I What Is the Frauchiger-Renner Theorem?

[DarMM]

Yes, I have concluded it already in #44, while my later arguments only served to refine that conclusion. Thank you very much for the discussion, without you I would never understood all that.

Thanks to you as well and also @atyy . I've learned a lot from this thread, including having a much better grasp of Old/Classic Copenhagen. I've come to have a better understanding of the need for the Heisenberg Cut and through discussions here and Bub's papers a better understanding of the strange implications of reversibility and how you have to be careful when reasoning about reversed results.

 

[A. Neumaier]

Just a comment that is often overlooked: Until at least the end of 1927 (Solvay conference), the quantum physicists in Göttingen and Copenhagen had a realistic view of quantum mechanics in which particles were always in stationary states (characterized by energy and momentum) and performed quantum jumps guided by the wave function. Thus in their writing, state = stationary state and not = wave function up to a phase! And only the wave function was sort of epistemic...

I haven't seen my claim explicitly researched on from a comparative historical point of view. But I am doing a historical study myself, and have plenty of detailed evidence, that will be the content of a paper to be finished later this year. Once one realizes what I wrote, many otherwise difficult to understand things get a straightforward sense.

Nice, can't wait to read it!

The essence is now here, rather than in a paper.