Roads to the past: how to go and not to go backward in time in quantum theories

2021

Euro Jnl Phil Sci

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The notion of time reversal has caused some recent controversy in philosophy of physics. The debate has mainly put the focus on how the concept of time reversal should be formally implemented across different physical theories and models, as if time reversal were a single, unified concept that physical theories should capture. In this paper, I shift the focus of the debate and defend that the concept of time reversal involves at least three facets, where each of them gives rise to opposing views. In particular, I submit that any account of time reversal presupposes (explicitly or implicitly) modal, metaphysical, and heuristic facets. The comprehension of this multi-faceted nature of time reversal, I conclude, shows that time reversal can be coherently said in many ways, suggesting a disunified concept.

Section: Metaphysical Facet: Relationalism Versus Substantivalismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Three facets of time-reversal symmetry

2021

Euro Jnl Phil Sci

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“…On the one hand, the overarching attitude (the orthodoxy, henceforth) points out that in order to reverse the dynamical evolution of a quantum system, an anti-unitary time-reversal operator must be given. On the other hand, some philosophers have lately argued that such orthodoxy might be challenged (Albert 2000, Callender 2000, Lopez 2019), which has paved the way for non-standard representations of time reversal in quantum mechanics (QM, henceforth), in general, in terms of a unitary implementation.…”

Section: Introductionmentioning

confidence: 99%

The physics and the philosophy of time reversal in standard quantum mechanics

2021

Synthese

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A widespread view in physics holds that the implementation of time reversal in standard quantum mechanics must be given by an anti-unitary operator. In foundations and philosophy of physics, however, there has been some discussion about the conceptual grounds of this orthodoxy, largely relying on either its obviousness or its mathematicalphysical virtues. My aim in this paper is to substantively change the traditional structure of the debate by highlighting the philosophical commitments underlying the orthodoxy. I argue the persuasive force of the orthodoxy greatly depends on a relationalist metaphysics of time and a by-stipulation view of time-reversal invariance. Only with such philosophical background can the orthodoxy of time reversal in standard quantum mechanics succeed and be properly justified.

“…We have a relatively sharp recipe of how time reversal should be formally implemented in abstract, but when it comes to details or concrete instantiations, some problems come up even in such an abstract level. For discussion, seeSachs 1987, Albert 2000, Callender 2000, Roberts 2017, Lopez 2019).…”

mentioning

confidence: 99%

Time’s Direction and Orthodox Quantum Mechanics: Time Symmetry and Measurement

2022

J Gen Philos Sci

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It has been argued in various places that measurement-induced collapses in Orthodox Quantum Mechanics yields a genuine structural (or intrinsic) quantum arrow of time. In this paper, I will critically assess this proposal. I begin by distinguishing between a structural and a non-structural arrow of time. After presenting the proposal of a collapse-based arrow of time in some detail and discussing some criticisms it has faced, I argue, first, that any quantum arrow of time in Orthodox Quantum Mechanics cannot be defined for the entire universe and, second, that it requires non-dynamical information to be established. Consequently, I deliver that any quantum arrow of time in Orthodox Quantum Mechanics is, at best, local and nonstructural, deflating the original proposal.