Quantum theory cannot consistently describe the use of itself

By Dustin Lazarovici, Mario Hubert. Nature Communications, 2016

453 citations recorded by the source corpus.

Quantum theory provides an extremely accurate description of fundamental processes in physics. It thus seems likely that the theory is applicable beyond the, mostly microscopic, domain in which it has been tested experimentally. Here, we propose a Gedankenexperiment to investigate the question whether quantum theory can, in principle, have universal validity. The idea is that, if the answer was yes, it must be possible to employ quantum theory to model complex systems that include agents who are themselves using quantum theory. Analysing the experiment under this presumption, we find that one agent, upon observing a particular measurement outcome, must conclude that another agent has predicted the opposite outcome with certainty. The agents’ conclusions, although all derived within quantum theory, are thus inconsistent. This indicates that quantum theory cannot be extrapolated to complex systems, at least not in a straightforward manner. Quantum mechanics is expected to provide a consistent description of reality, even when recursively describing systems contained in each other. Here, the authors develop a variant of Wigner’s friend Gedankenexperiment where each of the current interpretations of QM fails in giving a consistent description.

Subfields: Atomic and Molecular Physics, and Optics, Computational Theory and Mathematics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/612b12de314e91728d6e6ec63b91e099c5702eec

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

In Computational Theory and Mathematics

In Statistical and Nonlinear Physics

Citations in the corpus

A strong no-go theorem on the Wigner’s friend paradox (2019, unknown): “[16] Frauchiger, D.”
Discovering physical concepts with neural networks (2018, background): “classical mechanics; it has been impressively successful, but leads to conceptually challenging consequences (see [1, 2] for a review and [3] for a recent example).”
A Postquantum Theory of Classical Gravity? (2018, unknown): “There is thus no need for the mysterious measurement postulate of quantum theory, a postulate which has meant that the interpretation of quantum theory has been open to dispute, and whose problematic nature has received renewed attention [117].”
Resource-rational analysis vs. resource-rational humans (2019, background): “itional information can also accommodate several paradoxical decision scenarios, generate novel non-reductive models of how humans process concepts and generate new understandings of human cognition (Frauchiger and Renner, 2018, Vourdas, 2019). These distinctive features of quantum theory provide se”
Relativistic Quantum Theory (2019, background): “In order to avoid paradoxes [7, 8, 9], it is crucial to assume that the occurrence of an event (for example, the successful completion of a measurement) has an objective meaning independent of the “observer” – and independent of whether an “observer” is actually present or not.”