Re: Minds, Machines, and the Multiverse

From: Robin Hanson (
Date: Wed May 03 2000 - 11:59:49 MDT

John Clark quotes Julian Brown on Ed Fredkin:
>... the CA that operated at ... Plank length and Plank time would
>only need to be not much larger than a bigish star to faithfully
>simulate the entire macroscopic evolution of our universe from the
>Big Bang to the present in about 4 hours. The difference in
>space time volume between the universe and such a system is a factor
>of 10^63. This figure is Fredkin's "missing workload", .... "Either
>something else is going on in the universe that we don't know about"
>he says, "or God was incompetent on a scale that boggles the mind"."

This is interesting, but not that puzzling I think. If the resource
that "God" had to allocate was space-time volume, and if any set of
Plank-scale CA rules was equally cheap to create, and if the goal was
to compute the macroscopic end-state of the universe, then yes this
would be a puzzle.

The obvious solution to me is to guess that not all CA rules are
equally cheap to create -- some allow you to create more space-time
volume than others.

Robin Hanson
Asst. Prof. Economics, George Mason University
MSN 1D3, Carow Hall, Fairfax VA 22030
703-993-2326 FAX: 703-993-2323

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