Electromagnetism PATHS TO RESEARCH

Transcription

1 Electromagnetism PATHS TO RESEARCH

2 Electromagnetism PATHS TO RESEARCH Edited by DORIS TEPLITZ SPRINGER SCIENCE+BUSINESS MEDIA, LLC

3 Main entry under title: Library of Congress Cataloging in Publication Data Electromagnetism: paths to research. Includes bibliographical references and index. 1. Electromagnetism. I. Teplitz, Doris, Date- QC760.E ISBN ISBN (ebook) DOI / Springer Science+Business Media New York Originally published by Plenum Press, New York in 1982 All righ ts reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher

4 CONTRIBUTORS J. B. BRONZAN, Department of Physics, Rutgers University, New Brunswick, New Jersey G. CHANMUGAM, Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana SIDNEY COLEMAN, Department of Physics, Harvard University, Cambridge, Massachusetts JOHN R. FICENEC, Department of Physics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia SONIA FROTA-PESSOA, Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo S. P., Brazil, and Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts STEPHEN MAXON, Lawrence Livermore National Laboratory, University of California, Livermore, California PHILIP PEARLE, Department of Physics, Hamilton College, Clinton, New York BRIAN B. SCHWARTZ, Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Physics, Brooklyn College of the City University of New York, Brooklyn, New York ALWYN SCOTT, Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico VIGDOR L. TEPLITZ, Strategic Affairs Division, U. S. Arms Control and Disarmament Agency, Washington, D. C , and Physics Department, University of Maryland, College Park, Maryland v

5 PREFACE The intent of this book is to make broad, significant areas of research physics accessible to students still in the process of mastering graduate electricity and magnetism. Each chapter is designed to lead from the classical, standard material of the basic graduate electromagnetism course to a particular research specialty. Each author is active in the area he or she treats. The chapters were assembled with several objectives: (1) use of the book as a complementary volume in an introductory graduate electromagnetism course; (2) use of the book in a follow-on, special topics course; (3) use of the book in off-campus courses, or by nonacademic physicists who want a view of current basic research topics; or (4) use by anyone-past the physics B.S. level-who wants an account of what is going on in these specialties today, at a level accessible to nonspecialists. There are numerous paths to research, and in today's world of competition for scarce resources the research student needs to be aware of many and prepared to travel more than one. The practicing physicist, in pursuing research problems, searches for new techniques and applications, for new ideas from other fields, and for new, deeper ways of viewing old truths. The diversity of these chapters and their authors' affiliations illustrate these ideas. Two chapters highlight the importance of developing technology: B. B. Schwartz and S. Frota-Pessoa combine a heuristic treatment of the basic elements in the theory of superconductivity with an exciting discussion of its future uses in widely varying technologies. S. Maxon's chapter contains an incisive introduction to a range of nonlinear phenomena, including a detailed treatment of solitons, a subject of growing importance to a variety of research fields, in large part made possible by the development of the large computer. Electromagnetism's interfaces with such broadly separated fields as biology and astronomy are also covered. In A. Scott's chapter on nerve fibers, one sees the dramatic interplay of different disciplines in generating models of electromagnetic life processes. In G. Chanmugam's chapter one sees the search for an understanding of electromagnetic processes in extreme forms of astronomical matter. Two chapters illustrate the continual reinterpretation of basic ideas: In a previously unpublished but widely known treatment, S. Coleman views classical electron theory from a modem field theory point of view; J. B. Bronzan reformulates magnetostatics in terms of the magnetic scalar potential. (The reader is invited to see what material of the other chapters can be profitably reformulated in terms of Bronzan's vii

6 viii Preface potential.) Finally, two chapters illustrate continuing attacks on long-standing difficult problems. P. Pearle's chapter on classical models of the electron constitutes a m~or statement in the field and contains stimulating suggestions for future developments. J. R. Ficenec and V. L. Teplitz review some recent developments in the pursuit of an explanation for nature's apparent lack of symmetry between electricity and magnetism. Always, one may conclude, the student should be prepared to seize opportunities for research as they come. S. Coleman's chapter is drawn from a paper written at a summer job when he was a graduate student, and at least three research papers were written by the authors as a result of their preparation of these chapters. The book is designed to be a textbook. Each chapter has a bibliography, annotated as appropriate; each has problems to be solved, either interspersed with the text or collected at the end, or both; where specialized terms are used, a chapter has a glossary; the Gaussian system of units is used uniformly. Aside from following this general format, however, each author has developed his or her chapter in the manner that best leads the student to the research literature of the specialty. Common reference material is collected into three appendixes. It is a pleasure to acknowledge a number of people and places. First, I am grateful to the authors, not only for their efforts on their own chapters but also for their interest in, and suggestions for, the book as a whole. The Physics Departments of Northeastern University, the University of Maryland, and Virginia Polytechnic Institute and State University were generous in their hospitality during various stages of the preparation of the book. Both the publisher and I are grateful to the Rand Corporation for allowing the use of the 1960 Rand Report Classical Electron Theory from a Modern Standpoint by S. Coleman, which comprises the bulk of his chapter, and to the American Journal of Physics, in which portions of J. Bronzan's chapter on the magnetic scalar potential previously appeared. Finally, it is a special joy to thank V. L. Teplitz for technical advice, critical reading, and unflagging interest in this project. College Park, Maryland Doris Rosenbaum Teplitz

7 CONTENTS Chapter 1 Electromagnetic Properties of Superconductors Brian B. Schwartz and Sonia Frota-Pessoa Chapter 2 Solitons, Plasma Waves, and Laser Pulses Stephen Maxon Chapter 3 Neurophysics. Alwyn Scott 109 Chapter 4 High Magnetic Fields in Stars G. Chanmugam 137 Chapter 5 Magnetic Scalar Potentials and the Multipole Expansion for Magnetostatics B. Bronzan 171 Chapter 6 Classical Electron Theory from a Modern Standpoint. Sidney Coleman 183 Chapter 7 Classical Electron Models Philip Pearle ix

8 x Contents Chapter 8 Magnetic Charges John R. Ficenec and Vigdor L. Teplitz Appendixes Appendix A: Numerical Values, Units, and Vector Operators Appendix B: Standard Equations Appendix C: Selected Functions. Index

9 Electromagnetism