Le 05-juil.-07, à 14:19, Torgny Tholerus wrote:
>
> David Nyman skrev:
>> You have however drawn our attention to something very interesting and
>> important IMO. This concerns the necessary entailment of 'existence'.
> 1. The relation 1+1=2 is always true. It is true in all universes.
> Even if a universe does not contain any humans or any observers. The
> truth of 1+1=2 is independent of all observers.
I agree with you (despite a notion as "universe" is not primitive in my
opinion, unless you mean it a bit like the logician's notion of model
perhaps). As David said, this is arithmetical realism.
>
> 2. If you have a set of rules and an initial condition, then there
> exist a universe with this set of rules and this initial condition.
> Because it is possible to compute a new situation from a situation, and
> from this new situation it is possible to compute another new
> situation,
> and this can be done for ever. This unlimited set of situations will
> be
> a universe that exists independent of all humans and all observers.
> Noone needs to make these computations, the results of the computations
> will exist anyhow.
OK, but I would mention bifurcating computations (with respect to
Oracle or just Universal machine ...)
>
> 3. All mathmatically possible universes exists, and they all exist in
> the same way. Our universe is one of those possible universes. Our
> universe exists independant of any humans or any observers.
I can agree or disagree with the first sentence. It is too fuzzy. I
disagree with the second sentence. I have argued that the comp
assumption you should say "our universes" (note the "s"), and strictly
speaking all (accessible) universes are ours. Of course "universes", or
better (imo) computational histories (up to some equivalence) exists
independent of observers, like the fact that machine A on argument B
stops or does not stops independently of me.
>
> 4. For us humans are the universes that contain observers more
> interesting.
Oh! Surely the discovery of a baby tiny universe would be interesting,
even without observers .... (like the moon is not so bad ...)
> But there is no qualitaive difference between universes
> with observers and universes without observers. They all exist in the
> same way.
It really depends what you mean by "universe". This cannot be an
obvious notion in the comp setting. Have you read the UDA up to step 7
(at least) ?
> The GoL-universes (every initial condition will span a
> separate universe) exist in the same way as our universe. But because
> we are humans, we are more intrested in universes with observers, and
> we
> are specially interested in our own universe.
Again what do you mean by our own "universe"? Are you meaning Deutsch
Multiverse or the comp-many computations seen from inside ?
I think that apparent universes emerge from personal gluing of
histories.
> But otherwise there is
> noting special with our universe.
There is nothing special about our historical geographies I would say.
Bruno
http://iridia.ulb.ac.be/~marchal/
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Received on Sat Jul 07 2007 - 08:00:27 PDT