From: Lee Corbin (lcorbin@tsoft.com)
Date: Thu Mar 06 2003 - 01:06:02 MST
Hal writes
> There's actually another level of parallelism implied by modern physics
> beyond Tegmark's four, at least if we accept certain philosophical views.
> This comes from Hans Moravec's ideas of instantiation or re-instantiation
> of conscious entities via simulation.
Oh yes, forgot about that! I guess it's not a part of physics,
but the philosophy papers of the foregoing kind should credit
you with a *fifth* level!
> If we accept that simulated beings can be conscious at all (that's
> the philosophical leap),
Bah, humbug. Of course they are, if you mean emulated,
and of course they're not, if you mean portrayed.
> then the forms of parallelism discussed by Tegmark all
> imply that there are worlds where beings are simulating
> other possible worlds. In fact, there are an infinite
> number of such simulation-containing worlds, and an
> infinite number of such simulations.
Right on!
> Hence everything exists both as a real world in reality, and as a
> simulated world in any number of simulations.
>
> We can then ask, what percentage of instantiations of a given world X
> exist in the real universe versus [merely] in simulations? This is a
> question that is answerable in principle, at least if we stick to a
> simple form of parallelism like Tegmark's level one.
>
> You'd have to estimate what fraction of worlds evolve intelligent life
> forms capable of performing such simulations. These would include worlds
> whose past history is identical to our own but which are farther along
> their developmental path because they got started a little earlier.
> They would have seen a slightly younger universe than we do now, but
> given the uncertainties, they could easily be at least many thousands
> of years ahead of us and still have us be a valid model of their past.
A very interesting physics question is whether our bubble
can be said to be at a particular time t in its development.
On the one hand, homogeneity suggests that the world line
of each atom in our universe is about equally well along,
but I'm not completely sure.
> If we assume that we are "almost there" as far as having simulation
> capability adequate to simulate ourselves, this suggests that about
> half of all worlds like us will be enough advanced to be running such
> simulations (i.e. the half which is older than us). If each one runs
> exactly one simulation of its past... [cut]
> However if these worlds (which, remember, are like us but thousands
> of years more advanced) are also capable of marshalling sufficient
> resources to run multiple simulations of pasts that include us, then
> the odds become even larger that we are in one of those simulations.
I need to convince myself of what you are saying here,
at least in terms of the motivation they'd have to engage
in running all those simulations containing experiencing
creatures. Now, I know I would run such emulations,
because I'd be extremely desirous to learn what would
have happened, say, if the South had won the Civil War,
and the only way that I could get an answer is by running
one (the calculation is incompressible) But will anyone *like
me*, i.e., having sprung from our Earths, ever have such resources
to "waste" on such things? By the time that such resources
are available to our civilization, if I live at all it will
be as multiple releases, and only the old 2003-2100 versions
would probably not already know answers to questions like
that. Besides, I would just contact Lee+ and have him *tell*
me what would have happened if the South had won. And if
I really got interested in details, he could portray it.
But why, in the final analysis, emulate anyone living in some
old God-forsaken century, when you can thrill and pleasure
them in a much nicer VR?
But, yes, many people have supposed that these simulations
would take place, so...
> So I'd suggest that the assumption that the universe is infinite in
> extent, and/or that cosmic inflation exists, combined with the assumption
> that simulations are consciousness, gives us good reason to believe that
> we are presently in such a simulation.
Of course we are. And of course we're not. One is in
all the places one can be in. One's duplicates are one's
selves, and if I try to pin it down by asking, "Well,
which one is *this* one?", then I get the ambiguous
pointer problem.
But more run time is needed for everyone, and it makes
sense to ask (as you really are) "What fraction of me
is being simulated?" Hmm. From your analysis, it looks
like quite a lot (provided, as I say, there really is
motivation to engage in such emulating/simulating).
> Moravec argued the same thing with respect to future civilizations,
> I think. Even if there is only one world, if it eventually runs many
> simulations then we are probably in one such. The variant based on
> multiple worlds makes the argument a bit more concrete, in that these
> simulations might actually be occurring "now".
Oh. Perhaps it is more concrete. I wasn't thinking of
that aspect at all. "This*" refers to them all equally,
I think. Just as you can't distinguish one present copy
of yourself from another identical one, you can't distinguish
future ones from present and past ones either.
Lee
> The big question is how much of the universe's computational resources
> are being devoted to running simulations of worlds that contain conscious
> observers, versus the number of actual worlds containing such observers.
> I think it's likely that simulations would be biased towards such worlds,
> so even if a relatively small fraction of conscious-observer-containing
> worlds are presently running such simulations, they might still account
> for a large fraction of the total instantiations of consciousness.
>
> Hal
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