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I sketch a line of thought about consciousness and physics that gives some motivation for the hypothesis that conscious observers deviate - perhaps only very subtly and slightly - from quantum dynamics. Although it is hard to know just how…

Quantum Physics · Physics 2019-01-14 Adrian Kent

In this paper, I attempt a personal account of my understanding of the measurement problem in quantum mechanics, which has been largely in the tradition of the Copenhagen interpretation. I assume that (i) the quantum state is a…

Quantum Physics · Physics 2015-07-21 Caslav Brukner

We argue that Wigner's friend thought experiment does not support observer dependence of quantum states. An analysis in terms of history vectors suggests that quantum collapse is to be understood as collapse of histories rather than…

Quantum Physics · Physics 2021-06-09 Leonardo Castellani

According to QBism, quantum states, unitary evolutions, and measurement operators are all understood as personal judgments of the agent using the formalism. Meanwhile, quantum measurement outcomes are understood as the personal experiences…

Quantum Physics · Physics 2022-10-19 John B. DeBrota , Christopher A. Fuchs , Ruediger Schack

Schr\"odinger's famous Gedankenexperiment has inspired multiple generations of physicists to think about apparent paradoxes that arise when the logic of quantum physics is applied to macroscopic objects. The development of quantum…

Quantum Physics · Physics 2021-03-22 Demid V. Sychev , Valeriy A. Novikov , Khurram K. Pirov , Christoph Simon , A. I. Lvovsky

Erwin Schr\"odinger is famous for presenting his wave equation of motion that jump-started quantum mechanics. His disenchantment with the Copenhagen interpretation of quantum mechanics led him to unveil the Schr\"odinger's cat paradox,…

Popular Physics · Physics 2022-12-01 Mani L. Bhaumik

This is an attempt to create a consistent and non-trivial extension of quantum theory, describing in detail the quantum measurement process. A tentative but concrete model is presented, based on the concept of multiple…

Quantum Physics · Physics 2007-05-23 Jose L Balduz

I correct two misapprehensions, one historical and one conceptual, in the recent literature on extensions of the Wigner's Friend thought-experiment. Perhaps fittingly, both concern the accurate description of some quantum physicists'…

Quantum Physics · Physics 2019-07-18 Blake C. Stacey

The recently published "Oxford Questions" are supplemented with annotations concerning: doctrine of wave packets collapse (and sub- sidiarily Schrodinger's cat thought experiment), description of quan- tum measurements respectively…

General Physics · Physics 2013-11-13 Spiridon Dumitru

The notion of probability plays a crucial role in quantum mechanics. It appears in quantum mechanics as the Born rule. In modern mathematics which describes quantum mechanics, however, probability theory means nothing other than measure…

Quantum Physics · Physics 2026-05-22 Kohtaro Tadaki

It is hypothesised, following Conrad et al. (1988) (http://www.tcm.phy.cam.ac.uk/~bdj10/papers/urbino.html) that quantum physics is not the ultimate theory of nature, but merely a theoretical account of the phenomena manifested in nature…

Quantum Physics · Physics 2012-01-04 Brian D. Josephson

The ability of matter to be superposed at two different locations while being intrinsically connected by a quantum phase is among the most counterintuitive predictions of quantum physics. While such superpositions have been created for a…

Quantum Physics · Physics 2016-04-13 D. Kienzler , C. Flühmann , V. Negnevitsky , H. -Y. Lo , M. Marinelli , D. Nadlinger , J. P. Home

In this short paper a new thought experiment has been introduced to illustrate the famous Heisenberg's uncertainty principle based on Otto-Wiener's experiment (1890) associated with standing light waves. This illustration is quite easy as…

History and Philosophy of Physics · Physics 2014-10-17 Tapas Das

The Wigner's Friend (WF) thought experiment concerns quantum measurements by a 'superobserver' of an observer measuring a quantum system. Variations on the setup and its extended versions have seen a resurgence in recent years, in light of…

Quantum Physics · Physics 2025-07-30 Tom Rivlin , Sophie Engineer , Veronika Baumann

We extend Einstein's hole argument into the quantum domain, and argue that quantum observables for quasiclassical superpositional states of gravitational fields require additional information to be well-defined, namely, relative positions…

Quantum Physics · Physics 2009-02-13 I. Schmelzer

Both at formal and philosophical levels, decades of efforts have been devoted to a deciphering of the `quantum enigma', the `crazy way quantum objects behave', to quote R.P. Feynman's words. We posit that the enigma cannot recede without…

General Physics · Physics 2024-12-04 D-M. Cabaret , T. Grandou , E. Perrier

Proietti et al. (arXiv:1902.05080) reported on an experiment designed to settle, or at least to throw light upon, the paradox of Wigner's friend. Without questioning the rigor or ingenuity of the experimental protocol, I argue that its…

Quantum Physics · Physics 2019-10-29 Louis Marchildon

In quantum mechanics, the time evolution of particles is given by the Schr\"odinger equation. It is valid in a nonrelativistic regime where the interactions with the particle can be modelled by a potential and quantised fields are not…

Quantum Physics · Physics 2026-03-24 Martin Plávala , Stefan Nimmrichter , Matthias Kleinmann

The Extended Wigner's Friend thought experiment, which involves a quantum system with an agent who draws conclusions based on the results of a measurement of a quantum state provided in two nonorthogonal versions by another agent, led its…

Quantum Physics · Physics 2022-11-15 Szymon Łukaszyk

This paper provides a quantum-mechanical analysis of an artwork, `Wigner's friends,' by Diemut Strebe. The work consists of two telescopes, one on earth, one launched into space, and explores ideas of quantum correlations and quantum…

Popular Physics · Physics 2015-01-08 Seth Lloyd