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Deutsch and Aguirre have recently shown that the solutions of certain dynamical systems typically contain a point of minimum size that they identify as an entropy minimum and from which the size and entropy increase to infinity in both…

General Relativity and Quantum Cosmology · Physics 2021-08-24 Julian Barbour

I argue that opposite arrows of time, while being logically possible, cannot realistically be assumed to exist during one and the same epoch of this universe.

General Physics · Physics 2007-05-23 H. D. Zeh

We humans seem to have an innate understanding of the asymmetric progression of time, which we use to efficiently and safely perceive and manipulate our environment. Drawing inspiration from that, we address the problem of learning an arrow…

Machine Learning · Computer Science 2019-07-03 Nasim Rahaman , Steffen Wolf , Anirudh Goyal , Roman Remme , Yoshua Bengio

We argue that in Universes where future and past differ only by the entropy content a psychological arrow of time pointing in the direction of entropy increase can arise from natural selection in biological evolution. We show that this…

General Physics · Physics 2015-12-01 Torsten Heinrich , Benjamin Knopp , Heinrich Päs

Based on the hypothesis that the (non-reversible) arrow of time is intrinsic in any system, no matter how small, the consequences are discussed. Within the framework of local quantum physics it is shown how such a semi-group action of time…

Mathematical Physics · Physics 2023-05-22 Detlev Buchholz , Klaus Fredenhagen

This paper extends the work of a previous paper [arXiv:1208.2611] on the flow of time, to consider the origin of the arrow of time. It proposes that a `past condition' cascades down from cosmological to micro scales, being realized in many…

General Relativity and Quantum Cosmology · Physics 2013-03-04 George F R Ellis

In this paper we address the problem of the arrow of time from a cosmological point of view, rejecting the traditional entropic approach that defines the future direction of time as the direction of the entropy increase: from our…

Quantum Physics · Physics 2009-11-07 Mario Castagnino , Luis Lara , Olimpia Lombardi

The thermodynamic arrow-of-time problem is thought to be resolved by the observation that our universe initially was---and still is---far from equilibrium. The psychological arrow-of-time problem is often attributed the same resolution, but…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-19 Lucas Johns

It is generally believed that a cosmological arrow of time must be associated with entropy production. Indeed, in his seminal work on cyclic cosmology, Tolman introduced a viscous fluid in order to make successive expansion/contraction…

General Relativity and Quantum Cosmology · Physics 2018-10-26 Varun Sahni , Yuri Shtanov , Aleksey Toporensky

We find ourselves in an extended era of entropy production. Unlike most other observations, the arrow of time is usually regarded as a constraint on initial conditions. I argue, however, that it primarily constrains the vacuum structure of…

High Energy Physics - Theory · Physics 2013-05-30 Raphael Bousso

It is a truth universally acknowledged that all isolated macroscopic systems must be in want of ever greater disorder, with due apologies to Jane Austen for plagiarizing the opening line in her novel {\it Pride and Prejudice}. This common,…

Statistical Mechanics · Physics 2024-10-01 James P. Hurley

It is argued that the observed Thermodynamic Arrow of Time must arise from the boundary conditions of the universe. We analyse the consequences of the no boundary proposal, the only reasonably complete set of boundary conditions that has…

General Relativity and Quantum Cosmology · Physics 2009-10-22 S. W. Hawking , R. Laflamme , G. W. Lyons

Usually, it is supposed that irreversibility of time appears only in macrophysics. Here, we attempt to introduce the microphysical arrow of time assuming that at a fundamental level nature could be non-associative. Obtaining numerical…

General Physics · Physics 2022-11-02 Merab Gogberashvili

The laws of Physics are time-reversible, making no qualitative distinction between the past and the future -- yet we can only go towards the future. This apparent contradiction is known as the "arrow of time problem". Its current resolution…

Discrete Mathematics · Computer Science 2024-08-23 Pablo Arrighi , Gilles Dowek , Amélia Durbec

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.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Matias Aiello , Mario Castagnino , Olimpia Lombardi

The nature of time has beguiled philosophers for nearly three millennia. There are myriad types of time including cosmological time, biological time, psychological time, physical time, historical time, and even theological time. My brief…

History and Philosophy of Physics · Physics 2021-07-20 Stephen Boughn

We show that the Wheeler-DeWitt equation with a consistent boundary condition is only compatible with an arrow of time that formally reverses in a recollapsing universe. Consistency of these opposite arrows is facilitated by quantum effects…

General Relativity and Quantum Cosmology · Physics 2009-10-22 C. Kiefer , H. D. Zeh

This essay offers a meta-level analysis in the sociology and history of physics in the context of the so-called "Arrow of Time Problem" or "Two Times Problem," which asserts that the empirically observed directionality of time is in…

History and Philosophy of Physics · Physics 2024-06-11 R. E. Kastner

The second law of thermodynamics - the usual statement of the arrow of time - has been called the most fundamental law of physics. It is thus difficult to conceive that a single dynamical system could contain subsystems, in significant…

Statistical Mechanics · Physics 2007-05-23 L. S. Schulman

Any theory that states that the basic laws of physics are time-symmetric must be strictly deterministic. Only determinism enables time reversal of entropy increase. A contradiction therefore arises between two statements of Hawking. A…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Avshalom C. Elitzur , Shahar Dolev