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Photograph courtesy of Clarice Schwinger.

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JULIAN SCHWINGER
February 12, 1918–July 16, 1994
By PAUL C. MARTIN AND SHELDON L. GLASHOW
J ulian s chwinger, w ho d ied o n
July 16, 1994, at the age of
76, was a phenomenal theoretical physicist. Gentle but
steadfastly independent, quiet but dramatically eloquent, self-
taught and self-propelled, brilliant and prolific, Schwinger
remained active and productive until his death. His ideas,
discoveries, and techniques pervade all areas of physics.
Schwinger burst upon the scene meteorically in the late
1930s, and by the mid-20th century his reputation among
physicists matched those of earlier giants. To a public
vaguely conscious of relativity and quantum uncertainty
but keenly aware of nuclear energy, the New york Times
reported in 1948 that theorists regarded him as the heir
apparent to Einstein’s mantle and his work on the interac-
tion of energy and matter as the most important develop-
ment in the last 20 years. With the development of powerful
new theoretical methods for describing physical problems,
his influence grew. In the early 1950s the Journal of Jocular
Physics, a publication of the Bohr Institute for Theoretical
Physics in Copenhagen, included a template for articles by
aspiring theorists. It began “According to Julian Schwinger”
and invoked “the Green’s function expression for …”.
References to unpublished Schwinger lecture notes and
some classic Schwinger papers followed. The recipe elicited
333

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334 BIOGRAPHICAL MEMOIRS
smiles, but it accurately portrayed his preeminence at that
time. With this preeminence came stratospheric expectations,
which he continually strove to fulfill.
Schwinger was born in upper Manhattan on February 12,
1918. He went to P.S. 186, to Townsend Harris High School
(then New york City’s leading public high school), and to
the College of the City of New york, following brother Har-
old by six years. Harold was the outstanding student, the
valedictorian, their mother would explain. Julian took the
establishment of teachers, textbooks, and assignments less
seriously. From some, most notably physics teacher Irving
Lowen, he benefited greatly. But there were better things to
do with the 11th edition of the Encyclopaedia Britannica and
the books and journals in nearby libraries.
In 1926 when Werner Heisenberg and Paul Dirac were
developing quantum mechanics, Schwinger was in the third
grade. Eight years later, before completing high school, he
had assimilated these ideas and in an unpublished paper
extended Dirac’s ideas to many-electron systems. By then,
word of the wunderkind had spread among graduate students
at City College, where he enrolled in the fall of 1934 and at
Columbia University, to which—thanks to that institution’s
support and the subsequent intervention of I. I. Rabi—he
was able to transfer in 1936.
In a remarkable letter dated July 10, 1935, from Hans
Bethe to I. I. Rabi, Bethe describes his meeting with Schwing-
er:
I entirely forgot that he [Schwinger] was a sophomore 17 years of age. . . His
knowledge of quantum electrodynamics is certainly equal to my own, and
I can hardly understand how he could acquire that knowledge in less than
two years and almost all by himself.” Bethe concludes that “Schwinger will
develop into one of the world’s foremost theoretical physicists if properly
guided, i.e., if his curriculum is largely left to his own free choice.

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JULIAN SCHWINGER
Less than four years after he entered college Schwinger
had completed both the requirements for his undergraduate
and graduate degrees and the research for his doctoral thesis.
During his sophomore year, with Otto Halpern, he predicted
the polarization of electrons by double scattering and with
Lloyd Metz he computed the lifetime of the neutron. On
his own as a junior he computed how neutrons were polar-
ized by double scattering from atomic electrons. That the
electron current must be treated relativistically by the Dirac
equation (that is, that the classical approximations made
by Felix Bloch were inadequate) was noted sotto voce. Next,
he calculated the influence of a rotating magnetic field on
a spin of any magnitude j. His analysis for j = 1/2 remains
the prototype for all discussions of transitions in two-level
systems by “Rabi flipping.”
During the spring of 1937, he and Edward Teller studied
coherent neutron scattering by hydrogen molecules, showing
how the spin-dependent, zero-energy, neutron-proton-scatter-
ing amplitudes could be determined from the experimental
data. This topic was the theme of his doctoral thesis.
In the fall of 1937, with his undergraduate degree in
hand, eight significant papers published, and his doctoral
thesis virtually complete, Schwinger left New york, planning
to spend the fall term at the University of Wisconsin with
Gregory Breit and Eugene Wigner, and the spring term at
the University of California, Berkeley, with J. Robert Oppen-
heimer. In Madison he took such great pleasure in working
at night on problems of his own choosing that he stayed for
the entire year. He would maintain this nocturnal regimen
for most of his career.
Schwinger returned to Columbia for 1938-1939. As
house theorist he worked with Hyman Henry Goldsmith,
John Manley, Victor Cohen, and Morton Hammermesh

