This thesis is a study of the notion of time in modern physics, consisting of two parts. Part I takes seriously the doctrine that modern physics should be treated as the primary guide to the nature of time. To this end, it offers an analysis of the various conceptions of time that emerge in the context of various physical theories and, furthermore, an analysis of the relation between these conceptions of time and the more orthodox philosophical views on the nature (...) of time. In Part II I explore the interpretation of nonrelativistic quantum mechanics in light of the suggestion that an overly Newtonian conception of time might be contributing to some of the difficulties that we face in interpreting the quantum mechanical formalism. In particular, I argue in favour of introducing backwards-in-time causal influences as part of an alternative conception of time that is consistent with the picture of reality that arises in the context of the quantum formalism. Moreover, I demonstrate that this conception of time can already be found in a particular formulation of classical mechanics. One might see that one of the central themes of Part II originates from a failure to heed properly the doctrine of Part I: study into the nature of time should be guided by modern physics and thus we should be careful not to insert a preconceived Newtonian conception of time unwittingly into our interpretation of the quantum mechanical formalism. Thus, whereas Part I is intended as a demonstration of methodology with respect to the study of time, Part II in a sense explores a confusion that can be seen as arising in the absence of this methodology. (shrink)

Human beings seem to capture time and the temporal properties of events and things in thought by having beliefs usually expressed with statements using tense, or notions such as ‘now’, ‘past’ or ‘future’. Tensed beliefs like these seem indispensable for correct reasoning and timely action. For instance, my belief that my root canal is over seems inexpressible with a statement that does not use tense or a temporal indexical. However, the dominant view on the nature of time is that it (...) forms, with space, a four-dimensional continuum where time does not encompass private perspectives or an absolute, fixed present. This ‘tenseless’ theory of time encounters a challenge in integrating tensed belief, because it cannot easily explain what constitutes a tensed belief in a tenseless world and how such a belief works inside our cognitive network to bring about the actions it does. Providing such an account is the main goal of this dissertation. -/- I argue here that the correct way to proceed would be to utilize philosophical theories dealing with indexicality, as the puzzling features of tensed belief are shared with beliefs expressed by first-person or spatial indexicals. In chapters II and III I expand the dominant theories about indexicality (Lewis, Perry, Kaplan) and apply them to tensed belief. I show that each is in certain respects incomplete or inadequate. -/- My preferred account critiques the preceding theories as mis-attributing the indexicality involved to a fully conceptual element in the way people think about time. I argue that we should instead connect tensed belief to not fully conceptual elements thought. For support I turn to work in perceptual psychology that connects beliefs about space to perceptions of spatial features. In chapter IV I develop an analogous argument about temporal thought and discuss how mental representations involved in perceptions are constitutively related to the formation and preservation of tensed beliefs. Combining this story with a tenseless theory of time should give us a complete, metaphysically uncontroversial, account of the way a tensed belief functions in reasoning and produces timely action. (shrink)

Metaphysicians sometimes appeal to physics to establish claims about the fundamental nature of the world. But given the current state of inquiry in physics, where there are two most fundamental theories that are incompatible, such arguments of physics-based metaphysics are problematic. I support this line of thought by focussing on two sorts of problematic arguments, special-relativity-based arguments against presentism and big-bang-based arguments in favor of the existence of God. I am not arguing that physics-based metaphysics can’t be done; I am (...) just arguing that extant examples of physics-based metaphysics are flawed. I close by considering various ways that future versions of physics-based metaphysics could potentially be successful. (shrink)

