[extropy-chat] Re: Webcast of the First Workshop on Geoethical Nanotechnology

[Adrian Tymes]

--- Damien Sullivan <phoenix at ugcs.caltech.edu> wrote:
> On Mon, Jul 11, 2005 at 01:47:52PM -0700, Adrian Tymes wrote:
> > "grey goo", until new research (which would almost certainly be
> > impossible, or practically impossible, under a ban) discovered
> quite
> > recently that grey goo is actually impossible, at least on any
> large
> > and self-perpetuating scale.
> 
> Can you say more about that research?

It was posted to this list - last year, I think - partly in reaction
to Michael Chricton's "Prey".  I recall a few different threads -
though I'm not 100% sure I'm stating any of them completely correctly:

* Even if you had self-replicating, all-consuming nanites, they'd soon
  form a skin-and-interior system much like a growing cancer cell.
  Unfortunately, only the "skin" would be receiving new energy and new
  nutrients; for the interior to survive, you'd need so much heat that
  it would eventually disrupt the structures of the nanites.
  Otherwise, the skin's area would go up with the cube of the volume it
  covered, but it would need some method of obtaining power with which
  to break up matter (most matter is not explosive or otherwise
  contains easy-to-tap energy); solar power would, at best, go up with
  the square of the volume...and eventually, the nanites would run out.
  (Or at least slow down enough to allow countermeasures.  The world
  would not sit by indefinitely if something like this happened.)

* Unless you programmed it to avoid going down (for which you'd first
  need a way to measure gravity on the device), the mass would
  eventually break through the Earth's crust...and it seems highly
  unlikely that any nanites could survive the resulting magma flow.
  (Although, since this would disrupt an area for miles around, this
  could be counted as "large scale".)

* Nanotechnology in general requires knowing what atoms you're
  operating with.  A silicon atom can't do all the things a carbon atom
  can, and both have different properties from an oxygen atom.  Yet the
  very nature of an "all-consuming" nanite assumes that just any atom
  will do - which is not the case.  (Even if you just had it select
  favorable atoms from its environment, it would most likely come to
  some barrier - different types of rock, barren areas, et cetera -
  where its food completely ran out.  Although this isn't a barrier to
  large-scale disruption either - there's probably a continual-enough
  chain of carbon atoms in any large city, for example.)

Google around if you want more.