Artists have always struggled to represent the ephemeral phenomenon that is time, but since the beginning of the twentieth century it has become almost a fixation: in recent decades alone, consider On Kawara's series of dated one-day paintings, Janine Antoni's massive and gnawed-at hunks of chocolate and lard, Hiroshi Sugimoto's long-exposure photographs of movie theaters, or I igo Manglano-Ovalle's sped-up video of human motion in Mies van der Rohe's...