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30 October 2000

Climbing the Mountain: The Scientific Biography of
Julian Schwinger
by Jagdish Mehra and Kimball
Milton, Oxford, ISBN 0198506589.

Climbing
the Mountain
is the first full-length biography of
Julian Schwinger. There is also a companion volume,
A Quantum Legacy (World Scientific), edited by
Milton, which complements a previous collection of
Schwinger papers edited by C Fronsdal, M Flato and K
Milton. An earlier volume, Julian Schwinger, the
Physicist, the Teacher and the Man
(World
Scientific), is a compilation of tributes delivered at
various memorial symposia by friends and former
students and edited by Jack Ng. There is also a third
volume, QED and the Men Who Made It: Dyson,
Feynman, Schwinger and Tomonaga
by S S
Schweber (Princeton University Press).

This
biography describes Julian Schwinger’s life as well as his
work. The treatment of his scientific work is scholarly
and well done. The challenge faced by this book is well
stated in the preface: “Julian Schwinger was one of the
most important and influential scientists of the 20th
century…yet even among physicists recognition of his
fundamental contributions remains limited.” This is all
the more remarkable since Schwinger had more than 70
students, many of whom became very distinguished,
including three Nobel laureates.

Climbing the
Mountain
confronts this challenge by a very
extensive discussion of Schwinger’s manifold
contributions. On the other hand one may still ask how
it is possible that C N Yang can recall that when he
entered the University of Chicago in 1946 as a graduate
student, Julian Schwinger was already a legend (even
before he had published his monumental papers on
quantum electrodynamics), while in the year 2000 so
little is known about Schwinger and so much is known
about Feynman.

The answer lies partly in the
personalities of the two men, but also in the beautifully
simple and powerful diagrammatic notation invented by
Feynman (which, in Schwinger’s words, “like the silicon
chip, would bring computation to the masses”) and
finally his separation from the mainstream in his later
years.

The most important part of the
Schwinger-Feynman story is summarized by the
Michigan Summer Schools of 1948 and 1949. In 1948
Schwinger first described his breakthrough in QED to a
wider audience, including Dyson, Kroll, Lee and Yang. It
was then that Dyson wrote home that in a few months
we shall have forgotten what pre-Schwinger physics was
like.

In the following 1949 Michigan lectures,
Feynman described his version of QED, but at that time
he was unable to deal with vacuum polarization and it
was not generally clear how much he had been able to
accomplish.

By contrast, Schwinger had presented
an essentially complete package: a manifestly covariant
theory with which he had calculated in lowest order all
the previously inaccessible consequences of QED. He
had not only climbed the mountain but, more
importantly, had shown that it could be climbed. Shorter
routes were subsequently found. In the third year of the
Michigan series, Dyson lectured and showed that the
Schwinger theory and the completed Feynman theory
were equivalent. This history, as well as the parallel work
of Tomonaga, is well described in this book.

The
Schwinger theory of 1948, while adequate for its
original purpose, was, like every first invention, relatively
crude and could not easily be pushed to higher order.
Therefore during the 1950s he developed increasingly
powerful calculational techniques. To this period belong
the Schwinger action principle and the extensive use of
Green’s functions and functional techniques that are now
part of the standard literature.

During the 1960s
Schwinger began a total reconstruction of quantum field
theory that he named source theory. Here he was
attempting to replace the operator field theory, to which
he had contributed so much, by a philosophy and
methodology that eliminated all infinite quantities. He did
in fact succeed in constructing an infinity-free formalism
that was also receptive to new experimental information
and new theoretical ideas. It was not simply a
programme: Schwinger and his UCLA source theory
group, K Milton and colleagues, showed that it was a
very effective calculational tool. Source theory has not
until now found extensive use in the general theoretical
community, although it has elements in common with S
Weinberg’s use of phenomenological Lagrangians.
Schwinger’s determination to pursue this work for about
10 years led to his partial eclipse. Milton is obviously
well qualified to review this period.

One of the
more interesting chapters is entitled “Electroweak
Unification and Foreshadowing of the Standard Model”.
Not so well known is Schwinger’s role in the
development of the electroweak theory. In 1941 he
made the amazingly prescient remark that if the
significant mass scale for nuclear beta-decay were of the
order of several tens of nuclear masses, then there would
be the possibility of an intermediate vector theory with a
coupling of the order of alpha. The theory suggested by
this numerology was essentially realized in 1957 in his
beautiful paper “A Theory of the Fundamental
Interactions” (1957 Ann. Phys.2 407).
Schwinger comments on this paper (82) in the selected
papers (edited by Flato et al.):

“A
speculative paper that was remarkably on target: VA
weak interaction, two neutrinos, charged intermediate
vector meson, dynamical unification of weak and
electromagnetic interactions, scale invariance, chiral
transformations, mass generation through vacuum
expectation value of scalar field. Concerning the idea of
unifying the weak and electromagnetic interactions, Rabi
once reported to me: ‘They hate it’.”

However, he
was convinced and proposed a similar model to his
student, Glashow. Thanks to the efforts of Glashow,
Weinberg, Salam and ‘t Hooft the standard electroweak
SU(2) ¥ U(1) theory,
bearing enormous similarity to Schwinger’s paper of
1957, was born. The 1957 paper might well have led
directly to the standard electroweak theory if it had not
become bogged down in the infamous morass of 13
flawed experiments that seemed to imply that the
beta-interaction was not VA.

Schwinger’s
independence of the mainstream is discussed in this
biography and by many others including Schweber. It is
said that he didn’t like “conversational physics” but that
meant only that he didn’t like conversations unless they
interested him. In fact he was quite open to new
ideas.

