the early morning and others the late night. Some
always worked alone and others required discussions with their
peers.
But the founders of quantum theory had one thing in common: they
were geniuses at the particular calling known as theoretical physics.
They
had a second common trait, perhaps not independent of theoretical-physics
genius. Three of the scientists, all born between 1900
and 1902, stand out for their precocity: by their mid twenties
Pauli, Heisenberg, and Dirac were leaders in the founding of the
field. Several older theoretical physicists, notably Bohr, Einstein,
Max Born, and Erwin
Schrödinger, also played extremely important roles in the
revolution, but the youthfulness of its major participants remains
a striking feature.
All of them had revealed their powers and were famous in the field
by the time they were thirty. More accurately, all but one had
achieved great prominence by then, and that one, Schrödinger,
may have simply
been delayed in his intellectual flowering because his years between
ages
twenty-five and thirty were taken up by military service during
World
War I.
Among
all these physicists, one stands out for his personal impact
on the field and on the others, not simply for his thought or
achievements. In his obituary for Bohr, Heisenberg wrote, "Bohr's
influence on the physics and the physicists of our century was
stronger than that of anyone
else, even than that of Albert Einstein." This seems, at
first sight, to
be the sort of generous testimonial one makes in obituaries, but
Heisenberg
was not given to exaggeration. I was surprised to read it, for
my
generation does not think of Bohr this way (I confess to being
a theoretical
physicist myself, though hardly in the range of geniuses). But
the
more I delved into the matter, the more I came to understand its
truth.
It is not based on relative intellectual contributions, for Einstein's
were
certainly far greater than Bohr's. It revolves around how
Bohr's style affected the way physicists think and work,
how they individually and collectively strive for answers, how
they relate to their mentors, their peers,
and their students. In the process of wielding this power, Bohr
also became
the most loved theoretical physicist of the twentieth century.
Yes,
loved. Respect and admiration were feelings young physicists
had for all of these greats, but love is something different.
Yet it is a term
that appears again and again in memoirs when physicists speak of
Bohr.
It is interesting to explain why this is so, what
it was about
Bohr's persona, his behavior, his way of thinking and working,
that led
others to regard him with such warmth.
One of the many factors that contributed to this affection was
Bohr's
lack of pretension or pomp. There wasn't a trace of personal
ambition or
aggrandizement in him, though few of these geniuses seem to have
had
much need of this. They were all secure in the knowledge of their
own
stature, but Bohr had an almost childlike innocence about such
matters.
He also worked tirelessly to improve others' work and lives.
There
are countless examples of people owing him their positions, their
careers,
and sometimes their very survival. He had a sense of who was in
need, when and how to intervene, and how to make a difference.
But
combined with all this was something else that seems to have
played a role. Being connected to others, or as Bohr's biographer
Abraham
Pais calls it, being conjoined, was a need for Bohr, almost
a necessity.
His discussions were carried out as a kind of Socratic dialogue
in
which he slowly shaped and molded his thoughts, so much so that
some
said he was a philosopher, not a physicist. Bohr also loved paradoxes,
believing that seeing the many sides of a problem was the way
to reach
resolution and clarity. His close friend Einstein described him
as uttering
"his opinions like one who perpetually casts about, and never like
one who believes he holds the whole defining truth." This
astute remark
captures much of Bohr's essence—he constantly strove
for that defining
truth.
Bohr's
need for others, for conjointness, was displayed in his relaxation
as well, be that skiing, sailing, simply walking, playing a game,
or
going to the movies. He made others feel needed because he did
need
them. Bohr was certainly a great man and without guile, but his
constant
engaging of those he was involved with was a major factor in creating
the love they felt for him.
Another
of these theoretical physicists was also much loved, though his
peers would use that word guardedly. Later generations find the
love for him to be even more puzzling than that for Bohr. He
forms an interesting
contrast to Bohr because while Bohr was invariably polite, Wolfgang
Pauli was invariably rude. His insults and his aphorisms became
legend, but part of the legend lies in the realization that these
insults
were directed without regard for rank or age. Einstein, Bohr, or
Heisenberg
might just as easily be affronted as a student. In doing so, he
never
meant to hurt others. As the well-known physicist Victor Weisskopf
said, "Pauli possessed an almost childlike honesty, and always
expressed his
true thought directly," adding that once you became used
to his style, it
was easy to live with him.
Pauli
might insult you, but he never ignored you, and the biting remarks
directed at you became a kind of badge of honor, remembered and
told to friends. With a gift for the bon mot, Pauli was often
very
funny in his insults. Only he would describe someone as "so
young and
already so unknown." But his expressive language communicated
true
feeling and commitment. More than thirty years after a meeting
they
had at the height of the quantum mechanics revolution, Bohr recalled
a characteristic exchange for a historian: "I met Pauli who
expressed the
strongest dissatisfaction with my treason, and in his
emotional way,
which we all treasured so highly, deplored that a new heresy should
be
introduced into atomic physics."
The
athletic Bohr loved to go for long hikes, ski, and chop wood,
while portly Pauli preferred cabarets, nightlife, and good wine.
Bohr
had six sons to whom he was devoted, while Pauli had no children.
Bohr, while still being deeply attached to his native Denmark,
worked
tirelessly after World War II for world peace and disarmament.
