In this paper I will argue that if physics is to become a coherent metaphysics of nature it needs an “interpretation”. As I understand it, an interpretation of a physical theory amounts to offering (1) a precise formulation of its ontological claims and (2) a clear account of how such claims are related to the world of our experience. Notably, metaphysics enters importantly in both tasks: in (1), because interpreting our best physical theories requires going beyond a merely instrumentalist view (...) of science and therefore using our best metaphysical theories; in (2), because a philosophical elaboration of the theories of the world that are implicit in our experience is one of the tasks of analytic metaphysics, and bridging possible explanatory gaps or even conflicts between the physical image and the manifest image of the world is a typical philosophical task that involves science and metaphysics. (shrink)

The paper compares dispositionalism about laws of nature with primitivism. It argues that while the distinction between these two positions can be drawn in a clear-cut manner in classical mechanics, it is less clear in quantum mechanics, due to quantum non-locality. Nonetheless, the paper points out advantages for dispositionalism in comparison to primitivism also in the area of quantum mechanics, and of contemporary physics in general.

This chapter discusses some aspects of the relation between temporal experience and the A versus B debate. To begin with, I provide an overview of the A versus B debate and, following Baron et al. (2015), distinguish between two B-theoretic responses to the A- theoretic argument from experience, veridicalism and illusionism. I then argue for veridicalism over illusionism, by examining our (putative) experiences as of presentness and as of time passing. I close with some remarks on the relation between veridicalism (...) and a deflationary view of the A versus B debate. I suggest that the deflationary view can provide further support for veridicalism. (shrink)

In this paper, I try to make sense of the growing block view using Kit Fine’s three-fold classification of A-theoretic views of time. I begin by motivating the endeavor of making sense of the growing block view by examining John Earman’s project in ‘Reassessing the prospects for a growing block model of the universe’. Next, I review Fine’s reconstruction of McTaggart’s argument and its accompanying three-fold classification of A-theoretic views. I then consider three interpretations of Earman’s growing block model: the (...) hybrid growing block, the purely tensed growing block, and Michael Tooley’s growing block. I argue for three claims. First, Finean ‘standard’ versions of these views are less congenial to the growing blocker than ‘non-standard’ ones. Second, the hybrid view is problematic on either version. And third, ‘non-standard’ versions are not fully intelligible. I provide further support for the first and third of these claims and explain why I take them to support a minimal account of passage as succession, which undercuts some of the motivation for Earman’s project. Lastly, I answer three objections. (shrink)

This book defends a relational theory of the passage of time. The realist view of passage developed in this book differs from the robust, substantivalist position. According to relationism, passage is nothing over and above the succession of events, one thing coming after another. Causally related events are temporally arranged as they happen one after another along observers’ worldlines. There is no unique global passage but a multiplicity of local passages of time. After setting out this positive argument for relationism, (...) the author deals with five common objections to it: (a) triviality of deflationary passage, (b) a-directionality of passage, (c) the impossibility of experiencing passage, (d) fictionalism about passage, and (e) the incompatibility of passage with perduring objects. (shrink)

A short review of some recent developments in the philosophy of physics is presented. I focus on themes which illustrate relations and points of common interest between philosophy of physics and three of its `neighboring' elds: Physics, metaphysics and general philosophy of science. The main examples discussed in these three `border areas' are decoherence and the interpretation of quantum mechanics; time in physics and metaphysics; and methodological issues surrounding the multiverse idea in modern cosmology.

info:eu-repo/semantics/publishedVersion.

When addressing the notion of proper time in the theory of relativity, it is usually taken for granted that the time read by an accelerated clock is given by the Minkowski proper time. However, there are authors like Harvey Brown that consider necessary an extra assumption to arrive at this result, the so-called clock hypothesis. In opposition to Brown, Richard TW Arthur takes the clock hypothesis to be already implicit in the theory. In this paper I will present a view (...) different from these authors by taking into account Einstein’s notion of natural clock and showing its relevance to the debate. (shrink)

This work introduces a causal explanation of the passage of time, and contrasts it with rival explanations. In the causal explanation, laws of physics are shown to entail that events are in causal succession, and the passage of time is defined as their causal succession. The causal explanation is coupled with phenomenology of the passage of time, and contrasted with the project of making sense of the idea that time does not pass.

