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From: cipher@mmm.UUCP (Andre Guirard)
Newsgroups: sci.misc
Subject: Re: Engines of Creation: Nanotechnology
Message-ID: <1526@mmm.UUCP>
Date: Mon, 30-Nov-87 11:33:27 EST
Article-I.D.: mmm.1526
Posted: Mon Nov 30 11:33:27 1987
Date-Received: Thu, 3-Dec-87 07:20:26 EST
References: <799@sbcs.sunysb.edu> <2698@drivax.UUCP> <1063@sugar.UUCP> <2411@watcgl.waterloo.edu> <1445@m-net.UUCP>
Reply-To: cipher@mmm.UUCP (Andre Guirard)
Organization: Software & Electronics Resource Center/3M
Lines: 23
Keywords: nanotechnology foresight drexler

In article <1445@m-net.UUCP> russ@m-net.UUCP (Russ Cage) writes:
>In <2411@watcgl.waterloo.edu> kdmoen@watcgl.waterloo.edu (Doug Moen) writes:
>>[...]  If it *does* turn out to be possible to build Grey Goo,
>>then by the time fabrication technology catches up, perhaps we can have
>>a wide spectrum of Goo killing techniques already available.

>You have to find it first.  The difficulty is that, in order to decide
>if a particular bit of nanomachinery is Gray Goo (or a part thereof),
>you have to analyze its program to see if it ever quits reproducing.
>This is exactly equivalent to the halting problem, which is insoluble.

Fortunately solving the halting problem is not necessary to controlling
Grey Goo.  Better safe than sorry: we kill any nanomachinery that we
can't prove will stop reproducing in a reasonable amount of time.
After all, there is little practical difference between something that
never stops reproducing and something that stops after 100 million
years.

-- 
    o							Andre Guirard
   < '	  The race is not always to the swift...	"Thai green beads"
   / >	  but it's a pretty safe bet.			ihnp4!mmm!cipher
  '