[ExI] Many Worlds (was: A Simulation Argument)

[Lee Corbin]

Stathis and Vladimir wrote

> Stathis Papaioannou wrote:
>
>> It's important to point out (on my understanding of what Lee is
>> saying) that the worlds don't actually halve, double or undergo any
>> other special process at all when the "split" occurs.

Right, they just become distinguished.

>> Say there are two identical versions of you, A and B, contemplating
>> a quantum coin toss. Because A and B are identical, there is no way
>> for you to say that you are one or the other.

And I would further say that it's not the case that you *are* one
or *are* the other.  You are both.

>> After the coin toss, A sees heads and B sees tails. From a God's eye
>> view, the two parallel worlds of A and B continue, with different things
>> happening in each one. This is like the deterministic, unitary evolution
>> of the wave function. But from your point of view, you have a 1/2
>> chance of observing that the coin comes up heads or tails.

Well, that what it *feels* like, but the truth is that you have a 100%
chance of seeing heads, and a 100% chance of seeing tails. "Just as
it is possible to be at two different times in the same location, so it
is possible to be in two different locations at the same time", we just
aren't so used to it yet because we don't happen to have a lot of
duplicator and memory-merging equipment around right now. 

>> This is like the subjective appearance of a truly random wave
>> function "collapse". So there is no collapse, no splitting or
>> duplication, and no truly random (or equivalently, uncaused)
>> events; but for an observer embedded in the system, it looks
>> as if there is.

Why do you say that there is no splitting?  Say a GIU (Group of
Identical Universes, a term Deutsch uses over and over in the book
"Fabric of Reality") bifurcates into the "heads" and "tails" branches
you spoke of above.  Why don't you consider this splitting, or have
I misunderstood?

Vladimir writes

> Or, generalizing, there are no separate worlds. You 'select' specific
> properties of world that you observe from overall collection of
> interacting elements,

Yes, I guess so, but saying that they aren't separate may be going
a bit far:  we usually say that branches are separate when they 
can no longer interfere (and hence merge).

Lee

> ones that interacts with (and thus are observed
> by) given subsystem considering itself to be you.