Why Does Time Pass?

Abstract

According to the moving spotlight theory of time, the property of being present moves from earlier times to later times, like a spotlight shone on spacetime by God. In more detail, the theory has three components. First, it is a version of eternalism: all times, past present and future, exist. (Here I use “exist” in its tenseless sense.) Second, it is a version of the A-theory of time: there are non-relative facts about which times are past, which time is present, and which times are future. That is, it is not just that the year 1066 is past relative to 2007. The year 1066 is also past full-stop, not relative to any other time. (The A-theory is opposed to the B-theory of time, which says that facts about which times are past obtain only relative to other times.) And third, on this view the passage of time is a real phenomenon. Which moment is present keeps changing. As I will sometimes put it, the NOW moves from the past toward the future. And this does not mean that relative to di erent times, di erent times are present. Even the B-theory can say that 1999 is present relative to 1999 but is not present relative to 2007. No, according to the moving spotlight theory, the claim that which moment is present keeps changing is supposed to be true, even from a perspective outside time. My main goal in this paper is to present a new version of the moving spotlight theory (though in some respects the theory I present also resembles the growing block universe theory of time). This version makes a connection between the passage of time (the motion of the NOW) and change. In fact, it uses facts about change to explain facts about the passage of time. The bulk of the paper is devoted to describing, in detail, how the theory works. I also believe that my new version has advantages over the standard version. It explains things that the standard version cannot explain. It explains both why the NOW moves, and why it moves at a constant rate. I will discuss why I think these are advantages in the final section.