Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!ukma!nrl-cmf!ames!ucbcad!zen!ucbvax!bloom-beacon!athena.mit.edu!sethg
From: sethg@athena.mit.edu (Seth A. Gordon)
Newsgroups: sci.misc
Subject: Re: Engines of Creation: Nanotechnology
Message-ID: <1919@bloom-beacon.MIT.EDU>
Date: Tue, 1-Dec-87 00:10:43 EST
Article-I.D.: bloom-be.1919
Posted: Tue Dec  1 00:10:43 1987
Date-Received: Fri, 4-Dec-87 03:15:05 EST
References: <1445@m-net.UUCP> <4560@well.UUCP>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: sethg@athena.mit.edu (Seth A. Gordon)
Organization: Massachusetts Institute of Technology
Lines: 30

In article <4560@well.UUCP> pokey@well.UUCP (Jef Poskanzer) writes:
>In the referenced message, russ@m-net.UUCP (Russ Cage) wrote:
>}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.
>
>Congratulations, you've just proved that the human immune system is
>equivalent to solving the halting problem, and therefore impossible.
>---

From what I know of both subjects (i.e., about what Hofstadter wrote in
_Godel,_Escher,_Bach_ and _Metamagical_Themas_), a *PERFECT* immune
system is equivalent to solving the halting problem, and therefore
impossible.  Our immune system can IMPERFECTLY control infections, just
as there are ways to IMPERFECTLY recognize infinite loops.

We could always try using a blowtorch.  OK, so we wouldn't always
succeed...

>Jef
>
>              Jef Poskanzer   jef@lbl-rtsg.arpa   ...well!pokey
>                    "Greetings from the World's Biggest."


Seth Gordon, 52 Massachusetts Avenue #102, Cambridge, MA 02139-4324, US of A.
a.k.a. sethg@athena.mit.edu [Internet]     |----------------------------------
a.k.a. sethg%athena.mit.edu@mit-eddie.uucp | By the time you read this message
a.k.a. sethg%athena.mit.edu@mitvma.bitnet  | it may not even be *my* opinion.