I regret to hear of the passing of Professor Pierre Piroué (In Memoriam, March 18). I took an extremely challenging undergraduate physics course from him. While the name and the specific content of the course escape me, I have a vivid memory of Pierre twisting a piece of chalk and breaking it cleanly into two pieces. In a pleasant French accent (which still sometimes reverberates in my brain), he told us that he would make us learn how to calculate the beautiful spiral cross section of the break. I think that the course was a singular outlier in the standard undergraduate physics curriculum, even at Princeton in that bygone era. During the intervening decades, I have had absolutely no reason to calculate that particular cross section and have totally forgotten how to do it. Perhaps something to do with the stress and strain tensor?
The standard undergraduate physics curriculum in American universities has meanwhile been dumbed down, again, and yet again, to the point that such a course would now be unthinkable, possibly even leading to a lawsuit about cruelty to undergraduates. But I must have learned a great deal from Pierre, even though I am unable to retrieve it for the life of me.
Later, as a junior faculty member in the Princeton physics department, I had the good fortune of knowing Pierre better, and not as a demanding taskmaster.