Dear Lee and Bruno,
----- Original Message -----
From: "Lee Corbin" <[EMAIL PROTECTED]>
Sent: Friday, July 07, 2006 12:45 AM
Subject: RE: A calculus of personal identity
> Bruno writes
>> Actually I was about to say that nominal question are suggestive
>> (anybody can answer by principle of a mailing list), and nominal
>> question when thread interferes makes possible to send less
>> mails. But I agree here I miss miserably ...
> Not sure what mistake you think you made :-) but whatever, it
> could not have been very important.
>> I take the opportunity to ask you Lee what is your expectation in front
>> of the running of a Universal Dovetailer?
> Well, I once got fairly up to speed on the subject of the UD (i.e.,
> I understood it about half as well as you, Hal, Schmidhuber, and
> the rest of the gang here), but it just didn't grab my enthusiasm.
> So I will take the liberty of imagining a scenario that may have
> a (small) chance of answering your question.
> I find out that some aliens have set up a colony on the moon.
> Worse, they've subscribed to the everything list, and having
> never had had the notion before on their home planet, are
> designing---AND INTENDING TO CUT LOOSE---a Universal Dovetailer
> made from some weird computronium substance!
> This will either be very good news, or very bad news, because the
> compute speed of their substance is utterly incredible. If they
> turn the damned thing on for even one whole second, it's easy to
> calculate that any given human being will have most of his solar
> system OMs generated by it, all his life on Earth relegated to
> relative insignificance.
You might like to know that there is a specific quantity that is the
upper bound on the number of computations that can be implemented within a
given hyper-volume of Space-time:
Given this value, it should be easy to calculate the amount of
computational processing available (in principle) to those aliens with which
to run a UD program...
I seem to recall that Stephen Wolfram had a thing or two to say that
relates to this:
"The behavior of a physical system may always be calculated by simulating
explicitly each step in its evolution. Much of theoretical physics has,
however, been concerned with devising shorter methods of calculation that
reproduce the outcome without tracing each step. Such shortcuts can be made
if the computations used in the calculation are more sophisticated than
those that the physical system can itself perform. Any computations must,
however, be carried out on a computer. But the computer is itself an example
of a physical system. And it can determine the outcome of its own evolution
only by explicitly following it through: No shortcut is possible. Such
computational irreducibility occurs whenever a physical system can act as a
computer. The behavior of the system can be found only by direct simulation
or observation: No general predictive procedure is possible. Computational
irreducibility is common among the systems investigated in mathematics and
computation theory. This paper suggests that it is also common in
theoretical physics. Computational reducibility may well be the exception
rather than the rule: Most physical questions may be answerable only through
irreducible amounts of computation. Those that concern idealized limits of
infinite time, volume, or numerical precision can require arbitrarily long
computations, and so be formally undecidable."
"This paper has suggested that many physical systems are computationally
irreducible, so that their own evolution is effectively the most efficient
procedure for determining their future. As a consequence, many questions
about these systems can be answered only by very lengthy or potentially
infinite computations. But some questions answerable by simpler computations
may still be formulated. "
Given this argument, it follows that the world we collectively
experience can *not* be the the result of a computation that is run *inside*
the universe. If it is a grand computation, ala Schmidthuber, Fredkin, etc.
then the computer hardware exists, somehow, *outside" the Universe!
> I think that I would be in favor. Because I am having a good life
> (i.e. better than one-percent worth living), and believe than
> human happiness derives mostly from chemicals in the brain
> produced by genetic settings. So most of the copies of Lee
> Corbin that are generated by the UD should, on the average,
> also have good lives.
> (It's possible that even miserable people reading this can find
> solace in supposing that their genetic setting are not an
> intrinsic part of their identity, and that in most instantiations
> in most universes, their lives are rather good.)
It also seems to follow from Wolfram's argument that the world we
experience is the "best computation possible"...
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