Albert's narrative argument against Everett-type theories

[bohm2]

I hope this didn't come up and I'm not just repeating it but I did a search and couldn't find anything on it. So, how convincing do others find Albert’s narrative argument against the advantages of Everett-type theories:

If all this is right, then many-worlds and many-minds and many-histories theories have no advantage whatever - in so far as questions of Lorentz-invariance are concerned - over collapse theories. The Lorentz-invariance of many-worlds and many-minds and many-histories theories comes, after all, at the price of non-narratability - just as that of collapse theories does.

http://philosophyfaculty.ucsd.edu/faculty/wuthrich/PhilPhys/AlbertDavid2008Man_PhysicsNarrative.pdf

Albert calls a theory narratable if specifying a system’s state at all times is sufficient to specify all properties of a system. Poincare-covariant quantum mechanics is not narratable: if we give the state at all times on a given foliation, we have given something less than the complete description of the system. One of the common arguments used in favour of the Everett interpretation over other interpretations is that it is fully compatible with special relativity. The conclusion Albert draws from narratability failure is that this presumed advantage is overstated.

If he is correct, then if narratability failure is also acceptable in the Everett interpretation, why not in dynamical-collapse theories? On the other hand, if narratability failure is not acceptable, the only alternative is to give up on Lorentz covariance as fundamental and accept a preferred (albeit undetectable) foliation. But if this is acceptable in the Everett interpretation, why not in other interpretations (notably, hidden-variable theories like the Bohm theory, or non-covariant collapse theories)?

http://philsci-archive.pitt.edu/4621/1/ststaterealism.pdf

http://arxiv.org/PS_cache/arxiv/pdf/1002/1002.1726v1.pdf

 

[Demystifier]

I agree that relativistic covariant quantum theories are not narrative. For example, the relativistic covariant version of Bohmian mechanics
http://xxx.lanl.gov/abs/1002.3226 [Int. J. Quantum Inf. 9 (2011) 367-377]
is based on a many-time wave function and therefore non-narrative.

But the advantage of MWI over other interpretations is supposed to be something else, not Lorentz invariance.

 

[Fyzix]

But the advantage of MWI over other interpretations is supposed to be something else, not Lorentz invariance.

Well I'm not so sure about that statement.
They play the "Lorentz invariant" card quite a lot, without it MWI is no better than Bohm.
Actually it's worse than Bohm as Bohm can derive Born Rule and they can't :)

 

[Demystifier]

They play the "Lorentz invariant" card quite a lot, without it MWI is no better than Bohm.
Actually it's worse than Bohm as Bohm can derive Born Rule and they can't :)

I would put it this way:
They say that MWI is better then Bohm because MWI requires a smaller number of assumptions.
But what they usually omit to say is the fact that with this smaller number of assumptions they cannot derive the Born rule. To derive it they need to introduce some additional assumptions (e.g., certain decision-theoretic ones), but then the number of assumptions is no longer smaller than that for Bohm.

Concerning the (non)-narrative nature of MWI, it should be emphasized that the usual formulation of MWI is narrative and not Lorentz invariant, simply because it is based on a single-time wave function. To save Lorentz invariance one must abandon the usual formulation and introduce a many-time wave function, which makes the theory non-narrative.

 

[bohm2]

Demystifier:

What's your opinion of Tumulka's relativistic version of GRW (flash ontology version)? It is non-local but seems like the only "realist" formulation that is compatble with relativity. So I'm assuming here that this version is both narrative and Lorenz invariant?

http://arxiv.org/PS_cache/quant-ph/pdf/0406/0406094v2.pdf
http://www.maphy.uni-tuebingen.de/members/rotu/papers/losinj.pdf
http://www.maphy.uni-tuebingen.de/members/rotu/papers/bmgrw.pdf

 

[Demystifier]

Demystifier:

What's your opinion of Tumulka's relativistic version of GRW (flash ontology version)? It is non-local but seems like the only "realist" formulation that is compatble with relativity. So I'm assuming here that this version is both narrative and Lorenz invariant?

This may be the only narrative "realist" Lorentz invariant formulation currently known, but as I indicated in post #2, there is also a Bohmian non-narrative "realist" Lorenz invariant formulation.

 

[bohm2]

Thanks. Looks like another Lorentz invariant "realist" model has been produced:

Mathematical models for the stochastic evolution of wave functions that combine the unitary evolution according to the Schrodinger equation and the collapse postulate of quantum theory are well understood for non-relativistic quantum mechanics. Recently, there has been progress in making these models relativistic. But even with a fully relativistic law for the wave function evolution, a problem with relativity remains: Different Lorentz frames may yield conflicting values for the matter density at a space-time point. One solution to this problem is provided by Tumulka’s “flash” model. Another solution is presented here. We propose a relativistic version of the law for the matter density function. According to our proposal, the matter density function at a space-time point x is obtained from the wave function ψ on the past light cone of x by setting the i-th particle position in |ψ|2 equal to x, integrating over the other particle positions, and averaging over i. We show that the predictions that follow from this proposal agree with all known experimental facts.

http://arxiv.org/PS_cache/arxiv/pdf/1111/1111.1425v1.pdf

 

[bohm2]

I came across this interesting paper looking at Albert's "narrative" argument in more detail. An interesting quote from Albert in Myrvold's piece:

What it is for a theory to be metaphysically compatible with special relativity (which is to say: what it is for a theory to be compatible with special relativity in the highest degree) is for it to depict the world as unfolding in a four-dimensional Minkowskian space-time. And what it means to speak of the world as unfolding within a four-dimensional Minkowskian space-time is (i) that everything there is to say about the world can straightforwardly be read off of a catalogue of the local physical properties at every one of the continuous infinity of positions in a space-time like that, and (ii) that whatever lawlike relations there may be between the values of those local properties can be written down entirely in the language of a space-time [like] that—that whatever lawlike relations there may be between the values of those local properties are invariant under Lorentz-transformations. (Albert [2000], pp. 3–4).

Thus, Albert, like Valentini, seems very critical of attempts to unite special relativity with QM, "calling it a ‘trick’ by means of which the theory is made ‘formally compatible with special relativity’ (Albert [2000], p. 6). Such merely formal compatibility, according to Albert, pays a high price:

As things stand now we have let go not only of Minkowski-space as a realistic description of the stage on which the world is enacted, but (in so far as I can see) of any conception of that stage whatever. As things stand now (that is) we have let go of the idea of the world’s having anything along the lines of a narratable story at all! And all this just so as to guarantee that the fundamental laws remain exactly invariant under a certain hollowed-out set of mathematical transformations, a set which is now of no particularly deep conceptual interest, a set which is now utterly disconnected from any idea of an arena in which the world occurs.

Relativistic Quantum Becoming
http://publish.uwo.ca/~wmyrvold/RQB.pdf