From: eder@hsvaic.boeing.com (Dani Eder)
Newsgroups: sci.philosophy.tech
Subject: Re: nano-replicator assumptions
Keywords: nanotechnology, replicator, assembler
Date: 11 Aug 92 15:43:15 GMT
Distribution: na
Organization: Boeing AI Center, Huntsville, AL

snodgras@crash.cts.com (John Snodgrass) writes:

>In <1992Aug3.160058.11480@bnr.ca> bucknerb@bnr.ca (Brent Buckner) writes:

>      IMO, this doesn't cut it. In order for system A to copy system B,
>system A would have to have complete knowledge of system B. But in order
>for system B to copy system A, the same would have to be true; but consider
>the fact that system A contains complete knowledge of system B. Hence system
>B's picture of system A contains an inset which is system A's picture of
>system B, which in turn must contain an inset which is system B's picture of
>system A, ad infinitum.

Consider a system consisting of universal robotic modules.  Each module
contains a motor-driven joint, solar cells for power, a solid state
CCD for imaging, latches for attaching to other modules, and a processor
and memory for brains.  All modules are identical, but they can be
attached in various combinations.  Several joints in series can form
an arm or leg.  An array of modules with solar cells aligned can form
a solar array for power, with a couple of the joints on the sides
providing tracking, etc.

The modules may contain some dozens to a hundred discrete parts, which
are repeated in each module.  The memory of a large number of modules
can split up the task of memorizing the steps to manufacturing each
of the parts of a module.  A sufficiently large set of units can
remember all of the steps to making a module, which then needs to
be repeated enough times to make a second set which can then copy the
full set of instructions.

>      I would certainly be interested to see a detailed design of a system
>that could physically copy itself. It seems to me I heard of Godel making
>some such suggestion -- but I could be wrong. Anyway, as I said previously,
>the usual argument is that it is _possible_ (based on the fact that living
>systems already do it) but very complicated. My suggestion is that one may
>have to replace 'very' with 'infinitely'.

In the universal robot modules concept above, we have a single product
to make: a robot module.

This requires:

	Metal for structure
	Battery
	Solar cell
	memory
	processor
	CCD
	Wires
	motor for joint
	latch solenoids
	latch hardware

Assume that the robots are initially out in an un-developed area
with mixed fields and forest.  They will have to recapitulate 
the evolution of technology - starting with grasping stones and
using them as shovels and axes to build simple structures - such
as a smelting furnace to make iron - from which tools can be made.

If the modules have a flat shiny side, they can concentrate sunlight
to make a solar furnace, and reduce ores in that.  There are many steps
to get to all the parts listed above, but it is a finite number, so
a large enough set of robots would have enough memory capacity to
memorize them all.

Dani Eder


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Dani Eder/Boeing/Advanced Civil Space/(205)464-2697(w)/232-7467(h)/
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Newsgroups: sci.philosophy.tech