Why is the future so different from the past? Why does the past affect the future and not the other way round? The universe began with the Big Bang - will it end with a `Big Crunch'? Now in paperback, this book presents an innovative and controversial view of time and contemporary physics. Price urges physicists, philosophers, and anyone who has ever pondered the paradoxes of time to look at the world from a fresh perspective, and throws fascinating new light (...) on some of the great mysteries of the universe. (shrink)

In a revolutionary new book, a theoretical physicist attacks the foundations of modern scientific theory, including the notion of time, as he shares evidence of ...

This book is a defense of modal realism; the thesis that our world is but one of a plurality of worlds, and that the individuals that inhabit our world are only a few out of all the inhabitants of all the worlds. Lewis argues that the philosophical utility of modal realism is a good reason for believing that it is true.

We discuss from a philosophical perspective the way in which the normal concept of time might be said to `emerge' in a quantum theory of gravity. After an introduction, we briefly discuss the notion of emergence, without regard to time. We then introduce the search for a quantum theory of gravity ; and review some general interpretative issues about space, time and matter. We then discuss the emergence of time in simple quantum geometrodynamics, and in the Euclidean approach. Section 6 (...) concludes. (shrink)

The purpose of this paper is two fold: first, I look to show Oaklander’s theory of time to be false. Second, I show that the only way to salvage the B-theory is via the adopting of the causal theory of time, and allying this to Oaklander’s claim that tense is to be eliminated. I then raise some concerns with the causal theory of time. My conclusion is that, if one adopts eternalism, the unreality of time looks a better option than (...) the B-theory. (shrink)

Here, I defend the view that there is no sensible way to pin a truth-maker objection on presentism. First, I suggest that if we adopt truth-maker maximalism then the presentist can requisition appropriate ontological resources with impunity. Second, if we deny maximalism, then the presentist can sensibly restrict the truth-maker principle in order to avoid the demand for truth-makers for talk about the non-present.

In this paper I look to develop a defence of “presentist temporal passage” that renders presentism immune from recent arguments due to Eric Olson. During the course of the paper, I also offer comment on a recent reply to Olson’s argument due to Ian Phillips. I argue that it is not clear that Phillips’ arguments succeed.

Some philosophers believe that the passage of time is a real phenomenon. And some of them find a reason to believe this when they attend to features of their conscious experience. In fact this “argument from experience” is supposed to be one of the main arguments for passage. What exactly does this argument look like? Is it any good?

Following a line of research that I have developed for several years, I argue that the best strategy for understanding quantum gravity is to build a picture of the physical world where the notion of time plays no role at all. I summarize here this point of view, explaining why I think that in a fundamental description of nature we must “forget time”, and how this can be done in the classical and in the quantum theory. The idea is to (...) develop a formalism that treats dependent and independent variables on the same footing. In short, I propose to interpret mechanics as a theory of relations between variables, rather than the theory of the evolution of variables in time. (shrink)

This is an expanded and revised discussion of the argument briefly put forward in my 'A New Problem for the A-Theory of Time', where it is claimed that it is impossible to experience real temporal passage and that no such phenomenon exists. In the first half of the paper the premises of the argument are discussed in more detail than before. In the second half responses are given to several possible objections, none of which were addressed in the earlier paper. (...) There is also some discussion of some related epistemic arguments against the passage of time given by Huw Price and David Braddon-Mitchell along with objections raised against them recently by Tim Maudlin and Peter Forrest respectively. (shrink)

The question I want to explore is whether experience supports an antireductionist ontology of time, that is, whether we should take it to support an ontology that includes a primitive, monadic property of nowness responsible for the special feel of events in the present, and a relation of passage that events instantiate in virtue of literally passing from the future, to the present, and then into the past.

I want to consider some features of the position put forward by Julian Barbour in The End of Time that seem to me of particular philosophical interest. At the level of generality at which I'll be concerned with it, the view is relatively easy to describe. It can be arrived at by thinking of time as decomposing in some natural way linearly ordered atomic parts, ‘moments’, and combining an observation about the internal structure of moments with an epistemological doctrine about (...) our access to the past. The epistemological doctrine, which I'll call ‘Presentism’, following Butterfield, is the view that our access to the past is mediated by records, or local representations, of it. The observation is that the state of the world at any moment has the structure of what Barbour calls a ‘time capsule’, which is to say that it constitutes a partial record of its past, it is pregnant with interrelated mutually consistent representations of its own history. (shrink)

The conceptual and technical difficulties involved in creating a quantum theory of gravity have led some physicists to question, and even in some cases to deny, the reality of time. More surprisingly, this denial has found a sympathetic audience among certain philosophers of physics. What should we make of these wild ideas? Does it even make sense to deny the reality of time? In fact physical science has been chipping away at common sense aspects of time ever since its inception. (...) Section 1 offers a brief survey of the demolition process. Section 2 distinguishes a tempered from an extremely radical form that a denial of time might take, and argues that extreme radicalism is empirically self-refuting. Section 3 begins an investigation of the prospects for tempered radicalism in a timeless theory of quantum gravity. (shrink)

I discuss Julian Barbour's Machian theories of dynamics, and his proposal that a Machian perspective enables one to solve the problem of time in quantum geometrodynamics (by saying that there is no time!). I concentrate on his recent book, The End of Time (1999). A shortened version will appear in The British Journal for Philosophy of Science}.

