Table Of Content'Subtle is the Lord ...'
Albert Einstein in 1896.
(Einstein Archive)
'Subtle is the Lord...'
The Science and the Life of
Albert Einstein
ABRAHAM PAIS
Rockefeller University
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© Oxford University Press 1982
Foreword © Roger Penrose 2005
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First published 1982
First issued as an Oxford University Press paperback, 1983
Reissued with a new foreword, 2005
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British Library Cataloguing in Publication Data
Data available
Library of Congress Cataloging in Publication Data
Pais, Abraham, 1918-
Subtle is the Lord—.
Bibliography: p. Includes index.
1. Einstein, Albert, 1879-1955. 2. Physicists–
Biography. 3. Physics—History. I. Title.
QC16.E5P26 530'.092'4 [B] 82-2273 AACR2
Printed in Great Britain
on acid-free paper by
Ashford Colour Press Ltd.,
Gosport, Hampshire
ISBN 0-19-280672-6
ISBN 978-0-19-280672-7
02
XII
The last known picture of Einstein,
taken in March 1955, in front
of 112 Mercer Street.
(Einstein Archive, Courtesy United Press International)
To Joshua and Daniel
'Science without religion is lame, religion without science is
blind.' So Einstein once wrote to explain his personal creed: 'A
religious person is devout in the sense that he has no doubt of the
significance of those super-personal objects and goals which nei-
ther require nor are capable of rational foundation.' His was not
a life of prayer and worship. Yet he lived by a deep faith—a faith
not capable of rational foundation—that there are laws of Nature
to be discovered. His lifelong pursuit was to discover them. His
realism and his optimism are illuminated by his remark: 'Subtle
is the Lord, but malicious He is not' ('Raffiniert ist der Herrgott
aber boshaft ist er nicht.'). When asked by a colleague what he
meant by that, he replied: 'Nature hides her secret because of her
essential loftiness, but not by means of ruse' ('Die Natur verbirgt
ihr Geheimnis durch die Erhabenheit ihres Wesens, aber nicht
durch List.').
Foreword
The world of science is greatly fortunate that a theoretical physicist of the
distinction of Abraham Pais should have discovered within himself not only a
particular talent for scientific biography but also a passionate desire to convey to
us his unique perspective on the momentous developments in 20th-century
physics that he had witnessed. Himself a very significant later contributor, Pais
had been well acquainted with most of the key figures in this highly remarkable
period of scientific development, and he was able to combine his own deep
understanding of the central physical ideas with a personal knowledge of these
individuals.
Pais had worked with Niels Bohr in 1946 and later wrote a comprehensive
biography of Bohr's life and work.* Subsequently, he provided short biographies
of many other outstanding figures of the time, with whom he had been personally
acquainted, such as Paul Dirac, Wolfgang Pauli, John Von Neumann, and Eugene
Wigner.** But the book that launched Pais's biographical career was his landmark
biography of Einstein, entitled "Subtle is the Lord", the title being an English
translation of part of a quotation from Einstein (inscribed, in 1930, in marble
above the fireplace in the faculty lounge of the mathematics building in Princeton)
which in the original German reads
"Raffiniert ist der Herrgott aber boshaft ist er nicht."
Pais translates this as "Subtle is the Lord, but malicious He is not".
There have been numerous biographies of Einstein, both before and after this
one, but what distinguishes Pais's book is the detail and insight into Einstein's
scientfic contributions, with not so much emphasis on issues of a personal nature
that have little bearing on his role as a scientist. This book was surely the biography
that Einstein himself would have most valued.*** For whereas Pais does not at all
*Niels Bohr's Times: In Physics, Philosophy, and Polity (Oxford University Press, 1991).
**The Genius of Science: A Portrait Gallery of Twentieth Century Physicists (Oxford University Press,
2000). In his technical/historical book Inward Bound: Of Matter and Forces in the Physical World
(Oxford University Press, 1986), he addressed the important aspects of 20th-century physics not
covered in the current volume.
