 This difference as expressed here between Einstein and Carnap (that is, between the Heraclitean and Parmenidean attitude towards time and change) is the subject of this article, which will use modern physics—especially modern spacetime theories—as a set of lenses through which it is hoped the riddles of time will come into sharper focus. There are many ways, however, to approach these questions. Early in the twentieth century, Anglo-American philosophy turned to consideration of language as a way to clarify philosophical disputes. Philosophers of time debated the relations between and the relative primacy of tensed language (concerning the notions of present, past, and future) and tenseless language (concerning the relations of simultaneity and temporal precedence). Our considerations of physics will generally, though not completely, skirt linguistic disputes. The reader interested in following these debates can find a useful introduction in the entry on  time,  a classic presentation in Gale (1968), a review and discussion in Tooley (1999), and Dyke (2007 chapter 3, 2013).