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336 BIOGRAPHICAL MEMOIRS
on nuclear-energy-level widths and on the neutron-proton
interaction and with Rabi and his associates on molecular
beams. His doctoral degree under Rabi’s supervision was
awarded in 1939.
Schwinger spent the next two years at Berkeley working
with Oppenheimer, students, and visitors (Herbert Corbett,
Edward Gerjuoy, Herbert Nye, and William Rarita). With
Rarita he determined definitively the effects of the tensor
force on the deuteron’s magnetic and quadrupole moments.
He also examined the consequences of tensor and exchange
forces between pairs of nucleons on the magnetic and quad-
rupole moments of light nuclei, nuclear pair emission, deu-
teron photodisintegration, and other phenomena.
The Rarita-Schwinger equation—one of the few of his
many contributions that bear his name—was all but forgotten
for many years. But this generalization of the Dirac equation
to particles with spin 3/2, and the study of its invariances
when the particles are massless, has been recalled by theorists
who postulate a gravitino, a spin-3/2 fermion supersymmetric
partner of the graviton.
Notwithstanding a ticker tape parade for Albert Einstein,
theoretical physics held little fascination for the American
public or major American universities prior to the Second
World War. Even so, in 1941 the nation’s great universities
might have been expected to compete fiercely for an ac-
knowledged young genius who lectured along with Wolfgang
Pauli, Frederick Seitz, and Victor Weisskopf at the world-
famous Michigan summer school for physics. They did not.
In some cases, a long tradition of anti-Semitism may have
been a factor. Schwinger was offered and accepted a lowly
instructorship at Purdue University with just one concession
to his preferred work schedule: His introductory physics sec-
tion would start at noon.

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JULIAN SCHWINGER
Led by first-rank physicist Karl Lark-Horovitz, Purdue
attracted able graduate students and postdoctoral fellows.
Among them was Robert Sachs, who (as related by Sylvan
Schweber in his book on QED) recalled that in February
1942, “We had to spend the whole time trying to cheer Julian
up” at his 24th birthday party “because he had not yet made
the great discovery expected of him.”
Along with physicists at Cornell University and the Uni-
versity of Rochester and with colleagues at Purdue, Schwinger
spent the first year and a half of World War II working on the
properties of microwave cavities. The work was coordinated
with and supported by MIT Radiation Laboratory research
projects.
Invited by Oppenheimer to join the Manhattan Project,
Schwinger spent the summer of 1943 at the University of
Chicago’s Metallurgical Laboratory, where John Wheeler,
Eugene Wigner, and other scientists were designing the first
Hanford reactor. As in Madison, Schwinger worked nights,
and so Bernard Feld (who had worked with him at Columbia)
decided to work an intermediate afternoon-evening shift so
that he might help link Schwinger with those working normal
hours.
After “a brief sojourn to see if I wanted to help develop
the Bomb—I didn’t,” recalled Schwinger, “I spent the war
years helping to develop microwave radar.” Reluctance to
follow others’ agendas once again helped determine his
course. Thus, in the fall of 1943 after most luminaries with
nuclear expertise had left the MIT Rad Lab for Los Alamos,
Schwinger arrived in Cambridge with little notion that he
would remain in the area for more than a quarter century.
Many of Schwinger’s colleagues during his three-year
stint at the Rad Lab became his lifelong friends. Among
them were Harold Levine from Cornell; Nathan Marcuvitz,
an electrical engineer from Brooklyn College; and David