***It was clearly valued by others, as it became the winner of the 1963 American Book Award and
was selected by The New York Times Book Review as one of the best books of the year.
viii
FOREWORD
neglect Einstein's personal side—and an interesting picture of Einstein the man
indeed comes through—the real strength of this work lies in its handling of the
physical ideas. As Einstein had earlier commented: "The essential of the being of
a man of my type lies precisely in what he thinks and how he thinks, not what he
does or suffers".
On the scientific side, there is, indeed, much to be said. For Einstein contributed
far more to the physics of the early 20th century than just relativity. Apart from
Max Planck, with his ground-breaking work of 1900 (on the spectrum of black-
body radiation), Einstein was the first to break away from the classical physics of
the time and to introduce the crucial quantum "wave/particle" idea—the idea that
despite light being an electromagnetic wave, it sometimes had to be treated as a
collection of particles (now called "photons"). Through this work Einstein
discovered the explanation of the photo-electric effect, this eventually winning him
a Nobel Prize. He provided (in his doctorate thesis) a novel method of determining
the sizes of molecules, at a time when their very existence was still controversial.
He was one of the first to understand the detailed nature of the tiny wiggling
"Brownian" motion of small particles in suspension and to provide a beginning
to the new statistical physics. He contributed key ideas that led to the development
of lasers. And all this is not to mention his revolutionary theories of special and
general relativity!
In describing each of these contributions, Pais first sets the stage, lucidly
describing the state of the relevant parts of physics at the time Einstein entered
the scene, often explaining in significant detail the work of Einstein's precursors.
Then we find Einstein's own fundamental contributions, introduced and discussed
in depth, the essential novelty of Einstein's viewpoint being all very clearly set out,
as is the profound influence that it had on subsequent work. This account indeed
provides a wonderful overview of the developments in physics of the early 20th
century, as there seems to be no major area of theoretical physics on which Einstein
did not have some impact. This book is not a "popular" work, in the sense of the
term that so often seems to involve distortions and oversimplifications in attempts
to explain technical concepts to the lay reader. Instead, it comes seriously to grips
with the physics involved in each major area that is treated and, where appropriate,
mathematical equations are presented without apology.
Yet this is by no means simply a cold scientific account in which personal
influences are deemed irrelevant. Pais illuminates many facets of Einstein's life,
some of which may at first seem almost paradoxical. Pais may not always provide
answers, but he expounds these issues in insightful ways. The common picture of
Einstein is as an unworldly almost saintly old man, with twinkling eyes,
moustache, wild white hair, and attired in a floppy sweater. But this was the
Einstein who spent the last twenty years of his life in Princeton on a certain
approach to a unified field theory that the majority of physicists would now judge
to be basically misconceived. How does this picture relate to that of the Einstein
of the "miraculous" year 1905, with an apparently dapper appearance, working at
FOREWORD
IX
the Patent Office in Bern, and producing several epoch-making papers? What
about Einstein's relation to quantum mechanics? Can we understand why he had
set off on his lonely route, at first so much ahead of his contemporaries and then
very much to one side of them, so that eventually they seemed convincingly to
have passed him by? Do we find clues to his science in his early years, such as when
as a child of about five he was enchanted by the seemingly miraculous behaviour
of a pocket compass, or when at twelve he was enthralled by Euclid? Or may we
learn as much from a remark from his teacher in the Munich Gymnasium asserting
that he would have been much happier if young Albert had not been in his class:
"you sit there in the back row and smile, and that violates the feeling of respect
which a teacher needs from his class"? Einstein's early ability to find authority
funny was a trait which stayed with him until the end.
And we find that Einstein was certainly no saint, though he was an admirable
man in many ways. It is perhaps not surprising that he had a remarkable faculty
for detaching himself from his surroundings, no doubt both a necessary factor
for him and a cause of strain in his two marriages. But he certainly did not lack
personal feelings, as is made particularly clear in his highly sensitive obituary
notices and appreciations of fellow scientists and friends. And he clearly had a
sense of humour. He was a humanitarian, a pacifist, and an internationalist. His
feelings would, perhaps as often as not, be more directed at humanity as a whole
than at particular individuals.
