[extropy-chat] Casimir Torque Project

Mike Lorrey mlorrey at yahoo.com
Tue Jun 14 19:26:53 UTC 2005


http://www.its.caltech.edu/~nano/papers/buks-NATURE-sep2002.pdf

Just spotted this article on the Casimir Force in a CalTech newsletter.
Wasn't sure that Adrian was aware of its contents or not. It appears
that the force is a serious problem with nanomachinery, causing parts
to collapse into each other through 'stiction'.

Found it in researching for an article I'm writing for Neal
Stephenson's Metaweb on The Raft (from Snow Crash), explaining why such
a tight fleet of ordinary vessels may be impossible on the high seas in
rough wave conditions.

--- Adrian Tymes <wingcat at pacbell.net> wrote:

> --- Hal Finney <hal at finney.org> wrote:
> > Adrian might be especially interested in "A design manual for
> > micromachines using Casimir forces: preliminary considerations",
> > http://www.quantumfields.com/staif-2000paper.PDF , by Jordan
> Maclay.
> > This is not a journal article but it looks legit to me.
> 
> I note that all of the structures it proposes keep all the faces
> parallel, and do not attempt to bias the Casimir effect one way or
> another.  So of course those systems remain conservative.
> 
> > Two key points here: first, for other geometries than infinite,
> > parallel
> > plates, the Casimir force seems to be as often repulsive as
> > attractive.
> > The effect is apparently quite complex and has only been computed
> > from
> > first principles for a few geometries.
> 
> As noted in my project description, it's quite possible the geometry
> I'm using would indeed result in repulsive forces instead of
> attractive.  However, in most cases, I've found that the absolute
> magnitude of the force (for a certain separation, et al) does not
> vary
> that much, even if the direction inverts.
> 
> > And second, most importantly,
> > it conserves energy, exactly as I have been saying.
> 
> For the specific geometries the paper considers.  Just because
> parallel
> plates are conservative does not mean that all systems that can tap
> the
> Casimir effect must be conservative.
> 
> > Better
> > experimental technique could help to show whether more theory is
> > needed.
> > I would encourage Adrian to continue his experiments but base them
> on
> > realistic expectations.
> 
> *nods*  It may well be, given the amount of not-solidly-knowns here,
> that the system neither converts energy in the expected manner nor
> just
> sits in place (either doing nothing, or reaching some equilibrium
> from
> which it does not budge).  Other results are extremely unlikely, but
> not totally impossible given current experimental evidence.
> 
> I expect to discover something.  I do not know exactly what I will
> discover (if I did, it wouldn't be a discovery), nor do I know
> approximately how immediately useful it will be ("new energy source"
> and "minor academic curiosity" being almost at opposite ends of the
> immediate utility spectrum, yet both results are quite possible). 
> And
> I am already getting hints that the most useful thing to come out of
> it may have nothing to do with the initial objective at all...
> 
> > As for the larger question of whether it makes more sense for
> > Extropians
> > to work on concepts and ideas that are consistent with the laws of
> > physics
> > vs hoping to find that these laws are false, I still think it is
> > obvious
> > that the first path is more likely to succeed and advance one's
> > goals.
> 
> Actually, the question was more "whether it makes more sense for
> Extropians to actually do something that can improve the world, or to
> endlessly debate philosophy and not actually put it into practice in
> the real world".  Valid scientific criticism (trying to clarify what
> the laws of physics actually are and how they apply) was mistaken for
> the latter, though.
> _______________________________________________
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> extropy-chat at lists.extropy.org
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> 


Mike Lorrey
Vice-Chair, 2nd District, Libertarian Party of NH
"Necessity is the plea for every infringement of human freedom.
It is the argument of tyrants; it is the creed of slaves."
                                      -William Pitt (1759-1806) 
Blog: http://intlib.blogspot.com

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