Grasping Reality on TypePad, by Brad DeLong

Apropos of Wigner has many friends...: Renato Renner: It’s hard to think when someone Hadamards your brain: "Hi Scott: There are currently many who are blogging about our result, so I started to use my little quantum random number generator on my desk: outcome 0 means I don’t react to it, outcome 1 means I write a reply. For your blog the outcome was 1! Now, we are already in a situation that involves superposed agents...

Wigner has many friends, and they can disagree: Daniela Frauchiger and Renato Renner: Quantum Theory Cannot Consistently Describe the Use of Itself. Lidia del Rio: Journal club: Frauchiger-Renner No-Go theorem for Single-World Interpretations of Quantum Theory: "In this talk I will go over the recent paper by Daniela Frauchiger and Renato Renner, "Single-World Interpretations of Quantum Theory Cannot Be Self-Consistent" (arXiv:1604.07422)...

...The paper introduces an extended Wigner's friend thought experiment, which makes use of Hardy's paradox to show that agents will necessarily reach contradictory conclusions-unless they take into account that they themselves may be in a superposition, and that their subjective experience of observing an outcome is not the whole story. Frauchiger and Renner then put this experiment in context within a general framework to analyse physical theories. This leads to a theorem saying that a theory cannot be simultaneously (1) compliant with quantum theory, including at the macroscopic level, (2) single-world, and (3) self-consistent across different agents. In this talk I will (1) describe the experiment and its immediate consequences, (2) quickly review how different interpretations react to it, (3) explain the framework and theorem in more detail...

Scott Aaronson: It’s Hard to Think When Someone Hadamards Your Brain: "So: a bunch of people asked for my reaction to the new Nature Communications paper by Daniela Frauchiger and Renato Renner, provocatively titled 'Quantum Theory Cannot Consistently Describe the Use of Itself'...

Intelligent Models:

John Bell (1989): Against "Measurement":

Uncertainty over terms such as 'apparatus' is still rife in serious discussions of quantum mechanics, over 60 years after its conception:

This article is published with the permission of Plenum Publishing, New York; it will appear in the proceedings of 62 Years of Uncertainty (Erice, 5—14 August 1989):