[extropy-chat] Casimir Torque Project

Adrian Tymes wingcat at pacbell.net
Mon May 9 01:32:48 UTC 2005

--- 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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