Feels like there has to be something wrong with the paper. I don’t have the knowledge to analyze it myself, but I read through the paper until the methods section and they don’t discuss much beyond the math. It’s unclear to me how they’re arriving at a conclusion where different things happened from different perspectives, and particularly what percent of the time that would happen.
If someone familiar with the math could explain what the probability of each step is I think it could be a lot simpler to follow.
The paper was published in Nature Communications and its preprint was discussed widely for two years, so there is probably no flaws which could be easily picked up.
“The conceptual experiment has been debated with gusto in physics circles for more than two years — and has left most researchers stumped, even in a field accustomed to weird concepts. “I think this is a whole new level of weirdness,” says Matthew Leifer, a theoretical physicist at Chapman University in Orange, California.
The authors, Daniela Frauchiger and Renato Renner of the Swiss Federal Institute of Technology (ETH) in Zurich, posted their first version of the argument online in April 2016. The final paper appears in Nature Communications on 18 September1.”
Since that doesn’t seem to have been auto-linkfied, here’s an actual link: https://www.scottaaronson.com/blog/?p=3975 and a few extracts to help readers judge whether they want to follow the link:
I enjoyed figuring out exactly where I get off Frauchiger and Renner’s train—since I do get off their train.
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I reject an assumption that Frauchiger and Renner never formalize. That assumption is, basically: “it makes sense to chain together statements that involve superposed agents measuring each other’s brains in different incompatible bases, as if the statements still referred to a world where these measurements weren’t being done.”
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The first thing to understand about Frauchiger and Renner’s argument is that, as they acknowledge, it’s not entirely new. As Preskill helped me realize, the argument can be understood as the “Wigner’s-friendification” of Hardy’s Paradox.
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I don’t accept that we can take knowledge inferences that would hold in a hypothetical world where |ψ〉 remained unmeasured, with a particular “branching structure” (as a Many-Worlder might put it), and extend them to the situation where Alice performs a rather violent measurement on |ψ〉 that changes the branching structure by scrambling Charlie’s brain.
Feels like there has to be something wrong with the paper. I don’t have the knowledge to analyze it myself, but I read through the paper until the methods section and they don’t discuss much beyond the math. It’s unclear to me how they’re arriving at a conclusion where different things happened from different perspectives, and particularly what percent of the time that would happen.
If someone familiar with the math could explain what the probability of each step is I think it could be a lot simpler to follow.
https://link.springer.com/article/10.1007/s10701-017-0082-7
Here’s a paper claiming to identify the error. This is enough, I’m convinced the original paper is just mistaken
The paper was published in Nature Communications and its preprint was discussed widely for two years, so there is probably no flaws which could be easily picked up.
https://www.nature.com/articles/d41586-018-06749-8
“The conceptual experiment has been debated with gusto in physics circles for more than two years — and has left most researchers stumped, even in a field accustomed to weird concepts. “I think this is a whole new level of weirdness,” says Matthew Leifer, a theoretical physicist at Chapman University in Orange, California.
The authors, Daniela Frauchiger and Renato Renner of the Swiss Federal Institute of Technology (ETH) in Zurich, posted their first version of the argument online in April 2016. The final paper appears in Nature Communications on 18 September1.”
I identified one paper, and it cites another that also claims this is flawed. Don’t see a reason to believe the original paper over those
https://motls.blogspot.com/2018/09/frauchiger-renner-qm-is-inconsistent.html calls BS, now we just need Scott A to do the same and I’ll be convinced
https://www.scottaaronson.com/blog/?p=3975
Since that doesn’t seem to have been auto-linkfied, here’s an actual link: https://www.scottaaronson.com/blog/?p=3975 and a few extracts to help readers judge whether they want to follow the link:
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