Brian Clegg - Light Years: The Extraordinary Story of Mankind’s Fascination with Light

Praise for the previous editions of Light Years

A fascinating book on a fascinating subject. It brings together all aspects of light in an unusual and compelling way.
Sir Patrick Moore

Lights properties often seem mysterious to the point of being unfathomable. Yet in this extraordinary book Brian Clegg manages to explain them through the lives of those so fixated with light that they have shaped our perception of it Cleggs accessible writing style manages to encapsulate the lives of lights disciples with humorous and interesting anecdotes [He] also provides real scientific insight into how light behaves. He explains complex theories through lucid metaphors, without resorting to the elaborate diagrams so beloved of some popular science writers Clegg indulges in future gazing, too, the results of which are quite awesome
Karen Peploe, New Scientist

This immensely likeable work of pop science traces mans enduring fascination with light, from Aristotles plans for a death ray (burning enemy ships with a giant array of mirrors) through to a recent experiment that seems to have sent Mozarts 40th Symphony faster than light, and thus back through time. Clegg is very good at explaining the bizarre properties of light Steven Poole, The Guardian

A fascinating, non-technical treatment of the concept of light an excellent resource makes for compelling reading. ScienceScope, the magazine of the US National Science Teachers Association

LIGHT
YEARS

LIGHT YEARS

THE EXTRAORDINARY
STORY OF MANKINDS
FASCINATION
WITH LIGHT

BRIAN CLEGG

This revised edition published in the UK in 2015 by
Icon Books Ltd, Omnibus Business Centre,
3941 North Road, London N7 9DP
email:
www.iconbooks.com

Originally published in 2001 by Piatkus,
and in a fully revised version in 2008 by Macmillan

Sold in the UK, Europe and Asia
by Faber & Faber Ltd
Bloomsbury House, 7477 Great Russell Street,
London WC1B 3DA or their agents

Distributed in the UK, Europe and Asia
by TBS Ltd, TBS Distribution Centre, Colchester Road,
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Distributed in the USA by
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Distributed in Australia and New Zealand by
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Distributed in South Africa by
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Distributed in Canada by Publishers Group Canada,
76 Stafford Street, Unit 300
Toronto, Ontario M6J 2S1

ISBN: 978-184831-814-4

Text copyright 2008, 2015 Brian Clegg

The author has asserted his moral rights.

No part of this book may be reproduced in any form, or by any
means, without prior permission in writing from the publisher.

Typeset in Janson Text by Marie Doherty

Printed and bound in the UK
by Clays Ltd, St Ives plc

About the author

Science writer Brian Clegg studied physics at Cambridge University and specialises in making the strangest aspects of the universe from infinity to time travel and quantum theory accessible to the general reader. He is editor of www.popularscience.co.uk and a Fellow of the Royal Society of Arts. His previous books include Inflight Science, Build Your Own Time Machine, The Universe Inside You, Dice World, The Quantum Age, Science for Life and Introducing Infinity: A Graphic Guide.

www.brianclegg.net

Preface

And God said
Let there be light:
And there was light.
GENESIS 1:3

L ight is something that we take for granted. It is a fact of life, available at the press of a switch. It is the absence of darkness, the everyday gift of the Sun. It is a small part of the physics we are taught at school, a thing of ray diagrams and geometry, a natural phenomenon without substance. But light is not so easily compartmentalized. Its beguiling combination of fragility and endurance, of delicacy and power, captures the imagination just as it has fascinated scientists through the ages.

For thousands of years, uncovering the nature of light has proved an irresistible challenge. It forms a scientific quest that has endured from the conjectures of the ancient Greeks to the work of twentieth century geniuses like Albert Einstein and Richard Feynman. By combining lights history with the latest research we can assemble a complete picture of this remarkable phenomenon and its place at the centre of creation.

What first was seen as merely the mechanism of sight has proved to be so much more. The source of all life on Earth, providing warmth, powering the weather, driving the photo-synthetic process that generates oxygen. The self-sustaining interplay of magnetism and electricity that lies behind Einsteins special relativity. The fundamental glue that keeps all matter together. And perhaps even the key to time itself.

Looking back at the life and work of the extraordinary people who have uncovered lights secrets provides both an understanding of light and a front row seat in the development of the remarkable new light-based technologies that are appearing as we enter the twenty-first century. Technologies that have the potential to transform reality itself.

When I was at university studying physics, I was overwhelmed by the power and beauty of light, yet so much that I read at the time on this remarkable subject made it seem dull. You only have to look at optical diagrams with rays and lenses and focal points to feel a yawn coming on. Coming back to light now has been wonderful, a chance to rekindle the amazement and delight I felt 30 years ago. That sense of wonder is what Light Years is all about.

Acknowledgements

Thanks to all those who have helped in the production of various editions of this book, including my former agent Peter Cox, Sara Abdulla and Duncan Heath.

Specific thanks to Professor Edward H. Adelson, for permission to reproduce his stunning optical illusion, and Professor Gnter Nimtz for his considerable input and helpful comments on the manuscript. And a final thank you to the many individuals who have patiently helped with information and assistance. It would be boring to list them, but they know who they are.

Chapter One

At the speed of light

For now we see through a glass, darkly.
ST PAUL

I magine this. The dawn light is creeping into your room. You get up from your bed and open the curtains. Outside the window, the inferno of an active volcano distorts the air. A river of red-hot lava is streaming down the scarred mountain-side. A rain of ash falls near the window, yet you hear nothing, feel nothing.

Quickly, you move to the second window and pull back the curtain. Here, even though its morning, the sky is black, a crisper black than you have ever seen. The stars stand out, laser sharp. Before you is a rugged, near-white plain, surrounded by impossibly high, needle peaks. And then your eye is caught by something else. Standing out from the blackness is a bright circle of blues and greens with traceries of white. You are seeing the Earth from the surface of the Moon.

Nervously, half-expecting the air to rush out of the room, you open the window, to be struck by a burst of vertigo. Behind the glass is a leaden yellow-grey sky, hanging heavy over the already-bustling city streets 25 floors below. Nothing that you saw through the window glass exists. There is no volcano, no lunar landscape; there are no stars.

A magical tunnel

Close the window again and still the Earth is riding serenely in the sky. Its as if the windows glass were not looking out of the side of the building, but opening instead onto a magical tunnel leading straight onto the surface of the Moon. There are no video screens or electronics involved, just glass with very special properties. This is slow glass, first dreamed up by the 1970s visionary writer Bob Shaw. A special glass that light takes months or even years to pass through.