Can a model exist that is local yet realistic in quantum mechanics?

[maline]

Bell & Aspect proved you can't have local realism. Bohm set up a model that is realistic but not local. Is there a meaningful model that is local but not realistic? How would it explain the way measurement choices affect distant outcomes?

 

[DrChinese]

Bell & Aspect proved you can't have local realism. Bohm set up a model that is realistic but not local. Is there a meaningful model that is local but not realistic? How would it explain the way measurement choices affect distant outcomes?

There are a number of interpretations that are local but not realistic in the usual sense. Not all people classify these the same as I, but here are a couple:

- Many Worlds

- Time Symmetric/Retro-causal/Block world - these do not not exclude future setup/context from contributing to the present. The answer to the question of "where are the hidden variables": in the future.

 

[bhobba]

Bell & Aspect proved you can't have local realism. Bohm set up a model that is realistic but not local. Is there a meaningful model that is local but not realistic? How would it explain the way measurement choices affect distant outcomes?

The ignorance ensemble interpretation is usually considered local and not realistic - although that would not be my classification. The issue of locality depends on your view of the status of breaking entanglement when entanglement is simply a mathematical device to describe correlations. I personally don't look at it that way and say its both non local and not realistic - but opinions vary.

As you can see, and as Dr Chinese correctly pointed out, not everyone classifys things the same way. Many would classify MW as real because the only thing that exists in it is the universal wavefunction that is as real as they come - in that interpretation that is. So how does MW evade Bell? Its not counterfactual definite - you can't predict the outcome of observations. It's subtle like a lot of this stuff.

The other day I was trying to think of a theory that is real but not couterfactual definite - MW was the only one I could think of and even that required a bit of thought and reading of some literature.

Thanks
Bill

 

[Water nosfim]

In many worlds the worlds " can " be infinity worlds but some of them colapst by the viewer , and the numbers of the many world depend on stabilizesion on the viewer , so in bell when you check one side , it stabilize , colapst and afect on the ather side . It come from mulltiply worlds to feu and it some kind of geometry for the particle

 

[Demystifier]

Bell & Aspect proved you can't have local realism. Bohm set up a model that is realistic but not local. Is there a meaningful model that is local but not realistic? How would it explain the way measurement choices affect distant outcomes?

See e.g.
http://lanl.arxiv.org/abs/1112.2034 [Int. J. Quantum Inf. 10 (2012) 1241016]
which represents a model in which only observers are real, while the observed objects are not.

 

[bhobba]

In many worlds the worlds " can " be infinity worlds but some of them colapst by the viewer , and the numbers of the many world depend on stabilizesion on the viewer , so in bell when you check one side , it stabilize , colapst and afect on the ather side . It come from mulltiply worlds to feu and it some kind of geometry for the particle

I don't know what you mean.

But the situation in MW is that after decoherence, which is a purely quantum process, each outcome of an observation in the mixed state that results from decoherence, is interpreted as a new world. Its entirely real because the wavefunction in that interpretation is real, its local because the wavefunction is local, however you can't predict which world you will find yourself in so its not couterfactual definite.

Thanks
Bill

 

[Water nosfim]

You find yourself at the world you stabilize in , and it depend on the force you have use to fit in

 

[maline]

you can't predict which world you will find yourself in

Wouldn't the answer be "definitely both"? What's unpredictable there? and how doer this affect EPR?

 

[maline]

See e.g.
http://lanl.arxiv.org/abs/1112.2034 [Int. J. Quantum Inf. 10 (2012) 1241016]
which represents a model in which only observers are real, while the observed objects are not.

Thanks, but according to the abstract this model is still slightly non-local

 

[bhobba]

Wouldn't the answer be "definitely both"? What's unpredictable there? and how doer this affect EPR?

Yea - but how can you say which world you are in - you can't - because you are in all - it fails counterfactual definiteness.

Its subtle and a matter of semantic opinion. Semantics would have to be the silliest thing to argue about, so if you don't agree that's fine by me.

It doesn't affect EPR except as a possible example of an interpretation that is real, local but fails counterfactual definiteness.

Thanks
Bill

 

[Demystifier]

Thanks, but according to the abstract this model is still slightly non-local

Yes, but this "small" nonlocality appears only at small distances, not at large distances typical for the EPR experiments.