In the 1993 film Groundhog Day, the protagonist finds himself doomed to live the same day over and over again. Ever since, people have associated this Pennsylvania-German tradition with a time warp, or “time loop,” as it’s often called. Intended to mark the halfway point of winter, Groundhog Day has come to take on a second identity. So this Groundhog Day, we take time to consider the many great books that have a way of playing with time.