This essay aims to provide a self-contained introduction to time in relativistic cosmology that clarifies both how questions about the nature of time should be posed in this setting and the extent to which they have been or can be answered empirically. The first section below recounts the loss of Newtonian absolute time with the advent of special and general relativity, and the partial recovery of absolute time in the form of cosmic time in some cosmological models. Section II considers (...) the beginning and end of time in a broader class of models in which there is not an analog of Newtonian absolute time. As we will see, reasonable physical assumptions imply that the universe is finite to the past, and Section III turns to consideration of the “beginning” itself. We critically review conventional wisdom that a “singularity” reveals flaws in general relativity and briefly assess ways of avoiding the singularity. (shrink)

Given four modest verificationist theses, tying the meaning of talk about instants and periods to the events which (physically) could occur during, before or after them, the only content to the claim the Universe had a beginning (applicable equally to chaotic or orderly universes) is in terms of it being preceded by empty time. It follows that time cannot have a beginning. The Universe, however, could have a beginning--even if it has lasted for an infinite time.

This chapter provides a self‐contained introduction to time in relativistic cosmology that clarifies how questions about the nature of time should be posed and the extent to which they have been or can be answered empirically. The first section of the chapter recounts the loss of Newtonian absolute time with the advent of special and general relativity, and the partial recovery of absolute time in the form of cosmic time in cosmological models. The second considers the beginning and end of (...) time in a broader class of models in which there is not an analog of Newtonian absolute time. Reasonable physical assumptions imply that the universe is finite to the past, and the third section considers the “beginning” itself. The fourth section discusses the ramifications of the two recent debates of cosmology. The final section takes up the source of the asymmetry in people's experience of time. (shrink)

Foundational investigations in quantum mechanics, both experimental and theoretical, gave birth to the field of quantum information science. Nevertheless, the foundations of quantum mechanics themselves remain hotly debated in the scientific community, and no consensus on essential questions has been reached. Here, we present the results of a poll carried out among 33 participants of a conference on the foundations of quantum mechanics. The participants completed a questionnaire containing 16 multiple-choice questions probing opinions on quantum-foundational issues. Participants included physicists, philosophers, (...) and mathematicians. We describe our findings, identify commonly held views, and determine strong, medium, and weak correlations between the answers. Our study provides a unique snapshot of current views in the field of quantum foundations, as well as an analysis of the relationships between these views. (shrink)

Special relativity has been understood by many as vindicating a tenseless conception of time, denying the existence of tensed facts and a fortiori objective temporal passage. The reason for this is straightforward: both passage and the obtaining of tensed facts require a universal knife-edge present moment—yet this structure is not easily reconcilable with the relativity of simultaneity. The above being said, the prospects for tense and passage are sometimes claimed to be improved on moving to cosmological solutions of general relativity. (...) In this paper, we evaluate in detail these arguments, finding that there remain several open questions to be addressed if the introduction of tensed facts into the relativistic context is to be compelling. Moreover, we argue that, even setting aside these issues, objective tense stands and falls in relativity for exactly the same reasons that it does in classical philosophical discussions on the matter. (shrink)

The doctrine of the specious present, that we perceive or, at least, seem to perceive a period of time is often taken to be an obvious claim about perception. Yet, it also seems just as commonly rejected as being incoherent. In this paper, following a distinction between three conceptions of the specious present, it is argued that the incoherence is due to hidden metaphysical assumptions about perception and time. It is argued that for those who do not hold such assumptions, (...) so long as we are clear about what the doctrine is really saying, we can make perfect sense of the specious present doctrine. (shrink)

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)

Eternalism, the view that what we regard locally as being located in the past, the present and the future equally exists, is the best ontological account of temporal existence in line with special and general relativity. However, special and general relativity are not fundamental theories and several research programs aim at finding a more fundamental theory of quantum gravity weaving together all we know from relativistic physics and quantum physics. Interestingly, some of these approaches assert that time is not fundamental. (...) If time is not fundamental, what does it entail for eternalism and the standard debate over existence in time? First, I will argue that the non-fundamentality of time to be found in string theory entails standard eternalism. Second, I will argue that the non-fundamentality of time to be found in loop quantum gravity entails atemporal eternalism, namely a novel position in the spirit of standard eternalism. (shrink)

Numerous approaches to a quantum theory of gravity posit fundamental ontologies that exclude spacetime, either partially or wholly. This situation raises deep questions about how such theories could relate to the empirical realm, since arguably only entities localized in spacetime can ever be observed. Are such entities even possible in a theory without fundamental spacetime? How might they be derived, formally speaking? Moreover, since by assumption the fundamental entities cannot be smaller than the derived and so cannot ‘compose’ them in (...) any ordinary sense, would a formal derivation actually show the physical reality of localized entities? We address these questions via a survey of a range of theories of quantum gravity, and generally sketch how they may be answered positively. (shrink)

Since the death of strong reductionism, philosophers of science have expanded the horizons of their understandings of the physical, mental, and social worlds, and the complex relations among them. To give one interesting example, John Dupre has endorsed a notion of downward causation: ‘higher-level’ events causing events at a ‘lower’ ontological level. For example, my intention to type the letter ‘t’ causes the particular motions experienced by all the atoms in my left forefinger as I type it. The proper explanation (...) of the motions of an atom at the tip of my forefinger primarily involves my intentions, rather than the immediately preceding motions of other nearby atoms, or any other such particle–level events. (shrink)

