This is a very introductory introduction to some ways in which the special and general theories of relativity may bear upon metaphysical questions about the nature of time and space, and the persistence of objects.

There is a philosophical tradition of arguing against presentism, the thesis that only presently existing things exist, on the basis of its incompatibility with fundamental physics. I grant that presentism is incompatible with special and general relativity, but argue that presentism is not incompatible with quantum gravity, because there are some theories of quantum gravity that utilize a fixed foliation of spacetime. I reply to various objections to this defense of presentism, and point out a flaw in Gödel's modal argument (...) for the ideality of time. This paper provides an interesting case study of the interplay between physics and philosophy. (shrink)

∗ Apologies to Mark Hinchliff for stealing the title of his dissertation. (See Hinchliff, A Defense of Presentism. As it turns out, however, the version of Presentism defended here is different from the version defended by Hinchliff. See Section 3.1 below.).

Persistence through time is like extension through space. A road has spatial parts in the subregions of the region of space it occupies; likewise, an object that exists in time has temporal parts in the various subregions of the total region of time it occupies. This view — known variously as four dimensionalism, the doctrine of temporal parts, and the theory that objects “perdure” — is opposed to “three dimensionalism”, the doctrine that things “endure”, or are “wholly present”.1 I will (...) attempt to resolve this dispute in favor of four dimensionalism by means of a novel argument based on considerations of vagueness. But before argument in this area can be productive, I believe we must become much clearer than is customary about exactly what the dispute is, for the usual ways of formulating the dispute are flawed, especially where three dimensionalism is concerned. (shrink)

Neither special nor general relativity make any use of a notion of absolute simultaneity. Since A-Theories about time do make use of such a notion, it is natural to suspect that relativity and A-Theory are inconsistent. Many authors have argued that they are in fact not inconsistent, and I agree with that diagnosis here. But that doesn’t mean, as these authors seem to think, that A-Theory and relativity are happy bedfellows. I argue that relativity gives us good reason to reject (...) the A-Theory, even though strict inconsistency isn’t that reason. (shrink)

Those inclined to positions in the philosophy of time that take tense seriously have typically assumed that not all regions of space-time are equal: one special region of space-time corresponds to what is presently happening. When combined with assumptions from modern physics this has the unsettling consequence that the shape of this favored region distinguishes people in certain places or people traveling at certain velocities. In this paper I shall attempt to avoid this result by developing a tensed picture of (...) reality that is nonetheless consistent with ‘hypersurface egalitarianism’—the view that all hypersurfaces are equal. (shrink)

What does the passage of time consist in? There are some suggestive metaphors. âEvents approach us, pass us, and recede from us, like sticks and leaves floating on the river of time.â âWe are moving from the past into the future, like ships sailing into an unknown ocean.â There is surely something right and deep about these metaphors. But how close are they to the literal truth? In this book Bradford Skow argues that they are far from the literal truth. (...) Skowâs argument takes the form of a defense of the block universe theory of time, a theory that, in many ways, treats time as a dimension of reality that closely resembles the three dimensions of space. Opposed to the block universe theory of time are theories that take the metaphors more seriously: presentism, the moving spotlight theory, the growing block theory, and the branching time theory. These are theories of ârobustâ passage of time, or âobjective becoming.â Skow argues that the best of these theories, the block universe theoryâs most worthy opponent, is the moving spotlight theory, the theory that says that âpresentnessâ moves along the series of times from the past into the future. Skow defends the moving spotlight theory against the objection that it is inconsistent, and the objection that it cannot answer the question of how fast time passes. He also defends it against the objection that it is incompatible with Einsteinâs theory of relativity. Skow proposes several ways in which the moving spotlight theory may be made compatible with the theory of relativity. Still, this book is ultimately a defense of the block universe theory, not of the moving spotlight theory. Skow holds that the best arguments against the block universe theory, and for the moving spotlight theory, start from the idea that, somehow, the passage of time is given to us in experience. Skow discusses several different arguments that start from this idea, and argues that they all fail. (shrink)

But this picture of a ‘block universe’, composed of a timeless web of ‘world-lines’ in a four-dimensional space, however strongly suggested by the theory of relativity, is a piece of gratuitous metaphysics. Since the concept of change, of something happening, is an inseparable component of the common-sense concept of time and a necessary component of the scientist's view of reality, it is quite out of the question that theoretical physics should require us to hold the Eleatic view that nothing happens (...) in ‘the objective world’. Here, as so often in the philosophy of science, a useful limitation in the form of representation is mistaken for a deficiency of the universe. (shrink)

The aim of this paper is to describe and defend the moving spotlight theory of time. I characterise the moving spotlight theory as the conjunction of two theses: permanentism, the thesis that everything exists forever, and the A-theory, the thesis that there is an absolute, objective present time. I begin in Sect. 2 by clearing up some common misconceptions about the moving spotlight theory, focusing on the discussion of the theory in Sider. In doing so, I also fill-out the barebones (...) picture of the moving spotlight theory as the conjunction of permanentism and the A-theory. In Sect. 3 I show how moving spotlighters can avoid the two common objections to their view, the McTaggartian argument that the view is contradictory, and the epistemic argument that the view implies that we should believe we are not located at the present moment. I conclude that the moving spotlight theory does not deserve its current relative unpopularity. (shrink)

David Malament's (1977) well-known result, which is often taken to show the uniqueness of the Poincare-Einstein convention for defining simultaneity, involves an unwarranted physical assumption: that any simultaneity relation must remain invariant under temporal reflections. Once that assumption is removed, his other criteria for defining simultaneity are also satisfied by membership in the same backward (forward) null cone of the family of such cones with vertices on an inertial path. What is then unique about the Poincare-Einstein convention is that it (...) is independent of the choice of inertial path in a given inertial frame, confirming a remark in Einstein 1905. Similarly, what is unique about the backward (forward) null cone definition is that it is independent of the state of motion of an observer at a point on the inertial path. (shrink)

Defining ‘presentism’ in a way that saves it from being trivially false yet metaphysically substantively distinct from eternalism is no mean feat, as the first part of this collection testifies. In Wuthrich (forthcoming), I have offered an attempt to achieve just this, arguing that this is best done in the context of modern spacetime theories. Here, I shall refrain from going through all the motions again and simply state the characterization of an ersatzist version of presentism as it has emerged (...) from considerations there. Any acceptable formulation of presentism should remain neutral among competing spacetime theories in order to enable the present project of assessing the compatibility of presentism with various theories of modern physics, including both spacetime theories and theories of physical processes situated in a spatiotemporal setting. (shrink)

It has been repeatedly argued, most recently by Nicholas Maxwell, that the special theory of relativity is incompatible with the view that the future is in some degree undetermined; and Maxwell contends that this is a reason to reject that theory. In the present paper, an analysis is offered of the notion of indeterminateness (or "becoming") that is uniquely appropriate to the special theory of relativity, in the light of a set of natural conditions upon such a notion; and reasons (...) are given for regarding this conception as (not just formally consistent with relativity theory, but also) philosophically reasonable. The bearings upon Maxwell's program for quantum theory are briefly considered. (shrink)

Mark Hinchliff concludes a recent paper, "The Puzzle of Change," with a section entitled "Is the Presentist Refuted by the Special Theory of Relativity?" His answer is "no." I respond by arguing that presentists face great difficulties in merely stating their position in Minkowski spacetime. I round up some likely candidates for the job and exhibit their deficiencies.

Focusing on spacetime singularities, Earman engages with a host of foundational issues at the intersection of science and philosophy, ranging from the big bang to the possibility of time travel.