In light of the Special Theory of Relativity and the Minkowski creation of ‘spacetime’, the universe is taken to be a four-dimensional entity which postulates bodies as existing within a temporally extended reality. The Special Theory of Relativity’s implications liken the nature of the universe to a ‘block’ within which all events coexist equally in spacetime. Such a view strikes against the very essence of presentism, which holds that all that exists is the instantaneous state of objects in the present (...) moment. With respect to the present moment, events have a clear division into the past or future, however such regions do not exist in reality and the universe is a three-dimensional entity. The consequences of a four-dimensional universe are disturbing to say the least for our everyday human experience, with once objective facts about reality becoming dependent upon an observer’s relative motion and the debate over the extent of true free will in a Block Universe. This paper will look at arguments which seek to rescue the presentist view in light of Special Relativity so such four-dimensionalist implications do not have to be accepted. Two approaches will be considered. The first accepts that presentism is incompatible with Special Relativity, and seeks to show that the theory is ultimately false. The second holds that it is the Block Universe interpretation of Special Relativity that is wrong, and a version of presentism can be reconciled with Special Relativity. The paper will expound and critically examine both of these approaches to review whether the case for the three-dimensionalist and a fundamental passage of time can be made. (shrink)

In Minkowski spacetime, because of the relativity of simultaneity to the inertial frame chosen, there is no unique world-at-an-instant. Thus the classical view that there is a unique set of events existing now in a three dimensional space cannot be sustained. The two solutions most often advanced are that the four-dimensional structure of events and processes is alone real, and that becoming present is not an objective part of reality; and that present existence is not an absolute notion, but is (...) relative to inertial frame; the world-at-an-instant is a three dimensional, but relative, reality. According to a third view, advanced by Robb, Capek and Stein, what is present at a given spacetime point is, strictly speaking, constituted by that point alone. I argue here against the first of these views that the four-dimensional universe cannot be said to exist now, already, or indeed at any time at all; so that talk of its existence or reality as if that precludes the existence or reality of the present is a non sequitur. The second view assumes that in relativistic physics time lapse is measured by the time co-ordinate function; against this I maintain that it is in fact measured by the proper time, as I argue by reference to the Twin Paradox. The third view, although formally correct, is tarnished by its unrealistic assumption of point-events. This makes it susceptible to paradox, and also sets it at variance with our normal intuitions of the present. I argue that a defensible concept of the present is nonetheless obtainable when account is taken of the non-instantaneity of events, including that of conscious awareness, as that region of spacetime comprised between the forward lightcone of the beginning of a small interval of proper time t and the backward lightcone of the end of that interval. This gives a serviceable notion of what is present to a given event of short duration, as well as saving our intuition of the “reality” or robustness of present events. (shrink)

Hilary Putnam argued that the special theory of relativity shows that there can be no temporal becoming. Howard Stein replied by defining a becoming relation in Minkowski spacetime. Clifton and Hogarth extended and sharpened Stein’s results. Game over? To the contrary, it has been argued that the Stein-Clifton-Hogarth theorems actually support Putnam’s contention, in that if an apparently minimal condition is put on the becoming relation, then these theorems entail that the becoming relation must be the universal relation. I recount (...) this dialectic in some detail and then try to define and defend a becoming relation based on a present that does indeed consist of more than one point or event but still satisfies the sort of objectivity requirements that Stein-Clifton-Hogarth require of a becoming relation. This present is not a global hyperplane or surface, however; it is a local structure. I close with some methodological remarks about the relation between the present and the real and about the importance of the specious or psychological present. (shrink)

When we begin to investigate the persistence of objects through time, we find immediately that the sort of concerns embodied in Leibniz's Law cause philosophers to divide themselves into the two major camps of Purdurantists and Endurantists. What is required according to each for a given object at a given time to be identified with a given object at another time is held to be dramatically different, even while both often look to the same general sort of indicators for their (...) answers to identity questions: identity or similarity of physical properties, including relational properties like spatial location. I believe, however, that logically prior to the problem of the persistence of objects through time will be questions regarding the composition of objects--we must have coherent notions of what an object is, what it means for parts to compose an object, and what is required for an object to be considered to exist at a single time before we can discuss the continued existence of objects at other times. I believe that posing the problem of temporal gaps for both the Perdurantist and Endurantist to solve can help us uncover reasonable answers to these more basic questions, and thereby help us judge the comparative coherence of the parent theories. Towards this goal, we investigate here some of the assumptions of persistence theories--that Perdurantists are four-dimensionalists and Endurantists are Presentists, for example--before moving on to find reasonable explanations of the composition of objects from within each theory. Important at this stage is clarifying such concepts as parthood and the present. When we at length turn our attention to the problem of gaps, it becomes useful to distinguish two sorts of gaps, each with their own difficulties: a 'gap' as a length of time during which the proper parts of an object are scattered through space, and a 'gap' as a length of time during which the proper parts of an object do not exist in space at all. My contention here is that Perdurantism, paired with four-dimensional spacetime, provides the most coherent answers to the challenges presented throughout. (shrink)

