We review the status of bouncing cosmologies as alternatives to cosmological inflation for providing a description of the very early universe, and a source for the cosmological perturbations which are observed today. We focus on the motivation for considering bouncing cosmologies, the origin of fluctuations in these models, and the challenges which various implementations face.

This essay is the first act of a two-act play. My ultimate aim is to defend a simple proposition: time passes. To be more precise, I want to defend the claim that the passage of time is an intrinsic asymmetry in the structure of space-time itself, an asymmetry that has no spatial counterpart and is metaphysically independent of the material contents of space-time. It is independent, for example, of the entropy gradient of the universe. This view is part of common-sense, (...) but has been widely attacked by philosophers. The passage of time, we are told, is a myth, an illusion, even an incoherent notion. Because the notion that time passes is common sense, it perhaps requires little positive defence; if there are no weighty objections to the view, it ought to be accepted. So the first, and more important, act of the play is defusing the arguments which have been used to cast doubt on the passage of time. I have positive arguments to give, but not having space for them here, I will confine myself to an examination of the common philosophical arguments that have been used to cast doubt on the passage of time. (shrink)

I discuss "Poetic Naturalism" -- there is only one world, the natural world, but there are many ways of talking about it -- both as a general concept, and how it accounts for our actual world. I talk about emergence, fundamental physics, entropy and complexity, the origins of life and consciousness, and moral constructivism.

Physicalism is sometimes portrayed by its critics as a dogma, but there is an empirical argument for the position, one based on the accumulation of diverse microphysical causal explanations in physics, chemistry, and physiology. The canonical statement of this argument was presented in 2001 by David Papineau. The goal of this paper is to demonstrate a tension that arises between this way of understanding the empirical case for physicalism and a view that is becoming practically a received position in philosophy (...) of physics: that microphysics does not support the existence of causal facts (and so does not support causal explanations). Indeed this is a conclusion embraced in recent work by Papineau himself. This paper examines a range of natural ways of avoiding this tension and reconciling the empirical case for physicalism with the rejection of microphysical causation. (shrink)

Among the most important questions in the metaphysics of science are "What are the natures of fundamental laws and chances?" and "What grounds the direction of time?" My aim in this paper is to examine some connections between these questions, discuss two approaches to answering them and argue in favor of one. Along the way I will raise and comment on a number of issues concerning the relationship between physics and metaphysics and consequences for the subject matter and methodology of (...) metaphysics. (shrink)

I deny that the world is fundamentally causal, deriving the skepticism on non-Humean grounds from our enduring failures to find a contingent, universal principle of causality that holds true of our science. I explain the prevalence and fertility of causal notions in science by arguing that a causal character for many sciences can be recovered, when they are restricted to appropriately hospitable domains. There they conform to a loose collection of causal notions that form a folk science of causation. This (...) recovery of causation exploits the same generative power of reduction relations that allows us to recover gravity as a force from Einstein's general relativity and heat as a conserved fluid, the caloric, from modern thermal physics, when each theory is restricted to appropriate domains. Causes are real in science to the same degree as caloric and gravitational forces. (shrink)

: I offer a new approach to the increasingly convoluted debate between the A- and B-theories of time, the ‘tensed’ and ‘tenseless’ theories. It is often assumed that the B-theory faces more difficulties than the A-theory in explaining the apparently tensed features of temporal experience. I argue that the A-theory cannot explain these features at all, because on any physicalist or supervenience theory of the mind, in which the nature of experience is fixed by the physical state of the world, (...) the tensed properties of time posited by the A-theory could play no role in shaping temporal experience. It follows that the A-theory is false; even a priori arguments for it fail, because they still require the tensed vocabulary which is used to describe temporal experience. (shrink)

I deny that the world is fundamentally causal, deriving the skepticism on non-Humean grounds from our enduring failures to find a contingent, universal principle of causality that holds true of our science. I explain the prevalence and fertility of causal notions in science by arguing that a causal character for many sciences can be recovered, when they are restricted to appropriately hospitable domains. There they conform to loose and varying collections of causal notions that form folk sciences of causation. This (...) recovery of causation exploits the same generative power of reduction relations that allows us to recover gravity as a force from Einstein's general relativity and heat as a conserved fluid, the caloric, from modern thermal physics, when each theory is restricted to appropriate domains. Causes are real in science to the same degree as caloric and gravitational forces. (shrink)

