# Does the PBR theorem rule out the 'minimalist' Bohmian interpretation?

1. Aug 25, 2013

### bohm2

I had trouble understanding this and had brought it up before but I thought I'd start a new thread on it, in case anyone has any further insights. In the original Leifer summary discussing the implications of PBR theorem on the various QM interpretations, Leifer argued that realists should become ψ-ontologists. He writes:
Can the quantum state be interpreted statistically?
Can the quantum state be interpreted statistically? | Matt LeiferMatt Leifer

But this is what is confusing me. Harrigan and Spekken, whose definitions of ψ-ontic and ψ-epistemic are used in the PBR theorem briefly discuss the ontic nature of the different Bohmian interpretations and write:
Einstein, incompleteness, and the epistemic view of quantum states
403 Forbidden

Supporting this non-ontic reading for the nature of the minimalist Bohmian interpretation, Belousek writes:
Non‐separability, non‐supervenience, and quantum ontology
Non-separability, Non-supervenience, and Quantum Ontology | Darrin Snyder Belousek - Academia.edu

Assuming that the PBR theorem is accurate, does this imply that the Durr et al. minimalist Bohmian interpretation is ruled out?

Last edited: Aug 25, 2013
2. Aug 26, 2013

### Demystifier

I have already explained that, but let me repeat.

No, PBR does not exclude Bohmian interpretation. Why? Because the word "ontic" in the PBR context has a different meaning than the same word in the Bohmian context as defined by Durr et al. If you accept the PBR definition of the word "ontic", then Bohmian wave function is fully ontic. If you accept Bohmian definition of the word "ontic", then PBR reasoning does not prove that wave function is ontic.

By the way, nearly half of all disagreements between people can eventually be reduced to a use of different definitions for some word.

3. Aug 26, 2013

### bohm2

Thanks, I think I finally got. I was getting confused with the definition of "ontic". One of the assumptions of PBR is that there is an objective physical state λ for any quantum system. If one takes the minimalist (e.g. Durr et al.) Bohmian definition of "ontic", then this PBR assumption does not hold so PBR theorem does not apply.

Edit: I found this post on Physics Stack Exchange useful:

Bohmian loophole in PBR-like theorems
quantum interpretations - Bohmian loophole in PBR-like theorems - Physics Stack Exchange

Last edited: Aug 26, 2013
4. Aug 26, 2013

### audioloop

perhaps rules out also ontic models, as has been stated by schlosshauer and fine, or is flawed in its core assumption.

https://www.physicsforums.com/showpost.php?p=4427595&postcount=121

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Last edited: Aug 26, 2013
5. Aug 26, 2013

### bohm2

I can't see how the PBR theorem rules out ψ-ontic models. I think that if one of the PBR core assumptions is questionable (e.g. separability), then in that case it would just mean that interpretation would be unaffected by the PBR theorem.

Last edited: Aug 26, 2013
6. Aug 27, 2013

### audioloop

yes i am puzzled too, read this one:

that disqualifies pbr, can sound logic to me, cos how you state objectivity, reality, in one just sentence (assumption) is risible at least.

Last edited: Aug 27, 2013
7. Aug 27, 2013

### bohm2

I think this was Demystifier's original criticism of the PBR theorem to one of the authors of that paper. But I'm not sure if that's accurate because as I posted previously the authors argued that one of core and pertinent assumptions of PBR is preparation independence. I'm not sure what the difference is between this and separability assumption? This is summarized in these slides:
What is the quantum state?
http://www.cs.ox.ac.uk/qisw2012/slides/barrett.pdf

So it seems to me that one of the major assumption in PBR is preparation independence. Is that the same as a separability assumption? Well, if it is then would Bell's theorem also be prone to this criticism? Consider the summary of Bell's given in the link above:
As Demystifier pointed out the difference between these 2 assumptions (e.g. experimenter free will vs preparation independence is likely to be minor:
I'm not sure how this fits in with the separability criticism of the PBR theorem provided by Schlosshauer and Fine but would it not also apply to Bell's (assuming the summary given by slides is accurate). In fact, there are some physicists who argue that Bell's theorem does not make any "realism" assumptions (e.g. systems have an objective physical state). So this is kinda confusing me.

Last edited: Aug 27, 2013
8. Aug 27, 2013

### audioloop

no preparation independence -> no objectivity / ?

that is no objectivity.
you can do the experiment, experimenter free, so ?

more important, independence to me, is independence of anything.

you can not subordinate objectivity.

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Last edited: Aug 27, 2013
9. Aug 27, 2013