Two of the most difficult problems in the foundations of physics are (1) what gives rise to the arrow of time and (2) what the ontology of quantum mechanics is. I propose a unified 'Humean' solution to the two problems. Humeanism allows us to incorporate the Past Hypothesis and the Statistical Postulate into the best system, which we then use to simplify the quantum state of the universe. This enables us to confer the nomological status to the quantum state (...) in a way that adds no significant complexity to the best system and solves the ''supervenient-kind problem'' facing the original version of the Past Hypothesis. We call the resultant theory the Humean unification. It provides a unified explanation of time asymmetry and quantum entanglement. On this theory, what gives rise to time's arrow is also responsible for quantum phenomena. The new theory has a separable mosaic, a best system that is simple and non-vague, less tension between quantum mechanics and special relativity, and a higher degree of theoretical and dynamical unity. The Humean unification leads to new insights that can be useful to Humeans and non-Humeans alike. (shrink)

One of the most striking features of causation is that causes typically precede their effects – the causal arrow is strongly aligned with the temporal arrow. Why should this be so? We offer an opinionated guide to this problem, and to the solutions currently on offer. We conclude that the most promising strategy is to begin with the de facto asymmetry of human deliberation, characterised in epistemic terms, and to build out from there. More than any rival, this subjectivist (...) approach promises to demystify the asymmetry, temporal orientation, and deliberative relevance of causal judgements. (shrink)

This paper investigates what the source of time asymmetry is in thermodynamics, and comments on the question whether a time-symmetric formulation of the Second Law is possible.

This paper argues that the knowledge asymmetry (the fact that we know more about the past than the future) can be explained as a consequence of the causal Markov condition. The causal Markov condition implies that causes of a common effect are generally statistically independent, whereas effects of a common cause are generally correlated. I show that together with certain facts about the physics of our world, the statistical independence of causes severely limits our ability to predict the future, (...) whereas correlations between joint effects make it so that no such limitation holds in the reverse temporal direction. Insofar as the fact that our world conforms to the causal Markov condition can itself be explained in terms of the initial conditions of the universe, my view is compatible with Albert’s well-known account of the origins of temporal asymmetries, but also provides a more illuminating way to derive the knowledge asymmetry from those initial conditions. (shrink)

The physics of time asymmetry has never been a single well-defined subject, but more a collection of consistency problems which arise in almost all branches ...

In a recent book, Asymmetries in Time, Paul Horwich presents a systematic account of various temporal asymmetries, including a neo-Reichenbachian account of the (apparent) fact that we know more about the past than the future, the epistemological time asymmetry. I find some obscurities in Horwich's presentation, however, and I argue that when his view is understood in a way that I shall propose, it does represent an advance on Reichenbach's, but it fails to vindicate Horwich's "main point...that (...) our special knowledge of the past derives from the fork asymmetry. (shrink)

Accepted quantum description is stochastic, yet history is nonstochastic, i.e., not representable by a probability distribution. Therefore ordinary quantum mechanics is unsuited to describe history. This is a limitation of the accepted quantum theory, rather than a failing of mechanics in general. To remove the limitation, it would be desirable to find a form of quantum mechanics that describes the future stochastically and the past nonstochastically. For this purpose it proves sufficient to introduce into quantum mechanics, by means of a (...) perfected formal correspondence, certain analogs of the classical initial-condition constants. Through the restoration of such parameters at the quantum level one accomplishes a natural accommodation of time anisotropy, wave-function reduction, and “event” description by quantum mechanical equations of motion alone, without the need for extra postulates (e.g., a projection postulate). This requires a complete restructuring of quantum measurement theory. (shrink)

It is usually held that the standard collapse model of a quantum measurement process grounds a kind of fundamental time asymmetry. The question whether and how it should be possible to reconstruct uniquely one's own history in an Everett no-collapse interpretation of quantum theory is investigated. A particular approach to the Everett interpretation, due to John S. Bell, is considered, according to which one of the chief claims of the Everett quantum theory is precisely that it allows us (...) to do without the notion of history. (shrink)

This paper investigates what the source of time-asymmetry is in thermodynamics, and comments on the question whether a time-symmetric formulation of the Second Law is possible.

