Questions for…Walter Lewin
When we last saw MIT physics professor Walter Lewin—the craziest, funniest professor this side of Buddy Love—he was enjoying minute seven of his 15 minutes of fame. Looks like he’ll have his last quarter-hour soon, as the late-night talk shows want some of his beat-a-student-with-cat-fur hilarity. We couldn’t help but wonder when he’ll appear on the tube, and where, and how he came up with all those, um, unconventional lectures.
So, we asked him.
BostonDaily: I’ve been following the possibility of you appearing on a late show and I wanted to know if you have an update. Are you going to be appearing anytime this week on anything?
Lewin: Well, I want to be a little cagey about that because it’s a bit of a sticky point. Since I’m still negotiating with these people, I would rather, at this point in time, not mention which shows I have accepted. I can tell you one thing, and if you do your own homework you can probably figure out which one I have accepted, because I have decided not to cross any picket lines.
BD: If I can be so bold as to ask, uh, when you might appear on this…
L: Well that is still under—we are still negotiating that a little bit, you see. I will be on vacation which I badly need, from 7 January to 12 January. So it would be very shortly after that, I would say sometime mid-January.
BD: Are you surprised by the attention your lectures have received?
L: Well, the answer is yes and no. My lectures have been on TV in Seattle, Washington…It’s a public television station that was in University of Washington of Seattle…And so very slowly it began to dawn on me and others that my lectures were special and were definitely different. And then when I was persuaded by MIT to have the whole thing taped very professionally with a complete team of three cameras and two sound experts and a producer.
BD: And just for chronology’s sake, when was this when that started to occur?
L: That happened in the fall of 1999. And so then these lectures were all very professionally taped and I even edited them. So I watched them and I would take the slips of the tongue out and if I made a slip on the blackboard I would also say uh-oh oo-oo I’m sorry, I didn’t mean to write this down and so they’ve also been cleaned up. And then of course when OpenCourseWare came, they immediately grabbed the 1999 Newtonian mechanics series. Two years later I had my electricity and magnetism series. Then, in the fall of 2004 I added another 23 lectures of the physics of vibrations and waves, so that’s a total of 94 lectures. By the time that they were on OCW, of course, the mail that I started receiving was from all over the world. It changed from the Seattle area, where 2 million people had access to my lectures; it changed to a few billion people.
I mean, over the years I have received thousands of wonderful email messages from people who not only thank me, but who actually explain to me in what way I have actually made them look at the world in a different way. Some of them said, ‘Now when I wake up in the morning I have a smile on my face.’ And the kind of, the various kinds of people, that I reached were of course first of all freshmen anywhere in the world who were doing physics, graduate students who saw a great opportunity to refresh their memory on courses that they had taken long ago; physics teachers who said ‘Now that we have these great lectures on the web why should I prepare lectures? There’s absolutely no need.’
Then there were retired people who had done some science when they were young, but had all forgotten, and they found my lectures extremely helpful. And then there was, of course, there were a group of people who had never seen anything, people who didn’t even know how to spell the word physics who said, ‘Hey this man is explaining to me in a very rational way why the rainbows are there, why the red is on the outside of the rainbow, the blue is on the inside, and why on the second rainbow the colors are reversed.’ And they began to look at the world in a different way.
BD: I wonder if the people, the appeal that people have found with your lectures, I wonder if that drives you to think of increasingly creative way to approach each new lecture.
L: I think the answer is no. That would be no. The way I prepare lectures when I have never given a particular lecture on Newtonian mechanics, when I do that the first time, I give them so much thought, each one of those lectures would take easily 40 hours for me to prepare. So it is growing on me, it is ripening like cheese has to ripen to get the best flavor. And so once I have done that and given it so much thought and so much preparation and so many dry runs—I dry run each lecture three times in real time, pretend that there is a classroom and there is no one. I write everything on the blackboard just the way I would have written it on the blackboard when I give my real lecture—those dry runs are invaluable because when you do these dry runs you actually see what goes wrong and what is not so clear.
And so, out of these dry runs comes a very polished lecture with great clarity, with a lot of fun, with great humor. But, above all, clarity. Each lecture in a way is like a house. I call that the architecture of the lecture—it’s like a house that you’re building. That house has to be possible if you can do it somehow, each lecture should be a house on its own, have a start have a beginning and at the end of the lecture there are wonderful demonstrations also.
BD: So how long have you been pulling real life examples and actually going out there and modeling, showing people, physics in action?
L: Well when it is my first full time lecturing at MIT, when I had a class of about 400-500 hundred students, it was in 1972. That’s when I really started to work on full-fledged lectures which were polished, which were very well balanced, which were very accurately timed, and which had great demonstrations, some demonstrations that no other professor might have thought of but gets the point across in a way that is so convincing that they never forget.
I just got an email from someone in India who won a gold medal on physics and he was asking, ‘Why is it that when you have a pendulum, and you hang on a pendulum in increasing weight, that the period of one oscillation never changes?’ And he said that he immediately followed the lecture that I gave when I was actually swinging a pendulum with a 30 pound object at the end, and I timed how long it would take for one oscillation. And then, what I did, I was going to put myself at the end of the pendulum. And so if a student sees you swinging at the end of a pendulum, let me tell you, he will never forget—he will never forget—that the [oscillation] period is the same. It’s a hilarious thing when a professor is hanging at the end of pendulum. And I try to do that wherever I can.
L: So you ride a tricycle and put a carbon dioxide fire extinguisher on the back, pointing away from you, and then you open the fire extinguisher and you move like a rocket over the, in the auditorium.
BD: How fast are you going when you…
L: Oh you’ve got to be careful. It can be dangerous. It depends if you can control the amount of carbon dioxide that comes out, the rate at which it comes out, then you have it pretty much under control, you can change your speed, but if you open it a little too fast, you really take off like a rocket.
BD: How did you think of a tricycle with a fire extinguisher and this is going to show rockets lifting off? This will better demonstrate it. I’m just curious about the process.
L: How that comes about?
L: I was not the first to think of that so I inherited that. There are many other demonstrations that I did not inherit, which I did by myself.
BD: Well, let’s talk about one of those. One of those in which you did not inherit.
L. When I demonstrate in class the conservation of charge, what normally is done by professors, they charge one object positive then they show that they other object automatically must become negative because that’s the conservation of charge. The way I do that is very dramatic and students never forget that. I put a student on a plastic chair right on top of the desk. I stand next to him on a glass plate so that we are both completely electronically insulted from the rest of the world and then I start to beat the student with cat fur. And when I beat him with cat fur he will become positively charged, but since I am standing on a glass plate I cannot lose my charge so I must automatically become negatively charged. So now after about one minute or two minutes of beating, which is a riot, of course, you can imagine, then we turn the lights and then I have in my hand a small a small neon discharge tube and I just touch that to his nose and he will feel an enormous shock. They will never forget in their lives, ‘Hey, here we saw a demonstration of the conservation of charge. This crazy old Lewin was beating his students with cat fur.
I try whenever possible, when I discuss freefall, that you have no weight in freefall, I jump myself off of a desk in my lecture hall and I hold in my hand a gallon of water and I show them that during the fall that the gallon of water has no weight. I don’t think that too many professors would do it that way, that they would actually jump off a desk with a gallon of water in their hands to demonstrate that the water has lost its weight. So wherever possible you can be dry and boring about things and say, ‘Oh well, astronauts in orbit are weightless,’ and students are willing to accept that. But to actually see a professor jumping off the table, for that one-half of a second—that he is not only weightless, but of course the bottle of water is weightless—they will never forget that in their lives.