Eternalism is the view that all times are equally real. The relativity of simultaneity in special relativity backs this up. There is no cosmically extended, self-existing ‘now.’ This leads to a tricky problem. What makes statements about the present true? I shall approach the problem along the lines of perspectival realism and argue that the choice of the perspective does. To corroborate this point, the Lorentz transformations of special relativity are compared to the structurally similar equations of the Doppler effect. (...) The ‘now’ is perspectivally real in the same way as a particular electromagnetic spectrum frequency. I also argue that the ontology of time licensed by perspectival realism is more credible in this context than its current alternative, the fragmentalist interpretation of special relativity. (shrink)

A recently published hypothesis on the nature of time by physicist Richard A. Muller seeks to provide an objective account of the present moment and the ‘flow’ of time. Muller also claims that his hypothesis makes testable predictions. It is shown that the predictions offered cannot be used to test Muller’s hypothesis, that the hypothesis does not rate scientific status, has a number of questionable metaphysical premises, and is merely a re-fashioning of the Growing Block theory of time.

Is the objective passage of time compatible with relativistic physics? There are two easy routes to an affirmative answer: (1) provide a deflationary analysis of passage compatible with the block universe, or (2) argue that a privileged global present is compatible with relativity. (1) does not take passage seriously. (2) does not take relativity seriously. This paper is concerned with the viability of views that seek to take both passage and relativity seriously. The investigation proceeds by considering how traditional A-theoretic (...) conceptions of passage might be generalized to relativistic space-times without incorporating a privileged global present. I argue that the most promising position marries the idea that open possibilities for the future are settled as time passes with a ‘non-standard’ interpretation of the relevant formal models. (shrink)

By considering situations from the paradox of the twins in relativity, it is shown that time passes at different rates along different world lines, answering some well-known objections. The best explanation for the different rates is that time indeed passes. If time along a world line is something with a rate, and a variable rate, then it is difficult to see it as merely a unique, invariant, monotonic parameter without any further explanation of what it is. Although it could, conceivably, (...) be explained by the flow of something, it is better explained by the passing of a point present, which faces the problem that there is no absolute simultaneity in special relativity so that the present for an object is confined to just that object. This raises problems about presentism, eternalism, simultaneity, and special relativity. These issues are addressed first by giving accounts of presentism and eternalism and then an account of existence and times for objects relative to world lines. Finally, an analogy between a world of relativistic objects and Leibniz’s ontology of monads. (shrink)

© The Author 2018. Published by Oxford University Press on behalf of The Analysis Trust. All rights reserved. For Permissions, please email: [email protected] Objective Becoming, Bradford Skow declares that he aims to defend the ‘anaemic’ passage of time in the block universe. This is in contrast to the ‘robust’ kind of passage – normally understood as the change in an objectively privileged present moment, the NOW – associated with A-theories of time. The defence of any sense of passage in the (...) block universe is a growing endeavour, but Skow seeks to defend it in a peculiar and roundabout way. Specifically, Skow argues that the best A-theory of robust passage is the moving spotlight theory of time, and if the best theory is inadequate, then one should accept the anaemic passage of the block universe. Skow, obviously, finds MST inadequate, and in doing so, accepts the... (shrink)

The debate between Einstein and Bergson is a salient episode in the history of modern physics and a telling example of the interaction between science and philosophy. This paper initially discusses five reasons why Bergson criticised Einstein for giving up absolute time. The most important one was Bergson’s commitment to an intuitionist, anti-Kantian metaphysics informed by common sense. Apart from that, he knew that the theory of special relativity permits “duration” in the form of the passage of proper time, to (...) which Bergson referred as “real time”. Neither static eternalism nor dynamic eternalism are acceptable from Bergson’s philosophical perspective, which acknowledges the role of temporal experience and everyday thinking in addition to science and metaphysics. He understood temporal passage as creation of new existence, anticipating what later became known as the growing block theory of time. The pointy relativistic variant of this theory, which divides the universe into blocks of growing past light cones, does justice to large parts of his philosophy, including the distinction between the actual and the virtual. Supporters of Bergson’s account of duration should adopt this theory of time. (shrink)