He could sometimes be petulant, however, such as after learning that a paper
that he submitted to Physical Review had actually been sent to a referee(!), whose
lengthy report requested clarifications. Einstein angrily withdrew his paper and
never submitted another to that journal. And he could feel an understandable
human annoyance in matters of priority concerning his own scientific work.
Usually he would later check his over-reaction, and in these cases we might have
on record only the very gracious subsequent letters of reconciliation to suggest
any earlier friction. His correspondence with the renowned mathematician David
Hilbert was a case in point, concerning the issue of who had first correctly
formulated the full field equations of general relativity. But in the case of another
great mathematician, Henri Poincare, in relation to the origins of special relativity,
it took until towards the end of Einstein's life for him even to acknowledge the
existence of Poincare's contributions. There is little doubt that Einstein had been
influenced by Poincare, perhaps indirectly through Lorentz, or through Poincare's
popular writings. Poincare himself seems to have been less generous, as he never
even mentioned Einstein's contributions at all in his own later papers on the
subject!
It is interesting also to follow the developments in Einstein's approach to physics
as he grew older. It is a common view that Einstein slowed down dramatically as
he reached his 40s, or that he perhaps lost his earlier extraordinary instincts for
divining physical truth. What Pais's account makes clear, however, is that he found
himself driven more and more into areas where his own technical judgements were
X
FOREWORD
not so reliable. One must bear in mind that although Einstein was an able
mathematician, his profound natural gifts lay in physics not mathematics. This
comes through particularly in the section of the book on general relativity, where
Einstein's struggles are described, starting with his appreciation in 1907 of the
fundamenal role of the equivalence principle and ending with his final field
equations in 1915. In place of the sureness that Einstein exhibited in his earlier
work, now there is vacillation: he is continually saying that he believes that he has
found the final form of the theory, only to retract in a few months' time and to
present a quite different scheme with equal confidence.
This is not to belittle Einstein's supreme achievement, however. On the contrary,
the discovery of general relativity shines out as all the more remarkable, and it
speaks even more strongly of the sureness of Einstein's physical instincts when one
realizes how uncomfortable Einstein actually was with the mathematics. In his
work on unified field theories, which occupied him throughout the final twenty
years of his life, Einstein's vacillation is apparent to an even greater degree. He was
now in an area where guidance needed to come through mathematics rather than
through physics, so the sureness of Einstein's touch was no longer to be found.
Finally, there is the issue of Einstein's refusal to accept, fully, the quantum
theory, as that subject had been gradually developed by others during the course
of Einstein's life. Is this also an indication of a failing of Einstein's judgement, as
his years advanced, or of a lack of appreciation of the elegance of its mathematical
structure? I do not think so. It must be said that some of Einstein's objections to
quantum theory have not really stood the test of time—most notably that it was
"unreasonable" that the theory should possess strange non-local aspects (puzzling
features that Einstein correctly pointed out). Yet, his most fundamental criticism
does, I believe, remain valid. This objection is that the theory seems not to present
us with any fully objective picture of physical reality. Here, I would myself certainly
side with Einstein (and with certain other key figures in the development of the
theory, notably Schrodinger and Dirac) in the belief that quantum theory is not
yet complete.
But why should we still trust the views of a man whose instincts were fashioned
by the physics of over one hundred years ago? Surely Einstein's initial insights into
the quantum structure of things were simply overtaken by the impressively
successful theories of younger men. Why should we go along with Einstein's
"nineteenth-century" view of an objective physical reality when modern quantum
theory seems to be presenting us with a more subjective picture? Whatever one's
beliefs may be on this matter, Einstein's extraordinary record tells us that his views
are always worthy of the greatest respect. To understand what his views actually
were, you cannot do better than to read on...
ROGER PENROSE
Oxford
June 2005
To the Reader
Turn to the table of contents, follow the entries in italics, and you will find an
almost entirely nonscientific biography of Einstein. Turn to the first chapter and
you will find a nontechnical tour through this book, some personal reminiscences,
and an attempt at a general assessment.