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338 BIOGRAPHICAL MEMOIRS
Saxon, an MIT graduate student. Schwinger’s collaboration
with Levine led to a series of papers that creatively used
variational methods and Green’s functions—two approaches
central to so much of Schwinger’s work—to obtain important
new results on radiation and diffraction.
Schwinger and Marcuvitz appreciated the value of integral
equation formulations of waveguide theory that incorporate
the boundary conditions accompanying partial differential
equation formulations and can be cast in the engineering
language of transmission lines and networks. The isolation
of complex internal properties of components and the
characterization of these components through a small set of
parameters provided valuable insights—insights that would
later prove valuable in characterizing nuclear phenomena via
effective range theory, scattering matrices, and new formal
approaches to complex scattering processes.
At the Rad Lab Schwinger gave a series of lectures on
microwave propagation for which David Saxon served as
his Boswell. Many of the ideas and techniques in them re-
cur in his later theoretical work on quantum mechanics,
electrodynamics, nuclear physics, and statistical mechanics.
A small volume, titled Discontinuities in Waveguides, contain-
ing some of these lectures, was published decades later. In
the volume’s introduction and 138 pages of text, Schwinger
himself observed that the name “Green” or simply “G” (for
Green’s function) appeared more than 200 times. Some
powerful relations imposed on scattering amplitudes by time
reversibility and energy conservation can also be traced back
to Schwinger’s work at the time.
When the War ended, Schwinger’s attention turned to the
physics of high-energy accelerators and to the obstacles to
producing them. It struck him that the energy loss of a highly
relativistic electron accelerating in a circular orbit could be
simply and straightforwardly deduced from the covariant

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JULIAN SCHWINGER
expression for radiation damping, making the fourth power
law for the radiated energy transparent. “Manifest covari-
ance” would play an important role in Schwinger’s work on
quantum electrodynamics. During this period, Schwinger also
designed a novel accelerator, later named the minotron.
In addition to work on other aspects of synchrotron ra-
diations, notepads in his desk drawers at that time included
studies of neutron scattering in a Coulomb field, and a
group-theory-free approach to the properties of angular
momentum that expresses angular momentum operators in
terms of oscillator creation and annihilation operators. On
Angular Momentum, a set of his notes that makes exhaustive
use of this approach, circulated widely for 15 years prior to
its publication in 1965.
Schwinger’s long and diverse bibliography, with more than
200 publications, contains no publications over the period
1942 through 1946. However, the war produced sweeping
changes in the social and intellectual values and mores of
the public and the nation’s premier universities. Thus, in
February 1946, the month Schwinger turned 28, he was of-
fered and accepted a tenured position at Harvard. Profes-
sorship offers from Columbia and Berkeley soon followed,
but he turned them down.
Students attending topflight universities were also dif-
ferent before and after the war. Postwar students included
mature veterans whose studies had been interrupted by the
war and bright youth from a broader cross-section of the
nation’s preparatory schools. Doors were open, for example,
to outstanding students from New york’s select high schools
(for example, Bronx Science, Brooklyn Tech, and Stuyves-
ant, the successors to Schwinger’s alma mater, Townsend
Harris).
Schwinger’s first year at Harvard, 1946-1947, was a busy
one. He offered courses on waveguides and theoretical