Pettit (2006) argues that deferring to majority testimony is not generally rational: it may lead to inconsistent beliefs. He suggests that “another ... approach will do better”: deferring to supermajority testimony. But this approach may also lead to inconsistencies. In this paper, I describe conditions under which deference to supermajority testimony ensures consistency, and conditions under which it does not. I also introduce the concept of “consistency of degree k”, which is weaker than full consistency by ruling out only “blatant” (...) inconsistencies in an agent’s beliefs while permitting less blatant ones, and show that, while super-majoritarian deference often fails to ensure full consistency, it is a route to consistency in this weaker sense. (shrink)

Quantum gravity is expected to require modifications of the notions of space and time. I discuss and clarify how this happens in Loop Quantum Gravity.

Privileged-perspective realism (PPR) is a version of metaphysical realism that takes certain irreducibly perspectival facts to be partly constitutive of reality. PPR asserts that there is a single metaphysically privileged standpoint from which these perspectival facts obtain. This chapter discusses several views that fall under the category of privileged-perspective realism. These include presentism, which is PPR about tensed facts, and non-multiverse interpretations of quantum mechanics, which the chapter argues, constitute PPR about world-indexed facts. Using the framework of the bird perspective (...) and the frog perspective, it argues that PPR views methodologically treat the frog perspective as metaphysically primary. This chapter considers case studies of metaphysical interpretations of special relativity and quantum mechanics in order to demonstrate that such motivations for PPR are non-naturalistic. Further, it considers psychological factors that motivate the appeal of PPR views and offers naturalistic explanations of why we should not expect them to produce an adequate metaphysics of science. (shrink)

Under the eternalist hypothesis that objects or events exist temporally, but independently of being present two different views of persistence are on the market: Persisting objects endure if they are multiply located in time, and persisting objects perdure if they are singly located by having numerically different temporal parts. In the framework of the special theory of relativity, the metaphysics of persistence is confronted with peculiar difficulties. Things persist by being “wholly present” at more than one time; but what are (...) times within a temporally non-separated spacetime? Things persist by having different temporal parts at different times; but what are the temporal parts of a four-dimensional object in Minkowski spacetime? Recently, several authors have argued that SR favours perdurantism over its endurantist rival. In this paper, I intend to show that the purported arguments are only those against endurantism. The first simply fails, but the second, more convincing one, is such that with a similar strategy we should argue against perdurantism as well: Enduring and perduring entities are hence both in conflict with SR which undermines the eternalist hypothesis. (shrink)

A sentence's meaning may depend on the state of motion of the speaker. I argue that this context-sensitivity blocks the inference from special relativity to four-dimensionalism.

There are two main camps in 20th-century philosophy of time: A-theorists who believe in the dynamic model of reality, and B-theorists who maintain a static model of reality. After the publication of Putnam’s influential article, “time and physical geometry”, the implications of the Special Theory of Relativity became serious in metaphysical discussions about temporal reality. Some philosophers argued that this theory contradicts the dynamic model and implies the ontology of the static model, namely, the objective reality of the present, past (...) and future events. In response, some advocates of the dynamic model argued that there can be dynamic models in relativistic setting, though they are different, radically, from old theories of dynamic reality. In this paper, first, I shall discuss how special relativity contradicts the traditional dynamic model and, then, how new dynamic models imply a relative concept of reality, in contrast to its old absolute concept and, so, why these strategies are very unintuitive. Finally, I shall argue that this radical conceptual shift about reality is, not only unintuitive, but unwarranted and, in some sense, inconsistent as well. (shrink)