David Albert's Time and Chance (2000) provides a fresh and interesting perspective on the problem of the direction of time. Unfortunately, the book opens with a highly non-standard exposition of time reversal invariance that distorts the subsequent discussion. The present article not only has the remedial goal of setting the record straight about the meaning of time reversal invariance, but it also aims to show how the niceties of this symmetry concept matter to the problem of the direction of time (...) and to related foundation issues in physics. (shrink)

Are there really beliefs? Or are we learning (from neuroscience and psychology, presumably) that, strictly speaking, beliefs are figments of our imagination, items in a superceded ontology? Philosophers generally regard such ontological questions as admitting just two possible answers: either beliefs exist or they don't. There is no such state as quasi-existence; there are no stable doctrines of semi-realism. Beliefs must either be vindicated along with the viruses or banished along with the banshees. A bracing conviction prevails, then, to the (...) effect that when it comes to beliefs (and other mental items) one must be either a realist or an eliminative materialist. (shrink)

I ask whether what we know about the universe from modern physics and cosmology, including fine-tuning, provides compelling evidence for the existence of God, and answer largely in the negative.

In this paper I argue that causation is an essentially macroscopic phenomenon, and that mental causes are therefore capable of outcompeting their more specific physical realizers as causes of physical effects. But I also argue that any causes must be type-identical with physical properties, on pain of positing inexplicable physical conspiracies. I therefore allow macroscopic mental causation, but only when it is physically reducible.

This essay offers a reaction to the recent resurgence of presentism in the philosophy of time. What is of particular interest in this renaissance is that a number of recent arguments supporting presentism are crafted in an untypically naturalistic vein, breathing new life into a metaphysics of time with a bad track record of co-habitation with modern physics. Against this trend, the present essay argues that the pressure on presentism exerted by special relativity and its core lesson of Lorentz symmetry (...) cannot easily be shirked. A categorization of presentist responses to this pressure is offered. As a case in point, I analyze a recent argument by Monton (2006) presenting a case for the compatibility of presentism with quantum gravity. Monton claims that this compatibility arises because there are quantum theories of gravity that use fixed foliations of spacetime and that such fixed foliations provide a natural home for a metaphysically robust notion of the present. A careful analysis leaves Monton's argument wanting. In sum, the prospects of presentism to be alleviated from the stress applied by fundamental physics are faint. (shrink)

There is sufficient evidence at present to justify the belief that the universe began to exist without being caused to do so. This evidence includes the Hawking-Penrose singularity theorems that are based on Einstein's General Theory of Relativity, and the recently introduced Quantum Cosmological Models of the early universe. The singularity theorems lead to an explication of the beginning of the universe that involves the notion of a Big Bang singularity, and the Quantum Cosmological Models represent the beginning largely in (...) terms of the notion of a vacuum fluctuation. Theories that represent the universe as infinitely old or as caused to begin are shown to be at odds with or at least unsupported by these and other current cosmological notions. (shrink)

This paper examines two cosmological models of quantum gravity to investigate the foundational and conceptual issues arising from quantum treatments of the big bang. While the classical singularity is erased, the quantum evolution that replaces it may not correspond to classical spacetime: it may instead be a non-spatiotemporal region, which somehow transitions to a spatiotemporal state. The different kinds of transition involved are partially characterized, the concept of a physical transition without time is investigated, and the problem of empirical incoherence (...) for regions without spacetime is discussed. (shrink)

This chapter contains sections titled: * Arguments for Divine Timelessness * Arguments for Divine Temporality * Eternity and the Nature of Time * Notes.

The year 1927 is a landmark in the evolution of physics—the year which saw the obsequies of the notion of causality. To avoid misconceptions, it should not be thought that the concept fell a victim to the unbridled antipathy of certain physicists or their indulgence in fancies. The truth is that men of science came, very reluctantly and almost against their will, to recognize the impossibility of giving a coherent causal description of the happenings on the atomic scale, though some (...) of them—curiously enough, amongst them Planck, Einstein, de Broglie, Schrödinger—could never bring themselves to accept wholeheartedly so drastic a renunciation of classical ideals. (shrink)

Science and religion both make claims about the fundamental workings of the universe. Although these claims are not a priori incompatible (we could imaginebeing brought to religious belief through scientific investigation), I will argue that in practice they diverge. If we believe that the methods of science can be used to discriminate between fundamental pictures of reality, we are led to a strictly materialist conception of the universe. While the details of modern cosmology are not a necessary part of this (...) argument, they provide interesting clues as to how an ultimate picture may be constructed. (shrink)