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340 BIOGRAPHICAL MEMOIRS
nuclear physics, and accepted a number of graduate stu-
dents whom he set to work on a wide range of problems.
Among these early students were Bernard Lippmann who
investigated integral equation formulations of scattering
theory (Lippmann-Schwinger equations); Walter Kohn, who
studied variational principles for scattering; Ben Mottelson,
who worked on the properties of light nuclei; Bryce DeWitt,
who explored gravitation and the interaction of gravitation
with light; and Roy Glauber, who examined meson-nucleon
interactions and mesonic decay. He and longtime friend
Herman Feshbach pursued their studies of the internucleon
potential.
When the academic year ended, Schwinger and 22 other
physicists headed off to the Shelter Island conference on the
foundations of quantum physics, where the electrodynamic
origin of the spectral lineshift measured by Willis Lamb
and Robert Retherford was discussed. Legend has it that
Weisskopf and Schwinger proposed that in the Dirac theory
compensating effects of electrons and positrons could lead
to a cancellation of divergences, and that Hans Bethe—on
his way home from the conference—recognized that the bulk
of the effect could be estimated nonrelativistically.
Four days after the conference ended, Schwinger married
Clarice Carroll, whom he had been courting for several years
and with whom he would share the next 47 years.
Schwinger’s lectures, from his early days at Harvard on,
have been likened to concerts at which a virtuoso performs
pieces brilliantly. Each lecture was an event. Speaking elo-
quently, without notes, and writing deftly with both hands,
Schwinger would weave original examples and profound
insights into beautiful patterns. Audiences would listen rever-
ently seeking to discern the unheralded difficult cadenzas. As
at a concert, interruptions to the flow were out of place.

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JULIAN SCHWINGER
Schwinger’s masterly performances were not limited to
the Harvard community. His audiences quickly grew to in-
clude faculty and students from throughout the Boston area.
Notes taken by John Blatt, an MIT instructor, were shipped
to a team of Princeton graduate students, who in swift relays
copied them onto duplicator masters for reproduction. Un-
derground notes in multiple handwritings, with some pages
containing picturesque mistranscriptions (such as “military
matrices” for “unitary matrices”) spread quickly throughout
the country and overseas.
Schwinger was never satisfied with his expositions. Each
time he offered a course he carefully reworked and honed
his ideas, methods, and examples, presenting them in a new
way, a way that differed from his earlier versions circulating
in others’ articles and lecture notes, often without attribu-
tion. Significant portions of many classic texts on nuclear
physics, atomic physics, optics, electromagnetism, statistical
physics, quantum mechanics, and quantum field theory can
be traced to one or another version of his lectures.
As noted, a few isolated gems—his work on microwaves
and his notes on angular momentum—were eventually pub-
lished. He was also stimulated in 1964 “to rescue from the
quiet death of lecture notes” a beautiful discussion of Cou-
lomb Green’s functions “worked out to present to a quantum
mechanics course given in the late 1940s.” The bound-state
momentum space wave functions are deftly and concisely
constructed as four-dimensional spherical harmonics.
Notes for his early quantum mechanics courses also
include elegant and revealing unpublished treatments of
Coulomb scattering and of the unusual way that the Stark
effect lifts hydrogenic degeneracies. These and other jew-
els may be found in the archives assembled by UCLA of
lecture notes, chapters, and preliminary editions of books
on quantum mechanics, field theory, and electromagnetism

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342 BIOGRAPHICAL MEMOIRS
that failed to meet his exacting standards. A few appear in
Classical Electrodynamics, published in 1998.
Not until September 1947 did Schwinger begin to work
on the electrodynamic effects responsible for deviations of
experimental observations from values predicted by the Dirac
equation. Hyperfine structure measurements of hydrogen,
deuterium, and tritium by John Nafe, Edward Nelson, and
Rabi indicated a 0.12 percent error in the electron’s mag-
netic moment, and measurements by Lamb and Retherford
displayed a splitting of about 1050 megacycles between states
of the hydrogen atom with degenerate Dirac energies. “By
the end of November I had the results,” Schwinger later
recalled. He described them to a capacity audience at an
American Physical Society meeting at Columbia University
on a Saturday morning in January 1948, giving a command
repeat performance to an overflow audience that afternoon.
He discussed his calculations in fuller detail at the Pocono
conference in the spring and in lectures at the University of
Michigan summer school. Demonstrating his computational
virtuosity, he published his reformulation of quantum elec-
trodynamics in three long papers in Physical Review, Quantum
Electrodynamics I (1948), II (1949), and III (1949). They
include several of the results for which he, Richard Feynman,
and Sin-Itiro Tomanaga were eventually awarded the 1965
Nobel Prize in Physics. To those who admire the eloquence
of Schwinger’s expositions, it seems ironic that these three
uncharacteristically opaque papers should have helped secure
his place in Nobel history.
In light of his many spectacular achievements, including
his fundamental contributions to quantum electrodynamics,
Schwinger was elected to the National Academy of Sciences
at the exceptionally young age of 31.
By 1950 Schwinger recognized the need for a more system-
atic approach to quantum field theory utilizing a covariant

