[extropy-chat] Re: Nano-assembler feasibility

Robert J. Bradbury bradbury at aeiveos.com
Tue Apr 6 00:12:57 UTC 2004

On Mon, 5 Apr 2004, Chris Phoenix wrote:

> Biology uses active transport at many scales.

Hmmmm... I would not say that is strictly true Chris.
Much of biology is based on diffusion of one kind or another.
Yes there are molecular targeting tags in several cases
such as targeting to the mitochondria, targeting to the
nucleus, etc.  But much of the time biology is using the
latent heat in the environment to drive transport mechanisms.
I would say that biology may use active transport
(i.e. transport that consumes energy) in some specific
instances -- the heart pumping blood or the muscle
contractions of the intestines come to mind.

If you extend this you get into the entire question of
reversible computing.  You start to get into the things
that Landauer, Bennett and others worked on.  One
of their points was that if you wait long enough you
may be able to compute for "free".  I've never seen
an analysis of it but one might also be able to "assemble"
for "free".

So you have an interesting issue with regard to making
nanotech faster than biotech.  Why bother?  If the
future of the universe and the people in it is
indeterminate in the long run what is the point
of having nanotech that can go faster?  From the
perspective of surviving as long as possible one
might want to follow Dyson's suggestion [1] of going
slower and slower.


1. Dyson, F. J., "Time without End: Physics and Biology
in an open Universe", Reviews of Modern Physics, Vol. 51,
No. 3, p. 447, July 1979

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