A-theoretic presentness is commonly regarded as non-solipsist and non-relative. The non-solipsism of a non-relative, A-theoretic presentness requires at least two space-like separated things to be present simpliciter together – this co-presentness further implies the global, non-relative, non-conventional simultaneity of them. Yet, this implication clashes with the general view that there is no global, non-relative, non-conventional simultaneity in Minkowski space-time. In order to resolve this conflict, this paper explores the possibility that the non-solipsism of a non-relative, A-theoretic presentness does not require (...) at least two space-like separated things to be present simpliciter together. This can be done by holding exclusive disjunctivism –that mutually space-like separated things are present simpliciter exclusively disjunctively, and each one of them gets to be present simpliciter in a non-successive way (just like mutually time-like related things are present simpliciter exclusively disjunctively, and each one of them gets to be present simpliciter, but in a successive way). (shrink)

In this paper, I defend a theory of local temporality, sometimes referred to as a point-present theory. This theory has the great advantage that it allows for the possibility of an open future without requiring any alterations to our standard understanding of special relativity. Such theories, however, have regularly been rejected out of hand as metaphysically incoherent. After surveying the debate, I argue that such a transformation of temporal concepts (i) is suggested by the indexical semantics of tense in a (...) relativistic universe, (ii) when properly understood easily withstands the usual accusations of metaphysical incoherence and (iii) leads naturally to a meta-philosophical position from which we can understand and escape the increasing sterility of debates between radical Parmenideans and radical Heracliteans in the philosophy of time. (shrink)

The aim of this paper is to make presentism a dynamic view of reality by basing it on a notion of dynamic existence, that is, on a notion of existence which has a dynamic character. The paper shows that both of the notions of existence which are used in metaphysical theories of time have a static character and, while such a notion is useful for eternalists, it is useless for presentists if they want to make their view able to remain (...) in agreement with our everyday experience and self-consistent. It is demonstrated that both empirical and theoretical arguments indicate that the presentist should replace the notion of this static existence with the notion of a dynamic existence and that this maneuver allows the presentist to treat his/her existential thesis as equivalent to the thesis that time flows. Not only does this strategy allow us to express presentism in a simple, homogenous way which remains in agreement with our experience, but also permits us to solve some of the difficult problems which presentism faces, such as, for example, the objection of triviality and the question about the rate of time passage. Moreover, such an approach to presentism allows us to solve fundamental metaphysical problems concerning time such as the problem of the openness of the future and the fixity of the past, direction of causation, and relations between presentism and persistence through time by endurance. (shrink)

Callender [2017] claims that contemporary science demonstrates that there is no objective present and no objective flow of time, especially since all sensed events come from the past, our various senses need different amounts of time to react, and there are enough asymmetries in the physical world to explain our experience of time. This paper holds that, although Callender’s arguments for the subjectivity of the flow of time are unconvincing, the scientific discoveries and arguments he indicates can still be applied (...) to improve theories of the objective flow of time. The paper develops precisely such a theory, one which introduces multiple individual proper presents for all of the objects that make up our world. (shrink)

John Bell proposed an ontology for the GRW modification of quantum mechanics in terms of flashes occurring at space- time points. This article spells out the motivation for this ontology, inquires into the status of the wave function in it, critically examines the claim of its being Lorentz invariant, and considers whether it is a parsimonious but nevertheless physically adequate ontology.

