For the Love of Physics (2 page)

“I will repeat this. I want you to hear it tonight at three o’clock in the morning when you wake up.” He is holding both index fingers to his temples, twisting them, pretending to bore into his brain. “Any measurement that you make without knowledge of its uncertainty is completely
meaningless.
” The students stare at him, utterly rapt.

We’re just eleven minutes into the first class of Physics 8.01, the most famous introductory college physics course in the world.

The
New York Times
ran a front-page piece on Walter Lewin as an MIT “webstar” in December 2007, featuring his physics lectures available on the MIT OpenCourseWare site, as well as on YouTube, iTunes U, and Academic Earth. Lewin’s were among the first lectures that MIT posted on the Internet, and it paid off for MIT. They have been exceptionally popular. The ninety-four lectures—in three full courses, plus seven stand-alones—garner about three thousand viewers per day, a million hits a year. Those include quite a few visits from none other than Bill Gates, who’s watched all of courses 8.01, Classical Mechanics, and 8.02, Electricity and Magnetism, according to letters (snail mail!) he’s sent Walter, reporting that he was looking forward to moving on to 8.03, Vibrations and Waves.

“You have changed my life,” runs a common subject line in the emails Lewin receives every day from people of all ages and from all over the world. Steve, a florist from San Diego, wrote, “I walk with a new spring in my step and I look at life through physics-colored eyes.” Mohamed, an engineering prep school student in Tunisia wrote, “Unfortunately, here in my country my professors don’t see any beauty in physics as you do see, and I’ve suffered a lot from this. They just want us to learn how to solve ‘typical’ exercises to succeed in the exam, they don’t look beyond that tiny horizon.” Seyed, an Iranian who had already earned a couple of American master’s degrees, writes, “I never really enjoy of life until I have watched you teach physics. Professor Lewin you have changed my life Indeed. The way you teach it is worth 10 times the tuition, and make
SOME not all other teachers bunch of criminals. It is CAPITAL CRIME to teach bad.” Or Siddharth from India: “I could feel Physics beyond those equations. Your students will always remember you as I will always remember you—as a very-very fine teacher who made life and learning more interesting than I thought was possible.”

Mohamed enthusiastically quotes Lewin’s final lecture in Physics 8.01 with approval: “Perhaps you will always remember from my lectures that physics can be very exciting and beautiful and it’s everywhere around us, all the time, if only you have learned to see it and appreciate its beauty.” Marjory, another fan, wrote, “I watch you as often as I can; sometimes five times per week. I am fascinated by your personality, your sense of humor, and above all by your ability to simplify matters. I hated physics in high school, but you made me love it.”

Lewin receives dozens of such emails every week, and he answers each one.

Walter Lewin creates magic when he introduces the wonders of physics. What’s his secret? “I introduce people to their own world,” he says, “the world they live in and are familiar with, but don’t approach like a physicist—yet. If I talk about waves on water, I ask them to do certain experiments in their bathtubs; they can relate to that. They can relate to rainbows. That’s one of the things I love about physics: you get to explain anything. And that can be a wonderful experience—for them and for me. I make them love physics! Sometimes, when my students get really engaged, the classes almost feel like happenings.”

He might be perched at the top of a sixteen-foot ladder sucking cranberry juice out of a beaker on the floor with a long snaking straw made out of lab tubing. Or he could be courting serious injury by putting his head in the path of a small but quite powerful wrecking ball that swings to within millimeters of his chin. He might be firing a rifle into two paint cans filled with water, or charging himself with 300,000 volts of electricity with a large contraption called a Van de Graaff generator—like something out of a mad scientist’s laboratory in a science fiction movie—so that his already wild hair stands straight out from his skull. He uses
his body as a piece of experimental equipment. As he says often, “Science requires sacrifices, after all.” In one demonstration—captured in the photo on the jacket of this book—he sits on an extremely uncomfortable metal ball at the end of a rope suspended from the lecture hall’s ceiling (what he calls the mother of all pendulums) and swings back and forth while his students chant the number of swings, all to prove that the number of swings a pendulum makes in any given time is independent of the weight at its end.

