From: ghsvax!hal@uunet.uu.net (Hal Finney)
Newsgroups: sci.nanotech
Subject: Nanotech science fair projects
Date: 11 Nov 92 21:55:36 GMT

In reading through Nanosystems, it seems to me that there are a lot of
potential projects based on designs in the book which would be good
for science fairs and the like.  The general idea would be to make a
mechanical model of some nanotech gadget, along with diagrams showing
how it would be implemented at the atomic scale.

One example would be Drexler's mechanical computer.  Mechanical
computation devices have a long history, going back to Babbage, but
Drexler's designs would have added interest because of their potential
to actually be used someday.  The basic "and" and "or" gates would be
simple to do even in something like Lego blocks or some plastic rods
which could be cut and glued.  Likewise, Drexler's latching register
would be simple.  These could be put together to make some functional
circuit.  The hard part would be adding power to the clocking rods so
that the whole thing worked synchronously.  That sounds like it would
take a little more mechanical ingenuity.  Drexler talks about cam
followers pulling on flexible "cables" to tug on the logic rods.
Maybe something could be built using wire or string with a hand- or
electrically-cranked camshaft.

Another possibility would be a model of the pressure-based robot arm
which Drexler envisions as his "Stage 2" design.  This is supposed to
be the smallest, simplest possible self-reproducing machine.  To make
it small, power and intelligence are supplied from the outside
environment, in the form of pressure changes.  The arm contains
actuators which change their length in response to pressure
variations, with different actuators responding to different pressure
ranges (so that they can be cycled independently).  The actuators are
hooked up to ratchets so that repeatedly cycling one actuator extends
a sliding beam, moving the robot arm.

I had the idea that actuators could be modelled by small,
well-lubricated syringes, filled with air and sealed.  These would be
immersed in a sealed water-filled chamber which had some mechanism for
modulating the pressure.  Increasing the pressure would compress the
air inside the syringe and cause it to contract, pulling in the
plunger of the syringe.  Filling different syringes with different
amounts of air would change the pressure range over which each one
would respond.  If you then mounted them against bars with
appropriately sized ratchet steps cut in them, you could independently
extend each of a few bars, just by appropriate variations to the
pressure.  Drexler's six-degrees-of-freedom monster would probably be
too hard, but perhaps the two-dimensional version, which requires
three extensible legs, would be feasible.

These are just a couple of ideas.  Since nanotech is so mechanical,
many other mechanisms from the book could be modelled as well.

Another thing I'd think there would be a lot of interest in would be
computer-graphic pictures of nanotech devices.  When I've showed
people the pictures of the bearings in the book, explaining that each
little sphere is an atom, they are blown away.  Color pictures would
be even more impressive.  These devices are quite attractive and I'd
think they would generate interest like the fractal pictures you see
so much of.  (One thing that made me think of this was a poster in the
recent issue of the cyberpunk magazine "Mondo 2000", showing a bunch
of beautiful full-color representations of what I thought at first
were simple nanomachines but which turned out to be the active
molecules in various mind-altering drugs!)

Hal Finney
hal@ghs.com