I recall hearing once that Dirac was watching a woman knitting and applied knot theory to deduce the existence of the purl stitch. He told her about it and she was amused[1].
Another time, Dirac was watching Anya Kapitza knitting while he was talking physics with Peter Kapitza. A couple of hours after he left, Dirac rushed back, very excited. "You know, Anya," he said, "watching the way you were making this sweater I got interested in the topological aspect of the problem. I found that there is another way of doing it and that there are only two possible ways. One is the one you were using; another is like that. . . . " And he demonstrated the other way, using his long fingers. His newly discovered "other way," Anya informed him, is well known to women and is none other than "purling."
I recall hearing once that Dirac was watching a woman knitting and applied knot theory to deduce the existence of the purl stitch. He told her about it and she was amused[1].
[1] http://www.dirac.ch/PaulDirac.html