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Science · Philosophy “A brilliant and distinguished book . . . g Grandy introduces a trans-scientific r $19.95 understanding of light as a deep ordering a n principle within the universe.” d Thaddeus J. Trenn, University of Toronto y Imagine you are in a craft traveling Moving from the scientific to the T S p e e d L i g hT at great speed in the vacuum of space. existential, from Einstein to Merleau- h The of e Your task is to measure the speed of a Ponty, from light as a physical light ray coming from a star you have phenomenon to light as that which S left behind. Just as you pass a station- is constitutive of reality, this mind- p ary space platform nearby, another expanding exploration of light and observer will measure the same light how we experience the universe is e ray. Your intuition tells you that the quite a trip. David A. Grandy asks e light speed you measure should be what is the nature and role of light less than that observed on the space in relation to mind and matter. d platform by exactly the velocity you Light—our experience of light, our are moving relative to the platform. measurement of light, and the notion o Yet, you both get the same result. that light speed is constant—can be f How is that possible? The fact is that understood to mark our interface L when it comes to measuring and with the cosmos. To measure the i calculating speed, only light returns speed of light is to measure some- g the same value to all observers. thing about the way we are measured or blended into the cosmos, and that h universal blending predetermines our measurement of light speed in favor T of a universal or constant value. ConSTanCy + CoSmoS david a . g randy INDIANA David A. Grandy is Professor of Philosophy at Brigham Young University University Press and author (with Dan Burton) of Bloomington & Indianapolis Magic, Mystery, and Science (Indiana www.iupress.indiana.edu University Press, 2004) and Leo 1-800-842-6796 Szilard: Science as a Mode of Being. INDIANA SpeedLmec2.indd 1 5/5/09 3:25:39 PM S p e e d L i g hT The of Indiana University Press Bloomington & Indianapolis S p e e d L i g hT The of ConSTanCy + CoSmoS david a . g randy This book is a publication of Indiana University Press 601 North Morton Street Bloomington, IN 47404-3797 USA http://iupress.indiana.edu Telephone orders 800-842-6796 Fax orders 812-855-7931 Orders by e-mail [email protected] © 2009 by David A. Grandy 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 and recording, or by any information storage and retrieval system, without permission in writing from the publisher. The Association of American University Presses’ Resolution on Permissions constitutes the only exception to this prohibition. ∞ The paper used in this publication meets the minimum requirements of American National Standard for Information Sciences—Permanence of Paper for Printed Library Materials, ANSI Z39.48-1992. Manufactured in the United States of America Library of Congress Cataloging-in-Publication Data Grandy, David. The speed of light : constancy and cosmos / David A. Grandy. p. cm. Includes bibliographical references and index. ISBN 978-0-253-35322-1 (cloth : alk. paper) — ISBN 978-0-253-22086-8 (pbk. : alk. paper) 1. Light—Speed. 2. Space and time. 3. Time—Philosophy. I. Title. QC407.G73 2009 535—dc22 2008043194 1 2 3 4 5 14 13 12 11 10 09 To my parents, Grant and Barbara Grandy For as the eyes of bats are to the light of day, so is the intellect of our soul to the objects which in their nature are most evident of all. Aristotle ConTenTS acknowledgments xi Introduction 1 1 Space, Time, and Light Speed Constancy 10 2 Special Relativity 24 3 Horizonal Light 36 4 Experiential Light 48 5 Relational Light 60 6 Internal Relations 70 7 Light in a Vacuum 86 8 Ambient Light 96 9 Pre-reflective Experience 114 10 Body, World, and Light 128 11 Existential Light 146 Notes 166 Bibliography 182 Index 190