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[Phys-L] Re: Fields etc

At 01:06 PM 3/26/2005, Rodney Dunning, you wrote:

I don't think we need to pursue the question of "What is real?" in all
its philosophical glory. Simple, common-sense guidelines should be
enough to help us answer our questions. For me, electrons are obviously
real. And anything that can deflect the path of a moving electron is
also obviously real. ///
When an electron enters the region between the charged plates of a
parallel-plate capacitor, its path is deflected. If a student asks
"What deflects the electron?", we all say the deflection was caused by
the electric field between the plates. But if the electric field exists
only in our minds the question is still unanswered. What deflects the
path of the electron? If we dispense with the field concept and say the
accumulated charge on the plates deflected the electron (I see no
reasonable alternative), we are left with classical
action-at-a-distance. If we're going to be philosophical, a "real"
electric field is more palatable to me than pure action-at-a-distance.


Rodney Dunning
Assistant Professor of Physics
Birmingham-Southern College

I will offer a hostage to Rodney.
If I light a match to a piece of paper, it burns,
and it turns black, giving off heat.
Something real obviously changed the paper's state, so
the Phlogiston which departed the paper is evidently real.
Or is it?

To put it another way: we propose conceptual models
(mental models if you will), to describe REAL observations.
That doesn't make the electric field real, even though it
accounts for the electron deflection which we observe.

[Which reminds me: I read that one has lined up electrons,
identifiably in single-file - by a series of junctions through
which electrons tunnel, temporarily enforcing single
occupation of the gap.]

Brian Whatcott Altus OK Eureka!
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