Walter Thirring – författare

This volume combines the enlarged and corrected editions of both volumes on classical physics of Thirring's famous course in mathematical physics. With numerous examples and remarks accompanying the text, it is suitable as a textbook for students in physics, mathematics, and applied mathematics. The treatment of classical dynamical systems uses analysis on manifolds to provide the mathematical setting for discussions of Hamiltonian systems, canonical transformations, constants of motion, and pertubation theory. Problems discussed in considerable detail include: nonrelativistic motion of particles and systems, relativistic motion in electromagnetic and gravitational fields, and the structure of black holes. The treatment of classical fields uses the language of differenial geometry throughout, treating both Maxwell's and Einstein's equations in a compact and clear fashion. The book includes discussions of the electromagnetic field due to known charge distributions and in the presence of conductors as well as a new section on gauge theories.It discusses the solutions of the Einstein equations for maximally symmetric spaces and spaces with maximally symmetric submanifolds; it concludes by applying these results to the life and death of stars.

The last decade has seen a considerable renaissance in the realm of classical dynamical systems, and many things that may have appeared mathematically overly sophisticated at the time of the first appearance of this textbook have since become the everyday tools of working physicists. This new edition is intended to take this development into account. I have also tried to make the book more readable and to eradicate errors. Since the first edition already contained plenty of material for a one­ semester course, new material was added only when some of the original could be dropped or simplified. Even so, it was necessary to expand the chap­ ter with the proof of the K-A-M Theorem to make allowances for the cur­ rent trend in physics. This involved not only the use of more refined mathe­ matical tools, but also a reevaluation of the word "fundamental. " What was earlier dismissed as a grubby calculation is now seen as the consequence of a deep principle. Even Kepler's laws, which determine the radii of the planetary orbits, and which used to be passed over in silence as mystical nonsense, seem to point the way to a truth unattainable by superficial observation: The ratios of the radii of Platonic solids to the radii of inscribed Platonic solids are irrational, but satisfy algebraic equations of lower order.

In the past decade the language and methods ofmodern differential geometry have been increasingly used in theoretical physics. What seemed extravagant when this book first appeared 12 years ago, as lecture notes, is now a commonplace. This fact has strengthened my belief that today students of theoretical physics have to learn that language-and the sooner the better. Afterall, they willbe the professors ofthe twenty-first century and it would be absurd if they were to teach then the mathematics of the nineteenth century. Thus for this new edition I did not change the mathematical language. Apart from correcting some mistakes I have only added a section on gauge theories. In the last decade it has become evident that these theories describe fundamental interactions, and on the classical level their structure is suffi­ cientlyclear to qualify them for the minimum amount ofknowledge required by a theoretician. It is with much regret that I had to refrain from in­ corporating the interesting developments in Kaluza-Klein theories and in cosmology, but I felt bound to my promise not to burden the students with theoretical speculations for which there is no experimental evidence. I am indebted to many people for suggestions concerning this volume. In particular, P. Aichelburg, H. Rumpf and H. Urbantke have contributed generously to corrections and improvements. Finally, I would like to thank Dr. 1. Dahl-Jensen for redoing some of the figures on the computer.

Die Sprache und die Methoden der modernen Differentialgeometrie sind in der vergangenen Dekade immer mehr in die theoretische Physik eingedrungen. Was vor 15 Jahren, als das Buch zuerst als Vorlesungsskriptum herauskam, noch extravagant erschien, ist heute ein Gemeinplatz. Dies hat mich in der Ansicht gestärkt, daß die Studenten der theoretischen Physik diese Sprache lernen müssen, je eher desto besser. Schließlich werden sie die Professoren des 21. Jahrhunderts sein und es wäre absurd, würden sie dann die Mathematik des 19. Jahrhunderts lehren. Daher habe ich in der neuen Auflage auf dieser Symbolik beharrt, einige Fehler korrigiert und ein Kapi­ tel über Eichtheorien hinzugefügt. Da es sich gezeigt hat, daß sie die fundamentalen Wechselwirkungen beschreiben und ihre Struktur zumindest auf dem klassischen Ni­ veau hinreichend klar ist, scheinen sie mir zur Minimalausrüstung zu gehören, über die jeder Theoretiker verfügen muß. Mit Bedauern mußte ich davon Abstand nehmen, die neueren Entwicklungen der Kosmologie und Kaluza-Klein-artige Theorien aufzu­ nehmen, aber ich fühlte mich an mein ursprüngliches Versprechen gebunden, den Studenten keine theoretischen Spekulationen aufzubürden, für die es keine sichere experimentelle Evidenz gibt. Vielen Physikern bin ich für Hinweise bezüglich dieses Bandes sehr verpflichtet. Insbesondere P. Aichelburg, H. Rumpf und vor allem H. Urbantke haben zahlreiche Korrekturen und Verbesserungen angebracht. I. Dahl-Jensen sei dafür gedankt, daß sie manche nach Gefühl angefertigte Zeichnungen mit dem Computer ins richtige Lot gebracht hat.

