Werner Heisenberg - Physics and philosophy: the revolution in modern science

PENGUIN BOOKS

Physics and Philosophy

A winner of the Nobel Prize, Werner Heisenberg was born in 1901 in Wurzberg, Germany. He studied physics at the University of Munich and for his Ph.D. wrote a dissertation on turbulence in fluid streams.

Interested in Niels Bohr's account of the planetary atom, Heisenberg studied under Max Born at the University of Gottingen and then, in 1924, went to the Universitets Institut for Teoretisk Fysik in Copenhagen, where he studied under Bohr. In 1925 he published a paper, bout the Quantum-theoretical Reinterpretation of Kinetic and Mechanical Relationships', in which he proposed a reinterpretation of the basic concepts of mechanics, and this was followed by the publication of his indeterminacy principle in 1927. In that year he became professor at the University of Leipzig and held the post until 1941, when he was appointed director of the Kaiser Wilhelm Institute for Physics in Berlin. After the war he organized and became director of the Max Planck Institute for Physics and Astrophysics at Gottingen, later moving with the institute, in 1958, to Munich. As a public figure, he actively promoted the peaceful use of atomic power and, in 1957, led other German scientists in opposing a move to equip the West German army with nuclear weapons. In 1970 he became Director Emeritus of the Max Planck Institute. Heisenberg was awarded the Nobel Prize in 1932 and received numerous other honours. He died in 1976.

Paul Davies is an internationally acclaimed physicist, writer and broad-caster, now based in South Australia.

He obtained a Ph.D. from the University of London and has worked at the universities of London, Cambridge, Newcastle upon Tyne and Adelaide. He is currently Professor of Natural Philosophy at the Australian Centre for Astrobiology, Macquarie University, Sydney, and he holds a Visiting Professorship at Imperial College in London. His research interests are in the field of black holes, cosmology and quantum gravity. Professor Davies is the author of more than twenty books, including, in Penguin, Superforce, OtherWorlds, God and the New Physics, The Edge of Infinity, The Mind of God, The Cosmic Blueprint, Are WeAlone?, The Fifth Miracle and About Time.

He is the recipient of a Glaxo Science Writers' Fellowship, an Advance Australia Award and a Eureka prize for his contributions to Australian science, and in 1995 he won the prestigious Templeton Prize for his work on the deeper meaning of science. The Mind of God won the 1992 Eureka book prize and was also shortlisted for the Rhone-Poulenc Science Book Prize, as was About Time

in 1996 .

W E R N E R H E I S E N B E R G

Physics and Philosophy

The Revolution in Modern Science

Introduction by Paul Davies

PENGUIN BOOKS

Penguin Books Ltd, 8o Strand, London wczR 0 R L , England Penguin Putnam Inc., 375 Hudson Street, New York, New York 10014, USA Penguin Books Australia Ltd, 250 Camberwell Road, Camberwell, Victoria 3124, Australia Penguin Books Canada Ltd, 10 Alcorn Avenue, Toronto, Ontario, Canada M4V 3B2

Penguin Books India (P) Ltd, u, Community Centre, Panchsheel Park, New Delhi 110 017, India Penguin Books (NZ) Ltd, Cnr Rosedale and Airborne Roads, Albany, Auckland, New Zealand Penguin Books (South Africa) (Pty) Ltd, 24 Sturdee Avenue, Rosebank 2196, South Africa Penguin Books Ltd, Registered Offices: 80 Strand, London wczR 0RL, England www.penguin.com First published in the USA by Harper & Row Publishers, Inc., New York, New York 1962

First published in Great Britain, by arrangement with Harper & Row Publishers, Inc., in Pelican Books 1989

Reprinted in Penguin Books 1990

Reprinted in Penguin Classics 2 0 0 0

Copyright Werner Heisenberg, 1958

Introduction copyright Paul Davies, 1989

All rights reserved

Set in 10/12.5 pt Monotype Minion

Typeset by Rowland Phototypesetting Ltd, Bury St Edmunds, Suffolk Printed and bound in Great Britain by Antony Rowe Ltd.. Chippenham, Wiltshire Except in the United States of America, this book is sold subject to the condition that it shall not, by way of trade or otherwise, be lent, re-sold, hired out, or otherwise circulated without the publisher's prior consent in any form of binding or cover other than that in which it is published and without a similar condition including this condition being imposed on the subsequent purchaser Contents

An Old and a New Tradition

The History of Quantum Theory

The Copenhagen Interpretation of Quantum Theory

Quantum Theory and the Roots of Atomic Science

The Development of Philosophical Ideas Since

Descartes in Comparison with the New Situation

in Quantum Theory

The Relation of Quantum Theory to Other Parts

of Natural Science

The Theory of Relativity

Criticism and Counterproposals to the Copenhagen

Interpretation of Quantum Theory

Quantum Theory and the Structure of Matter

Language and Reality in Modern Physics

The Role of Modern Physics in the Present

Development of Human Thinking

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True revolutions in science involve more than spectacular discoveries and rapid advances in understanding. They also change the concepts on which the subject is based. Such a fundamental transformation took place in physics during the first thirty years of this century, culminating in what has been called the Golden Age of Physics. As a result the physicist's world view has been radically and irreversibly altered.

The developments that triggered this monumental convulsion involved the formulation of two dramatically new theories. The first was a theory of space, time and motion, called relativity. The second was a theory of the nature of matter and of the forces that act upon it. The latter had its origins in Max Planck's observation that electromagnetic radiation is emitted in discrete packets, or quanta. In the 1920S this quantum theory' was elaborated into a general quantum mechanics.

The author of this book played a leading role in the early formulation of quantum mechanics and in the subsequent clarification of its revolutionary implications. Those readers who know anything at all of quantum mechanics will know that the famous uncertainty principle', a key component in quantum physics, is named after Heisenberg.

Although a great deal has recently been written about the bizarre conceptual foundations of quantum mechanics, special importance must be attached to these deliberations of one of the principal architects of the theory. Right up to his death in 1 9 7 6 Heisenberg retained a deep

interest in the nature of the quantum universe and the profound philosophical implications that flow from it. The exposition that follows is a sweeping survey of these ideas, together with an appraisal

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of the theory of relativity and some aspects of nuclear and particle physics. It is a model of clarity and one of the most lucid accounts of the so-called Copenhagen interpretation of quantum mechanics that has become the standard viewpoint.

The central theme of Heisenberg's exposition, which is based on his 19556 Gifford lectures at the University of St Andrews, is that words and concepts familiar in daily life can lose their meaning in the world of relativity and quantum physics. Thus questions about space and time, or the qualities of material objects such as their positions, which seem entirely reasonable in everyday discourse, cannot always be meaningfully answered. This in turn has profound implications for the nature of reality and for our total world view.