Pauli had
no interest in world affairs. Living in quintessentially neutral
Switzerland,
he became a symbol of physics research unsullied by worldly concerns.
Pauli certainly had more warts and blemishes than Bohr, but as
we know, love is not only directed toward the pure. Weisskopf,
who knew
all of the physics geniuses of that era well, kept a photo of Pauli
on his
desk, while acknowledging that Bohr was his "intellectual
father."
The contrast between the two, the affection felt for both of them,
and the affection they felt for each other, is manifest in a skit
put on by
the young physicists at the April 1932 Copenhagen meeting. That
year
was the hundredth anniversary of the death of Johann Wolfgang von
Goethe, the passing of the man, both humanist and scientist, widely
regarded as the last true universal genius. As commemorations marking
the occasion took place all over Europe, this small band of physicists
at
the annual informal gathering decided to have a celebration of
their
own. It took the form of a sketch, a tongue-in-cheek adaptation
to the
world of physics of Faust, Goethe's great drama.
In the script, written
primarily by Delbrück, noble Bohr was identified as the Lord,
sardonic
Pauli as Mephistopheles, and troubled Ehrenfest as Faust. As in
Goethe's
version Mephistopheles has the wittiest lines, but that was of
course true
of Pauli's real-life speech as well.
The
skit, meant as comic relief from the intensity of the week's
discussions, remains a fascinating portrayal of the world of
physics seen through the eyes of its very young practitioners.
They were the writers
and producers of the parody as well as its actors. Though affectionately
mocking their distinguished elders, many only a few years older
than
they were, these young physicists knew all too well that Bohr,
Dirac,
Heisenberg, and Pauli had made lasting contributions to their field by
the time they were little older than twenty-five. They also remembered
the warning uttered by the student Baccalaureus in Goethe's Faust
When more than thirty years are told,
As good as dead one is indeed:
(Faust, Part II, act
2, 222–23)
and worried about their own immediate future.
The year of the meeting was a pivotal one for them. The midsummer
detection of the positron, the electron's antimatter companion,
marked, as we shall see, the joining of special relativity to quantum
mechanics. This completed for the community, with a few remarkable
exceptions, the experimental confirmation of what is still the
century's
most profound and far-reaching physics revolution.
On
the other hand, the discovery just before the meeting of the
neutron and, a few months later, the first experimentally induced
nuclear disintegration ushered in another revolution in physics,
introducing us
to the era of nuclear physics. Its effects on our world view and
on mankind's
potential for destruction still hover over us.
The year also saw the beginning of research with the cyclotron,
signaling
the transition in physics research from small science to big science.
Whereas a single individual, James Chadwick, had discovered
the neutron, efforts at the cyclotron required a team of experts
and considerable financial resources. Large-scale experiments now
became
common. Only seven years after the meeting, a skeptical Bohr would
comment that the fissionable material for a nuclear weapon could
only
be obtained by, metaphorically speaking, turning "the United
States
into one huge factory." And of course that happened.
Those discoveries of 1932, sometimes called the Miracle Year of
experimental
physics, also shifted the emphasis in physics from theory to
experiment, from research done with pencil and paper to research
done
with sophisticated tools in a laboratory. The two modes of working
inevitably
go hand in hand, but there are times when one takes center stage
and times when the other does. While theory's advances in
understanding
quantum physics had dominated the decade before the meeting, advances
achieved in the laboratory marked the immediate period after it.
By concluding with the neutron's discovery, the Copenhagen
skit
points to this shift. It also eerily prefigures many of the personal
problems
the physicists, young and old, would encounter in the years to
come.
With hindsight, we see what a watershed 1932 was for them. Prior
to it,
they were a small community, the only tension among them induced
by
who would be the first to reach commonly pursued goals. They worked,
ate, and traveled together, swam, played music, climbed mountains.
Above all the physicists talked endlessly to one another, occasionally
as
rivals, but only in an intellectual sense because, in the end,
they were
friends and comrades. That congeniality was shattered by the ascent
to
power in Germany of Adolf Hitler in January 1933.
Though none of the seven physicists who are this story's
focus was
religiously observant, four of them, including Bohr, were at least
part
Jewish. In 1933 they had to begin worrying about personal safety
and
emigration. By little more than a decade later many of that small
physics
community found themselves pitted against one another in a deadly
battle, thrust into the making of Faustian bargains they could
not have
contemplated a few years earlier.
I won't deny that I am prejudiced by a lifetime in the physics
profession,
but these individuals were true titans. We often do not know what
of recent science will stand the test of time, but the contributions
of
these people will last forever. Part of their success was due to
their being
young and enthusiastic at a crucial moment, the dawn of quantum
mechanics
and of nuclear physics, but they seized that moment and shaped
the field. Their work was the product of an ensemble: one of them
was
more original, another more critical, and yet another more daring.
Together
they created a magical instant in history. Hundreds of years from
now, their names may only be footnotes in science textbooks, but
their
work will continue to shape the way our descendants think.
This
singular time was epitomized by the few individuals gathering
for a weeklong meeting in a Copenhagen room in April 1932.
[Adapted from the Introduction of Faust
in Copenhagen: A Struggle for the Soul of Physics By Gino Segre,
Viking $24.95.] |
