Praise for For the Love of Physics “Fascinating A delightful scientific memoir combined with a memorable introduction to physics.” —Kirkus Reviews “MIT’s Lewin is deservedly popular for his memorable physics lectures (both live and on MIT’s OpenCourseWare website and YouTube), and this quick-paced autobiography-cum-physics intro fully captures his candor and lively teaching style joyful [this text] glows with energy and should please a wide range of readers.” —Publishers Weekly (starred review) “Lewin may be the only physics professor in the world who celebrates the beauty of Maxwell’s equations for electromagnetic fields by passing out flowers to his delighted students As the hundreds of thousands of students who have witnessed his lectures in person or online can attest, this classroom wizard transforms textbook formulas into magic Lewin’s rare creativity shines through a passport to adventure.” —Booklist (starred review) “Of all the souls made famous by YouTube—Justin Bieber, those wedding entrance dancers, that guy who loses his mind while videotaping a double-rainbow—none is more deserving than MIT physics professor Walter Lewin The professor’s sense of wonder is on full display in a new book: For the Love of Physics: From the End of the Rainbow to the Edge of Time—A Journey Through the Wonders of Physics Why is a rainbow an arc and not a straight line? Why can we typically see auroras only if we’re close to the North or South Pole? If you’ve ever been interested in learning— or relearning—the answers to these and a hundred other fascinating questions, Lewin’s book is for you.” —The Boston Globe “Everyone knows that rainbows appear after a storm But in his new book, Lewin reveals nature’s more unusual rainbows hiding in spray kicked up by ocean waves, in fog swirling around headlights, even in glass particles floating above construction sites After more than thirty years of teaching undergraduate physics at MIT, Lewin has honed a toolbox of clear, engaging explanations that present physics as a way of uncovering the world’s hidden wonders Quirky, playful, and brimming with earnestness, each chapter is a joyful sketch of a topic—from Newton’s laws to Lewin’s own pioneering discoveries in X-ray astronomy Lewin’s creativity offers lessons both for students and for educators Throughout it all, his sense of wonder is infectious.” —Science News “Walter Lewin’s unabashed passion for physics shines through on every page of this colorful, largely autobiographical tour of science The excitement of discovery is infectious.” —Mario Livio, author of The Golden Ratio and Is God a Mathematician? “In this fun, engaging, and accessible book, Walter Lewin, a superhero of the classroom, uses his powers for good—ours! The authors share the joy of learning that the world is a knowable place.” —James Kakalios, professor and author of The Physics of Superheroes and The Amazing Story of Quantum Mechanics Free Press A Division of Simon & Schuster, Inc 1230 Avenue of the Americas New York, NY 10020 www.SimonandSchuster.com Copyright © 2011 by Walter Lewin and Warren Goldstein All rights reserved, including the right to reproduce this book or portions thereof in any form whatsoever For information address Free Press Subsidiary Rights Department, 1230 Avenue of the Americas, New York, NY 10020 First Free Press hardcover edition May 2011 FREE PRESS and colophon are trademarks of Simon & Schuster, Inc The Simon & Schuster Speakers Bureau can bring authors to your live event For more information or to book an event contact the Simon & Schuster Speakers Bureau at 1-866-248-3049 or visit our website at www.simonspeakers.com Book design by Ellen R Sasahara Manufactured in the United States of America 10 Library of Congress Cataloging-in-Publication Data Lewin, Walter H G For the love of physics : from the end of the rainbow to the edge of time—a journey through the wonders of physics / by Walter Lewin with Warren Goldstein p cm Lewin, Walter H G Physicists—Massachusetts—Biography College teachers—Massachusetts—Biography Physics— Study and teaching—Netherlands Physics—Study and teaching—Massachusetts I Goldstein, Warren Jay II Title QC16.L485A3 2011 530.092—dc22 [B] 2010047737 ISBN 978-1-4391-0827-7 ISBN 978-1-4391-2354-6 (ebook) For all who inspired my love for physics and art —Walter lewin For my grandson Caleb Benjamin Luria —Warren Goldstein CONTENTS Introduction From the Nucleus to Deep Space Measurements, Uncertainties, and the Stars Bodies in Motion The Magic of Drinking with a Straw Over and Under—Outside and Inside—the Rainbow The Harmonies of Strings and Winds The Wonders of Electricity The Mysteries of Magnetism Energy ConservationPlus ỗa change 10 X-rays from Outer Space! 11 X-ray Ballooning, the Early Days 12 Cosmic Catastrophes, Neutron Stars, and Black Holes 13 Celestial Ballet 14 X-ray Bursters! 15 Ways of Seeing Acknowledgments Appendix Appendix Index * If you want to see my photo online, click on the website’s Archive and go to 2004 September 13 See text above for the general URL * If you want to use this equation at home, use 9.8 for g and give h in meters; v is then in meters per second If h is meters (above the floor), the object will hit the floor at about 5.4 meters per second which is about 12 miles per hour * For simplicity I have used 10 meters per second for g; we that often in physics * For rotating black holes the event horizon is oblate—fatter at the equator—not spherical * Little did I know at the time that Jan and I would become very close friends and that we would coauthor about 150 scientific publications before his untimely death in 1999 * This acceleration, by the way, is 0.18 percent lower at the equator than at the poles—because Earth is not a perfect sphere Objects at the equator are about 20 kilometers farther away from the Earth’s center than objects at the poles, so at the equator g is lower The 9.82 is an average value