A comparative study is made of the eigenvalue problems of electromagnetics and quantum mechanics, with special reference to the operations of spatial inversionP and time inversionT. Electromagnetics, which permits closer agreement with the dictates of relativity (when the latter is extended toP andT), exhibits characteristic differences with respect to quantum mechanics. An evaluation of these distinctions is presented against the backdrop of a choice between absolute scalar action and charge versus pseudoscalar action and charge.

There is a wide-spread belief that we know more about the past than we do about the future. It may be difficult to express the content of this belief exactly and it may turn out that, when we find some precise expression of this belief, it is not so obviously true. I shall assume, however, that there is something to a belief shared not only by eminent philosophers but by cultures wholly distinct from our own, as the following quote indicates.We (...) know where the future is. It’s in front of us. Right? It lies before us—a great future lies before us—we stride forward confidently into it, every commencement, every election year. And we know where the past is. Behind us, right? So that we have to turn around to see it, and that interrupts our progress ever forward into the future, so we don’t really much like to do it. (shrink)

I discuss the nature of the puzzle about the time‐asymmetry of radiation and argue that its most common formulation is flawed. As a result, many proposed solutions fail to solve the real problem. I discuss a recent proposal of Mathias Frisch as an example of the tendency to address the wrong problem. I go on to suggest that the asymmetry of radiation, like the asymmetry of thermodynamics, results from the initial state of the universe.

The relation between quantum measurement and thermodynamically irreversible processes is investigated. The reduction of the state vector is fundamentally asymmetric in time and shows an observer-relatedness which may explain the double interpretation of the state vector as a representation of physical states as well as ofinformation about physical states. The concept of relevance being used in all statistical theories of irreversible thermodynamics is demonstrated to be based on the same observer-relatedness. Quantum theories of irreversible processes implicitly use an objectivized (...) process of state vector reduction. The conditions for the reduction are discussed, and it is concluded that the final (subjective) observer system may be carried by a space point. (shrink)

The concepts underlying our present theoretical understanding of the radiative two-condensed-body problem in general relativity and in bimetric gravitation theory are critically reviewed. The relevance of the 1935 Einstein-Rosen “bridge” article is emphasized. The possibility (first suggested by N. Rosen, for the linearized approximation) of extending to gravity the Wheeler-Feynman time-symmetric approach is questioned.

Huw Price argues that there are two conceptions of the puzzle of the time‐asymmetry of thermodynamics. He thinks this puzzle has remained unsolved for so long partly due to a misunderstanding about which of these conceptions is the right one and what form a solution ought to take. I argue that it is Price's understanding of the problem which is mistaken. Further, it is on the basis of this and other misunderstandings that he disparages a type of account (...) which does, in fact, hold promise of a solution. (shrink)

Time is generally thought to be one of the more mysterious ingredients of the universe. In this intriguing book, Paul Horwich makes precise and explicit the interrelationships between time and a large number of philosophically important notions.Ideas of temporal order and priority interact in subtle and convoluted ways with the deepest elements in our network of basic concepts. Confronting this conceptual jigsaw puzzle, Horwich notes that there are glaring differences in how we regard the past and future directions (...) of time. For example, we can influence the future but not the past, and can easily gain knowledge of the past but not of the future. Moreover we see a profusion of decay processes but little spontaneous generation of order; time appears to "flow" in one privileged direction, not the other; and we tend to explain phenomena in terms of antecedent circumstances, rather than subsequent ones. Horwich explains such time asymmetries and examines their bearing on the nature of time itself.Asymmetries in Time covers many notoriously difficult problems in the philosophy of science: causation, knowledge, entropy, explanation, time travel, rational choice, laws of nature, and counterfactual implication -- and gives a unified treatment of these matters. The book covers an unusually broad range of topics in a lucid and nontechnical way and includes alternative points of view in the philosophical literature. (shrink)