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JULIAN SCHWINGER
quantum version of Hamilton’s principle. In 1951 in a pair
of brief papers in the Proceedings of the National Academy
of Sciences, the techniques and concepts on which field
theorists all rely made their appearance. Using “sources” as
fundamental variables, Schwinger provided the functional
differential equation version of what in integral form is now
called functional integration. Of lasting importance, much of
this material has been rediscovered by others. For theoretical
students at Harvard at the time, Schwinger’s techniques pro-
vided an Aladdin’s lamp for parsing, analyzing, and solving
problems. As a matter of principle, these papers noted,
The temporal development of quantized fields is described by propagation
functions, or Green’s functions. The construction of these functions for
coupled fields is usually considered from the viewpoint of perturbation
theory. Although the latter may be resorted to for detailed calculations, the
formal theory of Green’s functions should not be based on the assumption
of expandability in powers of the coupling constant.
After relating the outgoing wave boundary condition to
the vacuum, the second paper defined functions (such as self-
energies and effective interactions) that characterize exactly
(that is, not as power series in the coupling constant) the
propagation and interaction of quantum fields. This approach
opened the way for major conceptual and computational
advances in quantum electrodynamics. A series of papers
called “Theory of Quantized Fields” followed.
Word appears to have circulated that the stress Schwinger
placed on the properties of fields that transcended perturba-
tion theory, and his personal dislike of diagrams disadvantaged
those working for and with him in the 1950s. Hardly! His
students and postdoctoral fellows were fully conversant and
facile with the diagrammatic approaches of Feynman and
Freeman Dyson and analytic approaches. With Schwinger’s
tools, they generated directly and succinctly the connected
diagrams involving dressed propagators that describe vari-

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344 BIOGRAPHICAL MEMOIRS
ous processes. With them they evaluated a large share of
the quantum electrodynamic corrections to hydrogen and
positronium bound states and a large share of the higher
order corrections (for example, to the electron’s magnetic
moment) computed at that time.
Other aspects of Schwinger’s routine can also mistakenly
be cast in an unkindly light. It is true, for example, that stu-
dents might wait a long time to see him during his lengthy
office hours. He could have spent less time with each and
he could have accepted fewer. In his first year at Harvard
he accepted 10 graduate students, and in subsequent years
no one recalls his ever turning down a prospective student
whom the department certified as qualified. When requested,
Schwinger posed problems to students, sometimes offering
them and colleagues his notes. At the same time, he welcomed
students who preferred to formulate their own thesis topics.
If students told him they were stuck, he would offer sugges-
tions and proposals on the spot and at subsequent meetings.
Rare are the students who did not cherish their interactions
with Schwinger in sessions that were often lengthy.
His late arrival for classes was not because he left gath-
ering materials for his lecture to the last minute. Not only
in the early years but also throughout his long career he
insisted on remaining home the night before each lecture,
staying up late to prepare exactly what he would say and
how best to say it.
Among the giant figures in theoretical physics, his level
of commitment to course lectures and to the supervision of
large numbers of research students may be unmatched.
Schwinger’s investigations of quantum field theory con-
tinued through the 1950s. Relativistic invariance and gauge
invariance constrain the formally divergent expressions ap-
pearing in quantum electrodynamics calculations. Colleagues
of Pauli, ignoring the consequences of gauge invariance, had

