Re: ASSA and Many-Worlds

From: Brent Meeker <>
Date: Sun, 28 Jan 2007 15:28:39 -0800

Jason Resch wrote:
> On 1/28/07, *Brent Meeker* <
> <>> 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://
> 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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Received on Sun Jan 28 2007 - 18:28:59 PST

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