The A-theory of time has intuitive and metaphysical appeal, but suffers from tension, if not inconsistency, with the special and general theories of relativity (STR and GTR). The A-theory requires a notion of global simultaneity invariant under the symmetries of the world's laws, those ostensible transformations of the state of the world that in fact leave the world as it was before. Relativistic physics, if read in a realistic sense, denies that there exists any notion of global simultaneity that is (...) invariant under the symmetries of the world's laws. If physics is at least a decent guide to metaphysics--as sympathies for scientific realism would suggest--then relativistic physics supports the B-theory. If there were a physically natural way to modify the symmetries of the physical laws so as to remove those that are repugnant to the A-theory, while retaining empirical adequacy, then such an altered physics might be attractive to the A-theorist and would weaken the support given by relativity to the B-theory. I exhibit a way to do so here, displaying a Lagrangian density explicitly containing distant simultaneity, yet implying Einstein's field equations. The modification involves a change in the nature of the lapse function and makes use of the Dirac-Bergmann formalism of constrained dynamics, which recently has been discussed much by John Earman. Here this formalism is adapted slightly to permit both local and global generalized coordinates. A classification of senses in which time might be absolute or not is made along the way. Some suggestions for extending the work by finding a first principles motivation are made. An appendix outlines an argument why many local presents are insufficient and a global present is attractive, while two more appendices review the Dirac-Bergmann apparatus for GTR and then apply it to the theory at hand. (shrink)

My topic is the question 'Does time pass?'. Although much has been written in attempts to answer this question, not enough attention has been paid to the asking of the question itself. As a result, it has not been clear exactly what is at issue in this matter, and, consequently, it has not been clear just what are the different views available to one who wishes to give an answer to the question. I hope to ameliorate this situation. ;The aims (...) of my essay are: to state the issues involved in the controversy over temporal passage in a fruitful way; to formulate what I see as the leading candidates among the possible responses to those issues; and to consider the best arguments relevant to the choice among these alternative views. ;Roughly one-quarter of the essay is devoted to linguistic questions about time and tense. Another quarter is devoted to metaphysical matters involving the status of such putative properties as pastness, presentness and futurity. What emerge are not just two but, rather, five distinct views about whether or not time passes: one view, which I call the 4D view, to the effect that time does not pass, and four different views, which I call the 3D views, to the effect that time does pass. Each of these five views consists of a package of linguistic and metaphysical components. ;Once I have formulated these five different views, I present, for each of the five views, a formal language, with semantics, that would be appropriate for that view. Next, various arguments that have been suggested in the literature against the claim that time passes are considered as arguments against the 3D views; each such argument is found to be defective. Similarly, various arguments that have been suggested in the literature against the claim that time does not pass are considered as arguments against the 4D view; each of these arguments is also found to be defective. ;Finally, I explain why I prefer a certain one of the 3D views over its four rivals, and I consider some possible objections to that view. (shrink)

This paper distinguishes between 3 meanings of reversal, all of which are mathematically equivalent in classical mechanics: velocity reversal, retrodiction, and time reversal. It then concludes that in order to have well defined velocities a primitive arrow of time must be included in every time slice. The paper briefly mentions that this arrow cannot come from the Second Law of thermodynamics, but this point is developed in more details elsewhere.

In this article I try to once again endorse absolute time into the Philosophy of Physics. The way I endorse absolute time is quite natural and as far as I know is new in debate. If a manifold is stable causal one could provide it with a global time function f by intergating the entropy production over the chronological past of the event p. Time, thus defined, is coordinate independent and does not depend on the status of motion of any (...) observer. This idea is based on a theorem and its proof given by Hawking and Ellis in 1973 [16]. However, I am not a presentist, but I do think that we know something about the world of 1Cnoumena 1D from physics, even if I do not know exactly what. In this article I start with a discussion of special relativity giving emphasis to its constraints towards coordinate systems which are dropped in general relativity. In GR the space-time is a manifold of events, but without the notion of absolute time. After presenting this point of view I repeat Kant 19s theory about how our mind structures the manifold of events. I believe that one could match Kantian metaphysics more or less as well with non-equilibrium thermodynamics as with mechanics, like he did himself. However, unlike Kant, I match causality with the flow of entropy and not with the flow of impulse. I consider this to be a new idea around causality. (shrink)

