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Effective Dynamics of Self-Gravitating Extended Objects



S.Ansoldi1
Dipartimento di Fisica Teorica dell'Università,
Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
Strada Costiera 11, 34014-Trieste, Italy

A.Aurilia2
Department of Physics, California State Polytechnic University
Pomona, CA 91768, USA

R.Balbinot3
Dipartimento di Fisica dell'Università
Istituto Nazionale di Fisica Nucleare, Sezione di Bologna,
via Irnerio 46, 40126-Bologna, Italy

E.Spallucci4
Dipartimento di Fisica Teorica dell'Università,
Istituto Nazionale di Fisica Nucleare, Sezione di Trieste,
Strada Costiera 11, 34014-Trieste, Italy


Abstract:

We introduce an effective Lagrangian which describes the classical and semiclassical dynamics of spherically symmetric, self-gravitating objects that may populate the Universe at large and small (Planck) scale. These include wormholes, black holes and inflationary bubbles. We speculate that such objects represent some possible modes of fluctuation in the primordial spacetime foam out of which our universe was born. Several results obtained by different methods are encompassed and reinterpreted by our effective approach. As an example, we discuss: i) the gravitational nucleation coefficient for a pair of Minkowski bubbles, and ii) the nucleation coefficient of an inflationary vacuum bubble in a Minkowski background

PREFACE


IN REMEMBERANCE OF HIROOMI UMEZAWA

``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



 
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Next: 1. Introduction Up: HOME Previous: ARTICLES

Stefano Ansoldi
Department of Theoretical Physics
University of Trieste
TRIESTE - ITALY