To Walter Lewin, teaching physics is a passion, but it's also hard work: he spends 40 to 60 hours preparing each lecture; 2 weeks before a lecture, he rehearses in an empty room; the day of the lecture (at 5:30 am), he practices one last time before an empty room (Photo: Dominick Reuter).Last week, on May 16, he gave his last physics lecture For the love of physics to a hall packed (like transistors on a chip).
You can, and should, watch it here: http://www.ustream.tv/recorded/14756530
One of his most exciting experiments and "emotionally, the most difficult" one, was a demonstration that energy is indeed conserved, neither created nor destroyed. Attached to a pendulum was a wrecking ball, which he placed on his chin and let go, only to see it swing back towards, but never touching, his chin. After his successful attempt, he quipped: "physics works, and I'm still alive".
But this wasn't his only dangerous experiment. "For those of you who think lecturing is easy, no!", he said before lighting four cigarettes that he then put in his mouth. After some brief huffing and puffing, he hovered the cigarettes over a white-light source and the smoke appeared blue (because the atmosphere is filled with very small particles on which white light scatters; this is also why the sky is blue). However, when he inhaled the cigarette smoke for several seconds and then exhaled over the white light, the smoke appeared white this time (because water vapour particles in the lungs are much bigger relatively; this is also why clouds are white).
Before opening the floor to questions, he left the room with his "rocket", a bicycle with a fire extinguisher attached to the back for propulsion (Photo: Dominick Reuter).A long standing ovation ensued.
Walter Lewin is what every teacher ought to be--passionate--and does what every teacher ought to do--convey, amaze, and inspire. Asked what he does for fun, he replied that "physics is my life, and art/history is my love"
