In what sense is the direction of time a matter of convention? In 'The Direction of Time', Hans Reichenbach makes brief reference to parallels between his views about the status of time’s direction and his conventionalism about geometry. In this article, I: (1) provide a conventionalist account of time direction motivated by a number of Reichenbach’s claims in the book; (2) show how forwards and backwards time can give equivalent descriptions of (...) the world despite the former being the ‘natural’ direction of time; and (3) argue that this offers an important middle-ground position between existing realist and antirealist accounts of the direction of time. (shrink)

The physical possibility of spacetimes containing closed timelike curves (CTCs) challenges the philosophy of time in the way that temporal ordering is, at best, remarkably non-standard: events on CTCs precede themselves. Apparently, such universes do not possess a consistent time order but only a consistent time direction. Thus, temporal directionality seems to be more fundamental than ordering in earlier-later or past-present-future. I will argue that this favors presentism as the adequate ontology of spacetimes: only presentism consistently (...) copes with the idea that temporal ordering depends on empirical constraints. The presentist Now is fundamentally undivided and productively directed towards existence. Time order arises by extending the Now, which can fail and in fact fails in universes containing CTCs. (shrink)

This thesis introduces and defends a ‘C theory’ of time. The metaphysics of time literature is primarily concerned with the distinction between the A and B theories of time, with the disagreement concerning whether the passage of time is an objective feature of reality. I argue that the distinction between the B and C theories—in terms of whether time has a ‘privileged’ direction—is of more obvious relevance to the philosophy of physics than is the (...) distinction between the A and B theories. The thesis has three main contentions. (1) In order to maintain a substantial metaphysical dispute between the different theories of time, they must be defined in terms of structural properties, and the naturalistic metaphysics of time direction involves the assessment of these structures in light of contemporary physics. (2) The A theory of time requires a model with two temporal dimensions, and although such a model provides a resolution to a number of problems faced by standard A theories, it is not motivated by physical theory. (3) The dispute between the B and C theories of time is of direct relevance to the philosophy of physics: the B theorist’s assumption of the existence of a privileged temporal direction is of explanatory relevance to physics; and a comparison between unidirectional and adirectional explanations in physics can in principle shed light on whether time is B- or C-theoretic. (shrink)

The final work of a distinguished physicist, this remarkable volume examines the emotive significance of time, the time order of mechanics, the time direction of thermodynamics and microstatistics, the time direction of macrostatistics, and the time of quantum physics. Coherent discussions include accounts of analytic methods of scientific philosophy in the investigation of probability, quantum mechanics, the theory of relativity, and causality. "[Reichenbach’s] best by a good deal."—Physics Today. 1971 ed.

Modern physics has provided a range of motivations for holding time to be fundamentally undirected. But how does a temporally adirectional metaphysics, or ‘C-theory’ of time, fit with the time of experience? In this chapter, I look at what kind of problem human time poses for C-theories. First, I ask whether there is a ‘hard problem’ of human time: whether it is in principle impossible to have the kinds of experience we do in a temporally (...) adirectional world. Second I consider the ‘easy problem’: how specific directed aspects of our temporal experience are to be explained by C-theorists. This leads to a greater issue: is there such a thing as an experience of time direction at all to even be explained? I show how the kinds of experience we have that we typically associate with the idea of time being directed can be accommodated within a directionless picture of time. (shrink)

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)

A theory is usually said to be time reversible if whenever a sequence of states S 1 , S 2 , S 3 is possible according to that theory, then the reverse sequence of time reversed states S 3 T , S 2 T , S 1 T is also possible according to that theory; i.e., one normally not only inverts the sequence of states, but also operates on the states with a time reversal operator T . (...) David Albert and Paul Horwich have suggested that one should not allow such time reversal operations T on states. I will argue that time reversal operations on fundamental states should be allowed. I will furthermore argue that the form that time reversal operations take is determined by the type of fundamental geometric quantities that occur in nature and that we have good reason to believe that the fundamental geometric quantities that occur in nature correspond to irreducible representations of the Lorentz transformations. Finally, I will argue that we have good reason to believe that space-time has a temporal orientation. (shrink)