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JULIAN SCHWINGER
recast and manipulated these expressions to predict a finite
photon mass. Schwinger’s 1951 paper on vacuum polarization
and gauge invariance addressed some of these issues with a
novel and elegant proper-time formalism. The nonpertur-
bative properties of a Dirac field coupled to a prescribed
external electromagnetic field, first derived in this paper,
are still widely used and admired. Schwinger saw that many
ambiguities associated with interacting quantum fields lay
in the treatment of formal expressions for composite opera-
tors such as currents. Indeed, the “triangle anomalies” that
play a major role in modern (post-1969) field theory were
first identified here and studied further by Schwinger and
Ken Johnson during the 1950s. Further studies of quantized
fields led in 1958 to Schwinger’s important series of papers
on “Spin, Statistics, and the TCP Theorem.”
During the 1950s, puzzles posed by elementary particle
physics preoccupied Schwinger. What role could strange
particles, whose properties were just being elucidated, play
in the grand scheme of things? He was convinced that the
answer had to do with their transformation properties under
a generalization of isotopic-spin symmetry, which he took to
be the four-dimensional rotation group. The group genera-
tors, under commutation, defined what would later become
known as the “algebra of charges.”
Schwinger gathered particle species together, both strange
and nonstrange, into representations of his proposed group.
In this manner the otherwise mysterious Gell-Mann-Nishijima
formula—which relates charge, hypercharge, and isospin—had
a natural explanation. It later turned out that Schwinger’s
intuition was correct, although his choice for the relevant
transformation was not.
The approximate symmetries of mesons and baryons were
not shared by the leptons. For these particles, Schwinger
proposed a direct analog to isospin. Just such a group was

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346 BIOGRAPHICAL MEMOIRS
later to become an integral part of today’s successful elec-
troweak theory. The known leptons—in Schwinger’s per-
versely original interpretation—were to form a weak isospin
triplet: {μ+, ν, e−}. An immediate consequence of this notion
was the selection rule forbidding μ→e + γ and the obliga-
tory distinction between neutrinos associated with electrons
and muons. “Is there a family of bosons that realizes the
T=1 symmetry of [the lepton symmetry group]?” Schwinger
asked. If so, the charged counterparts of the photon could
mediate the weak interactions. Both the vectorial nature of
the weak force and its apparent universality would arise as
simple consequences of the underlying symmetry structure.
He also suggested that vacuum expectation values of scalar
fields could provide a way of breaking symmetries and giving
fermions their masses.
Schwinger’s 1957 paper on particle symmetries appeared
at a time of rapid progress and great confusion, between
the discoveries of parity violation and the V-A nature of the
weak interactions. His ambitious paper concluded with the
modest suggestion that “it can be of value if it provides a
convenient frame of reference in seeking a more coherent
account of natural phenomena.” For some of the theorists
who developed that coherent theory over the next 15 years,
it did just that. Schwinger himself, however, turned to other
problems.
A 1959 paper with Martin extended Schwinger’s nonper-
turbative field theoretic concepts and methods for the vacuum
state to material systems in equilibrium at nonvanishing densi-
ties and temperatures, and a 1961 paper, camouflaged by the
title “Brownian Motion of a Quantum Oscillator” paved the
way for the study of systems far from thermal equilibrium.
Extended by K. T. Mahantappa, Pradip Bakshi, and Victor
Korenman at Harvard, and rediscovered (independently)
by Leonid Keldysh, Schwinger’s “two-time” approach is now

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JULIAN SCHWINGER
widely used in studies of cosmology, quark-gluon plasmas,
and microelectronic devices.
As indicated above, Schwinger recognized in the early
1950s that the composite operators for observables must
be treated with care. Naive manipulations with canonical
commutation relations suggest that the space and time
components of a current commute with each other. In 1959
Schwinger published an argument, dazzling in its simplicity,
that moved this problem to the fore and identified a class of
anomalies, now called “Schwinger terms.” He followed it in
papers directed toward the gravitational field with a study of
the conditions imposed by consistency on stress tensor com-
mutation relations. Today we recognize the key roles such
terms play in particle physics and statistical mechanics.
In the late 1960s Schwinger directed much of his attention
to his source theory. The motivation was clear. In spite of
field theory’s many triumphs, the prospects then seemed dim
for predicting the results of experiments involving strongly
interacting particles from a unified field theory. Prospects
for a renormalizable theory of the electroweak interactions
also seemed dim. Why not try to develop a theory that would
progress in the same way as experiment—from lower to
higher energies? Source theory provided a framework for
pursuing this modest goal.
Soon thereafter these prospects brightened. Gauge field
theories were shown to be renormalizable and consonant
with an increasing number of phenomena. Quantum field
theory, to which Schwinger had contributed so much, might
describe all strong and electroweak phenomena. Schwinger
demurred, remaining steadfastly committed to the source
theory approach that he and his students were pursuing.
The philosophical basis of divergence-free “anabatic” (going
up) phenomenological source theory was, he maintained,
immensely different from “the speculative approach of