Presentists have typically argued that the Block View is incapable of explaining our experience of time. In this paper I argue that the phenomenology of our experience of time is, on the contrary, against presentism. My argument is based on a dilemma: presentists must either assume that the metaphysical present has no temporal extension, or that it is temporally extended. The former horn leads to phenomenological problems. The latter renders presentism metaphysically incoherent, unless one posits a discrete present that, however, (...) suffers from the same difficulties that the instantaneous present is prone to. After introducing the main phenomenological models of our experience of time that are discussed in the literature, I show that none of them favors presentism. I conclude by arguing that if even the phenomenology of time sides against presentism, the latter metaphysical theory has no scientific evidence in its favor and ought to be dropped. (shrink)

In the first part of the paper I argue that an ontology of events is precise, flexible and general enough so as to cover the three main alternative formulations of quantum mechanics as well as theories advocating an antirealistic view of the wave function. Since these formulations advocate a primitive ontology of entities living in four-dimensional spacetime, they are good candidates to connect that quantum image with the manifest image of the world. However, to the extent that some form of (...) realism about the wave function is also necessary, one needs to endorse also the idea that the wave function refers to some kind of power. In the second part, I discuss some difficulties raised by the recent proposal that in Bohmian mechanics this power is holistically possessed by all the particles in the universe. (shrink)

The literature on the compatibility between the time of our experience--characterized by passage or becoming--and time as is represented within spacetime theories has been affected by a persistent failure to get a clear grasp of the notion of becoming, both in its relation to an ontology of events tt"spreadtt" in a four-dimensional manifold, and in relation to temporally asymmetric physical processes.In the first part of my paper I try to remedy this situation by offering what I consider a clear and (...) faithful explication of becoming, valid independently of the particular spacetime setting in which we operate. Along the way, I will show why the metaphysical debate between the so-called tt"presentiststt" and tt"eternaliststt" is completely irrelevant to the question of becoming, as the debate itself is generated by a failure to distinguish between a tensed and a tenseless sense of tt"existencett". After a much needed distinction between absolute and relational becoming, I then show in what sense classical spacetime physics presupposes both types of becoming, for the simple reason that spacetime physics presupposes an ontology of events. As a consequence, not only does it turn out that using physics to try to provide empirical evidence for the existence of becoming amounts to putting the cart before the horses, but also that the order imposed by tt"the arrow of becomingtt" is more fundamental than any other physical arrow of time, despite the fact that becoming cannot be used to explain why entropy grows, or retarded electromagnetic radiation prevails versus advanced radiation. (shrink)

I examine the relation between naturalistically motivated and other critiques of grounding and similar critiques of the contrast between A- and B-theoretic views of time. I argue that even the combined dialectical upshot of nonunity objections in the latter case is not what it is in the former. I sympathetically discuss the objection that the notion of grounding is not intelligible and part of ‘esoteric’ metaphysics; this objection turns out to be just as serious in the case of the A/B (...) contrast. I then consider whether grounding is needed to draw the A/B contrast in the first place and answer this question in the negative. Finally, I comment on the costs of esotericism in both cases. (shrink)

A-theorists and B-theorists debate whether the "Now" is metaphysically distinguished from other time slices. Analogously, one may ask whether the "I" is metaphysically distinguished from other perspectives. Few philosophers would answer the second question in the affirmative. An exception is Caspar Hare, who has devoted two papers and a book to arguing for such a positive answer. In this paper, I argue that those who answer the first question in the affirmative---A-theorists---should also answer the second question in the affirmative. This (...) is because key arguments in favor of the A-theory are more effective asarguments in favor of the resulting combined position, and key arguments against the A-theory are ineffective against the combined position. (shrink)

V prvej časti príspevku s názvom Čas sa najprv na základe známeho textu Aurélia Augustína Vyznania vymedzujú hlavné problémy spojené s určovaním času, jeho reálnosťou, pretržitosťou, merateľnosťou atď. V druhej časti s názvom Veľký tresk sa uvádzajú rôzne vymedzenia tejto veľmi špecifickej udalosti, ktorá by mala byť počiatkom všetkého, čo skúmame a čím žijeme; najprv tie tradičné, kedy sa veľký tresk chápe ako explodujúca singularita a biela diera, a potom aj tie novšie, kedy prestáva byť absolútnym počiatkom vesmíru a stáva (...) sa opakujúcim fyzikálnym javom alebo procesom. Napokon v tretej časti s názvom Čas a veľký tresk sa v rámci diskusie o vhodnosti prezentistickej či eternalistickej (dynamickej či statickej) koncepcie času dáva veľký tresk do vzťahu s hypotetickým globálnym časom nášho vesmíru a zároveň sa ukazuje, že celá polemika medzi zástancami prezentistickej a eternalistickej koncepcie času je de facto založená na bežnej chybe - na nerozlišovaní medzi ontologickým a sémantickým realizmom. (shrink)