The Great Divide in metaphysical debates about laws of nature is between Humeans, who think that laws merely describe the distribution of matter, and non-Humeans, who think that laws govern it. The metaphysics can place demands on the proper formulations of physical theories. It is sometimes assumed that the governing view requires a fundamental / intrinsic direction of time: to govern, laws must be dynamical, producing later states of the world from earlier ones, in accord with the fundamental (...) direction of time in the universe. In this paper, we propose a minimal primitivism about laws of nature (MinP) according to which there is no such requirement. On our view, laws govern by constraining the physical possibilities. Our view captures the essence of the governing view without taking on extraneous commitments about the direction of time or dynamic production. Moreover, as a version of primitivism, our view requires no reduction / analysis of laws in terms of universals, powers, or dispositions. Our view accommodates several potential candidates for fundamental laws, including the principle of least action, the Past Hypothesis, the Einstein equation of general relativity, and even controversial examples found in the Wheeler-Feynman theory of electrodynamics and retrocausal theories of quantum mechanics. By understanding governing as constraining, non-Humeans who accept MinP have the same freedom to contemplate a wide variety of candidate fundamental laws as Humeans do. (shrink)

While experience tells us that time flows from the past to the present and into the future, a number of philosophical and physical objections exist to this commonsense view of dynamic time. In an attempt to make sense of this conundrum, philosophers and physicists are forced to confront fascinating questions, such as: Can effects precede causes? Can one travel in time? Can the expansion of the Universe or the process of measurement in quantum mechanics define a (...) class='Hi'>direction in time? In this book, researchers from both physics and philosophy attempt to answer these issues in an interesting, yet rigorous way. This fascinating book will be of interest to physicists and philosophers of science and educated general readers interested in the direction of time. (shrink)

A theory is usually said to be time reversible if whenever a sequence of states S 1, S 2, S 3 is possible according to that theory, then the reverse sequence of time reversed states S 3 T, S 2 T, S 1 T is also possible according to that theory; i.e., one normally not only inverts the sequence of states, but also operates on the states with a time reversal operator T. David Albert and Paul Horwich (...) have suggested that one should not allow such time reversal operations T on states. I will argue that time reversal operations on fundamental states should be allowed. I will furthermore argue that the form that time reversal operations take is determined by the type of fundamental geometric quantities that occur in nature and that we have good reason to believe that the fundamental geometric quantities that occur in nature correspond to irreducible representations of the Lorentz transformations. Finally, I will argue that we have good reason to believe that space-time has a temporal orientation. (shrink)

The aim of this essay is to introduce philosophers of science to some recent philosophical discussions of the nature and origin of the direction of time. The essay is organized around books by Hans Reichenbach, Paul Horwich, and Huw Price. I outline their major arguments and treat certain critical points in detail. I speculate at the end about the ways in which the subject may continue to develop and in which it may connect with other areas of philosophy.

I revise J L Mackie's first account of casual direction by replacing his notion of "fixity" by a newly defined notion of "sufficing" that is designed to accommodate indeterminism. Keeping Mackie's distinction between casual order and casual direction, I then consider another revision that replaces "fixity" with "one-way conditionship". In response to the charge that all such accounts of casual priority beg the question by making an unjustified appeal to temporal priority, i maintain that one-way conditionship explains rather (...) that assumes objective temporal dependence as well as objective casual dependence. (shrink)

Cybersecurity aggregates are numerical data obtained by aggregation on features along a database of cybersecurity reports. These aggregates are obtained by integration of time-stamped tables using some recent results of non-standard calculus. Time-series of aggregates are shown to contain relevant information about the concrete system dealt with. Trend time series is also forecasted using known data-driven methods. Although absolute forecasting of trend time series is not obtained, a directional forecasting of trend time series is achieved (...) thence validated by means of a rolling cross validation scheme on a public database of Scareware reports. (shrink)

In this article we discuss the validity of previous preferences and advance directives in cases of severe mental illness.

One of the questions that is addressed, from various perspectives, is the origin of time-asymmetry. Given the time-symmetry of the dynamical laws, all inferences about the future that are derivable from a dynamical theory are matched by inferences about the past. For Huw Price, who discusses the origins of cosmological time asymmetry, this is reason to treat all time-asymmetric cosmological theories with caution. He dismisses both the inflationary model and Stephen Hawking’s proposal to account for (...) class='Hi'>time-asymmetry with his famous “no boundary condition.” Instead, on the basis of the fact that we have no a priori reasons to distinguish between initial and final conditions, he advocates Gold’s time-symmetric model for the universe, in which the thermodynamical arrow of time is tied to the expansion of the universe, so that in the contracting phase towards the big crunch, entropy decreases. (shrink)

The frequencies with which photons pass through half-silvered mirrors in the forward direction of time is always approximately 1/2, whereas the frequencies with which photons pass through mirrors in the backward direction in time can be highly time-dependent. I argue that whether one should infer from this time-asymmetric phenomenon that time has an objective direction will depend on one's interpretation of quantum mechanics.

