[ExI] What should survive and why?

[Stathis Papaioannou]

On 06/05/07, Samantha Atkins <sjatkins at mac.com> wrote:

> Any of the Tegmark multiverse levels would give rise to this
> > situation. Would it upset you, for example, if it turns out to be the
> > case that the universe is infinite, which would mean that every
> > possible thing actually happens, infinitely often? Do you think that
> > it is more likely that the universe is unique and finite?
> >
> This is one of the reasons I have very little use for some of this
> thought and/or some of its interpretations.   Again it seems to me that
> you are crossing up orders of infinity.     I think you are engaging in
> a meaningless set of speculations.     That there is a multiverse does
> not automatically presume that every possible variation of every being
> and event occurs somewhere/sometime within the multiverse.  You can have
> a mulitverse of infinite diversity without all possible variations of
> any particular being or event occurring somewhere within it.


If the universe is infinite and uniform, then I think that everything that
can happen, does happen. By infinite I mean that there exists a countable
infinity of any given finite volume of space. By uniform I mean that the
physical laws remain uniform everywhere and that physical parameters such as
density and temperature limit towards some universal mean in any
sufficiently large volume, an assumption that most astronomers make about
subsets of our own Hubble volume. Now, with the conditions described there
is a non-zero probability, call it p, that any given physically possible
event E will be found to occur in a given volume of space, and this
probability is uniform over the infinite volumes of space available. So the
probability that E does not occur within n volumes of space is (1-p)^n. You
can see that as n-> infinity, (1-p)^n approaches zero, which means that for
sufficiently large finite n, Pr(E) can be made arbitrarily close to 1. E
could be something like "an arbitrarily close functional analogue of my
brain at the present moment".

The argument falls down if:

1) p=0, that is E is physically impossible, and the fact that I am conscious
is a miracle; or
2) the universe is finite; or
3) the universe is not uniform, such that p decreases as some function of
distance from my current position, even if it doesn't actually fall to zero

(Note that these considerations apply even if there is a unique universe
with a finite lifespan; adding infinite time or multiple universes produces
new opportunities for the realisation of E.)

If you really believe what you are proposing then it is inevitable that
> you will become posthuman somewhere in your notion of the infinite
> multiverse so why worry or sweat it much?  It can too easily become
> another pie in the sky in the sweet by and by.
>

Everything we do is perfectly determined by the laws of physics anyway, so
why worry about anything?

-- 
Stathis Papaioannou
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