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Time and Temporal Asymmetries

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A special issue of Entropy (ISSN 1099-4300). This special issue belongs to the section "Time".

Deadline for manuscript submissions: 26 May 2024 | Viewed by 2329

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Special Issue Editors

Prof. Dr. Olimpia Lombardi

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Guest Editor

Institute of Philosophy, CONICET and University of Buenos Aires, Buenos Aires 1406, Argentina
Interests: problem of the arrow of time; interpretation of quantum mechanics; nature of information; foundations of statistical mechanics; philosophy of chemistry
Special Issues, Collections and Topics in MDPI journals

Dr. Cristian López

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Guest Editor

Department of Philosophy, University of Lausanne, Anthropole, 1015 Lausanne, Switzerland
Interests: philosophy of time; philosophy of quantum mechanics; metaphysics; the relation between metaphysics and science

Special Issue Information

Dear Colleagues,

Time is probably one of the most mysterious ingredients of the universe. On the one hand, time is unique and elusive. On the other, it seems to be an intrinsic, familiar part of our lives and world. It is then no surprise that philosophers and scientists have found in the nature of time a fertile terrain for philosophical and scientific inquiry. However, the more we dig into the nature of time, the more mysteries emerge. It is plain that time seems to pass by, but how? What does it mean that time ‘passes by’? What is the physics behind the seeming passing of time? It is also plain that time is directed, pointing to the future, flying away from the past, but how? Does time really have a direction? What physical evidence do we have at disposal to make sense of the idea of a ‘direction of time’? May time be directionless?

Time is not only mysterious by itself, but also for its relations to many temporal asymmetries. Philosophers and scientists alike have suggested that time could be related to the increase of entropy in isolated systems, to the expansion of the universe, to electromagnetic radiation, to the geometry of space-time, etc. Yet, any of these temporal asymmetries involves further issues: symmetric boundary conditions or time-reversal invariant dynamics speak against, rather than in favor of, temporal asymmetries and many properties of time. Even more, according to cutting-edge science, as some theories of quantum gravity suggest, time might even dilute at the fundamental level, being considered as an emergent feature of reality. However, what is the relation between time and temporal asymmetries? Does time explain them? Or do they explain what time is? If time does not exist at the fundamental level, how do all the temporal asymmetries we have experience of emerge at the macroscopic level? Can we dispense with time to do science and philosophy?

The aim of this Special Issue is to explore these scientific and philosophical problems in an interdisciplinary manner by counting on the collaboration of scientists and philosophers working in the field. Scientific aspects of time and temporal asymmetries as well as more philosophically oriented discussions are thus equally welcome and strongly encouraged.

Prof. Dr. Olimpia Lombardi
Dr. Cristian López
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Entropy is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

direction of time
time-reversal invariance
irreversibility
entropy
quantum gravity
general relativity
thermodynamics
statistical mechanics
metaphysics of time
substantivalism vs. relationalism
topology of time
presentism, eternalism and block universe
time travel

Published Papers (2 papers)

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Research

23 pages, 331 KiB

Open AccessArticle

Memory Systems, the Epistemic Arrow of Time, and the Second Law

by David H. Wolpert and Jens Kipper

Entropy 2024, 26(2), 170; https://doi.org/10.3390/e26020170 - 16 Feb 2024

Viewed by 1058

Abstract

The epistemic arrow of time is the fact that our knowledge of the past seems to be both of a different kind and more detailed than our knowledge of the future. Just like with the other arrows of time, it has often been speculated that the epistemic arrow arises due to the second law of thermodynamics. In this paper, we investigate the epistemic arrow of time using a fully formal framework. We begin by defining a memory system as any physical system whose present state can provide information about the state of the external world at some time other than the present. We then identify two types of memory systems in our universe, along with an important special case of the first type, which we distinguish as a third type of memory system. We show that two of these types of memory systems are time-symmetric, able to provide knowledge about both the past and the future. However, the third type of memory systems exploits the second law of thermodynamics, at least in all of its instances in our universe that we are aware of. The result is that in our universe, this type of memory system only ever provides information about the past. We also argue that human memory is of this third type, completing the argument. We end by scrutinizing the basis of the second law itself. This uncovers a previously unappreciated formal problem for common arguments that try to derive the second law from the “Past Hypothesis”, i.e., from the claim that the very early universe was in a state of extremely low entropy. Our analysis is indebted to prior work by one of us but expands and improves upon this work in several respects. Full article

(This article belongs to the Special Issue Time and Temporal Asymmetries)

21 pages, 2427 KiB

Open AccessArticle

Nonlocality, Superposition, and Time in the 4+1 Formalism

by Filip Strubbe

Entropy 2023, 25(11), 1493; https://doi.org/10.3390/e25111493 - 29 Oct 2023

Viewed by 806

Abstract

The field of quantum gravity struggles with several problems related to time, quantum measurement, nonlocality, and realism. To address these issues, this study develops a 4+1 formalism featuring a flat 4D spacetime evolving with a second form of time,

τ

, worldlines that [...] Read more.

τ

, worldlines that locally conserve momentum, and a hypersurface representing the present. As a function of

τ

, worldlines can spatially readjust and influences can travel backward or forward in the time dimension along these worldlines, offering a physical mechanism for retrocausality. Three theoretical models are presented, elucidating how nonlocality in an EPR experiment, the arrival time problem, and superposition in a Mach–Zehnder interferometer can be understood within this 4+1 framework. These results demonstrate that essential quantum phenomena can be reproduced in the 4+1 formalism while upholding the principles of realism, locality, and determinism at a fundamental level. Additionally, there is no measurement or collapse problem, and a natural explanation for the quantum-to-classical transition is obtained. Furthermore, observations of a 4D block universe and of the flow of time can be simultaneously understood. With these properties, the presented 4+1 formalism lays an interesting foundation for a quantum gravity theory based on intuitive principles and compatible with our observation of time. Full article

(This article belongs to the Special Issue Time and Temporal Asymmetries)

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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Confirmed authors:

Prof. Tim Maudlin

Department of Philosophy, New York University, USA

Prof. Roman Frigg

London School of Economics, UK

Prof. Tim Koslowski

University of Würzburg, Germany