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Re: simplier is mor difficult

On Wed, 8 Oct 1997, LUDWIK KOWALSKI wrote:

Date: Wed, 08 Oct 1997 11:49:06 EDT
From: twayburn@juno.com (Thomas L Wayburn)

Now Tom is certainly writing about elecro-magnetism.
.... stuff about field lines, which must be the E & M version of
caloric (just kidding).

Why "just kidding"? Forget about B being a relativistic manifestation of
E and focus on the main issue of this thread. Once again it is a matter
of pedagogy, not physics. A caloric substance does not exist but we can
pretend it does exist and solve many practical problems. The magnetic
poles do not exist but we can pretend they do exist and understand many
gadgets, such as dc motors and galvanometers. By the way, Herb, when will
the correct answer to your bar magnet problem be posted? Are we allowed to
think in terms of the N and S poles?

I hope to learn more about the B versus E ideas from messages which follow
those of David Bowman and James Wheeler. But my initial purpose was to say
that magnetic poles should be part of our vocabulary. And I wanted to discuss
the concept of simplicity.

Avoiding the N-word is not easier than avoiding the Q-word. How can we
teach electricity to non-science majors without using the old magnetic
poles idea? Why should we try? What kind of harm can result from saying
that "in the first approximation a bar magnet, or a planet, behaves as
if ..."?

Yes, I do know that magnetism can be presented without introducing the
N-word. ... [Some] would say that physics becomes simplier when the
unnecessary concepts are eliminated. But what is simplier for them is not
always simplier for me, or for my students. Simplifications often make
things more difficult. Try to explain a primitive dc motor without using
the N, S and B words.
Ludwik Kowalski

I just know I am going to get into a peck of trouble from all of you E&M
types, but I just can't resist hopping in here. To use the Faraday
picture--field lines--I would say that charge and pole strength are
definitely not the same conceptually. Electrostatically speaking
electric field lines really do begin on positive charges and end on
negative charges--Gauss's Law. Magnetic field lines on the other hand do
not begin anywhere--they go around in closed loops like a snake
swallowing its tail. By the way for all of you who can't agree on
whether B or H is the magnetic field, I'm trying to talk about B. Poles
at the end of a piece of magnetized iron or steel may be used as
reference points through which many of these field lines extrapolate, but
they certainly should not be reguarded as the sources of the field.

Now, lets have a field day with that.

W. Barlow Newbolt 540-463-8881 (telephone)
218 Howe Hall 540-463-8884 (fax)
Washington and Lee University newbolt.w@fs.science.wlu.edu
Lexington, Virginia 24450 wnewbolt@liberty.uc.wlu.edu

"It is often stated that of all the theories proposed in this century,
the silliest is quantum theory. In fact, some say that the only thing
quantum theory has going for it is that it is unquestionably correct."

Michio Kaku, 1995