Alan Turing Alan Turing Computing Genius and Wartime Code Breaker HARRY HENDERSON Alan Turing: Computing Genius and Wartime Code Breaker Copyright © 2011 by Harry Henderson All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval systems, without permission in writing from the publisher. For information contact: Chelsea House An imprint of Infobase Publishing 132 West 31st Street New York NY 10001 Library of Congress Cataloging-in-Publication Data Henderson, Harry, 1951– Alan Turing : computing genius and wartime code breaker / Harry Henderson. p. cm.—(Makers of modern science) Includes bibliographical references and index. ISBN 978-0-8160-6175-4 ISBN 978-1-4381-3514-4 (e-book) 1. Turing, Alan Mathison, 1912–1954—Juvenile literature. 2. Mathematicians— Great Britain—Biography—Juvenile literature. I. Title. II. Series. QA29.T8H46. 2011 510.92—dc22 2010015798 Chelsea House books are available at special discounts when purchased in bulk quantities for businesses, associations, institutions, or sales promotions. Please call our Special Sales Department in New York at (212) 967-8800 or (800) 322-8755. You can find Chelsea House on the World Wide Web at http://www.chelseahouse.com Excerpts included herewith have been reprinted by permission of the copyright hold- ers; the author has made every effort to contact copyright holders. The publishers will be glad to rectify, in future editions, any errors or omissions brought to their notice. Text design by Kerry Casey Composition by Keith Trego Illustrations by Sholto Ainslie Photo research by Suzanne M. Tibor Cover printed by Art Print, Taylor, Pa. Book printed and bound by Maple Press, York, Pa. Date printed: February 2011 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 This book is printed on acid-free paper. For Will and Thad In gratitude for many hours of universal human conversation $ Contents Preface xi Acknowledgments xv Introduction xvii 1 An Unusual Child 1 Absent Parents 2 Hazelhurst 4 Sherborne School 5 An Intrepid Journey 6 Public School Life 7 The Public School in British Culture 7 Flashes of Genius 8 The Discovery of Friendship 10 Death of a Friend 11 The “Nature of Spirit” 12 2 The Frontiers of Mathematics 14 New Intellectual Opportunities 15 Mathematical Hurdles 17 The Scope of Mathematics 19 Mathematical Logic 20 Hilbert’s Challenge 22 3 Calculating Minds 24 From Abacus to Calculator 25 Babbage, Lovelace, and Their “Difference Engine” 26 Mechanical Calculators 28 Boole’s Bridge to the Computer 29 The Turing Machine 30 The Power of Simplicity 32 A Universal Machine 34 Graduate Study at Princeton 35 4 Enigma 39 The German Enigma 41 A Fiendishly Complicated Machine 42 The First Assault on the Enigma 45 Turing and Bletchley Park 47 The Battle of the Atlantic 48 New Code-breaking Techniques 50 Bletchley Park Today 52 A Desperate Plan 56 Turing Goes Afield 57 Electronics Advances 59 The Song of Delilah 60 5 The Birth of the Computer 63 Colossus: a Forgotten Computer 66 The First Electronic Computers 68 Who Was First—Turing or von Neumann? 70 A “Baby” Is Born 73 Christopher Strachey: Creative Computer Scientist 75 “Building a Brain” 76 6 Can Machines Think? 78 From Turbochamp to Deep Blue 79 Turing, Robots, and Machines That Learn 83 The Turing Test 84 Passing the Turing Test 86 Turing Begins the AI Debate 87 Will Computers Ever Be Smarter than People? 88 Turing’s Legacy in AI 90 7 The Poisoned Apple 92 Patterns of Development 93 The Code Breaker’s Secret 95 A Fateful Turn 96 Verdict and Aftermath 97 Homosexuality and the Law in Britain 98 Turing’s Inner Journey 101 Ambiguous Death and Certain Tragedy 102 Conclusion: Turing’s Shrouded Legacy 107 Mathematics and Computing 107 Artificial Intelligence 108 The Human Moment 109 Turing Today 111 Chronology 113 Glossary 119 Further Resources 123 Index 129