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



Thank you Bill. An excellent bit on philosophy of
science and philosophy of language simultaneously. I
hold that the field is just as real as any macroscopic
object and probably as real as any microscopic object
as well. This reminds me of something Einstein wrote,
I think in _Ideas and Opinions_ but its been to long
to say for sure. He discussed the idea that it might
be appropriate to say that the presence of mass curves
space-time or that mass simply is a curvature of
space-time. I only know GR in the most lay terms, but
the idea intrigued me.

Zach Wolff

--- William Beaty <billb@ESKIMO.COM> wrote:
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


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