[extropy-chat] VIDEO: NanoFactory
hal at finney.org
Thu Mar 16 20:08:13 UTC 2006
> Marcene Sonneborn just posted to a list I am on the updated nano film.
> CRN also has a blurb about it on their site:
A streaming version is also available from Google Video:
The resolution is not quite as good but it will let you watch it
without waiting for a long download.
I have criticized earlier versions of this video, and while I think this
one is entertaining (love the factory-style sound effects! I was waiting
for the lunch whistle...) and informative, I still have major concerns.
Here is my comment from the CRN blog:
: This is a great improvement from the earlier version, especially in the
: later portions where the higher level assembly is going on.
: I notice that they changed the early "mill" operation though. Previously
: they removed the two hydrogen atoms from the feedstock acetylene molecules
: separately. The second removal required the shielding effect of a metal
: atom as described in Merkle's "hydrogen metabolism" paper. Now, this all
: happens in one step - an abstraction tool swings down and presto, both
: hydrogens are hoovered away, while the carbons manage to be left behind.
: I have always thought these manipulations looked unreasonable, because
: the atoms that remain behind must be held pretty firmly; but then they
: are easily removed when applied to the work piece. I wonder if there
: is any actual science behind these manipulations or if they are just an
: artist's dreamy conceptions.
: I've also always wondered how the tool that abstracted away the two
: hydrogens gets rid of them. Wouldn't it need another tool that would take
: them off? But then, how does that tool get rid of them? Some people have
: suggested heat or electricity or something, but I don't know if there
: are any specific proposals to solve this. This is basically Smalley's
: "sticky fingers" problem (which some analysts claim does not exist).
: One other point that is questionable is how the blocks stick together. The
: narrator implies that they simply have dangling bonds that hook up. In
: that case, how come the blocks were picked up so easily? Wouldn't they
: have tended to bond to what they were sitting on?
: And then when they are placed, there will be hundreds or thousands of
: dangling bonds that are powerfully attracted to each other. Even assuming
: the surfaces are stable in an unterminated state, I can't help thinking
: that great quantities of energy will be liberated as the two surfaces are
: brought together, with possible reconstruction and dislocation. An analogy
: at the macroscopic scale would be to have surfaces with super-powerful
: magnets on them, which have to be brought together. It's easy to see how
: slight misalignments could occur as the surfaces slap together that last
: fraction of an inch.
: All in all it is an entertaining video but I still think there are
: enormous scientific holes in it. It is far from clear that the processes
: depicted can really work. In that sense I think it is unfortunate to
: see it endorsed by the mechanosynthesis nanotech community; in the end
: if the video is discredited it could hurt the credibility of other,
: more carefully analyzed proposals.
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