Re: all of me or one of me

From: Marchal <>
Date: Tue Apr 6 08:11:12 1999

Gilles Henri wrote:
>But what is the meaning of two identical Universes ? should they not be
>identified as a single one?

Yes, at least FAPP (For All Practical Purposes).

>And if the Universe are slightly different, what is the meaning of "copies
>of yourself"? Should not anybody consider himself as a unique copy of a
>single being, even if you share the same past with other beings (like
>normal twins) ? You could consider that two Universes could be locally
>identical but different outside some region, but it is not that obvious.
>For example if the physical fields are analytical they must be either equal
>everywhere or different in any neighborhood of any point....

Perhaps but it is relevant with Wei Dai question only as an argument
against either MWI, comp or everything-like realm or theory.
Nevertheless, with comp or MWI, there is a question.

 Wei Dai asks:

"Given the MWI or one of the "everything" theories we've discussed, the
universe must contain multiple observers who have exactly the same
memories and experiences as you do. Should you identify with all of them,
or should you think, "I am one of these people, but I don't know which"?"

Now, if all the Worlds are identical, you are right, we can identified
these worlds with a single one, at least FAPP.
When the worlds diverges, we cannot make these identifications and, my
feeling here, is that Wei Dai is correct when he proposes that we should
"I am one of these people, but I don't know which".

Let us look another illustration with a thought experiment.
Suppose I give you the choice between the experiments A and B (and
nothing else!):
In both experiments you are destroyed after being "read" (your
description is encoded on some disk) and then you are reconstituted in 1
000 000 boxes which are put at some places. The boxes are, from inside,
undistinguishable. There is a door in all the boxes.

In experiment A, one box is put in *paradise* and 999 999 are put in
In experiment B, one box is put in *hell* and 999 999 are put in

(I suppose also that the different places in *hell* (resp. *paradise*)
are distinctibles. Let us call that the DISTINCT hypothesis)

What will you choose ?

I would answer: if for some reason I know I will never open the door, I
 don't care and I can choose between A and B randomly. If I know I WILL
open the door then I choose A.
Put in another way: untill I open the door I can identify myself
 (*my-futur-self*) with all the copies FAPP, but once I open the door
then I identify myself with one of those copies, and I don't know which
one in advance. But I do have some "information" helping me in my choice.

Do you agree ?

Are there some computationnalist or many-worlders who disagrees?

Another question is what will happen if we relax the DISTINCT hypothesis.
 With both comp and MWI there are senses in which we can erase memories,
  making possible for the "corresponding worlds" to fuse, and making the
"uncertainty quantification" more difficult to define.

Received on Tue Apr 06 1999 - 08:11:12 PDT

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