Special relativity is most naturally formulated as a theory of spacetime geometry, but within the spacetime framework probability appears to be a purely epistemic notion. It is possible that progress can be made with rather different approaches - covariant stochastic equations, in particular - but the results to date are not encouraging. However, it seems a non-epistemic notion of probability can be made out in Minkowski space on Everett's terms. I shall work throughout with the consistent histories formalism. I shall (...) start with a conservative interpretation, and then go on to Everett's. (shrink)

The special theory of relativity is widely regarded as the primary threat to the otherwise intuitive presentist worldview. In particular, both the relativity and conventionality of simultaneity within STR appear to undermine presentism and support eternalism. However, the single term ‘simultaneity’ describes multiple potentially independent concepts. By establishing the mutual independence of the relevant concepts of simultaneity, the presentist and eternalist may agree to move past the initial threat to presentism posed by STR. The subsequent debate hinges on whether presentism (...) or eternalism best accounts for the principle of relativity. The presentist is often accused of initially failing to identify the absolute present and then constructing a model that hides it using an unlikely set of premises. As a result, the eternalist Minkowski space-time interpretation appears simpler in many respects. However, it is demonstrated that on presentism one may obtain the principle of relativity by simply prohibiting instantaneous signals between distant events. Many of the objections against the presentist Neo-Lorentzian interpretation of STR are answered in light of this demonstration. The partition between the experimental evidence provided by STR and human experience is found to be unnecessary. (shrink)

Presentism is roughly the view that only the present exists. This view requires an absolute simultaneity relation. The special theory of relativity, however, is highly successful and does not account for absolute simultaneity. This is widely regarded as an evidential threat to presentism. In what follows, I propose a modest evidential argument in support of presentism on the basis of the physical evidence itself. A weak relativity postulate is shown to follow from a weak light-speed postulate. The weak light-speed postulate, (...) in turn, is shown to be more probable on presentism than on its main rival doctrine, eternalism. Specifically, when one accounts for possible worlds in which the space-time metric is Euclidean rather than Lorentzian, the empirical evidence turns out to be more probable on presentism than on eternalism. If successful, this argument provides modest evidential support for presentism and against eternalism. However, the support is drawn from an unexpected source: the physical evidence itself. (shrink)

We investigate the concepts of past, present, and future that build upon a modal distinction between the settled past and the open future. The concepts are defined in terms of a pre-causal ordering and of qualitative differences between alternative histories. Finally, we look what an event's past, present, and future look like in the so-called Minkowskian Branching Structures, in which histories are isomorphic to Minkowski spacetime.

The discovery that the Universe is accelerating in its expansion has brought the basic concept of cosmic expansion into question. An analysis of the evolution of this concept suggests that the paradigm that was finally settled into prior to that discovery was not the best option, as the observed acceleration lends empirical support to an alternative which could incidentally explain expansion in general. I suggest, then, that incomplete reasoning regarding the nature of cosmic time in the derivation of the standard (...) model is the reason why the theory cannot coincide with this alternative concept. Therefore, through an investigation of the theoretical and empirical facts surrounding the nature of cosmic time, I argue that an enduring three-dimensional cosmic present must necessarily be assumed in relativistic cosmology---and in a stricter sense than it has been. Finally, I point to a related result which could offer a better explanation of the empirically constrained expansion rate. (shrink)

Over a hundred years ago in his paper "Space and Time" Hermann Minkowski demonstrated the profound meaning of the relativity postulate - the experimental fact that physical phenomena are the same in all inertial reference frames implies that the Universe is an absolute four-dimensional world in which all moments of time have equal existence due to their belonging to the fourth dimension. Since then there has been no consensus on the reality of this absolute world, which we now call Minkowski (...) spacetime or simply spacetime. I will argue that facing the ultimate judge - the experimental evidence - allows us to settle this issue once and for all. (shrink)