sci.physics.electromag

On Mar 5, 3:33=A0pm, Benj wrote:
> On Mar 5, 1:06 pm, "FrediFizzx" wrote:
>
> > Sorry, but you will never ever convince me that electric and magnetic
> > "force fields" do not exist. =A0I know from personal experience that
> > "force fields" do exist. =A0I suspect you are getting caught up in some
> > kind of semantics game here.
>
> Glad to see you have an open mind about physics! Yes it IS semantics
> but it's NOT a "game"!
>
> Obviously force distributions in space exist about magnets and
> balloons rubbed on the cat etc.
> Forces are real as can easily be determined by observation.
>
> BUT as soon as you start calling them "force fields" the word "field"
> immediately implies a whole host of mathematical definitions. These
> things include stuff like vector addition, curl, divergence and all
> the rest. =A0While the forces have been observed to follow field rules
> to a degree, there is no connection between mathematics and reality.
> Mathematics are self-consistent systems thought up by men. They are
> only a possible model for reality. =A0And being models they are NOT
> reality. =A0Therefore, to be sematically correct, one MUST say that
> "force fields do NOT exist!" =A0Yes, it's a word "game" but if you
> intend to do science it is essential to be precise in defining exactly
> what you mean by terms. [Actually one could argue that since "thoughts
> are things" that fields do in fact have an existence, but I really
> don't want to go there! ]

You may be familiar with the term "stadium wave".
http://www.glenbrook.k12.il.us/gbssci/Phys/Class/waves/u10l1a.html#stadium

A field of spectators is not the phrase "GO HOME TEAM".

But if the field of specators holds up contrasting panels
they can show that phrase to a blimp hovering over the
stadium. With different choreography, the same field
of spectators can also show "BEAT CALTECH" to the blimp.

So in classical EM:

The field is all the electrons and protons
involved in the interaction.
This is the choreography for combined
electric and magnetic force.

http://en.wikipedia.org/wiki/Lorentz_force

When moving charges return to their original
position there is *apparently* no dE component
but B component resulting from superpositon
from spatially (not necessarily temporally)
separated points.

Sue...

http://en.wikipedia.org/wiki/Multiple_integral#Some_practical_applications

Time-independent Maxwell equations
Time-dependent Maxwell's equations
http://farside.ph.utexas.edu/teaching/em/lectures/lectures.html


http://en.wikipedia.org/wiki/Jefimenko%27s_equations
"Purcell"
http://physics.weber.edu/schroeder/mrr/MRRtalk.html