In several previous papers we have argued for a global and non-entropic approach to the problem of the arrow of time, according to which the “arrow” is only a metaphorical way of expressing the geometrical time-asymmetry of the universe. We have also shown that, under definite conditions, this global time-asymmetry can be transferred to local contexts as an energy flow that points to the same temporal direction all over the spacetime. The aim of this paper (...) is to complete the global and non-entropic program by showing that our approach is able to account for irreversible local phenomena, which have been traditionally considered as the physical origin of the arrow of time. (shrink)

In this chapter on time‐the emotional asymmetry, the author addresses two questions concerning future‐bias. The first is with respect to the sorts of things are people future‐biased. Do people want all things that they regard as bad to be in the past, or just some of them? Second, are people justified in being future‐biased? The second question has received a good deal of attention from philosophers. The author aims to survey different answers to the question, and to give (...) a sense of how things presently lie. A section presents some poor arguments for future‐bias, including discussions on the shrinking block theory of time. It is also said that, even if four‐dimensionalism is false, a charge of arbitrariness can be leveled at future‐bias. Finally, the chapter presents a discussion on some incoherence arguments against future‐bias. (shrink)

Thermodynamics is the science that describes much of the time asymmetric behavior found in the world. This entry's first task, consequently, is to show how thermodynamics treats temporally ‘directed’ behavior. It then concentrates on the following two questions. (1) What is the origin of the thermodynamic asymmetry in time? In a world possibly governed by time symmetric laws, how should we understand the time asymmetric laws of thermodynamics? (2) Does the thermodynamic time asymmetry (...) explain the other temporal asymmetries? Does it account, for instance, for the fact that we know more about the past than the future? The discussion thus divides between thermodynamics being an explanandum or explanans. In the former case the answer will be found in philosophy of physics; in the latter case it will be found in metaphysics, epistemology, and other fields, though in each case there will be blurring between the disciplines. (shrink)

We standardly evaluate counterfactuals and abilities in temporally asymmetric terms—by keeping the past fixed and holding the future open. Only future events depend counterfactually on what happens now. Past events do not. Conversely, past events are relevant to what abilities one has now in a way that future events are not. Lewis, Sider and others continue to evaluate counterfactuals and abilities in temporally asymmetric terms, even in cases of backwards time travel. I’ll argue that we need more temporally neutral (...) methods. The past shouldn’t always be held fixed, because backwards time travel requires backwards counterfactual dependence. Future events should sometimes be held fixed, because they’re in the causal history of the past, and agents have evidence of them independently of their decisions now. We need temporally neutral methods to maintain connections between causation, counterfactuals and evidence, and if counterfactuals are used to explain the temporal asymmetry of causation. (shrink)

Mental timing studies may be influenced by powerful cognitive illusions that can produce an asymmetry in their rate of progress relative to neuronal timing studies. Both types of timing research are also governed by a temporal asymmetry, expressed by the fact that the direction of causation must follow time's arrow. Here we refresh our earlier suggestion that the temporal asymmetry offers promise as a means of timing mental activities. We update our earlier analysis of Libet's data (...) within this framework. Then we consider the surprises which often occur on those rare occasions when neural timing experiments parallel mental timing work exactly. Together, these surprises and asymmetries prescribe a relentlessly meticulous and fully transparent exposition of timing methods, terms, and concepts which shuns plausible narratives, even when buttressed by rigorous formal models, unless guided by apposite empirical evidence. (shrink)

(1) Certain of our intentional attitudes appear to have time-asymmetric manifestation conditions. For instance, we dread a certain painful episode only if (we believe) it is future and feel relief about that episode only when (we believe) it is past. We eagerly anticipate events only when they are future and regard them with nostalgia only when they are past.

