Time is a fundamental part of how we experience the world. But when we try to describe what time actually is, things get murky pretty fast. The philosopher J.M.E. McTaggart laid out a framework that underpins much of the contemporary debate about the nature of time. In “A-series” time, the concept of “now” is a real thing, and we are constantly moving from the past to the present to the future. In “B-series” time, everything exists all at once, like the frames on a movie reel where the “present” is just the projector light shining on a particular image. McTaggart himself thought that time was just an illusion. In this episode we review these two theories of time and try to work out which one is right. We also try to figure out why McTaggart had the same name twice why looks so much like Higgins from Magnum, P.I. You’ll get to hear a real live Socratic dialog and learn what happens when you put an atomic clock on a commercial airliner.