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From: russ@m-net.UUCP (Russ Cage)
Newsgroups: sci.misc
Subject: Re: Engines of Creation: Nanotechnology
Message-ID: <1445@m-net.UUCP>
Date: Thu, 26-Nov-87 10:12:02 EST
Article-I.D.: m-net.1445
Posted: Thu Nov 26 10:12:02 1987
Date-Received: Mon, 30-Nov-87 03:34:40 EST
References: <799@sbcs.sunysb.edu> <2698@drivax.UUCP> <1063@sugar.UUCP> <2411@watcgl.waterloo.edu>
Reply-To: russ@m-net.UUCP (Russ Cage)
Organization: M-NET, Ann Arbor, MI
Lines: 16
Keywords: nanotechnology foresight drexler
Summary: Stopping Gray Goo is like solving the halting problem.

In <2411@watcgl.waterloo.edu> kdmoen@watcgl.waterloo.edu (Doug Moen) writes:
>peter@sugar.UUCP (Peter da Silva) writes:
>>Even Drexler is uneasy about the "Grey Goo".

>[...]  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.
-- 
  The above are the official opinions and figures of Robust Software, Inc.
             Will you come quietly, or must I use earplugs? 
Russ Cage, Robust Software Inc.    (313) 662-4147    {sw1a7,umix}!m-net!rsi