For the Love of Physics: From the End of the Rainbow to the Edge of Time - A Journey Through the Wonders of Physics

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Simon and Schuster, Feb 7, 2012 - 302 pages
5 Reviews
This book is a largely autobiographical account of the author's life as one who fell in love first with physics and then with teaching physics to students. "You have changed my life" is a common refrain in the emails the author receives daily from fans who have been enthralled by his video lectures about the wonders of physics. "I walk with a new spring in my step and I look at life through physics colored eyes," wrote one such fan. When the lectures were made available online, he became an instant YouTube celebrity, and The New York Times declared, "Walter Lewin delivers his lectures with the panache of Julia Child bringing French cooking to amateurs and the zany theatricality of YouTube's greatest hits." For more than thirty years as a professor at the Massachusetts Institute of Technology, he honed his singular craft of making physics not only accessible but truly fun, whether putting his head in the path of a wrecking ball, supercharging himself with three hundred thousand volts of electricity, or demonstrating why the sky is blue and why clouds are white. Now, as Carl Sagan did for astronomy and Brian Green did for cosmology, the author takes readers on a journey in this book, opening our eyes as never before to the amazing beauty and power with which physics can reveal the hidden workings of the world all around us. "I introduce people to their own world," he writes, "the world they live in and are familiar with but don't approach like a physicist yet." Could it be true that we are shorter standing up than lying down? Why can we snorkel no deeper than about one foot below the surface? Why are the colors of a rainbow always in the same order, and would it be possible to put our hand out and touch one? Whether introducing why the air smells so fresh after a lightning storm, why we briefly lose (and gain) weight when we ride in an elevator, or what the big bang would have sounded like had anyone existed to hear it, he never ceases to surprise and delight with the extraordinary ability of physics to answer even the most elusive questions. Recounting his own exciting discoveries as a pioneer in the field of X-ray astronomy, arriving at MIT right at the start of an astonishing revolution in astronomy, he also brings to life the power of physics to reach into the vastness of space and unveil exotic uncharted territories, from the marvels of a supernova explosion in the Large Magellanic Cloud to the unseeable depths of black holes. "For me," he writes, "physics is a way of seeing the spectacular and the mundane, the immense and the minute, as a beautiful, thrillingly interwoven whole." His ways of introducing us to the revelations of physics impart to us a new appreciation of the remarkable beauty and intricate harmonies of the forces that govern our lives.
 

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LibraryThing Review

User Review  - LaPhenix - LibraryThing

Though I didn't quite gain the understanding that I'd expected, I love Lewin's passion and perspective, and he opened my eyes to a lot of gems we overlook in everyday life. Read full review

LibraryThing Review

User Review  - MartyBriggs - LibraryThing

Engaging, short chapters on the physics of various everyday phenomena. Could assign just one chapter, or a set of several for a book-length assignment. Read full review

Contents

From the Nucleus to Deep Space
1
Measurements Uncertainties and the Stars
21
Bodies in Motion
37
The Magic of Drinking with a Straw
59
Over and UnderOutside and Insidethe Rainbow
78
The Harmonies of Strings and Winds
103
The Wonders of Electricity
125
The Mysteries of Magnetism
149
Cosmic Catastrophes Neutron Stars and Black Holes
217
Celestial Ballet
235
Xray Bursters
248
Ways ofSeeing
263
Acknowledgments
273
Appendix 2
279
Index
285
15
297

Energy ConservationPlus ça change Xrays from Outer Space
200

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About the author (2012)

For the Love of Physics CHAPTER 1


From the Nucleus to Deep Space

It''s amazing, really. My mother''s father was illiterate, a custodian. Two generations later I''m a full professor at MIT. I owe a lot to the Dutch educational system. I went to graduate school at the Delft University of Technology in the Netherlands, and killed three birds with one stone.

Right from the start, I began teaching physics. To pay for school I had to take out a loan from the Dutch government, and if I taught full time, at least twenty hours a week, each year the government would forgive one-fifth of my loan. Another advantage of teaching was that I wouldn''t have to serve in the army. The military would have been the worst, an absolute disaster for me. I''m allergic to all forms of authority--it''s just in my personality--and I knew I would have ended up mouthing off and scrubbing floors. So I taught math and physics full time, twenty-two contact hours per week, at the Libanon Lyceum in Rotterdam, to sixteen-and seventeen-year-olds. I avoided the army, did not have to pay back my loan, and was getting my PhD, all at the same time.

I also learned to teach. For me, teaching high school students, being able to change the minds of young people in a positive way, that was thrilling. I always tried to make classes interesting but also fun for the students, even though the school itself was quite strict. The classroom doors had transom windows at the top, and one of the headmasters would sometimes climb up on a chair and spy on teachers through the transom. Can you believe it?

I wasn''t caught up in the school culture, and being in graduate school, I was boiling over with enthusiasm. My goal was to impart that enthusiasm to my students, to help them see the beauty of the world all around them in a new way, to change them so that they would see the world of physics as beautiful, and would understand that physics is everywhere, that it permeates our lives. What counts, I found, is not what you cover, but what you uncover. Covering subjects in a class can be a boring exercise, and students feel it. Uncovering the laws of physics and making them see through the equations, on the other hand, demonstrates the process of discovery, with all its newness and excitement, and students love being part of it.

I got to do this also in a different way far outside the classroom. Every year the school sponsored a week-long vacation when a teacher would take the kids on a trip to a fairly remote and primitive campsite. My wife, Huibertha, and I did it once and loved it. We all cooked together and slept in tents. Then, since we were so far from city lights, we woke all the kids up in the middle of one night, gave them hot chocolate, and took them out to look at the stars. We identified constellations and planets and they got to see the Milky Way in its full glory.

