Is a time symmetric interpretation of quantum theory possible without retrocausality?

Matthew S. Leifer, Matthew F. Pusey

Research output: Contribution to journalArticlepeer-review

Abstract

Huw Price has proposed an argument that suggests a time symmetric ontology for quantum theory must necessarily be retrocausal, i.e. it must involve influences that travel backwards in time. One of Price's assumptions is that the quantum state is a state of reality. However, one of the reasons for exploring retrocausality is that it offers the potential for evading the consequences of no-go theorems, including recent proofs of the reality of the quantum state. Here, we show that this assumption can be replaced by a different assumption, called λ-mediation, that plausibly holds independently of the status of the quantum state. We also reformulate the other assumptions behind the argument to place them in a more general framework and pin down the notion of time symmetry involved more precisely. We show that our assumptions imply a timelike analogue of Bell's local causality criterion and, in doing so, give a new interpretation of timelike violations of Bell inequalities. Namely, they show the impossibility of a (non-retrocausal) time symmetric ontology.
Original languageEnglish
Article number20160607
Number of pages25
JournalProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume473
Early online date21 Jun 2017
DOIs
Publication statusPublished - Jun 2017

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