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team yyepg digitally signed by team yyepg dn cn=team yyepg c=us o=team yyepg ou=team yyepg email=yyepg@msn.com reason i attest to the accuracy and integrity of this document date 2005.06.28 13:52:07 +08 00[close]
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mad about modern physics braintwisters paradoxes and curiosities franklin potter and christopher jargodzki john wiley sons inc.[close]
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this book is printed on acid-free paper copyright © 2005 by franklin potter and christopher jargodzki all rights reserved illustrations on pages 2 4 9 26 31 134 and 161 copyright © 2005 by tina cash-walsh published by john wiley sons inc hoboken new jersey published simultaneously in canada design and production by navta associates inc no part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording scanning or otherwise except as permitted under section 107 or 108 of the 1976 united states copyright act without either the prior written permission of the publisher or authorization through payment of the appropriate per-copy fee to the copyright clearance center 222 rosewood drive danvers ma 01923 978 750-8400 fax 978 646-8600 or on the web at www.copyright.com requests to the publisher for permission should be addressed to the permissions department john wiley sons inc 111 river street hoboken nj 07030 201 748-6011 fax 201 748-6008 limit of liability/disclaimer of warranty while the publisher and the author have used their best efforts in preparing this book they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose no warranty may be created or extended by sales representatives or written sales materials the advice and strategies contained herein may not be suitable for your situation you should consult with a professional where appropriate neither the publisher nor the author shall be liable for any loss of profit or any other commercial damages including but not limited to special incidental consequential or other damages for general information about our other products and services please contact our customer care department within the united states at 800 762-2974 outside the united states at 317 5723993 or fax 317 572-4002 wiley also publishes its books in a variety of electronic formats some content that appears in print may not be available in electronic books for more information about wiley products visit our web site at www.wiley.com library of congress cataloging-in-publication data potter frank date mad about modern physics braintwisters paradoxes and curiosities franklin potter and christopher jargodzki p cm includes index isbn 0-471-44855-9 1 physics popular works i jargodzki christopher ii title qc24.5.p68 2004 530 dc22 2004014941 printed in the united states of america 10 9 8 7 6 5 4 3 2 1[close]
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to my late parents who nourished my formative years and have now crossed that portal to another world f p to my late grandmother zofia lesinska who instilled in me the idea that the visible world owes its being to the invisible one c j.[close]
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contents preface acknowledgments to the reader chapter 1 chapter 2 the heat is on does anybody really know what time it is crazy circles fly me to the moon go ask alice start me up a whole new world chances are can this be real over my head crystal blue persuasion ix xii xiii 1 11 19 29 39 49 63 75 91 105 117 chapter 3 chapter 4 chapter 5 chapter 6 chapter 7 chapter 8 chapter 9 chapter 10 chapter 1 1 vii[close]
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answers the heat is on does anybody really know what time it is crazy circles fly me to the moon go ask alice start me up a whole new world chances are can this be real over my head crystal blue persuasion 139 151 164 181 192 206 224 24 1 257 27 7 125 index 287 viii contents[close]
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preface his book of almost 250 puzzles begins where our first book mad about physics braintwisters paradoxes and curiosities 2001 ended with the physics of the late nineteenth and early twentieth centuries the michelson-morley experiment of 1887 the challenges posed by atomic spectra and blackbody radiation the unexpected discoveries of x-rays in 1895 radioactivity in 1896 and the electron in 1897 all loosened the protective belt of ad hoc hypotheses around the mechanistic physics the nineteenth century had so laboriously built anomalies and paradoxes abounded ultimately necessitating a radical rethinking of the very foundations of physics and culminating in the theory of relativity and quantum mechanics numerous applications of these new and strange concepts followed very quickly as atomic and nuclear physics led to semiconductor devices on the small scale and nuclear energy on the large scale therefore we have developed a whole new set of challenges to tickle the minds of our scientifically literate readers from science students to engineers to professionals in the sciences the challenges begin with the classical problem of getting a cooked egg into a bottle through a narrow bottleneck and back out again and progress gradually to the famous aging-twin paradox of the theory of special relativity and eventually reach problems dealing with the largescale universe in between we explore the nature of time and of space as well as how the world of films and television tends to sacrifice physics for the sake of entertainment we also consider some of the more startling questions in relativity for example we ask whether a person can go on a space journey out to a star 7,000 light-years distant and return while aging only 40 years and we certainly want to emphasize the practical applications of microphysics through an examination of some properties of exotic fluids unusual motors running on air or on random motion as well as thermal electrical and photonic properties of materials in a challenging journey into the atomic world t ix[close]
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particularly important microworld challenges include what happened to schrödinger s cat can a cup of coffee be the ultimate quantum computer why is a bose-einstein condensate a new state of matter why is quantum mechanical coherent scattering so important in developing new detectors for neutrinos and gravitational waves when we reach the nucleus there are challenges about the accuracy of carbon-14 dating the reason for neutron decay and the amount of human radioactivity then our journey reverses as we reach for the stars to consider olbers paradox about why the night sky is dark instead of bursting with light how gravitational lensing by galaxies works and what the total energy in the universe might be this book finishes with a potpourri of challenges from all categories that ranges from using bicycle tracks in the mud to determine the direction of travel to analyzing water-spouting alligators and ending with a space-crawling mechanical invention that seems to defy the laws of physics the puzzles range in difficulty from simple questions e.g will an old mechanical watch run faster or slower when taken to the mountains to subtle problems requiring more analysis e.g is the bragg scattering of x-rays from an ideal crystal a coherent scattering process solutions and more than 300 references are provided and they constitute about two-thirds of the book as these examples demonstrate most of the puzzles contain an element of surprise indeed one finds that commonsense conjecture and proper physical reasoning often clash throughout this volume einstein characterized common sense as the collection of prejudices acquired by age eighteen and we agree at least in science common sense is to be refined and often transcended rather than venerated many of the challenges were devised to undermine physical preconceptions by employing paradoxes from the greek para and doxos meaning beyond belief to create cognitive dissonance far from being simply amusing paradoxes are uniquely effective in addressing specific deficiencies in understanding usually the contradiction between gut instinct and physical reasoning for some people will be so painful that they will go to great lengths to escape it even if it means having to learn some physics in the process philosopher ludwig wittgenstein considered paradoxes to be an embodiment of disquietude and as we have learned these disquietudes often foreshadow revolutionary developments in our thinking x preface[close]