What is the relationship between space and time in the human mind? Studies in adults show an asymmetric relationship between mental representations of these basic dimensions of experience: Representations of time depend on space more than representations of space depend on time. Here we investigated the relationship between space and time in the developing mind. Native Greek‐speaking children watched movies of two animals traveling along parallel paths for different distances or durations and judged the spatial and (...) temporal aspects of these events (e.g., Which animal went for a longer distance, or a longer time?). Results showed a reliable cross‐dimensional asymmetry. For the same stimuli, spatial information influenced temporal judgments more than temporal information influenced spatial judgments. This pattern was robust to variations in the age of the participants and the type of linguistic framing used to elicit responses. This finding demonstrates a continuity between space‐time representations in children and adults, and informs theories of analog magnitude representation. (shrink)

The subject of time travel has been receiving increasing attention in the recent philosophical literature. Most of the articles that deal with it have been concerned to defend the logical consistency of time travel against those who claim that it entails one or more contradictions. Two sorts of defences have been offered. The first sort of defence involves showing that time travel does not entail those consequences which other philosophers allege it does entail. The second sort of (...) defence involves an admission that time travel does indeed involve that which its opponents allege it does involve, e.g., being in more than one place at a time, but arguing that such consequences in no way vitiate the logical consistency of this notion.My first aim in this paper is to provide a defence of time travel of the second sort. More specifically, I want to cut the ground from under an argument which might run thus:Time travel entails that certain effects can precede their causes.It is logically impossible for an effect to precede its cause. (shrink)

The paper analyzes the philosophical consequences of the recent discovery of direct violations of the time–reversal symmetry of weak interactions. It shows that although we have here an important case of the time asymmetry of one of the fundamental physical forces which could have had a great impact on the form of our world with an excess of matter over antimatter, this asymmetry cannot be treated as the asymmetry of time itself but rather as (...) an asymmetry of some specific physical process in time. The paper also analyzes the consequences of the new discovery for the general problem of the possible connections between direction of time and time-asymmetric laws of nature. These problems are analyzed in the context of Horwich’s Asymmetries in time: problems in the philosophy of science argumentation, trying to show that existence of a time–asymmetric law of nature is a sufficient condition for time to be anisotropic. Instead of Horwich’s sufficient condition for anisotropy of time, it is stressed that for a theory of asymmetry of time to be acceptable it should explain all fundamental time asymmetries: the asymmetry of traces, the asymmetry of causation, and the asymmetry between the fixed past and open future. It is so because the problem of the direction of time has originated from our attempts to understand these asymmetries and every plausible theory of the direction of time should explain them. (shrink)

The ancient problem of whether our asymmetrical attitudes towards time are justified remains a live one in contemporary philosophy. Drawing on themes in the work of McTaggart, Parfit, and Heidegger, I argue that this problem is also a key concern of Kierkegaard’s Either/Or. Part I of Either/Or presents the “aesthete” as living a temporally volatilized form of life, devoid of temporal location, sequence and direction. Like Parfit’s character “Timeless,” these aesthetes are indifferent to the direction of time and (...) seemingly do not experience McTaggart’s “A-Series” mode of temporality. The “ethical” conception of time that Judge William offers in Part II contains an attempt to normativize the direction of time, by re-orienting the aesthete towards an awareness of time ’s finitude. However, the form of life Judge William articulates gives time sequentiality but not necessarily the robust directionality necessary to justify our asymmetrical attitudes to time. Hence while Either/Or raises this problem it remains unanswered until The Concept of Anxiety. Only with the eschatological understanding of time developed in The Concept of Anxiety does Kierkegaard answer the question of why directional and asymmetrical conative and affective attitudes towards time are normative. (shrink)

An important aspect of the debate between the A-theory and the B-theory of time relates to the supposed implications of each for some of the most basic human attitudes and stances. The asymmetry in our attitudes towards past and future events in our life (pleasant and unpleasant), and towards the temporal limits of our existence, that is, toward birth and death, is supposedly considered differently by the two theories. I argue that our attitudes are neither justified nor discredited (...) by anything which is in debate between the A-Theory and the B-theory, and therefore that neither theory of time is supported by the asymmetry in our attitudes. (shrink)

