General argument that entanglement can only be created locally

[PeterDonis]

So how is 1,4 entanglement being created when 1,2,3,4 are all distant from each other?

Note that this question assumes realism--that entanglement is something that has to be "created". In other words, it is interpretation dependent, as @Cthugha has pointed out.

 

[PeterDonis]

As far as I know, entanglement can initially only be created locally

As the discussion here has shown, this is not true, in the sense that two particles can be entangled without ever having undergone a common local interaction. That is an experimental fact.

How that fact is interpreted is a matter of QM interpretation, and discussion of that, as has been remarked, belongs in the interpretations subforum.

And with that, this thread is closed. Thanks to all who participated.