Alice in Quantumland: An Allegory of Quantum Physics

189 Pages·2013·7.28 MB·English

by  Robert Gilmore

Alice
in
Quantumland
AN ALLEGORY OF QUANTUM PHYSICS
Alice
in
Quantumland
Robert Gilmore
COPERNICUS
AN IMPRINT OF SPRINGER-VERLAG
© 1995 Springer-Verlag New York, Inc. All rights reserved. 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, or otherwise, without the prior written permission of the
publisher. Published in the United States by Copernicus Books, an imprint of Springer-Verlag New
York, LLC by arrangement with Birkhauser Boston. A member of Springer Science+Business Media
Copernicus Books 37 East 7th Street New York, NY 10003
www.copernicusbooks.com Library of Congress Cataloging-in-Publication Data Gilmore, Robert,
1938Alice in Quantumland : an allegory of quantum physics / Robert Gilmore p. cm. Includes
bibliographical references and index. ISBN 0-387-91495-1 (acid-free paper) 1. Quantum theory-
Fiction. I. Title PS3557.14595A45 1995 813 x.54- dc20 95-10163
Manufactured in the United States of America. Printed on acid-free paper. 19 18 17 16 15 14 13 12
11 ISBN 0-387-91495-1 SPIN 10992432
Preface
n the first half of the twentieth century, our understanding of the Universe was turned upside
down. The old classical theories of physics were replaced by a new way of looking at the world-
quantum mechanics. This is in many ways at variance with the ideas of the older Newtonian
mechanics; indeed, in many ways it is at variance with our common sense. Nevertheless, the strangest
thing about these theories is their extraordinary success in predicting the observed behavior of
physical systems. However nonsensical quantum mechanics may at times appear to us, that seems to
be the way that Nature wants it-and so we have to play along.
This book is an allegory of quantum physics, in the dictionary sense of "a narrative describing
one subject under the guise of another." The way that things behave in quantum mechanics seems very
odd to our normal way of thinking and is made more acceptable when we consider analogies to
situations with which we are familiar, even though the analogies may be inexact. Such analogies can
never be very true to reality as quantum processes are really quite different from our normal
experience.
An allegory is an extended analogy, or series of analogies. As such, this book follows more in
the footsteps of Pilgrim's Progress or Gulliver's Travels than of Alice in Wonderland. "Alice"
appears the more suitable model, however, when we examine the world that we inhabit.
The Quantumland in which Alice travels is rather like a theme park in which Alice is sometimes
an observer, while sometimes she behaves as a sort of particle with varying electric charge. This
Quantumland shows the essential features of the quantum world: the world that we all inhabit.
Much of the story is pure fiction and the characters are imaginary, although the "real-world"
notes described below are true. Throughout the narrative you will find many statements that are
obviously nonsensical and quite at variance with common sense. For the most part these are true.
Neils Bohr, the father figure of quantum mechanics in its early days, is said to have remarked that
anyone who did not feel dizzy when thinking about quantum theory had not understood it.
Seriously, Though . . .
The description of the world that is given by quantum mechanics is undoubtedly interesting and
remarkable, but are we seriously expected to believe that it is true? Amazingly, we find that we must.
To underline this assertion, throughout this book you will find brief notes which emphasize the
importance of quantum mechanics in the real world. The notes look like this:
There are also some longer, end-of-chapter, notes. These amplify some of the trickier points in
the text and are denoted thus:
See end-of-chapter note 1
Much of the way that quantum theory describes the world may seem at first sight to be nonsense-
and possibly it may seem so at the second, third, and twenty-fifth sight as well. It is, however, the
only game in town. The old classical mechanics of Newton and his followers is unable to give any
sort of explanation for atoms and other small systems. Quantum mechanics agrees very well with
observation. The calculations are often difficult and tedious, but where they have been made, they
have agreed perfectly with what has really been seen.
It is impossible to stress too strongly the remarkable practical success of quantum mechanics.
Although the outcome of one measurement may be random and unpredictable, the predictions of
quantum theory agree consistently with the average results obtained from many measurements. Any
large-scale observation will involve very many atoms and thus very many observations on the atomic
scale. We again find that quantum mechanics is successful, in that it automatically agrees with the
results of classical mechanics for large objects. The converse is not true.
Quantum theory was developed to explain observations made on atoms. Since its conception, it
has successfully been applied to atomic nuclei, to the strongly interacting particles which derive from
the nucleus, and to the behavior of the quarks of which these are composed. The application of the
theory has been extended over a factor of some hundred thousand million. The systems considered
have both decreased in size and increased in energy by this factor. This is a long way to extrapolate a
theory from its original conception, but so far quantum mechanics appears to be quite able to deal
with these extreme systems.
Insofar as it has been investigated, quantum mechanics appears to be of universal applicability.
On a large scale, the predictions of quantum theory lose their random aspect and agree with those of
classical mechanics, which works very well for large objects. On a small scale, however, the
predictions of quantum theory are consistently borne out by experiment. Even those predictions,
which seem to imply a nonsensical picture of the world, are supported by experimental evidence.
Intriguingly, as is discussed in Chapter 4, quantum mechanics would appear to be in the strange
position of agreeing with all observations made, while disputing that any observations can actually be
made at all. It seems that the world is stranger than we imagine and perhaps stranger than we can
imagine.
For the present, however, let us accompany Alice as she begins her journey into Quantumland.
Robert Gilmore

Contents
Into Quantumland
The Heisenberg Bank
The Mechanic's Institute
The Copenhagen School
The Fermi-Bose Academy
Virtual Reality
Atoms in the Void
Castle Rutherford
The Particle MASSquerade
The Experimental Physics Phun Phair
lice was bored. All her friends were on holiday or visiting relations and it was raining,
so that she was marooned indoors watching television. So far that afternoon she had watched part five
of a series on introductory Esperanto, a program on gardening, and a paid political broadcast. Alice
was really bored.
She looked down at the book lying on the floor beside her chair. It was a copy of Alice in
Wonderland, which she had been reading earlier and had dropped there when she finished it. "I do
not know why there cannot be more cartoons and interesting programs on the television," she
wondered idly to herself. "I wish I could be like that other Alice. She was feeling bored and then she
found her way to a land full of interesting creatures and strange happenings. If I could shrink down
somehow and float through the television screen perhaps I might find all sorts of fascinating things."
She stared in frustration at the screen, which at that moment carried a picture of the Prime
Minister telling her how, all things considered, everything was really far better than it had been three
years ago, even if it didn't always seem that way. As she watched she was mildly surprised to see the
picture of the Prime Minister's face slowly break apart into a mist of bright dancing speckles which
all seemed to be rushing inward, as if they were beckoning her. "Why," said Alice, "I do believe that
they want me to follow them in!" She leapt to her feet and started toward the television, but tripped on
the book which she had discarded so untidily on the floor and fell headlong.