AI and cognitive psychology rant (getting more and more OT - tell me if I should shut up)

[Michele Simionato]

anton at vredegoor.doge.nl (Anton Vredegoor) wrote in message news:<bnm0pv$a39$1 at news.hccnet.nl>...
> In Scientific American (I think it was the may 2003 issue) I read
> something about parallel universes. One idea goes like this (adapted
> to make it fit my brain).
> 
> Suppose you're sitting in a chair in the middle of a virtual 2X2X2
> cube. Next imagine a cube filled with protons (or some even smaller
> particles) as tightly as possible. The difference between this cube
> and the cube you are sitting in is that in your cube some of the
> protons are absent. The cubes could possibly be represented by Python
> long integers [1], where the full cube would be a long with all bits
> set to one and different cubes would have some zero bits at
> corresponding positions.
> 
> There can not be more different cubes than 2**(number of protons per
> cube) so in an infinite universe (or even in a big enough universe) at
> some distance from you a cube identical to the one you are occupying
> would exist, or else one would need a very good reason why the cube
> you are occupying is unique.
> 
> Anton
> 

I fail to see the argument, sorry. OTOH, I have few observations
that may be of interest (even if way off topics, as all of this
most interesting thread ;)

According to the inflationary paradigm (which is a serious
paradigm with observational support) we live in a small
portion of the entire Universe. That means the following:

1. the observable Universe, i.e. the causally connected part of the
   Universe, is next to nothing with respect to the full Universe;

2. there could be infinitely many other words in the outer part of the
   Universe;

3. the cosmological horizon is expanding with time, so those others 
   worlds will become available to us if we wait a few billions years;

4. we still live in an inflationary epoch, so the rate of expansion
   of the universe will increase with time.

I would consider all these points (including the last one, only discovered
2-3 years ago) serious science. This means, they may be wrong, but they are 
serious, based on some experimental/observational evidence.

So, I would say that serious science (at least serious according to me ;) 
can accept many worlds in the inflationary context: actually it predicts 
them. The real point is that there is only ONE universe that matters, i.e.
the casually connected part of the Universe where we live: the rest of
the Universe cannot influence us in any way. Nevertheless, it influenced
us in the far far away past (when we were in causal contact with a much 
bigger part of the Universe) and it will influence us in the far far
away future, as the cosmological horizon increases.

Nowadays, the causal radius of the Universe is something like 45 billions
of light years (notice that the Universe is 15 billions of years old,
but the causal radius is not 15 billions of light years, since the concept
of "distance" is rather tricky in general relativity), so it contains 
only 10^52 cubes of 2x2x2 meters. I strongly disbelieve that in some of
the other cubes there is a copy of myself replying to a copy of Anton
Vredegoor in a copy of c.l.py. 

10^52 is a very little number as compared to infinity!
 
Moreover: reasoning about infinity is tricky. An infinite Universe does not
necessarely means that all possible combinations are available. The
set of even numbers is infinite, but does not contain any copy of the
number "2", nor it contains any odd number, by definition.
It is quite risky to make any statement about infinity, unless you are 
talking about a very specific kind of infinite that we have under mathematical
control, such as Cantor theory of transfinite sets. So, be careful:
the infinity of mathematicians and physicists is quite different 
from the infinity of the philosopher.


                         Michele Simionato