Relativity and the Moving Spotlight

Abstract

The moving spotlight theory of time is usually introduced as follows. The theory combines eternalism—the doctrine that past, present, and future times all exist— with “objective becoming.” The claim that there is objective becoming has two parts. First, facts about which time is present are non-relative. That is, even if in some sense each time is present relative to itself, only one time is absolutely present. That time, and only that time, glows with a special metaphysical status. And second, which instant is absolutely present keeps changing. The NOW moves along the series of times from earlier times to later times. There are lots of objections to the moving spotlight theory. But one objection to the theory looks particularly devastating. The objection is that the theory is incompatible with special relativity. Whatever the force of the other objections to the moving spotlight theory, I do not think that this one is good. My goal in this paper is to explain how to formulate the moving spotlight theory so that it is compatible with special relativity. Before proceeding I want to make a remark about the moving spotlight theory’s place in the philosophy of time. There are two types of theories about the nature of time: A-theories and B-theories. Roughly speaking, A-theorists say that there is some absolute (that is, non-relative) distinction between the past, present, and future. B-theorists deny this. The moving spotlight theory is one version of the A-theory of time. But it is not the most popular. Instead, most A-theorists prefer presentism—the view that everything that exists is present. (In fact, while ∗Published in The Journal of Philosophy 106 (2009): 666-678.