Galileo's Pendulum

One of my personal holiday traditions involves reading Terry Pratchett’s novel Hogfather. Strictly speaking, Hogfather is a Christmas book: the Hogfather of the title is the Santa Claus/Father Christmas figure in Pratchett’s imaginary flat planet Discworld, and the Hogswatchnight festival plays the role of Christmas. As usual with Pratchett, the story is wide-ranging and hard to…