It has been argued that the standard formulation of the Special Theory of Relativity is not only incompatible with presentism, but also strongly indicates the truth of eternalism. We should, however, distinguish two claims concerning the ontological implications of STR: STR is inconsistent with every ontology which requires an absolute relation of simultaneity; and STR implies that eternalism is the only possible ontology of time. There have been a wide range of responses designed to reject these claims, both jointly and (...) independently. For example, one way of rejecting claim is by rejecting claim : thus, one would argue that STR can be revised or interpreted in such a way that it allows an absolute relation of simultaneity. Another way of rejecting claim is by questioning the equivalency of the relation ‘being real as of’. The main purpose of this paper is to raise a new line of objection against concluding eternalism from the relativity of simultaneity. I argue that there is a way to deny claim without denying claim and also without denying the equivalency of relation R. The argument which I present rests on a metaphysical assumption concerning the relation of simultaneity : the assumption that the SIM holds basically between space–time points as opposed to holding basically between events. (shrink)

The theory of relativity is often regarded as inhospitable to the idea that there is an objective passage of time in the world. In light of this, many philosophers and physicists embrace a “block universe” view, according to which change and temporal passage are merely a subjective appearance or illusion. My aim in this paper is to argue against such a view, and show that we can make sense of an objective passage of time in the setting of relativity theory (...) by abandoning the assumption that the now must be global, and re-conceiving temporal passage as a purely local phenomenon. Various versions of local becoming have been proposed in the literature. Here I focus on the causal diamond theory proposed by Steven F. Savitt and Richard Arthur, which models the now in terms of a local structure called a causal diamond. After defending the reality of temporal passage and exploring its compatibility with relativity theory, I show how the causal diamond approach can be used to counter the argument for the ideality of time due to Kurt Gödel, based on his “rotating universe” solution to the Einstein field equations. I defend the second component of his argument, the modal step, against the consensus view that finds it wanting, and reject the first step, showing that the Gödel universe is compatible with an objective passage of time as long as the latter is construed locally, along the lines of the causal diamond approach. (shrink)

This chapter explores some of the relations between Quine’s and Carnap’s metaontological stances on the one hand, and contemporary work in the metaphysics of time, on the other. Contemporary metaphysics of time, like analytic metaphysics in general, grew out of the revival of the discipline that Quine’s critique of the logical empiricists (such as Carnap) made possible. At the same time, the metaphysics of time has, in some respects, strayed far from its Quinean roots. This chapter examines some likely Quinean (...) and Carnapian reactions to elements of the contemporary scene. (shrink)

Ajan luonnetta koskevissa käsityksissä on tyypillistä erottaa kaksi eriävää kantaa: A-teoreettinen presentismi ja B-teoreettinen eternalismi. Edeltävän väitetään tyypillisesti sopivan yhteen inhimillisen ajallisen kokemuksen kanssa ja jälkimmäisen ontologisesti perustavanlaatuisen luonnontieteen kanssa. Ilmikuvamme ajasta sisältää ehdottoman nykyisyyden ja yksisuuntaisen ajan kulun menneestä tulevaan. Tieteellinen kuva ajasta ei sisällä erityistä nykyisyyttä eikä ajan kulun edellyttämää dynaamista aikamuotojen muutosta. Monet ovat pitäneet kokemustamme ajan kulusta illuusiona. Tässä artikkelissa keskitytään A-sarjan mukaisen ajankulun virheteoreettiseen tulkintaan. Tarkastellaan mahdollisuutta, jonka mukaan meillä ei ole kyseistä kokemusta vaan kuvailemme (...) kokemustamme virheellisesti ajan virtaukseen liittyvillä vertauskuvilla. Tätä tukee fysikalistinen argumentti: Jos ajan kulun kokemuksellamme ei ole fysikaalista perustaa, meillä ei voi olla sen mukaista kokemustakaan ajasta. (shrink)

