Undergrad What did Omnès mean with this?

[Suekdccia]

TL;DR

What did Omnès mean with this?

Summary: What did Omnès mean with this?

I found an old article by Roland Omnès which analyzes the EPR paradox and offers a solution to it (https://www.sciencedirect.com/science/article/abs/pii/0375960189900182).

At some point, the article says:

"Some macroscopic systems do not satisfy the conditions of the proof and classical logic cannot be applied to them [ 8 ]. Physical facts are defined as described by chains of propositions deterministic towards the future"

What did the author mean with this? Did he mention these macroscopic systems as problems that would have to be solved (so classical logic could be applied to them) like the EPR paradox? Or are these macroscopic systems perfectly possible and he was just mentioning them to inform the reader that these systems do exist?

 

[vanhees71]

This belongs to the "foundations subforum".

 

[DarMM]

Summary: What did Omnès mean with this?

What did the author mean with this?

Omnes, like Asher Peres, Jeffrey Bub, Rudolf Haag, Jürg Martin Fröhlich and Robert Griffiths (and others), has essentially come up with a definition of "classical" as meaning all "observables commute". They all use different conditions to formulate when this commutation holds, but since each condition implies the others this doesn't matter too much.

Here Omnes just means there are some macroscopic systems for which this doesn't hold like superfluids. It's not a problem really, just a statement of fact.