Re: Electric Field Lines

["RAUBER, JOEL" <JOEL_RAUBER@SDSTATE.EDU>]

> John Denker continues
>    "IF (big if) we are going to describe the field in terms
> of field lines,
> the physics has
>      numerous things to say about how the field lines behave.
>      1) The field lines start and stop only on charges.
>      2) There is tension in each line.
>      3) There is repulsion between lines."
>
>     The field lines in my algorithm are just a map of the
> field, not literal
> things. They do not have  a tension. And they no more repel
> each other than
> the lines on a contour map are pulled down hill by gravity.

I thought I'd wait and see if John replied to this, but decided to go ahead
and give it a go, and let him correct me as needed.

I was delighted and amused to see the three enumerated items on the list.
John D. doesn't mean, of course, that field lines are literal corporal
entities having tension and repulsion. He was describing how they *behave*.
As I understand it, one can model the structure and placement of the fields
lines in the manner he described.  I.e. the mathematics for the two ways of
modeling the field lines arrive at the same picture.

IIRC, perhaps incorrectly, this harkens back to the middle nineteenth
century and the Maxwellian School of interpreting E&M, where they thought
quite literally in terms of tensions developed in a mechanical medium.  BTW
I think this is the origin of such archaic terminology as, "high tension"
power lines.

Joel Rauber