His son, Emanuel (Chuck) Lewin, has attended some of these lectures and recounts, “I saw him once inhale helium to change his voice. To get the effect right—the devil is in the details—he typically gets pretty close to the point of fainting.” An accomplished artist of the blackboard, Lewin draws geometrical figures, vectors, graphs, astronomical phenomena, and animals with abandon. His method of drawing dotted lines so entranced several students that they produced a funny YouTube video titled “Some of Walter Lewin’s Best Lines,” consisting simply of lecture excerpts showing Lewin drawing his famous dotted lines on different blackboards during his 8.01 lectures. (You can watch it here:
www.youtube.com/watch?v=raurl4s0pjU
.)

A commanding, charismatic presence, Lewin is a genuine eccentric: quirky and physics obsessed. He carries two devices called polarizers in his wallet at all times, so that at a moment’s notice he can see if any source of light, such as the blue sky, a rainbow, or reflections off windows, is polarized, and whoever he might be with can see it too.

What about those blue work shirts he wears to class? Not work shirts at all, it turns out. Lewin orders them, custom made to his specifications, of high-grade cotton, a dozen at a time every few years, from a tailor in Hong Kong. The oversize pocket on the left side Lewin designed to accommodate his calendar. No pocket protectors here—this physicist-performer-teacher is a man of meticulous fashion—which makes a person wonder why he appears to be wearing the oddest brooch ever worn by a university professor: a plastic fried egg. “Better,” he says, “to have egg on my shirt than on my face.”

What is that oversize pink Lucite ring doing on his left hand? And what is that silvery thing pinching his shirt right at belly-button level, which he keeps sneaking looks at?

Every morning as Lewin dresses, he has the choice of forty rings and thirty-five brooches, as well as dozens of bracelets and necklaces. His taste runs from the eclectic (Kenyan beaded bracelets, a necklace of large amber pieces, plastic fruit brooches) to the antique (a heavy silver Turkmen cuff bracelet) to designer and artist-created jewelry, to the simply and hilariously outrageous (a necklace of felt licorice candies). “The students started noticing,” he says, “so I began wearing a different piece every lecture. And especially when I give talks to kids. They love it.”

And that thing clipped to his shirt that looks like an oversize tie clip? It’s a specially designed watch (the gift of an artist friend) with the face upside down, so Lewin can look down at his shirt and keep track of time.

It sometimes seems to others that Lewin is distracted, perhaps a classic absentminded professor. But in reality, he is usually deeply engaged in thinking about some aspect of physics. As his wife Susan Kaufman recently recalled, “When we go to New York I always drive. But recently I took this map out, I’m not sure why, but when I did I noticed there were equations all over the margins of the states. Those margins were done when he was last lecturing, and he was bored when we were driving. Physics was always on his mind. His students and school were with him twenty-four hours a day.”

Perhaps most striking of all about Lewin’s personality, according to his longtime friend the architectural historian Nancy Stieber, is “the laser-sharp intensity of his interest. He seems always to be maximally engaged in whatever he chooses to be involved in, and eliminates 90 percent of the world. With that laserlike focus, he eliminates what’s inessential to him, getting to a form of engagement that is so intense, it produces a remarkable
joie de vivre.
”

Lewin is a perfectionist; he has an almost fanatical obsession with detail. He is not only the world’s premier physics teacher; he was also a pioneer in the field of X-ray astronomy, and he spent two decades building,
testing, and observing subatomic and astronomical phenomena with ultrasensitive equipment designed to measure X-rays to a remarkable degree of accuracy. Launching enormous and extremely delicate balloons that skimmed the upper limit of Earth’s atmosphere, he began to uncover an exotic menagerie of astronomical phenomena, such as X-ray bursters. The discoveries he and his colleagues in the field made helped to demystify the nature of the death of stars in massive supernova explosions and to verify that black holes really do exist.

