By Paul Craig
This note is in the spirit of David Hafemeister’s comment in the April, 2008 issue on bribing his way out of collapsing Soviet Union. I encourage you to run more reminiscences. To help this process along, here’s one of mine.
The year was 1957. I was completing my Ph.D. dissertation at Caltech. Feynman had recently moved to Caltech from Cornell. All eyes were on him. Feynman was working on his theory of quantization in superfluid helium II. He had developed the idea that quantization could occur in macroscopic samples of superfluid. Feynman got together with my thesis advisor, John Pellam. Pellam had me working on what later became known as the “fly wing” experiment.
Pellam’s idea was to test the concept of identically zero viscosity in superfluid helium II by looking at the lift on airfoil. Absent viscosity the circulation around an airfoil is indeterminate. In a viscous fluid, even the tiniest amount of viscosity establishes circulation around the wing of just the right amount so that the fluid velocity at the trailing edge of the wing vanishes. This is known as the Kutta boundary condition. Feynman realized that the circulation around my airfoil might be quantized.
I immediately began to search for the effect. My apparatus consisted of a superfluid wind tunnel in which was suspended a propeller – initially wings torn from dead flies -- hanging from a torsion fiber. To everyone’s amazement, I found the effect. My world turned upside down. Feynman was in my laboratory for what seemed like half the time. Virtually every visitor to the Physics department or to the Aeronautics Department came to watch the wing jump. I spent my time giving demonstrations.
In short order a paper was prepared for Physical Review Letters
. A Physics colloquium was scheduled, to be given jointly by Feynman and John Pellam.
At this stage Feynman began to review the experiment in great detail. He said the only way to confirm the experiment was to take it apart and rebuild it with different parameters. This I did. The effect went away. It turned out to be an artifact of my design. The only reason it was seen at all was graduate student error. I figured my career in physics had come to an end.
Feynman and Pellam decided to go ahead with the colloquium. Rather than presenting an exciting new result, they’d describe a proposed experiment. While everyone knew that a graduate student had screwed up, that question was never asked during the colloquium. They covered for me.
Feynman took the position that was his job to cross check everything, and that one should never expect very much of a graduate student unless or until they’d proved themselves. I never discovered what he thought about my advisor’s inadequate quality control.
In due course the “fly wing” paper was published in Physical Review. It demonstrated experimentally that when the viscosity term is removed from the Stokes-Navier fluid flow equations, the order of the differential equations drops and the viscosity boundary condition is lost. Interesting, but not nearly as exciting.
Feynman continued to come to our graduate student parties, and he approved my dissertation. To my complete amazement I was offered several jobs, and took one at Los Alamos.
As I was cleaning out my laboratory I chanced upon a pile of handwritten papers. These turned out to be Feynman’s draft manuscript of his classic paper on superfluid helium II. I didn’t realize what a treasure I was holding, and discarded them. Bummer. Years later John Pellam died. A day of memorial speeches in his honor was scheduled at UC Irvine. In the morning I gave a talk about my experiences with Pellam. Mostly I concentrated on Pellam’s research. Toward the end, however, I focused on his humanity. I told the story.
In the afternoon Feynman showed up and talked on his current research. At the reception Feynman came up to me, looked directly at me, and without preface said “Did you tell them?” Fortunately I had learned well the lesson of intellectual honesty Feynman had taught me. I replied “Yes”. That was the totality of our conversation, and the last time I saw him.
Paul Craig Ppcraig@ucdavis.edu
This contribution has not been peer refereed. It represents solely the view(s) of the author(s) and not necessarily the views of APS.