Re: Why no white talking rabbits?

From: Jesse Mazer <>
Date: Fri, 09 Jan 2004 15:38:19 -0500

>From: Eric Hawthorne <>
>Subject: Re: Why no white talking rabbits?
>Date: Fri, 09 Jan 2004 10:36:41 -0800
>Hal Finney wrote:
>>What about a universe whose space-time was subject to all the same
>>physical laws as ours in all regions - except in the vicinity of rabbits?
>>And in those other regions some other laws applied which allow rabbits
>>to behave magically?
>While this may be possible, we seem to have found so far that the universe
>admits of many
>simple regularities in its complex systems and its fundamental laws.
>Therefore many of the
>essential properties (future-form-and-behaviour-determining properties) of
>these complex
>systems admit of accurate description by SIMPLE, SMALL theories that
>describe these
>simple regularities in the complex systems.

But that's an empirical observation about our universe, it doesn't tell us
anything about *why* this should be true if you take seriously the
"everything that can exist, does exist" theory that this list is meant to
discuss. For example, if you consider the set of all possible Turing machine
programs, then for any given complexity, there are an infinite number of
programs that are more complex than that but only a finite number less
complex. So it seems like you need to assign progressively less measure to
the more complex programs in order to get a high likelihood of living in a
universe defined by a simple program (assuming you believe in 'universes' at
all, which advocates of TOEs that deal with first-person probabilities might
not). One solution might be that more complex programs tend to run simpler
ones inside them somehow, increasing their measure (like a detailed physical
simulation which contains, among other things, a simulated computer running
a simpler program), but then you have to address the problem in that
Chalmers paper I posted about how to identify instantiations of a given
program in a way that doesn't imply that every program instantiates every
other possible program.

Also, the problem with taking the "white rabbit" example too literally is
that programs that create orderly phenomena like talking white rabbits would
almost certainly be very rare unless you had a measure that was specifically
picked to make them likely--this is why I prefer examples where the laws of
physics break down in a region in a more random way, like getting a
completely wrong pattern of photons hitting the screen in the double-slit
experiment. Among the set of all possible distributions of photons you could
get in this experiment, the number of possible "wrong" ones should vastly
outnumber the number of "right" ones that quantum mechanics assigns a high
probability to, so why do we never see such violations? This is another form
of the "white rabbit problem", but without the misleading orderliness of
examples like an actual talking white rabbit, a man walking on water, etc.


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Received on Fri Jan 09 2004 - 15:57:40 PST

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