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31.7.16

Locality The reference frame


Locality has come upon The Reference Frame again. I was looking for some old comment by the author that said in the most clear way possible that nature is local and there is no action at a distance but still could not find it or forgot how he said it and so maybe I saw it but did not recognize it.

At any rate, the knowledge of Nature is unavoidably subjective 




Lubos

"Nature is local, at least whenever a quantum field theory is a sufficiently good description. String theory is local in some respects, subtly nonlocal in others. But no nonlocality is ever needed to explain the results of EPR-like experiments. The experiments testing entanglement have nothing to do with nonlocality."


What I think he meant by this comment was that Field Theory is local but it gets that locality after there is a propagator. Kind of like a Hamiltonian description of a system. The fact that you describe it as a system does not mean non locality. 

I was looking for some comment by Lubos that said this idea that nature is radically local but I still can't find it. [That is nature is subjective and local. There is no objective state of affairs until you make  a measurement]


[Maybe it was this blog entry] I wish I had made a link to it when I first saw it.

Locality correct. Realism incorrect.



"Realism" means the assumption that the state of the Universe is described by the choice of - possible time-dependent - information about the "right points in the phase space", the space of possible states, and this information is objective and in principle, every honest observer would have to agree with any physically meaningful statement about this information if he tried hard.
Realism, in this valid definition, doesn't imply determinism or causality.





"Quantum mechanics says that there is no underlying objective state of affairs.

One can still say that "the existence of Nature" itself is an objective fact. But it's an empty statement and none of the detailed properties of Nature are objectively well-defined (before the measurement)."
[from this link]


" But I'm saying just the opposite! You can have an objective world that is fundamentally probabilistic." [from this link]