{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:02:39Z","timestamp":1760058159204,"version":"build-2065373602"},"reference-count":26,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2025,3,14]],"date-time":"2025-03-14T00:00:00Z","timestamp":1741910400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>A number of no-go theorems have shown that Wigner\u2019s Friend scenarios combined with various metaphysical assumptions lead to contradictions in any version of quantum theory. We present an alternative constructive approach that only assumes that agents make properly qualified true statements. Quantum observers are modeled rigorously, although simplistically, using quantum circuits. Terminology is suggested to help avoid contradictions. Our methodology is applied to the Frauchiger-Renner paradox and results in statements by all agents that are both true and consistent. Quantum theory evades the no-go theorems because they make an incorrect implicit assumption about how quantum agents behave.<\/jats:p>","DOI":"10.3390\/e27030302","type":"journal-article","created":{"date-parts":[[2025,3,14]],"date-time":"2025-03-14T07:02:16Z","timestamp":1741935736000},"page":"302","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Consistent Approach to Modeling Quantum Observers"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-0807-5152","authenticated-orcid":false,"given":"David W.","family":"Ring","sequence":"first","affiliation":[{"name":"Independent Researcher, Longmont, CO 80503, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,3,14]]},"reference":[{"key":"ref_1","unstructured":"Good, I.J., Mayne, A.J., and Smith, J.M. (1962). Remarks on the Mind-Body Question. The Scientist Speculates: An Anthology of Partly-Baked Ideas, Heinemann."},{"key":"ref_2","unstructured":"Zalta, E.N. (2019). Copenhagen Interpretation of Quantum Mechanics. The Stanford Encyclopedia of Philosophy, Metaphysics Research Lab, Stanford University. [Winter 2019 ed.]."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"3711","DOI":"10.1038\/s41467-018-05739-8","article-title":"Quantum theory cannot consistently describe the use of itself","volume":"9","author":"Frauchiger","year":"2018","journal-title":"Nat. Commun."},{"key":"ref_4","unstructured":"Baumann, V., Hansen, A., and Wolf, S. (2016). The measurement problem is the measurement problem is the measurement problem. arXiv."},{"key":"ref_5","unstructured":"Araujo, M. (2024, May 05). The Flaw in Frauchiger and Renner\u2019s Argument. Available online: https:\/\/mateusaraujo.info\/2018\/10\/24\/the-flaw-in-frauchiger-and-renners-argument."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"658","DOI":"10.1007\/s10701-017-0082-7","article-title":"Single-World Theory of the Extended Wigner\u2019s Friend Experiment","volume":"47","author":"Sudbery","year":"2017","journal-title":"Found. Phys."},{"key":"ref_7","unstructured":"Fuchs, C.A. (2018). Notwithstanding Bohr, the Reasons for QBism. arXiv."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1016\/j.shpsb.2018.03.002","article-title":"In defense of a \u201csingle-world\u201d interpretation of quantum mechanics","volume":"72","author":"Bub","year":"2020","journal-title":"Stud. Hist. Philos. Sci. Part B Stud. Hist. Philos. Mod. Phys."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"062204","DOI":"10.1103\/PhysRevA.102.062204","article-title":"Wigner-friend scenarios with noninvasive weak measurements","volume":"102","author":"Matzkin","year":"2020","journal-title":"Phys. Rev. A"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Brukner, C. (2018). A No-Go Theorem for Observer-Independent Facts. Entropy, 20.","DOI":"10.3390\/e20050350"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1568","DOI":"10.1007\/s10701-018-0216-6","article-title":"Quantum Theory and the Limits of Objectivity","volume":"48","author":"Healey","year":"2018","journal-title":"Found. Phys."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1199","DOI":"10.1038\/s41567-020-0990-x","article-title":"A strong no-go theorem on the Wigner\u2019s friend paradox","volume":"16","author":"Bong","year":"2020","journal-title":"Nat. Phys."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"093028","DOI":"10.1088\/1367-2630\/aceea3","article-title":"A possibilistic no-go theorem on the Wigner\u2019s friend paradox","volume":"25","author":"Haddara","year":"2023","journal-title":"N. J. Phys."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1007\/s10701-022-00586-6","article-title":"When Greenberger, Horne and Zeilinger Meet Wigner\u2019s Friend","volume":"52","author":"Leegwater","year":"2022","journal-title":"Found. Phys."},{"key":"ref_15","unstructured":"Ormrod, N., and Barrett, J. (2022). A no-go theorem for absolute observed events without inequalities or modal logic. arXiv."},{"key":"ref_16","unstructured":"Jones, C.L., and Mueller, M.P. (2025). On the significance of Wigner\u2019s Friend in contexts beyond quantum foundations. arXiv."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1112","DOI":"10.22331\/q-2023-09-14-1112","article-title":"A \u201cthoughtful\u201d Local Friendliness no-go theorem: A prospective experiment with new assumptions to suit","volume":"7","author":"Wiseman","year":"2023","journal-title":"Quantum"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1759","DOI":"10.1098\/rspa.2000.0585","article-title":"Information flow in entangled quantum systems","volume":"456","author":"Deutsch","year":"2000","journal-title":"Proc. R. Soc. Lond. Ser. A Math. Phys. Eng. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/BF00670071","article-title":"Quantum theory as a universal physical theory","volume":"24","author":"Deutsch","year":"1985","journal-title":"Int. J. Theor. Phys."},{"key":"ref_20","unstructured":"Feynman, R., Leighton, R., and Sands, M. (2006). The Feynman Lectures on Physics, Pearson\/Addison-Wesley. Chapter 3.1."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Ring, D. (2024). Quantum Collapse in an Isolated Laboratory. Preprints.","DOI":"10.20944\/preprints202408.1434.v1"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1036","DOI":"10.1038\/4351036a","article-title":"Friends and grandmothers","volume":"435","author":"Connor","year":"2005","journal-title":"Nature"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1351","DOI":"10.1103\/PhysRevLett.60.1351","article-title":"How the result of a measurement of a component of the spin of a spin-1\/2 particle can turn out to be 100","volume":"60","author":"Aharonov","year":"1988","journal-title":"Phys. Rev. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"18","DOI":"10.12743\/quanta.v2i1.12","article-title":"Pedagogical Review of Quantum Measurement Theory with an Emphasis on Weak Measurements","volume":"2","author":"Svensson","year":"2013","journal-title":"Quanta"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"298","DOI":"10.1007\/s10701-019-00245-3","article-title":"Weak Values and Quantum Properties","volume":"49","author":"Matzkin","year":"2019","journal-title":"Found. Phys."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"745","DOI":"10.1119\/1.11393","article-title":"Unperformed experiments have no results","volume":"46","author":"Peres","year":"1978","journal-title":"Am. J. Phys."}],"container-title":["Entropy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1099-4300\/27\/3\/302\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T16:53:40Z","timestamp":1760028820000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1099-4300\/27\/3\/302"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,3,14]]},"references-count":26,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2025,3]]}},"alternative-id":["e27030302"],"URL":"https:\/\/doi.org\/10.3390\/e27030302","relation":{},"ISSN":["1099-4300"],"issn-type":[{"type":"electronic","value":"1099-4300"}],"subject":[],"published":{"date-parts":[[2025,3,14]]}}}