This article proposes an explanation of the way information about time is conveyed in Navajo.1 We assume that all sentences have a temporal interpretation, direct or indirect. We have two main purposes in this article. The first is to discuss temporal interpretation in this Athabaskan language. The Navajo temporal system, which is varied, has not yet been described in detail. Further, the language allows sentences without explicit temporal information. In such sentences temporal interpretation is indirect - arrived at by (...) inference. We outline the principles underlying the default inferences. Our second purpose is to show that a few general principles of temporal interpretation, which hold for some other languages, apply very nicely to Navajo. The principles include semantic rules for 1 interpreting explicit expressions about time, and pragmatic principles for inferring temporal location indirectly. The applicability of these principles to Navajo is a satisfying though unsurprising result; but it is worth working out explicitly. The temporal system of Navajo offers a future verb inflection, temporal particles, and temporal adverbs. Although a well-formed sentence need not have any of these forms, speakers consistently agree on temporal interpretation. To account for these facts, we must consider sentences with and without direct temporal information. In this article we propose semantic and pragmatic principles that account for both types of cases. The temporal interpretation of all sentences is deictically based. For sentences without direct temporal forms, aspectual information allows the inference of temporal location. We propose three general pragmatic principles to account for this, which we call temporal interpretation: the Deictic Principle, the Bounded Event Constraint, and a Simplicity Principle. The key factor in temporal inference is boundedness, direct or inferred. To arrive at the inference of boundedness we use the Temporal Schema Principle, a special case of the simplicity principle.. (shrink)

The meaning of the phrase “the direction of time” and the physical problems involved are considered. These problems are discussed and plausibility arguments are given to show that all clocks run in the same direction (almost always), that the most probable development of the Universe during the early stages of the expansion would result in the introduction of some internal organization, and that the expansion of the Universe and the increase in entropy define time directions that (...) have the same sense. The question of what properties of the laws governing the Universe lead to these results is studied. (shrink)

Many phenomena in the world display a striking time-asymmetry: the forwards transition frequencies are approximately invariant while the backwards ones are not. I argue in this paper that theories of such phenomena will entail that time has a direction, and that quantum mechanics in particular entails that the future is objectively different from the past.

My main point is that the creation of a free public time implies the creation of a democratic collective inspired by the project of social ecology. The first and second parts of this article focus on the modern social phenomena correlated to the general crisis and the emergence of the Internet Age (Castells, 2012). The third and fourth parts focus on new significations that seem to inspire modern social movements and the challenges that modern democratic ecological collectivities face. I (...) use the term “social ecology” as defined by Murray Bookchin: “Social ecology is based on the conviction that nearly all of our present ecological problems originate in deep-seated social problems” (Bookchin, 2006, p. 19). And I use the term “democracy” exclusively in the original, true meaning, of direct democracy where society is self-governed by the equal participation of every individual to political decisions and functions, as opposed to a modern representative democracy or republic, where political decisions rest in the hands of an oligarchy. In this sense, a truly democratic political collectivity is a truly ecological collectivity and vice versa. (shrink)

There is an analogy between Timaeus's act of describing a world in words and the demiurge's task of making a world of matter. This analogy implies a parallel between language as a system of reproducing ideas in words, and the world, which reproduces reality in particular things. Authority lies in the creation of a likeness in words of the eternal Forms. The Forms serve as paradigms both for the physical world created by the demiurge, and for the world in discourse (...) created by Timaeus: his discourse gains its validity not from faithfulness to the way things appear, or the way particular things 'actually happened', but in virtue of its attempt to express in words a likeness of the perfect and eternal reality. There are implications for Plato's philosophy of language, and for the relation between words and things (words do not depict or name things but can be used to construct worlds in a parallel way to the manner in which things construct worlds, both worlds being modelled on one common world of ideas). The match between world and discourse is because of their common pictorial relation (likeness) to an independent model. (shrink)