He learned to test, and test, and test again—which not only accounts for his success as an observational astrophysicist, but also for the remarkable clarity he brings to revealing the majesty of Newton’s laws, why the strings of a violin produce such beautifully resonant notes, and why you lose and gain weight, be it only very briefly, when you ride in an elevator.

For his lectures, he always practiced at least three times in an empty classroom, with the last rehearsal being at five a.m. on lecture day. “What makes his lectures work,” says astrophysicist David Pooley, a former student who worked with him in the classroom, “is the time he puts into them.”

When MIT’s Physics Department nominated Lewin for a prestigious teaching award in 2002, a number of his colleagues zeroed in on these exact qualities. One of the most evocative descriptions of the experience of learning physics from Lewin is from Steven Leeb, now a professor of electrical engineering and computer science at MIT’s Laboratory for Electromagnetic and Electronic Systems, who took his Electricity and Magnetism course in 1984. “He exploded onto the stage,” Leeb recalls, “seized us by the brains, and took off on a roller-coaster ride of electromagnetics that I can still feel on the back of my neck. He is a genius in the classroom with an unmatched resourcefulness for finding ways to make concepts plain.”

Robert Hulsizer, one of Lewin’s Physics Department colleagues, tried to excerpt some of Lewin’s in-class demonstrations on video to make a kind of highlight film for other universities. He found the task impossible. “The demonstrations were so well woven into the development
of the ideas, including a buildup and denouement, that there was no clear time when the demonstration started and when it finished. To my mind, Walter had a richness of presentation that could not be sliced into bites.”

The thrill of Walter Lewin’s approach to introducing the wonders of physics is the great joy he conveys about all the wonders of our world. His son Chuck fondly recalls his father’s devotion to imparting that sense of joy to him and his siblings: “He has this ability to get you to see things and to be overwhelmed by how beautiful they are, to stir the pot in you of joy and amazement and excitement. I’m talking about little unbelievable windows he was at the center of, you felt so happy to be alive, in his presence, in this event that he created. We were on vacation in Maine once. It wasn’t great weather, I recall, and we kids were just hanging out, the way kids do, bored. Somehow my father got a little ball and spontaneously created this strange little game, and in a minute some of the other beach kids from next door came over, and suddenly there were four, five, six of us throwing, catching, and laughing. I remember being so utterly excited and joyful. If I look back and think about what’s motivated me in my life, having those moments of pure joy, having a vision of how good life can be, a sense of what life can hold—I’ve gotten that from my father.”

Walter used to organize his children to play a game in the winter, testing the aerodynamic quality of paper airplanes—by flying them into the family’s big open living room fireplace. “To my mother’s horror,” Chuck recalled, “we would recover them from the fire—we were determined to win the competition the next time round!”

When guests came for dinner, Walter would preside over the game of Going to the Moon. As Chuck remembers it, “We would dim the lights, pound our fists on the table making a drumroll kind of sound, simulating the noise of a rocket launch. Some of the kids would even go under the table and pound. Then, as we reached space, we stopped the pounding, and once we landed on the Moon, all of us would walk around the living room pretending to be in very low gravity, taking crazy exaggerated
steps. Meanwhile, the guests must have been thinking, ‘These people are nuts!’ But for us kids, it was fantastic! Going to the Moon!”

Walter Lewin has been taking students to the Moon since he first walked into a classroom more than a half century ago. Perpetually entranced by the mystery and beauty of the natural world—from rainbows to neutron stars, from the femur of a mouse to the sounds of music—and by the efforts of scientists and artists to explain, interpret, and represent this world, Walter Lewin is one of the most passionate, devoted, and skillful scientific guides to that world now alive. In the chapters that follow you will be able to experience that passion, devotion, and skill as he uncovers his lifelong love of physics and shares it with you. Enjoy the journey!

—Warren Goldstein

CHAPTER 1