The Directions of Time: how physics develops its temporal asymmetries

时间的方向：物理学如何发展其时间不对称性

• 批准号: AH/J001147/1
• 负责人: David Wallace
• 金额: $ 6.54万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=AH%2FJ001147%2F1
• 关键词: Directions; Time; how; physics; develops

The fundamental laws of physics do not make reference to the difference between past and future. If some sequence of states of the world solves the equations of fundamental physics, so does the very same sequence, run backwards. In occasional situations in large-scale physics (think of the motion of the planets, or of a table-tennis ball) the same is (approximately) true. But in most situations studied in science - and most situations encountered in the everyday world - there is a clear distinction between past and future. Ice cubes in a drink melt; they do not spontaneously form. Fires consume things; they do not spontaneously create them. Hot coffee cools down.Since we normally think - for good reason - that the facts of the macroscopic world can ultimately be explained by the laws of the microscopic world, there is a paradox here. How can the past/future distinction emerge at the large scale unless it is already present at the small? This profoundly puzzled the physicists who, at the start of the 20th century, developed statistical mechanics, the branch of physics that allows us to work out the laws governing large-scale phenomena - like heat and pressure - given only the laws governing microscopic particles. Despite the practical success of statistical mechanics, it continues to puzzle physicists and philosophers today: there is no generally-accepted explanation of where the difference between past and future originates. The philosophy of statistical mechanics, to which this project aims to contribute, is concerned above all else with this continuing puzzle. Its implications in physics are profound and widespread, and it matters well beyond physics, influencing our approach to philosophical problems such as the distinction between cause and effect, or between memory and anticipation.Too much research in philosophy of statistical mechanics, though, has fixated on the puzzle to the extent that it ignores the positive achievements of statistical mechanics, which are enormous. Whatever the conceptual difficulties of the subject, its methods succeed, with great reliability and great accuracy, at predicting just how large-scale phenomena turn out. This has been largely missed by a subject whose question has been 'how in principle could microscopic physics lead to a direction of time?' and not 'how can we understand, justify, make sense of the actual methods used by physicists to construct time-directed laws from a starting point which lacks that direction?'This project aims to rectify this mistake. Its goal is to study, in some detail, just what the quantitative methods are that physicists use to perform calculations and make predictions in statistical mechanics, and to see exactly what must be added or assumed to make those methods philosophically justified. The hope is that doing so will give the insight that is needed to really succeed in understanding statistical mechanics, and through it, the direction of time.

物理学的基本定律并不涉及过去和未来之间的差异。如果世界的某些状态序列解出了基础物理学的方程，那么同样的序列也可以反向运行。在大尺度物理学中的偶然情况下（想想行星的运动，或乒乓球的运动），情况（大致）也是如此。但在科学研究的大多数情况下--以及在日常生活中遇到的大多数情况下--过去和未来之间有着明显的区别。饮料中的冰块会融化;它们不会自发形成。火会吞噬事物，而不是自发地创造事物。热咖啡冷却下来，因为我们通常认为--有充分的理由--宏观世界的事实最终可以用微观世界的定律来解释，这里有一个悖论。过去/未来的区别如何在大尺度上出现，除非它已经存在于小尺度上？这让物理学家们深感困惑，他们在世纪初发展了统计力学。统计力学是物理学的一个分支，它让我们能够在只给出微观粒子定律的情况下，计算出控制大尺度现象（比如热和压力）的定律。尽管统计力学在实践中取得了成功，但它仍然困扰着今天的物理学家和哲学家：对于过去和未来之间的差异起源于何处，没有普遍接受的解释。统计力学的哲学，这一项目的目的是作出贡献，是最重要的是与这个持续的难题。它在物理学中的意义是深远而广泛的，它的重要性远远超出了物理学，影响了我们对哲学问题的态度，例如因果之间的区别，或者记忆和预期之间的区别。然而，太多的统计力学哲学研究已经固定在这个难题上，以至于忽略了统计力学的积极成就，这些成就是巨大的。无论这门学科在概念上有多么困难，它的方法在预测大规模现象的结果方面都是成功的，具有很高的可靠性和很高的准确性。这一点在很大程度上被一个问题所忽略，这个问题一直是“微观物理学原则上如何导致时间的方向？”而不是“我们怎么能理解，证明，理解物理学家们从一个缺乏方向的起点出发，用来构建时间导向定律的实际方法呢？“这个项目旨在纠正这个错误。它的目标是详细研究物理学家在统计力学中用来进行计算和预测的定量方法，并确切地了解必须添加或假设什么才能使这些方法在理论上合理。我们希望这样做能够提供真正成功理解统计力学所需的洞察力，并通过它了解时间的方向。

项目成果

Thermodynamics as Control Theory

作为控制理论的热力学

• DOI: 10.3390/e16020699
• 发表时间: 2014
• 期刊: Entropy
• 影响因子: 2.7
• 作者: Wallace D

Recurrence theorems: A unified account

递归定理：一个统一的帐户

• DOI: 10.1063/1.4907384
• 发表时间: 2015
• 期刊: Journal of Mathematical Physics
• 影响因子: 1.3
• 作者: Wallace D

The quantitative content of statistical mechanics

统计力学的定量内容

• DOI: 10.1016/j.shpsb.2015.08.012
• 发表时间: 2015
• 期刊: Studies in History and Philosophy of Modern Physics
• 作者: Wallace D