The principal aim of this work is to present a scientific biography of Albert
Einstein. I shall attempt to sketch the concepts of the physical world as they were
when Einstein became a physicist, how he changed them, and what scientific
inheritance he left. This book is an essay in open history, open because Einstein's
oeuvre left us with unresolved questions of principle. The search for their answers
is a central quest of physics today. Some issues cannot be discussed without enter-
ing into mathematical details, but I have tried to hold these to a minimum by
directing the reader to standard texts wherever possible.
Science, more than anything else, was Einstein's life, his devotion, his refuge,
and his source of detachment. In order to understand the man, it is necessary to
follow his scientific ways of thinking and doing. But that is not sufficient. He was
also a highly gifted stylist of the German language, a lover of music, a student of
philosophy. He was deeply concerned about the human condition. (In his later
years, he used to refer to his daily reading of The New York Times as his adren-
aline treatment.) He was a husband, a father, a stepfather. He was a Jew. And
he is a legend. All these elements are touched on in this story; follow the entries
in italics.
Were I asked for a one-sentence biography of Einstein, I would say, 'He was
the freest man I have ever known.' Had I to compose a one-sentence scientific
biography of him, I would write, "Better than anyone before or after him, he knew
how to invent invariance principles and make use of statistical fluctuations.' Were
I permitted to use one illustration, I would offer the following drawing:
Special relativity
Statistical physics
General relativity
Quantum theory
^ Unified *
field theory
Xll
TO THE READER
with the caption, 'The science and the life of Albert Einstein.' This picture with
its entries and its arrows represents my most concise summary of Einstein's great-
ness, his vision, and his frailty. This book is largely an attempt to explain this
cryptic description of the skeletal drawing. Toward the end of the book, the draw-
ing will return.
The generosity, wisdom, knowledge, and criticism of many have been invalu-
able to me in preparing this work. To all of them I express my deep gratitude.
No one helped me more than Helen Dukas, more familiar than anyone else at
this time with Einstein's life, trusted guide through the Einstein Archives in
Princeton. Dear Helen, thank you; it was wonderful. I have benefited importantly
from discussions with Res Jost, Sam Treiman, and George Uhlenbeck, each of
whom read nearly the whole manuscript, made many suggestions for improve-
ment, and gave me much encouragement. I also gratefully record discussions on
particular subjects: with Valentin Bargmann, Banesh Hoffmann, and Ernst
Straus on Einstein's life, on general relativity, and on unified field theory; with
Robert Dicke, Peter Havas, Malcolm Perry, Dennis Sciama, and John Stachel on
relativity; with Armand Borel on Poincare; with Eddie Cohen, Mark Kac, and
Martin Klein on statistical physics; with Anne Kox on Lorentz; and with Harold
Cherniss and Felix Gilbert on topics ranging from Greek atomism to the Weimar
Republic. Special thanks go to Beat Glaus from the ETH and Gunther Rasche
from the University of Zurich for helping me find my way in archives in Zurich.
To all of them as well as to those numerous others who answered questions and
inspired with comments: thank you again.
This book was completed at The Institute for Advanced Study in Princeton. I
thank Harry Woolf for his hospitality and for support from the Director's Fund.
I am greatly beholden to the Alfred P. Sloan Foundation for an important grant
that helped me in many phases of preparation. For permission to quote from
unpublished material, I express my deep appreciation to the Einstein Estate, the
Pauli Estate, the Rijksarchief in the Hague (Lorentz correspondence), and the
Boerhaave Museum in Leiden (Ehrenfest correspondence). I also thank the K.
Vetenskapsakademiens Nobel Kommitteer in Stockholm, and in particular Bengt
Nagel, for making available to me the documentation regarding Einstein's Nobel
Prize.
I have left the text of this Preface as it was written before the death of Helen
Dukas on February 10, 1982.
TO THE READER
Xlll
On references
Each chapter has its own set of references, which are marked in the text by a
square bracket containing a letter and a number. The following abbreviations
have been used for entries that occur frequently:
AdP: Annalen der Physik (Leipzig).
EB: Albert Einstein-Michele Besso Correspondance 1903-1955 (P. Speziali,
Ed.). Hermann, Paris, 1972.
PAW: Sitzungsberichte, Preussische Akademie der Wissenschaften.
Se: Carl Seelig, Albert Einstein. Europa Verlag, Zurich, 1960.