An influential thought-experiment by Derek Parfit sought to establish that people have a preference for unpleasant events to lie in the past rather than the future. In recent discussions of Parfit’s argument, this purported preference is modelled as a discounting phenomenon, as is the tensed emotion of relief, which Arthur Prior argued demonstrated that there is an objective metaphysical difference between the past and the future. Looking at recent work demonstrating some psychological past/future asymmetries that are more clearly instances of (...) discounting I argue that this existing philosophical literature fails to distinguish between what are clearly two quite different psychological phenomena. This affects recent attempts to respond to Prior’s metaphysical argument, because it is not clear that they have identified the right phenomenon to be explained. It also affects Parfit’s thought-experiment, because the purported unitary ‘preference’ may in fact be an amalgam of these two quite different psychological phenomena. (shrink)

Causes always seem to come prior to their effects. What might explain this asymmetry? Causation's temporal asymmetry isn't straightforwardly due to a temporal asymmetry in the laws of nature—the laws are, by and large, temporally symmetric. Nor does the asymmetry appear due to an asymmetry in time itself. This Element examines recent empirical attempts to explain the temporal asymmetry of causation: statistical mechanical accounts, agency accounts and fork asymmetry accounts. None of these (...) accounts are complete yet and a full explanation of the temporal asymmetry of causation will likely require contributions from all three programs. (shrink)

In this paper I shall try to clarify Husserl’s conception of time-consciousness. In particular, I try to explain what exactly the asymmetry between protention and retention consists in. I argue (i) that Rodemeyer’s understanding of the protention-retention relationship, as developed, seems misleading, mainly for two reasons: first, it does not take into account that the ‘now’ has duration; second, she conceives the relation between protention and retention as symmetric, (ii) that the asymmetry between protention and retention could (...) be better understood if we could not only take into account the influence that retention and affect have on protention, but also if we could take into consideration the conceptual difference between surprise and disappointment. This difference, I suggest, reveals new ways to understand the protention-retention asymmetry. (shrink)

We consider the mind-dependence or independence of the "now," of "becoming," and of "time's arrow," by considering the various senses in which these notions might be mind-dependent or not. These matters cannot be sensibly discussed without taking a stand regarding criteria of "reality." Proceeding from a basically phenomenalist position we conclude that merely to differentiate between appearance and reality is implicitly to assume a directed flow of time. We discuss the relationship between phenomenological and physical time and (...) their possible asymmetries. We find that physical time acquires meaning only through phenomenological time, and that phenomenological time is fundamentally asymmetric. This still leaves room for the question: Is there anything in physical time which reflects the fact that it, to be meaningful, must be applied asymmetrically? The relevance of relativity theory to this question is discussed. (shrink)

While the fundamental laws of physics are time-reversal invariant, most macroscopic processes are irreversible. Given that the fundamental laws are taken to underpin all other processes, how can the fundamental time-symmetry be reconciled with the asymmetry manifest elsewhere? In statistical mechanics, progress can be made with this question. What I dub the ‘Zwanzig–Zeh–Wallace framework’ can be used to construct the irreversible equations of SM from the underlying microdynamics. Yet this framework uses coarse-graining, a procedure that has faced (...) much criticism. I focus on two objections in the literature: claims that coarse-graining makes time-asymmetry ‘illusory’ and ‘anthropocentric’. I argue that these objections arise from an unsatisfactory justification of coarse-graining prevalent in the literature, rather than from coarse-graining itself. This justification relies on the idea of measurement imprecision. By considering the role that abstraction and autonomy play, I provide an alternative justification and offer replies to the illusory and anthropocentric objections. Finally, I consider the broader consequences of this alternative justification: the connection to debates about inter-theoretic reduction and the implication that the time-asymmetry in SM is weakly emergent. 1Introduction 1.1Prospectus2The Zwanzig–Zeh–Wallace Framework3Why Does This Method Work? 3.1The special conditions account3.2When is a density forwards-compatible?4Anthropocentrism and Illusion: Two Objections 4.1The two objections in more detail4.2Against the justification by measurement imprecision5An Alternative Justification 5.1Abstraction and autonomy5.2An illustration: the Game of Life6Reply to Illusory7Reply to Anthropocentric8The Wider Landscape: Concluding Remarks 8.1Inter-theoretic relations8.2The nature of irreversibility. (shrink)