Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!aramis.rutgers.edu!caen.engin.umich.edu!offutt
From: offutt@CAEN.ENGIN.UMICH.EDU (daniel m offutt)
Newsgroups: sci.nanotech
Subject: Is active shield design intractable?
Message-ID: <8906010521.AA05561@athos.rutgers.edu>
Date: 31 May 89 17:27:00 GMT
References: <8905310354.AA19565@athos.rutgers.edu>
Sender: nanotech@aramis.rutgers.edu
Organization: U of M Engineering, Ann Arbor, Mich.
Lines: 31
Approved: nanotech@aramis.rutgers.edu


I have seen no evidence that the task of developing
effective active shields is tractable, even if almost everyone on the
planet were a "good guy"/active shield researcher.  To build something
that destroys is easy.  To build an active shield that protects a
complex system such as the human body or a forest from damage by
replicators seems orders of magnitude more difficult.  In some cases,
certainly impossible.  The task of an active shield is not just to stop
noxious replicators, it is to do so without disrupting the protected
system.  And to establish that a candidate active shield does not
seriously disrupt its host in any way seems difficult or impossible
due to the complexity of the host and the resulting large number of
unpredictable side-effects of the resident candidate active shield.
Moreover, as Mr.  Papiewski pointed out in an earlier article, the
great variety of potential gray goo makes the problem even more
difficult, since the active shield must be proof against nanoreplicators
it has never seen.

Animal immune systems have been evolving for hundreds of millions of
years.  If immune systems and active shields are to be of comparable
complexity, they are not going to be developed by only five or fifty
billion people in a matter of decades, or even centuries.

Dan Offutt
offutt@caen.engin.umich.edu


[The same arguments could be brought against the possibility of
 building gray goo in the first place.  This is one reason to hope 
 that the two might occur with some parity of capabilities...
 --JoSH]