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Quantum field theory and observers

V. P. Nair*

  • *Contact author: vpnair@ccny.cuny.edu
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Phys. Rev. D 112, 125022 – Published 22 December, 2025

DOI: https://doi.org/10.1103/n41c-1l9q

Abstract

A generalization of the coadjoint orbit action describes the dynamics of an observer (or instrument). We consider how this fits in with the view of observables in field theory being correlations of readouts of instruments and show how one recovers the usual S-matrix formulas. A simple resolution of the Fermi paradox is also pointed out.

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Phys. Rev. D 112, 125022– Published 22 December, 2025
  • Received 1 October 2025
  • Accepted 26 November 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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