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348 BIOGRAPHICAL MEMOIRS
trickle-down” field theory. So too were its predictive powers.
He espoused this contrarian position steadfastly.
During the 1960s, Schwinger’s lifestyle expanded in other
ways. He began playing tennis regularly, and he and Clarice
spent time in distant places, including Paris and Tokyo. In
1971 the Schwingers left Harvard and their Belmont home
for UCLA and the Bel Aire hills. In sunny southern Califor-
nia, with students, new collaborators, and longtime friends,
Schwinger continued working on source theory (“source”
appears in the title of more than 15 publications) and contrib-
uting significantly to a host of interesting physical problems
not in vogue. With Lester DeRaad Jr. and Berthold-Georg
Englert, he explored statistical models of the atom that extend
the Fermi-Thomas approximation and, with Kimball Milton
and DeRaad, various aspects of the Casimir effect. In his new
surroundings he published more than 70 papers.
Reports of cold fusion whetted his contrarian appetite. The
publicized experiments might be flawed, he would observe,
but fundamental physical principles do not rigorously exclude
the possibility that without tokamaks and high-temperature
plasmas, somehow, in some way, in some material, the energy
required for fusion might be coherently concentrated and
transferred from atoms to nuclei.
One of Schwinger’s last papers is a 1993 talk titled “The
Greening of Quantum Field Theory: George and I, Lecture
at Nottingham, July 14, 1993.” It contains the count of refer-
ences to Green in Discontinuities in Waveguides mentioned
earlier and a recital of a multitude of the linkages with
George Green of Schwinger’s research on field and particle
theory, statistical mechanics, through to work on the Casimir
effect and sonoluminescence. Although Schwinger’s genius
was widely recognized immediately, and Green’s very slowly.
Schwinger concludes his talk by answering the question,

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JULIAN SCHWINGER
“What then shall we say about George Green?” with “He is,
in a manner of speaking, alive, well, and living among us.”
That, too, can be said for Schwinger.
Schwinger’s legacy has also been greatly amplified by the
70 doctoral students and 20 postdoctoral fellows who worked
with him. For their research they have innumerable major
awards, including four Nobel prizes; nine of his students have
been elected to the National Academy of Sciences.
Two features shared by Schwinger’s professional off-
spring are striking: the diversity of their specialties and the
consistently high regard and great debt they express for his
mentorship. The group includes leaders in particle theory,
nuclear physics, astrophysics, gravity, space physics, optics,
atomic physics, condensed matter physics, electromagnetic
phenomena, applied physics, mathematics, and biology. It
also includes many who, like Schwinger, have worked in a
variety of fields, mirroring Schwinger’s own broad interests
and his passion for seeking patterns and paradigms that put
new facts in proper perspective.
Their recollections are remarkably uniform. While few
former students considered him a close friend, almost all
speak fondly of his kindness and generosity. He was consid-
erate and willing to do his best to provide scientific advice
when he thought help was needed. His insight and sugges-
tions were often decisive.
By example he conveyed lofty aspirations: to approach
every problem in a broad context, with as few assumptions
as possible; to seek new and verifiable results and to present
them as elegantly as possible; to avoid energy- and time-
consuming political maneuvering; to understand, extend,
unify, and generalize; and to reveal the hidden beauty of
nature. Walter Kohn spoke for all of Schwinger’s students
in saying,

