The Universe And The Atom PDF
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THE UNIVERSE ATOM AND THE TThhiiss ppaaggee iinntteennttiioonnaallllyy lleefftt bbllaannkk T H E U N I V E R S E AND THE ATOM Don Lichtenberg Indiana University, Bloomington, USA World Scientific N E W J E R S E Y • L O N D O N • S I N G A P O R E • B E I J I N G • S H A N G H A I • H O N G K O N G • TA I P E I • C H E N N A I (cid:13)(cid:10) Published by World Scientific Publishing Co. Pte. Ltd. 5 Toh Tuck Link, Singapore 596224 USA office: 27 Warren Street, Suite 401-402, Hackensack, NJ 07601 UK office: 57 Shelton Street, Covent Garden, London WC2H 9HE British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. THE UNIVERSE AND THE ATOM Copyright © 2007 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage and retrieval system now known or to be invented, without written permission from the Publisher. For photocopying of material in this volume, please pay a copying fee through the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. In this case permission to photocopy is not required from the publisher. ISBN-13 978-981-270-606-5 ISBN-10 981-270-606-2 ISBN-13 978-981-270-561-7 (pbk) ISBN-10 981-270-561-9 (pbk) Printed in Singapore. To Rita, Naomi and Rebecca TThhiiss ppaaggee iinntteennttiioonnaallllyy lleefftt bbllaannkk Preface One thing that distinguishes human beings from the other animals is our curiosity about nature. A wolf may look at the moon and howl at it, but only human beings want to know how big it is and howfar away,what itismadeof andwhy itchangesits appearance. More generally, we want to know the way nature works, even if our knowledge brings no practical bene(cid:2)t. As history has turned out so far, some of the knowledge we have gained about nature has not helpedusmateriallyatall,butotherknowledgehasledtoprofound changesinourcivilization. Unfortunately,notallthesechangeshave beenfor thegood. Our senses let us perceive nature only at intermediate sizes, but notattheverysmallandtheverylarge. Wecanlook atatreebutwe cannot seethe atomsthat makeupthetree. Wecanlook ataportion of the earth, but our vantage point does not let us see directly that theearthisasphere. Inthisbookweshallbeprincipallyconcernedwithnatureatboth the smallest and the largest scales, from atomic and subatomic par- ticles to the universe as a whole. We want to answer as well we can the questions: (cid:147)What are we made of?(cid:148) and (cid:147)What is the nature of theuniverseinwhichwelive?(cid:148) vii viii PREFACE We are, of course, made of (cid:3)esh and blood, bones and hair, and we live on the earth. But on a smaller scale our bodies are made of cells, and the cells are made of molecules. In turn, the molecules are made of atoms, and atoms are made of electrons and atomic nu- clei. As far as we know, the electrons are elementary in the sense that they are not composed of smaller things. However, atomic nu- clei are made of protons and neutrons, which in turn are made of quarks. That is where our present understanding of the nature of matter ends, although there are speculations about even deeper lev- els. Onalargerscale,theearthisthethirdplanetfromthesuninour solar system, and the solar system is in our galaxy, the Milky Way, whichisasystemofmorethanahundredbillionstarsplusdustand other kinds of matter held subject to their mutual gravitational at- traction. The Milky Way in turn is only one galaxy (system of stars) of many billions of galaxies that exist in the visible universe. And therehavebeenspeculationsabout whatliesbeyondthevisibleuni- verseandwhetherwecaneverknowanything about it. We are about to take a journey into the world of the very small andtheworldoftheverylarge. Whatweshall(cid:2)ndwillbesoforeign to our senses and so much against our intuition as to be almost be- yond belief. Mankind has long thought about what matter is made of andwhat theuniverse islike. However,itwas not untilthe twen- tieth century that our knowledge has grown so much that today we have a largely coherent picture at what nature is like at both large andsmallscales. Inordertomakesenseoutoftheverylargeandtheverysmall,we have to devote some of our effort to examining nature on a human PREFACE ix scale. Inthisway,welearnsomeofthelawsofphysicsthatweneed, and we also learn of some laws that seem to satisfy common sense, but have only a limited range of validity. We often take a historical approachanddiscussoldideasthatseemeitherquaintorsillytoday, but it is bene(cid:2)cial to learn what went wrong with earlier scienti(cid:2)c ideas. Scienti(cid:2)cknowledgeisalwaysprovisional. Basedonpastexperi- ence, we can be con(cid:2)dent that new discoveries will change the way we look at nature in many ways. However, many of our present ideas are rooted (cid:2)rmly in the results of a large number of observa- tions and experiments, and so we can be con(cid:2)dent that much of our presentpicture willendure. ThebibliographycontainsanumberofbooksonthetopicsItreat here. I acknowledge freely consulting several of these books to ob- tain part of the material I used. I consulted other sources, especially on the web, as well. I have made decisions about what informa- tion to include, updated material when necessary, and put my own stamp on the presentation. I also acknowledge bene(cid:2)cial conver- sations with my good friends and colleages at Indiana University, Steven Gottlieb and Roger Newton. I am thankful to Bruce Car- penter of IndianaUniversity for doing the drawings andto Andrew Chan Yeu Tong for his assistance with the editing and Alvin Chong ofWorldScienti(cid:2)c forhis cooperation inpublishingthis book.
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