Can you explain, in the simplest layman terms, why this argument can be 
thrown out? The details are over my head, but it seems to me that the 
argument is simply that in order to make universes separate, you would need 
a whole other information architecture (which would also have to be 
information-theoretically multiplied) to create and preserve that 
separation. For each universe, you would need multiple universes of 
overhead outside of all universes. Or if that is not his argument in the 
paper, then consider it mine. Why does MWI not in itself require a second 
order MW to propagate and maintain the multiplicity? If it needs no 
resources, then why not use the same argument for the single universe?

Craig


On Sunday, November 18, 2012 8:29:54 AM UTC-5, Bruno Marchal wrote:
>
>
> On 18 Nov 2012, at 09:19, Russell Standish wrote: 
>
> > On Sat, Nov 17, 2012 at 11:01:49PM -0800, Craig Weinberg wrote: 
> >> 
> >> 
> >> In a recent paper entitled 
> >>> “Nothing happens in the Universe of the Everett Interpretation”: 
> >>> http://arxiv.org/abs/1210.8447 
> >>> Jan-Markus Schwindt has presented an impressive argument against the 
> >>> many-world interpretation of quantum mechanics. 
> >>> 
> >>> The argument he presents is not new, but, in my opinion, nobody ever 
> >>> presented this argument so clearly. 
> >>> 
> >>> In a nutshell, the argument is this: 
> >>> To define separate worlds of MWI, one needs a preferred basis,   
> >>> which is an 
> >>> old well-known problem of MWI. In modern literature, one often   
> >>> finds the 
> >>> claim that the basis problem is solved by decoherence. What J-M   
> >>> Schwindt 
> >>> points out is that decoherence is not enough. Namely, decoherence   
> >>> solves 
> >>> the basis problem only if it is already known how to split the   
> >>> system into 
> >>> subsystems (typically, the measured system and the environment).   
> >>> But if the 
> >>> state in the Hilbert space is all what exists, then such a split   
> >>> is not 
> >>> unique. Therefore, MWI claiming that state in the Hilbert space is   
> >>> all what 
> >>> exists cannot resolve the basis problem, and thus cannot define   
> >>> separate 
> >>> worlds. Period! One needs some additional structure not present in   
> >>> the 
> >>> states of the Hilbert space themselves. 
> >>> 
> >>> As reasonable possibilities for the additional structure, he   
> >>> mentions 
> >>> observers of the Copenhagen interpretation, particles of the Bohmian 
> >>> interpretation, and the possibility that quantum mechanics is not 
> >>> fundamental at all. 
> >>> 
> >> source <http://www.physicsforums.com/blog.php?b=4289> 
> > 
> > Rather than Copenhagen observers, the many minds of Everett fits the 
> > bill. 
> > 
> > See http://en.wikipedia.org/wiki/Many-minds_interpretation 
> > 
> > As I see it - the argument is not new, 
>
> Yes old argument keep getting copied and pasted, probably due to   
> "perish or publish". 
>
>
>
> > and has been adequately 
> > addressed within the Everett framework. 
>
> Absolutely so. Even in Everett original long version text (his thesis). 
>
>
> > What surprises me are people 
> > like Deutsch sticking to their preferred bases... 
>
> I agree, although I thought that David changed his mind on this.   
> People does not read the original work of Everett which shows clearly   
> the independence from the choice of a basis, even if the global   
> picture remains unclear. About this, with comp we know why (there are   
> no global physical picture a priori). 
>
> Best, 
>
> Bruno 
>
>
>
> http://iridia.ulb.ac.be/~marchal/ 
>
>
>
>

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