“Tense” is an ambiguous term. It refers to a grammatical feature of natural languages, and also to a disputed metaphysical feature of temporal reality. The chapter examines both the linguistic and the metaphysical issue, and considers the relation between them. Then, it presents and evaluates some linguistic, metaphysical and evolutionary arguments that the inference from language to metaphysics is not justified. The metaphysical debate is concerned with whether or not tense exists in reality. The linguistic issues are interesting, and worthy (...) of study in their own right, but care should be taken not to run them together with the metaphysical issues. Finally, the chapter explores the importance of tensed belief and notion of ‘taking tense seriously’, which has been much discussed in the philosophical literature, and the importance of tensed beliefs to agency and successful timely action. (shrink)

It has notoriously been supposed that the doctrine of determinism conflicts with the belief in human freedom. Yet it is not readily apparent how indeterminism, the denial of determinism, makes human freedom any less problematic. It has sometimes been suggested that the arrival of quantum mechanics should immediately have solved the problem of free will and determinism. It was proposed, perhaps more often by scientists than by philosophers, that the brain would need only to be fitted with a device for (...) amplifying indeterministic quantum phenomena for the bogey of determinism to be defeated. Acts of free will could then be those that were initiated by such indeterministic nudges. Recently there has been some inclination to revive such a story as part of the fallout from the trend for chaos theory. Chaotic systems in the brain, being indefinitely sensitive to the precise details of initial conditions, seem to provide fine candidates for the hypothetical amplifiers of quantum events. (shrink)

Time, along with concepts as space and matter, is bound to be a central concept of any physical theory. The chapter first discusses how time is treated similarly in quantum and classical theories. It then provides a few references on time‐reversal. The chapter discusses three chosen authors' (Paul Busch, Jan Hilgevoord and Jos Uffink) clarifications of uncertainty principles in general. Next, the chapter follows Busch in distinguishing three roles for time in quantum physics. They are external time, intrinsic time and (...) observable time. It also provides a brief discussion on time operators, in particular Pauli's influential proof. Finally, the chapter talks about time‐energy uncertainty principles with intrinsic times. (shrink)

Carl Hoefer has argued that determinism in block universes does not privilege any particular time slice as the fundamental determiner of other time slices. He concludes from this that our actions are free, insofar as they are pieces of time slices we may legitimately regard as fundamental determiners. However, I argue that Hoefer does not adequately deal with certain remaining problems. For one, there remain pervasive asymmetries in causation and the macroscopic efficacy of our actions. I suggest that what Hoefer (...) may have shown us is that causation, not determinism, was the threat to free will all along. Additionally, Hoefer might avoid the problem of the asymmetry of macroscopic efficacy by noting we have a very small region of space-time completely determined by our choices. However, this move implies our freedom to act is freedom to do very little, given that the region is trivial. I suggest that Hoefer should instead claim that we do have pervasive macroscopic efficacy toward the past, though I am unsure of how well this thesis works. Regardless, there remains a problem that the inside-out perspective requires us to see our choices as brute facts or random occurrences. Attempts to resolve this problem seem to require either a theory of agent causation or a traditional compatibilist argument, making Hoefer’s thesis extraneous, unless he can show us that these require the inside-out perspective. However, Hoefer has not yet shown us this, so there is work to be done. (shrink)

Four principles about Time have the consequence that God must be everlasting, and not timeless. These are 1) events occur over periods of time, never at instants, 2) Time has a metric if and only if there is a unified system of laws of nature, 3) The past is the realm of the causally unaffectible, the future of the causally affectible, 4) Some truths can only be known at certain periods. Yet God is not Time’s prisoner’, for the unwelcome features (...) of Time--the increase of unaffectible events, the cosmic clock’ ticking away--only occur if God so chooses. (shrink)

Arguments pertaining to the mind-brain connection and to the physical effectiveness of our conscious choices have been presented in two recent books, one by John Searle, the other by Jaegwon Kim. These arguments are examined, and it is explained how the encountered difficulties arise from a defective understanding and application of a pertinent part of contemporary science, namely quantum mechanics. The principled quantum uncertainties entering at the microscopic levels of brain processing cannot be confined to the micro level, but percolate (...) up to the macroscopic regime. To cope with the conflict between the resulting macroscopic indefiniteness and the definiteness of our conscious experiences, orthodox quantum mechanics introduces the idea of agent-generated probing actions, each of which specifies a definite set of alternative possible empirically/experientially distinguishable outcomes. Quantum theory then introduces the mathematical concept of randomness to describe the probabilities of the various alternative possible outcomes of the chosen probing action. But the agent-generated choice of which probing action to perform is not governed by any known law or rule, statistical or otherwise. This causal gap provides a logical opening, and indeed a logical need, for the entry into the dynamical structure of nature of a process that goes beyond the currently understood quantum mechanical statistical generalization of the deterministic laws of classical physics. The well-known quantum Zeno effect can then be exploited to provide a natural process that establishes a causal psychophysical link within the complex structure consisting of a stream of conscious experiences and certain macroscopic classical features of a quantum mechanically described brain. This naturally created causal link effectively allows consciously felt intentions to affect brain activity in a way that tends to produce the intended feedback. This quantum mechanism provides an eminently satisfactory alternative to the classical physics conclusion that the physical present is 1 completely determined by the physical past, and hence provides a physicsbased way out of the dilemma that Searle and Kim tried to resolve by philosophical analysis.. (shrink)