sci.physics.electromag

"Timo A. Nieminen" wrote in message
news:Pine.WNT.4.64.0803110602110.296@serene.st...
> On Mon, 10 Mar 2008, Bill Miller wrote:
>
>>
>> "Timo A. Nieminen" wrote in message
>> news:Pine.WNT.4.64.0803090613190.296@serene.st...
>>> On Sat, 8 Mar 2008, Benj wrote:
>>>
>>>> On Mar 7, 7:17 pm, "Timo A. Nieminen" wrote:
>>>>
>>> No. If you use the Maxwell equations, you are taking retardation into
>>> account. Notice that you can extract the wave equation from the Maxwell
>>> equations.
>>
>> Sorry, Timo, but Maxwell's equations are a wonderful example of action at
>> a
>> distance. Retardation plays no part whatsoever in their constitution.
>
> Not so. Consider Maxwell's remarks on Faraday vs the German
> electrodynamicists (I'd quote it if the appropriate google words came to
> me, but they don't).

Hmmm... I wish I could refer to non-referenced sources to prove MY points.
Oh well.
>
>> Likewise, extracting the wave equation has nothing to do with
>> retardation.
>
> It has everything to do with it. If you get the wave equation, with a
> non-infinite speed of propagation of effects, then you have retardation.

Yes, but Maxwell's Equations do not provide explicit information about the
nature of the retardation. In other words, Maxwell's equations -- of and by
themselves -- do not define the nature of the starting points of E and H.
See both Panofsky and Jefimenko, as well as McDonald, for an analysis of
what actually *causes* E and H.

Hint: E cannot cause H and H cannot cause E because they occur
simultaneously. Causality requires that a cause must precede an event. It
cannot be simultaneous with the event.

Of course, if you wish to discard causality, then all your statements are
correct. But many of them, like E causes H & vice versa seem to defy
experimental verification.


> The accounting for retardation in the usual version of classical
> electrodynamics is implicit, not explicit.

Herein lies a major problem. Something as important as retardation should
_never_be implicit. Too many erroneous conclusions can arise if the implicit
nature of something is not made explicit.

Ask the owners and investors of EH and CFA antennas about this statement.
(The ones that are still economically solvent will have a lot to say!)

The equivalence of the Coulomb
> and Lorenz gauges shows that it is there. But it's there in Maxwell's work
> too, in his assumption that there is a mechanical medium - the ether -
> through which effects take a finite time to propagate.
>
>> It is interesting that "Displacement Current" provides the missing
>> ingredient without which the wave equation does not exist. And THAT has
>> led
>> several generations of scientists and engineers to believe in the
>> physical
>> existence of Displacement Current as a *cause* of a magnetic field, even
>> though over a century of measurements have not detected any such
>> magnetism.
>
> A different story (but an interesting one).

Yep. Except that it causes otherwise-brilliant engineers and physicists to
dogmatically (there's that word again) hang onto concepts that should have
been expunged from textbooks decades ago.


All the best,

Bill
> --
> Timo