Wigner's friend, Feynman's paths and material records

Abstract

The place and role of an Observer in quantum mechanics has been a subject of an ongoing debate since the theory's inception. Wigner brought this question to the fore in a celebrated scenario in which a super-Observer observes a Friend making a measurement. Here we briefly review why this \e{Wigner Friend scenario} has been taken to require the introduction of the Observer's consciousness, or alternatively to show the inconsistency of quantum measurement theory. We will argue that quantum theory can consistently leave observers outside its narrative, by making only minimal assumptions about how the information about the observed results is stored in material records.

arXiv comment7 pages, 2 figures

References in corpus (6)

• How Quantum Mechanics can consistently describe the use of itself
• Quantum theory cannot consistently describe the use of itself
• A no-go theorem for observer-independent facts
• Single-world theory of the extended Wigner's world experiment
• Path probabilities for consecutive measurements, and certain "quantum paradoxes"
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Cited by in corpus (9)

• Wigner Friend scenarios with non-invasive weak measurements
• Quantum erasing the memory of Wigner's friend
• Quantum measurements with, and yet without an Observer
• Extended Wigner's friend problem and the internal consistency of standard quantum mechanics
• Classical information and collapse in Wigner's friend setups
• Wigner's friends, tunnelling times and Feynman's "only mystery of quantum mechanics"
• From observer-dependent facts to frame-dependent measurement records in Wigner friend scenarios
• Demonstration of quantum correlations that are incompatible with absoluteness of measurement
• Unitary evolution and elements of reality in consecutive quantum measurements