Benjamin Udell, <[EMAIL PROTECTED]>, writes:

> As I recall, Tegmark also said that there would be classically
> deterministic universes, with no quantum physics at all. So, it seems
> that an SAS in such a universe would have no reason to surmise a Level
> III multiverse. It makes you wonder what things we SASs don't know about,
> that might have led us to surmise still further Levels of the multiverse.

That's a good point.  Historically, scientists initially assumed a
deterministic universe (which is why we call it classical!).  It was only
when indeterminism was forced on them by the bizarre experimental results
in the late 19th and early 20th centuries that they changed their minds.
I don't know if any philosophers of earlier eras conceived of anything
like the MWI.

> Or conceivably could an SAS in a classically deterministic universe
> surmise something like a Level III multiverse, from considerations of
> the (ontological?) status(es) of terms of alternatives, alternatives
> of the types studied in logic (e.g. multivalue logic), mathematical
> theory of probability, & ("pure") mathematical theory of information --
> such disciplines as consider structures of alternatives that exhaust
> the possibilities (a la "p or ~p")?

I think so; in principle some mathematician could explore the implications
of the Schrodinger equation (or whatever mathematics turns out to
underly our universe), just as we play with toy universes such as
Conway's Life.  Wolfram has spent years looking at cellular automata to
try to see which ones might produce structure and, by implication, life
and SAS's.  Our tools are not strong enough to get very far with this,
but in the future we might even simulate universes far enough elong that
life evolves.  And someone in a deterministic universe might eventually
simulate our own.  In fact we could be living there, in a sense.

And it is possible, as you suggest above, that we might eventually
discover or invent or create universes which have other forms of
multiplicity than either the everything-exists (level 4) multiverse
or the MWI (level 3).  For example, one could imagine a universe where
you could create a split any time you wanted to, and talk to the other
branch for a short time, enough to be convinced that it is real, before
the two branches are irrevocably separated.  That would be the "have
you cake and eat it too" universe.

Hal

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