S.Ansoldi1
Dipartimento di Fisica Teorica dell'Università,
Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
Strada Costiera 11, 34014-Trieste, Italy
``Umezawa vive e interpreta personalmente la Meccanica Quantistica'', a
colleague of ours at the University of Naples once said of Hiroomi
Umezawa.
Loosely translated, that quote is a statement about Umezawa's involment
with the quantum world of particles and fields; an involment as intense,
personal and creative as only a love affair can be. That passion
sustained
him throughout a lifetime of research, solitary at times, nomadic in some
respect, but always enriched by the beauty that he uncovered in his
relentless effort to make some sense of the world around us. Many claim
to
possess that drive, but few are compelled to act because of it. Among
that
company, Umezawa is singled out by his creative use of quantum field
theory, the theoretical framework common to many branches of physics
today.
This ``creative'' aspect of Umezawa, the physicist, is particularly
significant
to me and I wish to expand slightly on it. To my mind, quantum field
theory
was to Umezawa what a ``music score'' is to a composer, namely, a
powerful
tool to crystallize and to project out of one's inner ego, deep thoughts,
emotions and perceptions about the world we live in. Of course, one could
draw a parallel with other forms of artistic expression. However, as it
happens, Umezawa was especially fond of classical music (and the whole
array of musical equipment that goes with it). Schumann was one of his
favorite composers, ``because of his crazyness'', in Hiroomi's own words.
Like Schumann's music scores, Umezawa's ``physics scores'' are sometimes
difficult to comprehend, but one cannot fail to appreciate their
originality,
as I did, when, as an undergraduate student of Hiroomi at the University
of
Naples, I was confronted with his first book on quantum field theory.
In 1966, Umezawa left Italy to join the Physics Department at the
University of Wisconsin-Milwaukee. In 1967 I followed him, and, of
course,
my life changed forever. I still remember vividly the many nights spent
at Umezawa's house discussing physics, politics, history,
philosophy, ...until the early hours in the morning, ...
with the sound of
classical music in the background. In retrospect, those long, ponderous
conversations in broken english (interrupted by a stream of delicious
``Japanese snacks'' exquisitely prepared by Mrs. Umezawa), were formative
as
well as informative and amounted to a worldly experience destined to have
a
profound
and lasting influence on a young graduate student suddenly transplanted
from Naples to a Japanese home in Milwaukee, Wisconsin.
After my graduation in 1970, we hardly kept in touch. This may sound
strange, but it isn't: I guess ``children'' have to grow up, and I simply
moved
along my world-line, intellectually speaking. However, there was a bond
between us that no geographical separation, nor length of time could
possibly break.
1974 represents another turning point in my life and in my relationship
with
Umezawa. In that year I returned to Italy, at a time when the world was
feeling the convulsions of the end of the Vietnam war, the Nixon era,
etc.
By then I was married, with our first son on his way. From the narrow and
strangely detached vantage point of high energy physics, it was the time
when the discovery of special ``string-like'' solutions in quantum field
theory was attracting the attention of most theoretical physicists
because
of their potential use as simulators of meson resonances. At that time,
gravity played no role in particle physics, and general relativity was
the
playground of a distinctly narrow academic community of mathematical
physicists. At any rate, with different motivations and methodologies,
both
Umezawa and I became interested in the general properties of strings and
other relativistic extended objects.
With hindsight, as I write these lines close to my 54th birthday, I am
pondering the impact that Umezawa has had on my research as well as on
the international physics community. My assessment is that Umezawa was,
and remains one of the most original thinkers among the post-world-war
generation of physicists: his methodology of physics is not
``mainstream''. It
never was. Neverthless, it represents an intellectual legacy that
stretches
across the continents, as witnessed by the remarkable group of people
contributing to this memorial volume of Physics Essays. Many of these
authors are now conducting their own original research, and the essay
that
follows is intended as a tribute to Umezawa's creative genius and as an
acknowledgement of his far reaching influence, direct or indirect, on
other's
people work. The
essay is submitted by a group of four physicists, three of whom never met
Umezawa. However, they are talented enough to be able to read and play
his
``physics scores'', while adding their own characteristic key-notes.
Thus,
the essay deals with the theory of closed membranes, in the presence of
gravity, with an eye on the fundamental, but as yet poorly understood,
physical processes taking place in
the early universe. At first glance, this may seem somewhat removed from
Umezawa's major interests in physics. On closer inspection, however, the
attentive reader will recognize that the underlying ``music score'' is a
variation on a major theme by that great physics composer.
Farewell, Hiroomi.
Antonio Aurilia
Upland, California
May 1,1996
Stefano Ansoldi
Department of Theoretical Physics
University of Trieste
TRIESTE - ITALY