Philip J. Davis. The Thread: A Mathematical Yarn (1989)

     Philip J. Davis The Thread: A Mathematical Yarn (1989) A charming book, telling how the author, a mathematician, became curious about Pafnuty, the first name of his hero, Pafnuty Lvovitch Tschebyscheff, a pioneer in the mathematics of approximation. Approximation has become a central motif of computing, since every computer can calculate only to some finite number of decimal places. It was the rounding off the 17th digit to display a 16-digit result that led to the discovery of chaos theory. That tiny difference of a few parts in 100 quadrillion made all the difference when the result was fed back into the equations for a second run of a weather prediction model.
     But I digress. Which is what Davis does. Some of his digressions are personal, some technical, some historical. But he leads us down these byways so gracefully that we hardly notice that we are moving further and further away from the ostensible theme of the book: whare does the name Pafnuty come from? Davis brings the thread of his narrative back to this question several times, and finally gives us the answer: it derives from an Egyptian god’s name.
     Along the way, Davis instructs us in all manner of interesting facts. He illustrates one of my dicta: There is no such thing as useless knowledge; at the very least, a fact will serve to link two others. I’ll now add another corollary: and usually, this linkage satisfies our thirst for order and meaning. For order and meaning are fancy words for linkages.
     This is the second time I've read the book, and I enjoyed it just as much as the first time. ****