Bell's theorem, QFT, and the Relativity of Simultaneity

[Elias1960]

On the other hand, dBB is a viable interpretation of QM that lacks classical causality despite what you say. Obviously, there are FTL effects present which remove what is usually considered the classical element. Not sure why you would claim otherwise. The whole point of dBB is that its non-locality is manifest.

No. There is no lack of classical causality in dBB. There is no Einstein locality in dBB, but classical causality in a preferred frame.

 

[PeterDonis]

classical causality

What is your definition of "classical causality"?

 

[DrChinese]

No. There is no lack of classical causality in dBB. There is no Einstein locality in dBB, but classical causality in a preferred frame.

When an action here affects an outcome there (and vice versa), that is not "classical causality" in my book since it is quite obviously the "out" needed a la Bell. It is causal/deterministic, as you say, and locality fails. To use Bell's words, it has a "grossly nonlocal structure". I won't even begin to discuss the issue of preferred frames in dBB, as that is entirely different discussion and belongs in a different thread.

At this point we are arguing about the definition of a word ("classical"), and I doubt we gain anything from tripping down that path.

 

[Elias1960]

What is your definition of "classical causality"?

Causality as used in classical, pre-relativistic physics. Where Newtonian mechanics, despite its action at a distance, is nonetheless considered causal. The cause has to precede the effect in Newtonian absolute time. Reichenbach's common cause principle holds.

When an action here affects an outcome there (and vice versa), that is not "classical causality" in my book since it is quite obviously the "out" needed a la Bell. It is causal/deterministic, as you say, and locality fails. To use Bell's words, it has a "grossly nonlocal structure". I won't even begin to discuss the issue of preferred frames in dBB, as that is entirely different discussion and belongs in a different thread.

At this point we are arguing about the definition of a word ("classical"), and I doubt we gain anything from tripping down that path.

The first sentence simply does not make sense to me. I don't see any issue of a preferred frame in dBB, it is quite obvious that if a preferred frame is allowed, dBB can be defined so that it will be causal, deterministic and nonlocal in the absolute time of the preferred frame.

So I don't understand the problems you have with the notion of classical causality, simply because I don't see any different notions of classical causality which could be confused.

 

[PeterDonis]

Causality as used in classical, pre-relativistic physics.

Ok, that makes your position clearer.

I don't see any different notions of classical causality which could be confused.

The term "classical" is often used to include relativity. Those who prefer such usage (which includes me) will certainly have a different notion of "classical causality" from yours, since in relativity causality is limited to within the light cone.