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Showing posts from March 15, 2017

What was it like to meet Richard Feynman? Anecdote by Neil King

I sat in on Physics X at Caltech for a year: This is where Feynman would take questions from freshmen and sophomores, and try to answer them. He didn't like the more 'formal' questions that upper-division and grad students would ask: he wanted questions driven by real curiosity. I had a lot of fun in Physics X: One time I mentioned something that had bugged more for a long time: "Why is the gamma function generally considered the 'natural generalization' of n-factorial (n!)?". He didn't answer directly; instead, he turned to the classroom and issued a challenge: "Over the break, think about this: 'What is (1/2)!, the factorial of (1/2)?' OK, Merry Christmas!" Three students actually thought about this over the break. One girl pointed out that (d/dx)^n[x^n] = n!; I thought something could be done with that. Another fellow expanded the factorial function in a complex power series about z = (1/2,0), imposing the conditions that (z +1)! =