RE: Turing vs math

From: Marchal <marchal.domain.name.hidden>
Date: Thu Oct 21 09:28:26 1999

Brief answer to Juergen and James:

Juergen wrote:

>Bruno wrote:
>
>> I don't take the notion of observer for granted.
>
>Neither do I, of course. The observer O is something computable that
>evolves in some universe U.

Sorry but this doesn't help me. Neither for "observer" nor for
"universe".

Juergen wrote:

> Bruno wrote:
>> The problem is that "to be in a universe" has no clear meaning
>
>But it does. There is a computable predicate S such that S(U)=TRUE if
>"O inhabits U." Fortunately, there is no need for us to further specify
>what it means to ``inhabit,'' to be ``conscious'' or ``self-aware,'' or
>whether there is some other observer who applies S to U and uses S(U)
>to identify O, etc.
>
>Now we have a formally defined, conditional probability distribution
>on all universes satisfying S. I thought this to be clear, but maybe
>I should have written it down explicitly.

Honestly it is still not clear. How could ever "S(U)=TRUE" be computable ?
As a computer scientist I guess you know that even the apparently simple
question "does that piece of code computes the factorial function" is not
computable.
Beside, I am still feeling that you take the terms "observer" and
"universe" for granted.
I appreciate very much you article in the sense that it is correct with
comp, but you don't even broach the question I'm trying to formulate.

James wrote:

>It seems we're losing track of the original objection, which is to say that:
>
>1. everything exists (all relationships are equally valid, all worlds
>exists, you can string 'snapshots in time' together any way you wish - with
>a glass unsmashing or whatever - and all are equally likeley, as all exist
>with a probability off one.)
>and 2. WAP (we see a stable environment suited to us because we otherwise
>wouldn't be here to see it).
>
>...seem to explain the entire universe, except in that there's nothing
>stopping temporary minor abberations such as a flying rabbit.
>
>I haven't been reading recent posts but from this one I don't think we're
>much closer than we were a few months ago. Am I wrong (I hope so). And if
>so, can someone explain why in one simple paragraph?

Everybody agrees in this list that "everything exists" is a good basic
axiom
in search for a TOE. But nobody agrees on the meaning of "every" and
"things"
and even "exists". What I appreciate in the list is the big effort people
are making for trying to explain how they understand the problem.
I confess I loose the track in the RSSA/SSA discussion (because it seems
to
me that RSSA = SSA + conditionalisation). It seems to me that people
switch
back and forth between first and third person point of view without
mentioning
it, and that doesn't help me. I feel "guilty" not insisting more about
the need to define more clearly what we mean by "observation", and, at
least
for the moment, I cannot help it if only by pointing toward modal logic.
You should not underestimate the difficulties if only to formulate our
questions.
Beside you are the one who say that the "measure problem" is a red
herring.
And most of our current discussion (since months) are relative to the
finding of a frame to define this measure.

When you add (replying Juergen more quickly than I am able to write this
post):

>Yes but the everything universe has the shortest algorithm, containing just
>one bit of information. The sub-universes do not need algorithms, just the
>WAP.

I agree with you, and that is why there is no need of any universes AT
ALL,
but there is still need for "observers", and those observers need relative
computations, and everythings will be settled once we got a way
to put the right measure on it, and I got a beginning of a beginning of an
answer (my thesis), but I guess I am waiting people formulate in a clearer
way the question (and let us say I am waiting people get the Chellas'
Modal
Logic, and let us add I am waiting for being a little less busy ...).

Bruno
Received on Thu Oct 21 1999 - 09:28:26 PDT