Re: Parallel Universe

[Hugh Logan <HloganPHY@CFL.RR.COM>]

John Denker wrote:
> Hugh Logan wrote:
>
> > I have read that Maxwell literally tried to explain his
> > electromagnetic theory in terms of "gears and machinery," well at
> > least gears (like differential gears), but I never heard that he
>
>  > got it right.
> .     ^^
> .     ^^
>
> Upon reflection, I assume that "it" refers back to "machinery".
Yes. I have long been aware that Maxwell's equations were
relativistically correct.

> (The first time I read that msg, I thought the antecedent of
> "it" was electromagnetic theory.  Maxwell got that right,
> pretty much!)
Agreed (that "Maxwell got that right,
> pretty much!") However, I was of the impression that Maxwell, at
least at first, wanted to retain the concept of an aether, of which the
vortex theory is a manifestation.

> As for "machinery", Maxwell for years favored the idea that
> lines of force were like vortices in a fluid.

Apparently, the idea of vortices was related to the gear machinery
analogy. I can't remember exactly where I read about Maxwell's use of
gears. It might have been in one of the (Harvard) Project Physics
Readers. I just did a web search for "Maxwell model gears," getting a
number of hits. Some cognitive researchers have been interested in the
connection of Maxwell's gears and the vortex theory with discovery by
visual analogy. One by Jim Davies [1] refers to a diagram of vortices
with idle wheels between them, apparently related to Maxwell's concern
that friction would cause the vortices to stop their motion. Davies
refers to articles on the subject by N.J. Nersessian. Two such articles
[2], [3], may be found online, the latter a Powerpoint presentation.
There is even an animation of a Maxwell gear system on a Russian web
site [4], though the web site does not specifically relate it to
Maxwell's electromagnetic theory.

[1] "The role of visual analogy in scientific discovery," Jim Davies,
   http://repo-nt.tcc.virginia.edu/cogwkshop/davies.html

[2]"Model-based reasoning in conceptual change,"
http://www.cc.gatech.edu/~jimmyd/summaries/nersessian1998.html

[3] "Visual Analogy in Scientific Discovery; A Hypothesis for the Use of
Mental Imagery in Visual Analogy" by Davies, Nersessian, and Goel,
http://www.cc.gatech.edu/~jimmyd/research/visual-analogy/cognitive-studies-workshop-2001/workshop.ppt

[4]"The Maxwell's gears models the structure of nanoworld. Four gear
forms an elementary cell of the structure of nanoworld,"
http://ftp.decsy.ru/nanoworld/DATA/AVI/PREVIEW/nano_m.htm . The web site
does not relate this animation to the vortex model, but it gives a
general idea of Maxwell gears. Note: There is advertising on this web
site. There are many other animations in the index at
http://ftp.decsy.ru/nanoworld/DATA/AVI/index-e.htm, apparently
pertaining to the nanoworld.


But eventually
> he wised up and took the "hypotheses non fingo" approach.  That
> is, the equations are primary and fundamental.  The field is
> what the equations say it is, whether we can visualize the
> "machinery" or not.
>
> The vortex-machinery approach wasn't silly;  keep in mind
> that the equations of magnetostatics look a whole lot like
> the equations of inviscid fluid flow.  "The same equations
> have the same solutions."  See the Feynman chapter on "The
> Flow of Dry Water".

I suspect the gear-machinery was not silly in Maxwell's day, especially
if it helped him formulate the vortex theory. Yet, I don't think Maxwell
got either a gear and/or a vortex model just right as a representation
of what happens in the aether, particularly as the aether as a medium
for electromagnetic waves was later discarded.

Hugh Logan