I wasn''t studying or even teaching astrophysics--in fact, I was designing experiments to detect some of the smallest particles in the universe--but I''d always been fascinated by astronomy. The truth is that just about every physicist who walks the Earth has a love for astronomy. Many physicists I know built their own telescopes when they were in high school. My longtime friend and MIT colleague George Clark ground and polished a 6-inch mirror for a telescope when he was in high school. Why do physicists love astronomy so much? For one thing, many advances in physics--theories of orbital motion, for instance--have resulted from astronomical questions, observations, and theories. But also, astronomy is physics, writ large across the night sky: eclipses, comets, shooting stars, globular clusters, neutron stars, gamma-ray bursts, jets, planetary nebulae, supernovae, clusters of galaxies, black holes.

Just look up in the sky and ask yourself some obvious questions: Why is the sky blue, why are sunsets red, why are clouds white? Physics has the answers! The light of the Sun is composed of all the colors of the rainbow. But as it makes its way through the atmosphere it scatters in all directions off air molecules and very tiny dust particles (much smaller than a micron, which is 1/250,000 of an inch). This is called Rayleigh scattering. Blue light scatters the most of all colors, about five times more than red light. Thus when you look at the sky during the day in any direction*, blue dominates, which is why the sky is blue. If you look at the sky from the surface of the Moon (you may have seen pictures), the sky is not blue--it''s black, like our sky at night. Why? Because the Moon has no atmosphere.

Why are sunsets red? For exactly the same reason that the sky is blue. When the Sun is at the horizon, its rays have to travel through more atmosphere, and the green, blue, and violet light get scattered the most--filtered out of the light, basically. By the time the light reaches our eyes--and the clouds above us--it''s made up largely of yellow, orange, and especially red. That''s why the sky sometimes almost appears to be on fire at sunset and sunrise.

Why are clouds white? The water drops in clouds are much larger than the tiny particles that make our sky blue, and when light scatters off these much larger particles, all the colors in it scatter equally. This causes the light to stay white. But if a cloud is very thick with moisture, or if it is in the shadow of another cloud, then not much light will get through, and the cloud will turn dark.

One of the demonstrations I love to do is to create a patch of "blue sky" in my classes. I turn all the lights off and aim a very bright spotlight of white light at the ceiling of the classroom near my blackboard. The spotlight is carefully shielded. Then I light a few cigarettes and hold them in the light beam. The smoke particles are small enough to produce Rayleigh scattering, and because blue light scatters the most, the students see blue smoke. I then carry this demonstration one step further. I inhale the smoke and keep it in my lungs for a minute or so--this is not always easy, but science occasionally requires sacrifices. I then let go and exhale the smoke into the light beam. The students now see white smoke--I have created a white cloud! The tiny smoke particles have grown in my lungs, as there is a lot of water vapor there. So now all the colors scatter equally, and the scattered light is white. The color change from blue light to white light is truly amazing!

With this demonstration, I''m able to answer two questions at once: Why is the sky blue, and why are clouds white? Actually, there is also a third very interesting question, having to do with the polarization of light. I''ll get to this in chapter 5.

Out in the country with my students I could show them the Andromeda galaxy, the only one you can see with the naked eye, around 2.5 million light-years away (15 million trillion miles), which is next door as far as astronomical distances go. It''s made up of about 200 billion stars. Imagine that--200 billion stars, and we could just make it out as a faint fuzzy patch. We also spotted lots of meteorites--most people call them shooting stars. If you were patient, you''d see one about every four or five minutes. In those days there were no satellites, but now you''d see a host of those as well. There are more than two thousand now orbiting Earth, and if you can hold your gaze for five minutes you''ll almost surely see one, especially within a few hours after sunset or before sunrise, when the Sun hasn''t yet set or risen on the satellite itself and sunlight still reflects off it to your eyes. The more distant the satellite, and therefore the greater the difference in time between sunset on Earth and at the satellite, the later you can see it at night. You recognize satellites because they move faster than anything else in the sky (except meteors); if it blinks, believe me, it''s an airplane.

I have always especially liked to point out Mercury to people when we''re stargazing. As the planet closest to the Sun, it''s very difficult to see it with the naked eye. The conditions are best only about two dozen evenings and mornings a year. Mercury orbits the Sun in just eighty-eight days, which is why it was named for the fleet-footed Roman messenger god; and the reason it''s so hard to see is that its orbit is so close to the Sun. It''s never more than about 25 degrees away from the Sun when we look at it from Earth--that''s smaller than the angle between the two hands of a watch at eleven o''clock. You can only see it shortly after sunset and before sunrise, and when it''s farthest from the Sun as seen from Earth. In the United States it''s always close to the horizon; you almost have to be in the countryside to see it. How wonderful it is when you actually find it!

Stargazing connects us to the vastness of the universe. If we keep staring up at the night sky, and let our eyes adjust long enough, we can see the superstructure of the farther reaches of our own Milky Way galaxy quite beautifully--some 100 billion to 200 billion stars, clustered as if woven into a diaphanous fabric, so delightfully delicate. The size of the universe is incomprehensible, but you can begin to grasp it by first considering the Milky Way.

Our current estimate is that there may be as many galaxies in the universe as there are stars in our own galaxy. In fact, whenever a telescope observes deep space, what it sees is mostly galaxies--it''s impossible to distinguish single stars at truly great distances--and each contains

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