This review of Julian Barbour's The End of Time ([1999]) discusses his Machian theories of dynamics, and his proposal that a Machian perspective enables one to solve the problem of time in quantum geometrodynamics, viz. by saying that there is no time! 1 Introduction 2 Machian themes in classical physics 2.1 The status quo 2.2 Machianism 2.2.1 The temporal metric as emergent 2.2.2 Machian theories 2.2.3 Assessing intrinsic dynamics 3 The end of time? 3.1 Time unreal? The classical case 3.1.1 (...) Spontaneity 3.1.2 Barbour's vision: time capsules 3.2 Evidence from quantum physics? 3.2.1 Mott scattering as a model for time capsules 3.2.2 Solving the problem of time? (shrink)

This paper offers a new way to evaluate counterfactual conditionals on the supposition that actually, there is no time. We then parlay this method of evaluation into a way of evaluating causal claims. Our primary aim is to preserve, at a minimum, the assertibility of certain counterfactual and causal claims once time has been excised from reality. This is an important first step in a more general reconstruction project that has two important components. First, recovering our ordinary language claims involving (...) notions such as persistence, change and agency and, second, recovering enough observational evidence so that any timeless metaphysics is not empirically self-refuting. However, the project of investigating causation in a timeless setting has a greater relevance than its application to timeless physical theory alone. For, as we show, it can be used to model the assertibility conditions of causal claims more generally. (shrink)

How can we talk meaningfully about the past if it does not exist to be talked about? What gives time its direction? Is time travel possible? This defence of presentism - the view that only the present exists - makes an original contribution to a fast growing and exciting debate.

"A leading scientist interweaves evolution, theoretical physics, and computer science to offer a new understanding of reality"--Cover.

Quantum gravity poses the problem of merging quantum mechanics and general relativity, the two great conceptual revolutions in the physics of the twentieth century. The loop and spinfoam approach, presented in this book, is one of the leading research programs in the field. The first part of the book discusses the reformulation of the basis of classical and quantum Hamiltonian physics required by general relativity. The second part covers the basic technical research directions. Appendices include a detailed history of the (...) subject of quantum gravity, hard-to-find mathematical material, and a discussion of some philosophical issues raised by the subject. This fascinating text is ideal for graduate students entering the field, as well as researchers already working in quantum gravity. It will also appeal to philosophers and other scholars interested in the nature of space and time. (shrink)

An extraordinary and challenging synthesis of ideas uniting Quantum Theory, and the theories of Computation, Knowledge and Evolution, Deutsch's extraordinary book explores the deep connections between these strands which reveal the fabric ...

How can we talk meaningfully about the past if it does not exist to be talked about? What gives time its direction? Is time travel possible? This defence of presentism - the view that only the present exists - makes an original contribution to a fast growing and exciting debate.

The philosophical literature on time and change is fixated on the issue of whether the B-series account of change is adequate or whether real change requires Becoming of either the property-based variety of McTaggart's A-series or the non-property-based form embodied in C. D. Broad's idea of the piling up of successive layers of existence. For present purposes it is assumed that the B-series suffices to ground real change. But then it is noted that modern science in the guise of Einstein's (...) general theory poses a threat to real change by implying that none of the genuine physical magnitudes countenanced by the theory changes its value with time. The aims of this paper are to explain how this seemingly paradoxical conclusion arises and to assess the merits and demerits of possible reactions to it. (shrink)

A solution to the issue of time in quantum gravity is proposed. The hypothesis that time is not defined at the fundamental level (at the Planck scale) is considered. A natural extension of canonical Heisenberg-picture quantum mechanics is defined. It is shown that this extension is well defined and can be used to describe the "non-Schrödinger regime," in which a fundamental time variable is not defined. This conclusion rests on a detailed analysis of which quantities are the physical observables of (...) the theory; a main technical result of the paper is the identification of a class of gauge-invariant observables that can describe the (observable) evolution in the absence of a fundamental definition of time. The choice of the scalar product and the interpretation of the wave function are carefully discussed. The physical interpretation of the extreme "no time" quantum gravitational physics is considered. (shrink)

This paper addresses the extent to which both Julian Barbour‘s Machian formulation of general relativity and his interpretation of canonical quantum gravity can be called timeless. We differentiate two types of timelessness in Barbour‘s (1994a, 1994b and 1999c). We argue that Barbour‘s metaphysical contention that ours is a timeless world is crucially lacking an account of the essential features of time—an account of what features our world would need to have if it were to count as being one in which (...) there is time. We attempt to provide such an account through considerations of both the representation of time in physical theory and in orthodox metaphysical analyses. We subsequently argue that Barbour‘s claim of timelessness is dubious with respect to his Machian formulation of general relativity but warranted with respect to his interpretation of canonical quantum gravity. We conclude by discussing the extent to which we should be concerned by the implications of Barbour‘s view. (shrink)

Presentism is a controversial and much discussed position in the metaphysics of time. The position is often glossed as simply the view that everything that exists is present. This gloss, however, does not in itself characterize a single view. In this paper, I first propound the variety of presentist views, characterizing the primary dimensions along which the views differ. I then present the version of presentism I deem optimal. The variety among presentist views is so great that the version that (...) I prefer and shall defend—transient presentism—is not even characterized by the standard gloss given above. I next discuss all of the objections to presentism of which I am aware, considering the relevance of each to transient presentism. I conclude that transient presentism provides the most satisfying responses to the traditional objections and, furthermore, captures very well the motivation for adopting a presentist position in the first place. The grounds for these two conclusions constitute my defense of transient presentism. (shrink)