Paradox of the Thoughts' Reading Experiment

Y. Ben-Aryeh

In the present Note it is shown that Hardy thought experiment does not lead to any paradox and its explanation can be made by using quantum mechanical methods, without the need of weak measurements theories. The confusion arising about this thought experiment follows from ignoring the use of a projective measurement of the kind of knowledge. A certain comment about the realization of Hardy thought experiment with photons is made.

Robert M. French

Nikolaos Mitrakos, Maria Papageorgiou, T. Rick Perche +1 more

Detection of entanglement through the Newtonian potential has been claimed to support the existence of gravitons, by extrapolating to a thought experiment which demonstrates that complementarity and causality would be in conflict unless quantum fluctuations exist. We critically assess this consistency argument using scalar field models. We show that whether complementarity or no-signalling is violated when quantum fluctuations are neglected, depends on how this approximation is taken, while in both cases entanglement is generated locally in spacetime. We clarify that the correct reading of the paradox requires making a clear distinction between two notions of causality violation: Newtonian action-at-a-distance and the quantum mechanical no-signalling; the latter is pertinent while the former is not. We conclude that the thought experiment (a) does not add to the epistemological relevance of entanglement through Newtonian potentials (b) lends support for the existence of gravitons, if retardation effects are detected in entanglement through gravity.

Xiaojin Li (152688)

Colin James

We use modal logic to evaluate a quantum rendition of the Frauchiger-Renner thought experiment to refute it as paradox (contradiction) and as tautology.

Richard Webb