It has been argued that measurement-induced collapses in Orthodox Quantum Mechanics generates an intrinsic (or built-in) quantum arrow of time. In this paper, I critically assess this proposal. I begin by distinguishing between an intrinsic and non-intrinsic arrow of time. After presenting the proposal of a collapse-based arrow of time in some detail, I argue, first, that any quantum arrow of time in Orthodox Quantum Mechanics is non-intrinsic since it depends on external information about the measurement (...) context, and second, that it cannot be global, but just local. I complement these arguments by assessing some criticisms and considerations about the implementation of time reversal in contexts wherein measurement-induced collapses work. I conclude that the quantum arrow of time delivered by Orthodox Quantum Mechanics is much weaker than usually thought. (shrink)

Introduction: The potential therapeutic efficacy of real-time fMRI Neurofeedback has received increasing attention in a variety of psychological and neurological disorders and as a tool to probe cognition. Despite its growing popularity, the success rate varies significantly, and the underlying neural mechanisms are still a matter of debate. The question whether an individually tailored framework positively influences neurofeedback success remains largely unexplored.Methods: To address this question, participants were trained to modulate the activity of a target brain region, the visual (...) motion area hMT+/V5, based on the performance of three imagery tasks with increasing complexity: imagery of a static dot, imagery of a moving dot with two and with four opposite directions. Participants received auditory feedback in the form of vocalizations with either negative, neutral or positive valence. The modulation thresholds were defined for each participant according to the maximum BOLD signal change of their target region during the localizer run.Results: We found that 4 out of 10 participants were able to modulate brain activity in this region-of-interest during neurofeedback training. This rate of success is consistent with the neurofeedback literature. Whole-brain analysis revealed the recruitment of specific cortical regions involved in cognitive control, reward monitoring, and feedback processing during neurofeedback training. Individually tailored feedback thresholds did not correlate with the success level. We found region-dependent neuromodulation profiles associated with task complexity and feedback valence.Discussion: Findings support the strategic role of task complexity and feedback valence on the modulation of the network nodes involved in monitoring and feedback control, key variables in neurofeedback frameworks optimization. Considering the elaborate design, the small sample size here tested impairs external validity in comparison to our previous studies. Future work will address this limitation. Ultimately, our results contribute to the discussion of individually tailored solutions, and justify further investigation concerning volitional control over brain activity. (shrink)

The paper tries to demonstrate that the process of the increase of entropy does not explain the asymmetry of time itself because it is unable to account for its fundamental asymmetries, that is, the asymmetry of traces (we have traces of the past and no traces of the future), the asymmetry of causation (we have an impact on future events with no possibility of having an impact on the past), and the asymmetry between the fixed past and the open (...) future, To this end, the approaches of Boltzmann, Reichenbach (and his followers), and Albert are analysed. It is argued that we should look for alternative approaches instead of this, namely we should consider a temporally asymmetrical physical theory or seek a source of the asymmetry of time in metaphysics. This second approach may even turn out to be complementary if only we accept that metaphysics can complement scientific research programmes. (shrink)

It seems that time has direction which points ahead from the past to the future. Traditionally, the main efforts to explain the arrow of time were carried out within the domain of physics, primarily utilizing statistical mechanics laws. Here, I attempt to explain how the forward direction of time is configured from the viewpoint of the mind. At first impression the concept of forward direction stems from the meeting of subjectivity with space and as (...) such it is applied to time. However, I show that the forward direction of time has a unique temporal sense not derived from space. Later I relate phenomenological explanations of the flow of time to the direction of time. (shrink)

The question why natural processes tend to flow along a preferred direction has always been considered from within the perspective of the Second Law of Thermodynamics, especially its statistical formulation due to Maxwell and Boltzmann. In this article, we re-examine the subject from the perspective of a new historico-philosophical formulation based on the careful use of selected theoretical elements taken from three key modern thinkers: Hans Reichenbach, Ilya Prigogine, and Roger Penrose, who are seldom considered together in the literature. (...) We emphasize in our analysis how the entropy concept was introduced in response to the desire to extend the applicability of the Second Law to the cosmos at large (Reichenbach and Penrose), and to examine whether intrinsic irreversibility is a fundamental universal characteristics of nature (Prigogine). While the three thinkers operate with vastly different technical proposals and belong to quite distinct intellectual backgrounds, some similarities are detected in their thinking. We philosophically examine these similarities but also bring into focus the uniqueness of each approach. Our purpose is not providing an exhaustive derivations of logical concepts identified in one thinker in terms of ideas found in the others. Instead, the main objective of this work is to stimulate historico-philosophical investigations and inquiries into the problem of the direction of time in nature by way of crossdisciplinary examinations of previous theories commonly treated in literature as disparate domains. (shrink)