This paper seeks to recover the function of universal history, which was to place particulars into relation with universals. By the 20th century universal history was largely discredited because of an idealism that served to lend epistemic coherence to the overwhelming complexity arising from universal history's comprehensive scope. Idealism also attempted to account for history's being "open"--for the human ability to transcend circumstance. The paper attempts to recover these virtues without the idealism by defining universal history not by its scope (...) but rather as a scientific method that provides an understanding of any kind of historical process, be it physical, biological or human. While this method is not new, it is in need of a development that offers a more robust historiography and warrant as a liberating historical consciousness. The first section constructs an ontology of process by defining matter as ontic probabilities rather than as closed entities. This is lent warrant in the next section through an appeal to contemporary physical science. The resulting conceptual frame and method is applied to the physical domain of existents, to the biological domain of social being and finally to the human domain of species being. It is then used to account for the emergence of human history's initial stage--the Archaic Socio-Economic Formation and for history' stadial trajectory--its alternation of evolution and revolution. (shrink)

In the transition to Einstein’s theory of Special Relativity (SR), certain concepts that had previously been thought to be univocal or absolute properties of systems turn out not to be. For instance, mass bifurcates into (i) the relativistically invariant proper mass m0, and (ii) the mass relative to an inertial frame in which it is moving at a speed v = βc, its relative mass m, whose quantity is a factor γ = (1 – β2) -1/2 times the proper mass, (...) m = γm0. (shrink)

According to Dennis Dieks, in the theory of relativity, the «flow of time» results from the succession of events along time-like worldlines. We have a flow of time per worldline. This leads to a view of now as local to each worldline. In this approach there is no global temporal order of the now-points of different worldlines. For a consistency reason it is imposed a limitation on the assignment of different now-points. Here it is made the claim that this consistency (...) requirement is inbuilt in the theory, and it is presented a detailed analysis of this approach. (shrink)

Unatoč naslovu koji pokriva iznimno opširno područje, članak se usredotočuje na blisko pitanje da li Specijalna teorija relativnosti nužno zagovara ukidanje ontološke razlike između prošlih i budućih događaja, između prošlosti i budućnosti općenito. Izraženo žargonom koji uvodi Stein: jesmo li u okviru STR prinuđeni birati isključivo između ‘solipsizma’ i ‘determinizma’? Posebice će biti riječi o ulozi koju konvencionalnost istovremenosti u STR ima u pokušaju odgovora na ovo pitanje. Standardni argumenti pozivaju se na relativnost istovremenosti, tvrdnju da STR negira postojanje univerzalne (...) ‘sadašnjosti’ koja razgraničava ‘prošlost’ i ‘budućnost’, kako bi pokazali da nema ontološke razlike između prošlosti i budućnosti, da su obje jednako određene/zbiljne . Pritom se prešutno prelazi preko činjenice da je za uspostavu ontoloških tvrdnji vezanih uz relativnost istovremenosti potrebno prvo riješiti pitanje konvencionalnosti istovremenosti u okviru STR. U članku će se nastojati pokazati da promatranjem pitanja konvencionalnosti istovremenosti iz perspektive ‘čisto filozofskog’ Dummettovog određenja razlike između prošlosti i budućnosti možemo u okviru STR pokušati razviti shvaćanje razlikovanja prošlosti i budućnosti mimo stroge ontološke dihotomije ‘solipsizam’/‘determinizam’, ukoliko kriterij koji postavlja STR shvatimo kao epistemički, a ne kao ontološki.Despite a broad-range title the paper settles for the related issue of whether the Special Theory of Relativity necessarily advocates the demise of an ontological difference between past and future events, between past and future in general. In the jargon of H. Stein: are we forced, within the framework of the STR, to choose only between ‘solipsism’ and ‘determinism’ exclusively? A special emphasis is placed on the role that the conventionality of simultaneity plays in the STR with regards to this question. The standard arguments rely on the relativity of simultaneity, the claim that the STR negates the existence of a universal ‘present’ that divides the ‘past’ and the ‘future’, so as to conclude that there is no ontological difference between past and future events, that both are equally determined/real . This often neglects the fact that to establish the ontological claims related to relativity of simultaneity, one must first resolve the issues of conventionality of simultaneity within the STR. The paper will aim to show that by addressing the issue of conventionality from Dummett’s ‘purely philosophical’ determination of the difference between the past and the future, we develop an understanding of the said difference, within the framework of the STR, beyond the strict ontological dichotomy of ‘solipsism/determinism’, given that the criterion that is provided by the STR is understood as epistemic and not ontological. (shrink)

