Jason Resch wrote:
> On 1/28/07, *Brent Meeker* <[EMAIL PROTECTED] 
> <mailto:[EMAIL PROTECTED]>> wrote:
> I don't think this is the way to look at it.  It's true that QM 
> predicts an uncountably infinite number of branchings, even for an 
> universe containing only a single unstable particle.  But these 
> branchings don't produce different copies of Stathis.  As a big 
> macroscopic object he is described by a reduced density matrix that 
> has only extremely tiny off-diagonal terms. So he is a stable entity 
> against these microscopic quantum events unless they are amplified so
> as to change his macroscopic state - as for example if he heard a 
> geiger counter click.  The microscopic events just add a little fuzz 
> to his reduced density matrix - and the same for all of the classical
> world.
> Although microscopic quantum events don't immediatly produce
> macroscopic changes, I think the butterfly effect implies that given
> sufficient time, they certainly do.  

Maybe.  But it is also the case that there is no chaos in QM.  And even if 
Stathis evolves in a way sensitive to initial conditions it doesn't imply that 
the chaotic evolution carries him far from his classical path - even in chaos 
the deviations may be bounded.

>Consider how brownian motion
> could effect which sperm results in a pregnancy.  

Sure, but this is an example of amplification of microscopic randomness. I 
agree that produces a split.  

What do you say to the prediction that the decay of an unstable atom must 
produce a *continuum* of splittings?

> Considering this, I
>  think that if you looked at two histories that branched a century
> ago, you would find two Earths inhabited by entirely different sets
> of individuals. 

> Even if Stathis's brain itself were never effected
> directly by quantum events, the fact that he ends up in branchings
> that produce different sensory input will no doubt produce new
> distnguishable observer moments.
> You might be interested in Greg Egan's excellent SF story "Singleton"
> which is available online:
> ttp://gregegan.customer.netspace.net.au/MISC/SINGLETON/Singleton.html
> Egan says "People who professed belief in the MWI never seemed to 
> want to take it seriously, let alone personally."  So he wrote a 
> story in which it is taken personally.
> Thanks, that was an interesting read.  I find it surprising how many
>  people find MWI so disturbing, perhaps it is the pessimists always 
> assuming the worst is happening.  Instead of focusing on the good or
>  bad, I look at the variety it produces.  Many worlds leaves no rock
>  unturned and no path untread, it realizes every possibility and to
> me this is an amazing and beautiful result.

It's not a result yet - just a speculation.  I don't think it's even a well 
defined theory yet.

Brent Meeker

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