From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Tue Aug 20 2002 - 10:14:36 MDT
On Tue, 20 Aug 2002, Anders Sandberg wrote:
> On Tue, Aug 20, 2002 at 06:07:25AM -0700, Robert J. Bradbury wrote:
> >
> > Right now I'm of the opinion that an enzyme to manufacture small
> > diameter nanotubes might be very difficult, perhaps impossible,
> > but an enzyme to manufacture large diameter nanotubes might be
> > feasible.
>
> Too many strained bonds?
In part, but of more significance is I think you may not have enough
to grab onto. The way the bacterial flagella is built, the enzyme
complex kinds of rotates around the end adding subunits that are
sent up through the central core. It would take a pretty small
enzyme to pull off the same trick with a small diameter nanotube.
Of course you might design one to sit over the entire end of the
nanotube grabbing onto the outside edges but that is more complex
and figuring out how to rotate it around given the slippery outer
surface seems problematic. I'm assuming one is adding something
like benzene subunits one at a time.
> Another enzyme to look for would be one to link nanotube endcaps.
> Preferably it should link three tubes a time into a Y, so that one gets a
> polymer with redundancy and force distribution.
I haven't looked at the paper in detail to see how they propose
dealing with the elevator cable threads from sliding against
each other. It is certainly something that needs to be thought
about. I would agree that it seems important at first glance
to have an end-to-end joining mechanism -- it seems unlikely
that you could grow a thread the entire length of the elevator
and simply unspool it.
> Hey! You are trying to sneakily stop the greenhouse effect, aren't you?!
> I'm sure you have no consideration for us summer- and warmth-deprived
> Swedes! :-)
Actually I think I've argued that one ought to ask people like the
Swedes or the Russians their opinions about global warming before
you label it all bad. If you could warm up Siberia a bit and then
find ways of making use of salt water productively in near-equatorial
regions (that may get warmer) one might have the best of both worlds
in terms of being able to support an increased population.
Robert
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