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350 BIOGRAPHICAL MEMOIRS
We carried away the self-admonition to try and measure up to his high stan -
dards; to dig for the essential; to pay attention to the experimental facts;
to try to say something precise and operationally meaningful, even if—as
is usual—one cannot calculate everything a priori; not to be satisfied until
ideas have been embedded in a coherent, logical and aesthetically satisfy-
ing structure.
Schwinger also had a remarkable knowledge of matters
nonscientific and a gentle humor. While too reserved to savor
media stardom, he enjoyed presenting relativity to a wide
audience in a popular book and on BBC television. He was
always willing to lend his name and support to worthy causes.
Fond recollections of the hospitality, warmth, and interest
displayed by both Julian and Clarice Schwinger abound.
An article about Julian Schwinger was published by the authors of this
memoir in Physics Today, Oct. 1995, pp. 40-46, under the copyright
of the American Institute of Physics. With AIP permission the authors
have presented here a slightly modified version of that article.

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351
JULIAN SCHWINGER
SELECTED BIBLIOGRAPHy
1935
With O. Halpern. On the polarization of electrons by double scat-
tering. Phys. Rev. 48:109.
1937
On the magnetic scattering of neutrons. Phys. Rev. 51:544-552.
On the non-adiabatic processes in inhomogeneous fields. Phys. Rev.
51:648-651.
With E. Teller. The scattering of neutrons by ortho and para hydro-
gen. Phys. Rev. 51:775.
On the spin of the neutron. Phys. Rev. 52:1250.
1941
With W. Rarita. On the neutron-proton interaction. Phys. Rev. 59:436-
452.
With R. Rarita. On a theory of particles with half-integral spin. Phys.
Rev. 60:61.
1946
Electron radiation in high energy accelerators. Phys. Rev. 70:798.
1947
A variational principle for scattering problems. Phys. Rev. 72:742.
1948
On quantum electrodynamics and the magnetic moment of the
electron. Phys. Rev. 73:416-441.
Quantum electrodynamics. I. A covariant formulation. Phys. Rev.
74:1439-1461.
1949
Quantum electrodynamics. II. Vacuum polarization and self-energy.
Phys. Rev. 75:651-679.
Quantum electrodynamics. III. The electrodynamic properties of the
electron Phys. Rev. 76:790.

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352 BIOGRAPHICAL MEMOIRS
1950
With B. Lippman. Variational principles for scattering processes. I.
Phys. Rev. 79:469-480.
1951
On gauge invariance and vacuum polarization. Phys. Rev. 82:664-
679.
On the Green’s functions of quantized fields. I, II. Proc. Natl. Acad.
Sci. U. S. A. 37:452-459.
1958
Spin, statistics and the TCP theorem. Proc. Natl. Acad. Sci. U. S. A.
44:223-228, 617-619.
1959
With P. C. Martin. Theory of many-particle systems. I. Phys. Rev.
115:1342-1373.
Field theory commutators. Phys. Rev. Lett. 3:269.
1961
Brownian motion of a quantum oscillator. J. Math. Phys. 2:407.
1963
Commutation relations and conservation laws. Phys. Rev. 130:406-
409.
1964
Coulomb Green’s function. J. Math. Phys. 5:1606.
1965
Quantum Theory of Angular Momentum (eds. L. Biedenharn and H.
van Dam). New york: Academic Press.
1966
Magnetic charge and quantum field theory. Phys. Rev. 144:1087-
1093.

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JULIAN SCHWINGER
1968
With D. Saxon. Discontinuities in Wave Guides. New york: Gordon
and Breach.
1970
Particles, Sources, and Fields. I. Reading, Mass.: Addison-Wesley.
1973
Particles, Sources, and Fields. II. Reading, Mass.: Addison-Wesley.
1978
With L. L. DeRaad Jr. and K. A. Milton. Casimir effect in dielectrics.
Ann. Phys. 115(1):1-23.
1985
With B. G. Englert. Semiclassical atom. Phys. Rev. A 32:26-35.
1986
Einstein’s Legacy: The Unity of Space and Time. New york: W. H. Free-
man and Co.
1996
The Greening of Quantum Field Theory: George and I, Lecture at
Nottingham, July 14, 1993. Printed in Julian Schwinger: The Physicist,
the Teacher, the Man, ed. y. J. Ng. Singapore: World Scientific.