Re: MWI

On 27 May 2013, at 16:33, hibbsa wrote:

>
>
> --- In [email protected], Bruno Marchal  
> <marchal@...> wrote:
> >
> >
> > On 27 May 2013, at 14:32, hibbsa wrote:
> >
> > > Does this question an answer?
> > >
> > > Is it logically possible for the multiverse to produce macroscopic
> > > universes exhibiting any statistically significant differences   than
> > > our own universe?
> > >
> > > I mean "statistically significant" in the most rounded possible   sense.
> > >
> > > - Any difference that our universe couldn't have gone the way of,
> > > consistent with its initial conditions all laws of physics assumed
> > > constant
> > >
> > > - Any difference in terms of any phenomena existing at any level  of
> > > abstraction in greater or lesser or with any difference in any
> > > attribute including (a) abundance (b) probability of occurrence   (c)
> > > relation with other phenomena (d) internal constituents.
> > >
> > > - Any difference on any level at all where to be different at the
> > > bottom level requires contradicting the probabilistic rules of QM
> > > and/or causing unique consequences of those rules as a result of
> > > interaction with macroscopic phenomena and at the top level   requires
> > > any significant difference in the timing, macroscopic and
> > > microscopic structure, and ultimate fate of the universe.
> > >
> > > The reason I think this question deserves a proper full answer.   And
> > > by that I mean...not just a criticism of the way the question is
> > > formed is because there could be important consequences...which   may
> > > not be worked through. And the philosophy is all about intrepidly
> > > working through the consequences?
> > >
> > > I've got some consequences waiting for your criticism. But I think
> > > it's important to establish your criticism or acceptance of the
> > > above first.
> > >
> >
> > What do you mean by "exhibiting any statistically significant
> > differences than our own universe? "
> >
> > If you prepare an electron in the up + down state, and if you  measure
> > its up/down state, QM predicts that you will end up yourself in the
> > "seeing-up + seeing-down" state. If you had decided to go in the   North
> > or in the south, according to the result of that measurement, you   end
> > up in the visiting-North + visiting-South. from your points of view
> > that is statistically different, imo. You get two macroscopically
> > quite different lives. This with a probability 1/2, when evaluated
> > before the measurement, about your future first person points of   view.
> >
> > Now if your question is just "is there a macroscopic world in which
> > elephant can fly?", the answer is also "yes", but the probability,
> > here-and-now, that you will see such an elephant is equivalent to
> > winning the big lottery every second for a time much bigger than the
> > age of the universe, so don't count on it. Near death, that question
> > is just much more complex to get an answer today.
> >
> > The MWI is just the statement that the SWE applies to everything,
> > macrosocopic, mesoscopic, microscopic, etc.
> >
> > OK?
> >
> > Bruno
> >
>
> Hi Bruno - no not OK but my fault. I meant statistically different  
> macroscopic universes. So you need to name your macroscopic  
> object...preferably with clear, known emergent properties. And show  
> how those emergent properties are altered in any of its associated  
> quantum histories, from say,....the differences that would be  
> exhibited by enough copies of the object in this universe to  
> represent all the possible quantum histories.
>
> And if there aren't any differences...and if our macroscopic world  
> is emergent phenomena from the quantum state, then it's hard to see  
> how the multiverse can exhibit statistically significant differences  
> between its macroscopic universes.
>
I am still not sure I really grasp your question. Planck constant is  
very little. So if you decide to boil some water, QM predicts that it  
will boil normally in most of the branches you can access in the  
multiverse, with some non negligible probability. Then you will have  
the many universes fluctuating from that behavior, but,  
proportionally, they will be rarer. At the extremal point of the  
spectrum of the possibilities, you will have the "Harry Potter"  
universe, but those are quasi-impossible to access (a good thing),  
except perhaps near death, as the probabilities on the first person  
expectancies get harder to compute.

Our macroscopic world is not emergent from the multiverse, except for  
most quantum properties, so our universe is quantum normal, with  
solid, liquid and gaz well described by the quantum statistics. but  
each branches differ on orthogonal or quasi orthogonal state, and so  
can differ in macroscopic properties (like if earth was not hit by an  
asteroid a long time ago), but such branches will still obeys the same  
macroscopic laws, like classical mechanics, for example.

Our local realities are Gaussian, and that's why we can discern all  
sort of laws. In fact that appears with just computationalism too.  
Below our level of substitution, we emerge from infinities of  
computations, which interfere statiostically, but above that level, we  
have much simpler classical laws. In QM this is explained by MWI +  
decoherence. With digital mechanism it is far more complex, but then  
we can explain where the quantum comes from.

I hope this help, feel free to make your question more precise, if I  
miss your point,

Bruno





>
> 

http://iridia.ulb.ac.be/~marchal/





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