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Hey there!

I was recently pointed to this thought experiment, claiming an apparent 'contradiction' involving the various predictions of the observers.

Now, this has been discussed on PF quite recently, but I found the discussion rather hard to follow. I've read the paper, the PF discussion, and tried to just do the maths myself. There is also a section on Wikipedia that goes through it and helpfully spells out the full state in the various bases. I'll just copy the statements here:

Statement 1 by F

Statement 2 by F

Statement 3 by W

Statement 4 by W

Statement 4 seems to be correct. Even statements 1 to 3 individually look fine to me, but I may be wrong. I can only conclude that there is an issue with combining the first three statements to make the conclusion that if W

So my question is specifically whether this is the source of the paradox, and if so, why?

Thanks in advance!

I was recently pointed to this thought experiment, claiming an apparent 'contradiction' involving the various predictions of the observers.

Now, this has been discussed on PF quite recently, but I found the discussion rather hard to follow. I've read the paper, the PF discussion, and tried to just do the maths myself. There is also a section on Wikipedia that goes through it and helpfully spells out the full state in the various bases. I'll just copy the statements here:

Statement 1 by F

_{1}: "If I get**t**, I know that W_{2}will measure**plus**"Statement 2 by F

_{2}: "If I get**up**, I know that F_{1}had measured**t**"Statement 3 by W

_{1}: "If I get**minus**, I know that F_{2}had measured**up**"Statement 4 by W

_{2}: "If I get**minus**, I know that there exists one round of the experiment in which W_{1}also gets**minus**"Statement 4 seems to be correct. Even statements 1 to 3 individually look fine to me, but I may be wrong. I can only conclude that there is an issue with combining the first three statements to make the conclusion that if W

_{1}gets**minus**, W_{2}*will*measure**plus**, because this is clearly not true from just looking at the state, but I can't put my finger on it.So my question is specifically whether this is the source of the paradox, and if so, why?

Thanks in advance!

__So I went through the PF thread again and this post by stevendaryl seems to agree with this lack of transitivity from statement 3 through to 1. However, I still don't think I understand__**EDIT:***why*this is the case.
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