Space, Time and Einstein: An Introduction

255 Pages·2003·3 MB·English

by  J.B. Kennedy

Space, Time and Einstein

Space, Time and Einstein
An Introduction
J. B. Kennedy
© J. B. Kennedy 2003
This book is copyright under the Berne Convention.
No reproduction without permission.
All rights reserved.
First published in 2003 by Acumen
Acumen Publishing Limited
15A Lewins Yard
East Street
Chesham HP5 1HQ
www.acumenpublishing.co.uk
ISBN: 1-902683-66-8 (hardcover)
ISBN: 1-902683-67-6 (paperback)
British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library.
Designed and typeset by Kate Williams, Abergavenny.
Printed and bound by Biddles Ltd., Guildford and King’s Lynn.
For Carole and John Crascall

Contents
Preface and acknowledgements ix
Part I: Einstein’s revolution 1
1 From Aristotle to Hiroshima 3
2 Einstein in a nutshell 7
3 The twin paradox 31
4 How to build an atomic bomb 40
5 The four-dimensional universe 50
6 Time travel is possible 66
7 Can the mind understand the world? 71
Part II: Philosophical progress 75
8 Who invented space? 77
9 Zeno’s paradoxes: is motion impossible? 92
10 Philosophers at war: Newton vs. Leibniz 104
11 The philosophy of left and right 126
12 The unreality of time 133
13 General relativity: is space curved? 139
14 The fall of geometry: is mathematics certain? 149
15 The resurrection of absolutes 159
16 The resilience of space 172
vii
SPACE, TIME AND EINSTEIN
Part III: Frontiers 175
17 Faster than light: was Einstein wrong? 177
18 The Big Bang: how did the universe begin? 185
19 Black holes: trapdoors to nowhere 188
20 Why haven’t aliens come visiting? 193
21 The inflationary and accelerating universe 197
22 Should we believe the physicists? 202
Appendix A: Spacetime diagrams 207
Appendix B: Symmetry and Lorentz’s minority interpretation 222
Appendix C: Simple formulas for special relativity 225
Appendix D: Websites 227
Appendix E: Guide to further reading 229
Index 239
viii
Preface and acknowledgements
The ongoing revolution in our understanding of space and time is so
central to the drama of our times that no educated person can remain
ignorant of it. There is no better illustration of the adventure of ideas,
nor the power and practical importance of abstract thought.
Introductory texts should be brief, easy to read and seductive. This
text aims to be the clearest philosophical introduction to relativity
theory available. It exposes the philosophical heart of issues without
jargon, mathematics or logical formulas. Our patron saint is lucidity.
It is aimed at those without a background in science, mathematics or
philosophy. The hope is to provide thoughtful readers with a sense of
where we have come from and where we are going, and thus to offer
an invitation to further studies.
This book is a threefold invitation to the philosophy of space and
time. It introduces – gently and simply – the new, revolutionary ideas
of Einstein. It introduces the concepts and arguments of philosophers,
both ancient and modern, which have proved of lasting value. Finally,
it introduces the most recent discoveries and the debates raging now,
in philosophy and physics, and points out how future developments
may unfold.
The text does aim to teach one skill. Careful thinking is at the core
of our conception of philosophy. Now that many nations have
reorganized themselves as democracies, which depend so much on
reasoned debate and persuasion, careful thinking has become a
foundation of our social and political lives as well. But clear thinking
is an art: it requires patience, practice and cultivation. This text does
not teach or use formal logic, but it pays great attention to the careful
ix