In der Quantentheorie werden Observable durch Operatoren im Hilbert-Raum dargestellt. Der dafür geeignete mathematische Rahmen sind die Cx - Algebren, welche Matrizen und komplexe Funktionen verallgemeinern. Allerdings benötigt man in der Physik auch unbeschränkte Operatoren, deren Problematik eigens untersucht werden muß. Dementsprechend werden zunächst mathematische Fragen studiert und dann die Methoden auf atomare Systeme angewandt. Obgleich man außer dem Wasserstoffatom kaum explizit lösbare Probleme findet, lassen sich nicht nur allgemeine qualitative Fragen, etwa bezüglich des Energiespektrums und Streuverhaltens, beantworten, sondern auch quantitativ kann man auch für kompliziertere Systeme für meßbare Größen Schranken teils befriedigender Genauigkeit finden.Inhaltsverzeichnis:Einleitung: Die Struktur der Quantentheorie; Größenordnungen atomarer Systeme.-Die mathematische Formulierung der Quantenmechanik: Lineare Räume; Algebren; Darstellungen im Hilbertraum; Einparametrige Gruppen; Unbeschränkte Operatoren und quadratische Formen.-Quantendynamik: Das Weyl-System; Der Drehimpuls; Die Zeitentwicklung; Der Limes t ; Störungstheorie; Stationäre Streutheorie.-Atomare Systeme: Das Wasserstoffatom; Das H-Atom in äußeren Feldern; Heliumartige Atome; Streuung am einfachen Atom; Komplexe Atome; Kernbewegung und einfache Moleküle.

This fourth edition of selecta of my work on the stability of matter contains recent work on two topics that continue to fascinate me: Quantum electrodynamics (QED) and the Bose gas. Three papers have been added to Part VII on QED. As I mentioned in the preface to the third edition, there must be a way to formulate a non-perturbative QED, presumably with an ultraviolet cutoff, that correctly describes low energy physics, i.e., ordinary matter and its interaction with the electromagnetic field. The new paper VII.5, which “quantizes” the results in V.9, shows that the elementary ‘no-pair’ version of relativistic QED (using the Dirac operator) is unstable when many-body effects are taken into account. Stability can be restored, however, if the Dirac operator with the field, instead of the bare Dirac operator, is used to define an electron. Thus, the notion of a “bare” electron without its self-field is physically questionable.

This edition combines the earlier two volumes on Quantum Mechanics of Atoms and Molecules and on Quantum Mechanics of Large Systems, thus including in a single volume the material for a two-semester course on quantum physics. Since this volume is already quite heavy, I could not include many new results which show how lively the subject is. I just want to mention that inequality (IV:4. 1. l. 1) has been sharpened by T. Weidl by a factor 2][ and the difficult problem 1 of (III:4. 6) has been solved by A. Martin. I have to thank N. Ilieva for the devotion in preparing this new edition. Vienna, November 2001 Walter Thirring Preface to the Second Edition: Quantum Mechanics of Atoms and Molecules Ever since the first edition of this volume appeared in 1980 quantum statistical mechanics has florished. Innumerable results in many areas have been obtained and it would require a series of volumes to do justice to all of them. On the other hand the first edition was already rather crowded with many details so it would not be overburdened any more. Thus I added only one chapter on quantum ergodic theory where one can get the main notions across without too much pain. Nevertheless many subjects treated in the book had splendidely developed ever since and the only way out I could see is to add some recent references which the interested reader can consult.

This edition combines the earlier two volumes on Quantum Mechanics of Atoms and Molecules and on Quantum Mechanics of Large Systems, thus including in a single volume the material for a two-semester course on quantum physics.

The book addresses three major topics in mathematical physics: 1. recent rigorous results in potential theory with appli- cations in particle physics, 2. analyticity in quantum field theory and its applica- tions, and 3. fundamentals and applications of the inverse problem. In addition, the book contains some contributions on questions of general interest in quantum field theory such as nonperturbative solutions of quantum chromodynamics, bifurcation theory applied to chiral symmetry, as well as exactly soluable models. The volume closes with a brief review of geometric approaches to particle physics and a phenomenological discussion of Higgs interactions.

In this final volume I have tried to present the subject of statistical mechanics in accordance with the basic principles of the series. The effort again entailed following Gustav Mahler's maxim, "Tradition = Schlamperei" (i.e., filth) and clearing away a large portion of this tradition-laden area. The result is a book with little in common with most other books on the subject. The ordinary perturbation-theoretic calculations are not very useful in this field. Those methods have never led to propositions of much substance. Even when perturbation series, which for the most part never converge, can be given some asymptotic meaning, it cannot be determined how close the nth order approximation comes to the exact result. Since analytic solutions of nontrivial problems are beyond human capabilities, for better or worse we must settle for sharp bounds on the quantities of interest, and can at most strive to make the degree of accuracy satisfactory.

On the occasion of the 50th anniversary of the discovery of the Schrodinger equation a small symposium was organized in Vienna. It had mainly retrospective character, where after an appreciation of Schrodinger's scientific achievements the results were collected which one could extract from his equation. Of course not all the developments which originated in Schrodingers dis­ coveries could be included. Instead, it was attempted to present a review of the established predictions which follow directly from his equation. Despite the 50 years of its existence there are always new results of this sort being found, especially because the necessary mathe­ matical methods are being developed and become known to the physicists slowly only now .. I want to take the opportunity here to thank the lecturers for their efforts which they put into their excellent talks and their written versions. With their help this volume should become a useful document on the current mathematical art in the treatment of the Schrodinger equation. Finally it is my pleasant obligation to thank the Bundesministerium fUr Wissenschaft und Forschung and the Kulturamt der Gemeinde Wien for their financial support which made it possible to honor one of the great Austrian scientists.