From: "John Ku" <[EMAIL PROTECTED]>
I actually think there is reason to think we are not living in a computer
simulation. From what I've read, inflationary cosmology seems to be very
well supported.
[...]
Once you admit that you (and your whole species/civilization, assuming that
it was real) may have always been living in a simulation, any cosmological
reasoning that was empirically supported becomes moot. "Inflationary
cosmology seems to be very well supported" - here inside the simulation!
That tells you nothing about the external world. This line of thought would
matter only if inflationary cosmology were well-supported A PRIORI, out of
all possible worlds.
In other words: you are attempting to reason about the odds that we are
living in a simulation. *If* the possibilities were limited to "We are
embodied natural intelligences living in a Standard Model cosmology, just as
we seem to be", and "We are brains-in-vats / deluded software daemons ..,
whose captors / makers are living in a Standard Model cosmology" - then one
could makes some guesses about probable demographics across the whole of
space-time in such a universe, including space colonization by
post-Singularity civilizations, etc., and derive the relative odds of the
two scenarios. But the possibilities are not limited in this way.
I see that Nick Bostrom acknowledges this consideration in FAQ 11 at his
'simulation argument' site, and says he knows no way of estimating the
probabilities if one discards the implicit assumption that real-world
physics resembles that of the simulation. The attempt to treat the universe
as a Turing machine, and to make one's absolute prior a distribution across
all possible programs, or all possible Turing machines, or all possible
programs in all possible Turing machines - that is something of an attempt
to get away from the implicit restriction involved in only thinking about
M-theory universes, or whatever. But it still has problems. The classic
model of a Turing machine is of an infinite tape, with a programmable
read-write head moving along it. If one performs one's calculations in this
context, isn't one supposing that *that* is the ultimate reality - a
one-dimensional chain of n-state systems, and one more complex system which
takes turns interacting with them individually? Well, there are theorems in
algorithmic complexity theory regarding the independence of certain results
from the specific model of computation used to prove them; as I recall,
along the lines of "the time complexity of algorithm X is the same in all
models, except for an unknown additive constant". One might hope to carry
through a generalized simulation argument in a similarly
platform-independent fashion... But I think that's a false hope. Eventually,
the ontological problem of locating 'observers' in such a 'universe' would
have to be faced. One has to define a concept of possible world which is not
just dictated by the current fashions in physics (e.g. M-theory's
'landscape'), which is not so abstract as the logical space of Wittgenstein
and Lewis (any element of which is really just a set of truth values for
anonymous atomic propositions, so far as I can see), and which is not so
muddled as the crypto-idealist suggestions that any 'mathematical structure'
or any 'program' defines a possible world.
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