The more accurate view is that he was
simply an independent thinker who guarded his time and
set his own goals, toward which he worked intensely
and constantly. Much of his work he made no effort to
publish. For some of his work, like the Bethe-Salpeter
equation and the TCP theorem, he received no
recognition.

It is arguable that the creativity of an
original mind such as Schwinger’s or Dirac’s would have
been enhanced by more interaction with others in later
years. In Schwinger’s case, in spite of the undeniable
handicaps of isolation, the following assessment appears
in the Festschrift published on the occasion of his 60th
birthday:

“His work during the 44 years
preceding his 60th birthday extends to almost every
frontier of modern theoretical physics. He has made
far-reaching contributions to nuclear, particle and atomic
physics, to statistical mechanics, to classical
electrodynamics and to general relativity. Many of the
mathematical techniques he developed can be found in
every theorist’s arsenal…He is one of the prophets and
pioneers in the uses of gauge theories…Schwinger’s
influence, however, extends beyond his papers and
books. His course lectures and their derivatives
constitute the substance of graduate physics courses
throughout the world, and in addition to directing about
70 doctoral theses, he is now the ancestor of at least four
generations of physicists…The influence of Julian
Schwinger on the physics of his time has been
profound.”
Robert Finkelstein,
UCLA.

Managing Science –
Management for R&D Laboratories
by Claude
Gelès, Gilles Lindecker, Mel Month and Christian Roche,
Wiley Series in Beam Physics and Accelerator
Technology, ISBN 0471185086.

Managing
Science
is a book based on a graduate level course
given by the authors at several editions of the US
Particle Physics Accelerator School.

The book
contains a didactic presentation and in-depth discussion
of a complete set of management issues affecting big
scientific laboratories, as well as analyses of their possible
evolutions. Items including motivations for creating a
laboratory, decision-making systems, organization and
communication, policy implementation, project
methodology, infrastructure, human resources
management, financial management and logistics are
treated with a direct and comprehensive style. The
discussions on alternatives and their associated risks and
opportunities are very educational.

Of particular
interest is the second part of the book, entitled “The
Human Drama”. The typical evolution of the life of a
scientific laboratory is described in terms of three main
stages – growth, steady state and decline, just as in
individuals, according to age. The analysis presented on
the way of revitalizing the laboratory, identifying what
are only fluctuations which might give a wrong
impression of revitalization, is very interesting and of
particular importance for already old but successful
scientific organizations. The experience of the authors,
mainly from particle physics laboratories, and the
fast-changing evolution of the organizational methods of
this type of research make the analysis especially
adequate for high-energy physics labs.

In
summary, the book contains a complete and useful
description of the management tools for major scientific
organizations and can also be useful for consultation.
The reference material is plentiful and well
selected.
Juan-Antonio Rubio,
CERN.

The Quest for Symmetry –
Selected Works of Bunji Sakita
edited by K
Kikkawa, M Virasoro and S Wadia, World Scientific,
ISBN 9810236433, £49.

World Scientific’s series
on 20th century physics includes scientific anthologies
about many famous figures and/or edited by many
authoritative names. Volume 22 continues this tradition
and includes a collection of key papers (without
commentary) on SU(6) symmetry, the strong coupling
group, the string model, supersymmetry and the use of
collective variables in quantum field theory. Especially
interesting is the autobiographical introduction by a
scientist born and educated in Japan but who has spent
almost his entire professional career outside that
country.

Insertion Devices for
Synchrotron Radiation and Free Electron Laser
by
F Ciocci, G Dattoli, A Torre and A Renieri, World
Scientific, ISBN 9810238320, £49.

A further
volume in World Scientific’s series Synchrotron
Radiation Techniques and Applications,
this provides
much general coverage of the theory of charged particle
transport, synchrotron radiation and free electron lasers
before going on to the specifics of insertion devices
(which generate synchrotron radiation) and X-ray
optics.

Principles of Fusion Energy
by A A Harms, K F Schoepf, G H Miley and D R
Kingdon, World Scientific, ISBN 9810243359,
£35.

Fusion energy powers the stars and is
perceived as the ultimate source of energy on Earth.
R&D work has followed diverse paths. Much effort has
gone into the design and construction of a series of
toroidal machines (tokamaks, stellarators) to contain the
hot thermonuclear fuel. This approach was initially
heralded as a fountainhead of inexhaustible energy, but
attention is also focusing on more fundamental
approaches such as inertial confinement of hot plasma
and muon catalysis. This textbook provides a useful
summary of the relevant physics and an objective
overview of the possible systems that could allow and
contain thermonuclear fusion.

XIX
International Symposium on Lepton and Photon
Interactions at High Energies, Stanford, California, 9-14
August 1999
edited by John Jaros and Michael
Peskin, World Scientific, ISBN 9810241895,
920pp.

Proceedings of the meeting which
traditionally includes only plenary
sessions.

High Energy Physics 99:
Proceedings of the International Europhysics Conference
on High Energy Physics, Tampere, Finland, 15-21 July
1999
edited by K Huitu, H Kurki-Suonio and J
Maalampi, University of Helsinki, Finland. Institute of
Physics Publishing, ISBN 0750306610, 1000 pp, illus.
hbk £220/$359.

This volume contains the 18
invited plenary presentations and 250 contributions to
parallel sessions presented at the
conference.

An Introduction to the
Theory of Spinors
by M Carmeli and S Malin,
World Scientific, ISBN 9810242611, £35.

Spinor
treatments can be easier to handle than conventional
tensor approaches. This compact textbook provides an
introduction to spinors and examples of their application
in general relativity and gauge theories.

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