The causal set programme towards a quantum theory of gravity is situated vis-à-vis the long-standing debate between eternalism (block theory) and past-presentism or possibilism (growing block theory) in the philosophy of time. It is argued that despite 'appearances' and declarations to the contrary, the programme does not side with growing block theorists when it comes to harboring a robust notion of Becoming - at least, not more than familiar relativistic theories on continuous spacetime manifolds. The problem stems mainly from the (...) postulate of discrete general covariance - a requirement imposed upon the only fully worked out kind of dynamics for causal sets to date, a dynamics of a classical stochastic process. (shrink)

According to conventional wisdom, local gauge symmetry is not a symmetry of nature, but an artifact of how our theories represent nature. But a study of the so-called theta-vacuum appears to refute this view. The ground state of a quantized non-Abelian Yang-Mills gauge theory is characterized by a real-valued, dimensionless parameter theta—a fundamental new constant of nature. The structure of this vacuum state is often said to arise from a degeneracy of the vacuum of the corresponding classical theory, which degeneracy (...) allegedly arises from the fact that “large” (but not “small”) local gauge transformations connect physically distinct states of zero field energy. If that is right, then some local gauge transformations do generate empirical symmetries. In defending conventional wisdom against this challenge I hope to clarify the meaning of empirical symmetry while deepening our understanding of gauge transformations. I distinguish empirical from theoretical symmetries. Using Galileo’s ship and Faraday’s cube as illustrations, I say when an empirical symmetry is implied by a theoretical symmetry. I explain how the theta-vacuum arises, and how “large” gauge transformations differ from “small” ones. I then present two analogies from elementary quantum mechanics. By applying my analysis of the relation between empirical and theoretical symmetries, I show which analogy faithfully portrays the character of the vacuum state of a classical non-Abelian Yang-Mills gauge theory. The upshot is that “large” as well as “small” gauge transformations are purely formal symmetries of non-Abelian Yang-Mills gauge theories, whether classical or quantized. It is still worth distinguishing between these kinds of symmetries. An analysis of gauge within the constrained-Hamiltonian formalism yields the result that “large” gauge transformations should not be classified as gauge transformations; indeed, nor should “global” gauge transformations. In a theory in which boundary conditions are modeled dynamically, “global” gauge transformations may be associated with physical symmetries, corresponding to translations of these extra dynamical variables. Such translations are symmetries if and only if charge is conserved. But it is hard to argue that these symmetries are empirical, and in any case they do not correspond to any constant phase change in a quantum state. (shrink)

I present an account of the passage of time and the present in relativistic spacetimes, and I defend these views against recent criticism by Oliver Pooley and Craig Callender.

We review the current situation in the philosophy of time, partly to investigate Michael Dummett’s complaint that the philosophy of physics has become too specialized and technical to be able to communicate with mainstream philosophy. We conclude that the situation in this case is different: there is no special difficulty of intelligibility---the obstacle for communication between science and philosophy here is rather that what physics, or science in general, tells us is prima facie in conflict with common sense and intuition. (...) We argue that this difficulty is indeed prima facie: on closer inspection it appears that the scientific B-theory may explain our intuition better than the A-theory, even though the latter at first sight seems to completely mirror our direct experience. (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)

In this paper it is argued that if physics is to become a coherent metaphysics of nature, it needs an interpretation, namely (i) a clear formulation of its ontological/metaphysical claims and (ii) and a precise understanding of how such claims are related to the world of our experience, which is the most important reservoir of traditional, merely aprioristic metaphysical speculations. Such speculations − especially if conducted in full autonomy from physics, or imposed upon it “from the outside” − risk to (...) turn analytic metaphysics into a “rigorous” but fully sterile intellectual game. (shrink)