Unitary Interactions Do Not Yield Outcomes: Attempting to Model “Wigner’s Friend”

  title={Unitary Interactions Do Not Yield Outcomes: Attempting to Model “Wigner’s Friend”},
  author={Ruth E. Kastner},
  journal={Foundations of Physics},
  • R. Kastner
  • Published 4 May 2021
  • Physics
  • Foundations of Physics
An experiment by Proietti et al purporting to instantiate the ‘Wigner’s Friend’ thought experiment is discussed. It is pointed out that the stated implications of the experiment regarding the alleged irreconcilability of facts attributed to different observers warrant critical review. In particular, violation of a Clauser-Horne-Shimony inequality by the experimental data actually shows that the attribution of measurement outcomes to the “Friends” (modeled by internal photons undergoing unitary… 



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