Are EM fields "real," or are they abstract concepts?

[William Beaty <billb@ESKIMO.COM>]

> > Yes, this emphasis is very important -- together with the teaching that a
> > "field" is a mathematical invention and really doesn't exist ...

But *something* does exist.  Behind the abstract concepts, something
really is there.  If we cannot call it "field", then what do we call it?
If it "really" is made of EM forces between charged particles, then what
comes out of a laser?  A beam of "delayed action-at-a-distance forces?"

What should we name the weird "stuff" that surrounds magnets and charged
balloons, and which is sent out when charges accelerate?  What breaks
loose from radio antennas and goes flying away?  What is focussed by
convex lenses? Electromagnetic energy?  But everyone says that "energy"
is also nothing but an abstract concept.  Photons?  Are the photons
surrounding a magnet "real" objects, or are they just one facet of the
particles/fields mental model?

I think the answer is this: fields are a mental model, and flux lines are
a mental model, and we can't really understand the "real stuff" that's out
there.  We can only understand our models of it.  It is impossible to
avoid mistaking the models for reality, because we can only perceive
models, never reality itself.

We cannot understand a REAL rubber ball, or a human being, or the
government, or the internet; all we have is our mental models named
"object" or "person", etc.   If you doubt that the government exists, stop
paying taxes and see what action it takes against you.

If we say that electromagnetic fields are not "real", it's dangerously
close to saying that rubber balls are not "real".    You can fry your hand
with a badly shielded microwave source.  You can be struck in the eye by a
fast-moving rubber ball.  Heh.  But nothing "real" happened, eh?  It was
only an abstract concept, a mental model.  But then the philosopher says
"I refute you thus" and kicks a rock with a bare foot.  Would the same
philosopher look at a bottle of oil with suspended iron fibers outlining a
field pattern surrounding a bar magnet, and say that fields are not real
things?

I'm not trying to play word games here.  This is a genuine problem.  But
perhaps we can turn it around:  point out that the difference between our
mental models and REAL reality is an important issue in physics, and note
that the "true" nature of "fields" is one place where this issue becomes
clear.  "Fields" aren't quite as real as a rubber ball or a person.  But
also they aren't purely mathematical abstractions such as "integers" or
"subtraction."  "Fields" are a concept for organizing a set of perceived
events.  "Rubber ball" is a concept for organizing a set of perceived
events.  You can reach out and grab a ball.  You can dump iron filings
onto the paper near the magnet and expose the existence of the field.

Imagine an alien being who had no experience on earth, but who was trying
to figure out how our everyday world works.  Perhaps that alien was
composed of 2D wave patterns on the surface of a neutron star.  That alien
would see what we cannot: the fact that "rubber ball" is an artificial
mental model created by humans in order to organize their perceptions.  It
is just as abstract and artificial a concept as "fields."  The line is
very fuzzy between "reality" and "nothing but a mental model."


((((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))))
William J. Beaty                                  SCIENCE HOBBYIST website
billb@eskimo.com                                  http://www.amasci.com
EE/programmer/sci-exhibits          science projects, tesla, weird science
Seattle, WA   206-789-0775          freenrg-L taoshum-L vortex-L webhead-L