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about the natural world the counterintuitive upheavals resulting from relativity theory and quantum mechanics in the twentieth century only enhanced the reputation of the paradox as an agent for change in our understanding of physical reality such disquietudes rather than unexplained experimental facts writes gerald holton in thematic origins of scientific thought were what led einstein to rethink the foundations of physics in his three papers of 1905 each begins with the statement of formal asymmetries of a predominantly aesthetic nature then proposes a general postulate not derivable directly from experience that removes the asymmetries for example in the paper on the quantum theory of light formal asymmetry existed between the discontinuous nature of particles and the continuous functions used to describe electromagnetic radiation as holton notes the discussion of the photoelectric effect for which this paper is mostly remembered occurs toward the end in a little over two pages out of the total sixteen consistent with this approach is einstein s statement in physics and reality 1936 we now realize how much in error are those theorists who believe that theory comes inductively from experience and later in the evolution of physics 1938 coauthored with the polish physicist leopold infeld physical concepts are free creations of the human mind and are not however it may seem uniquely determined by the external world as another sore point the term quantum mechanics is really a misnomer quantum systems cannot be regarded as made up of separate building blocks in the helium atom for instance we do not have electron a and electron b but simply a two-electron pattern in which all separate identity is lost this indivisible unity of the quantum world is paralleled by another kind of unity between subject and object is light a wave or a particle the answer seems to depend on the experimental setup in the double-slit experiment the observations of light yield characteristics of the box and its slits as much as of light itself is reality then observer-dependent and would this justify einstein s insistence on the power of pure thought in the construction of physical reality modern physics seems particularly adept at generating such disquietudes if that s the case then perhaps the word mad in the title of our book should not be construed as a mere metaphor preface xi[close]
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acknowledgments e all stand on the shoulders of giants as we develop our minds to become individuals living today on our planet earth and we owe so much to so many people that we cannot acknowledge all of them franklin potter would like to express appreciation to his wife patricia and their two sons david and steven for their love and inspiration through many wonderful years of family adventures he also treasures the numerous inspiring physics discussions over the decades with many friends and colleagues howard g preston gregory endo fletcher goldin david m scott john priest lowell wood julius s miller george e miller leigh h palmer charles w peck myron bander joseph weber richard feynman willard libby edward teller and kamal das gupta christopher jargodzki would like to express appreciation to myron bander of the university of california at irvine stephen reucroft of northeastern university in boston and james h taylor of central missouri state university in warrensburg his interactions with close to twenty thousand students and counting in his classes at uc irvine northeastern university and cmsu have been over the years never-ending sources of stimulation as well as occasional exasperation in fact the present volume got its start in 1975 when one of us c j still a graduate student at uc irvine put together a proposal for a book of paradoxes in modern physics partly to allay his own exasperation with the koanlike conundrums that abound in modern physics alas the project had to wait several decades for the author to mature and join forces with franklin potter in our joint inquiry into the nature of physical reality the authors hope that physical reality is duly impressed with their efforts both authors sincerely thank kate c bradford senior editor at john wiley sons inc who continues to support our paradoxical adventures into the world of physics w xii[close]
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to the reader t hese puzzles are meant to be fun how many puzzles you solve is not as important as how many you enjoy thinking about some of them are even challenging to research physicists and some were generated by research articles that have appeared only recently in physics journals so these topics may not have been part of physics just 10 years ago it would be a rare reader who could provide detailed solutions to all the puzzles indeed sometimes you may need to think a bit to even understand the answer if we included all the steps this book would double its present size we offer no apologies but we do try to provide all the key steps to make each answer complete on its own if you find the puzzles perplexing and intriguing we have succeeded in our mission mad about modern physics can be read with profit by anyone who has had some exposure to a year of introductory physics and is eager to learn more about its applications and its more recent discoveries most puzzles are nonmathematical in character and require only a qualitative application of fundamental physics principles many physics concepts are defined directly or indirectly in the questions or in the answers so they can be found with the aid of the index however even someone who knows the subject will quickly realize that the application of physics to the real world can be quite challenging and in this sense this is not an elementary book more than three hundred follow-up references provide further resources for interested readers these references to journal research papers books and magazine articles are included with only some of the puzzles typically those that are either controversial or that involve relatively new concepts there was no space to include a more complete list of references consequently we had to make choices and we apologize to the authors whose work may have been left out or inadvertently overlooked xiii[close]
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any errors are solely those of the authors and we would appreciate your communications via e-mail to franklin potter see www.sciencegems.com with regard to the puzzles and their answers xiv to the reader[close]
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