Introductory Statistical Mechanics, Second Edition

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Introductory Statistical Mechanics

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Second Edition ROGER BOWLEY D"/1ur//lumt (!lPhysics. L'lIil'"rsity o(,vOltillghom

MARIANA

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SANCHEZ

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CLARENDON PRESS • OXFORD '. 1999

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OXFORD ~[vEIlSITY

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Great Clarendon Street, Oxford OX2 6DP 'Oxford University Press is a department of the Unh'ersity of Oxford. It fl!rthers the University's obje.:ti,·e of excellence in research. $cholarship, and education by publishing worldwide in Oxford New York Athens Auckland Bangkok Bogota Buenos Aires Calcutta Town Chennai Dar es Salaam Delhi Florence Hong Kong Istanbul . Kuala Lumpur !'.fadrid Melbourne Mexico City !'.Iumbai ..........';rt,h,· Paris Silo Paulo Singapore Taipei Tokyo Toronto Warmv with associa,ted companies in Berlin Ibadan

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Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries Published in the United States by Oxford Uninirsity Prcss Inc., Ncw York

To Alexander Edward and Peter Anthony Xavier.

© R. M. Bowley and M. Sanchez. 1996, 1999 The moral rights oflhe authors ha,'e been asserted Database right Oxford University Press (maker) Fim publishcd 1996 Second edition 1999 All rights reserved. No part of this publication may bc repr"duccd. stored in J retrie"al system. N transmilled. in any fonn or by any means. •. withClut the prior pennissi,'n in writing of Oxford Univcr$ity Press. or as expressly pemlitted by law. or under tenns agreed with the appropriate reprographie rights organization. Enquiries concerning reproduction outside the scope of the abo\ c should be sent to the Rights Dcpartmcnt. Oxford UniverSllY Press, at the address above You must not circulate this book in any other binding or covcr ar.d you must impo~e this same condition on any acquirer A catalogue record for this book is available from the British Library Library of Congress Cataloging in Publication Data ISBN 0 19 850575 2 (Hbk) o 19 850576 0 (Pbk)

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Typeset by the authors Printed in Greal Britain by Bookcraft (Bath) Ltd Midsomcr Norton, Avon

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Preface to the first edition

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Our aim in writing this book is to provide a clear and accessible introduction to statistical mechanics, the physics of matter made up of a large number of particles. Statistical mechanics is the theory of condensed matter. The content of our book is based on a course of lectures given to physics undergraduates at Nottingham University by one of us (R.M.B.). The lectures have been substantially revised by both of us partly to remove repetition of material-repetition that may be effective in a lecture is redundant in print-and partly to improve the presentation. Some of the history of the subject has been included during the revision, so that t.he reader may be able to appreciate the central importance of statistical mechanics to the development of physics. Some of the concepts of statistical mechanics arc old, but t.hey are as useful ami relevant now as when they were first proposed. It is our hope that students will not regard the subject as old-fashioned, and that our book will be of use to allstudent.s, not. only to those at Nottingham Cniversit.y. Thp. reader is assumed to have attended introductory courses on quantum mechanics and kinetic theory of gases, as well as having a knowledge of calculus. In Nottingham, students would have also taken a course in thermodynamics before studying statistical mechanics. The first few lectures of thE!'o