Re: A NASA displacement current motor!- was Re: TC Secondary Currents - was

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Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Paul,

At 11:38 PM 3/5/2002 +0000, you wrote:
>Hi All
>
>Folk do seem to have trouble coming to terms with displacement
>current.  It's just the coupling between the E field and the B field,
>complimentary to Faraday's law which couples the B field back to the
>E field.  Considering the overwhelming evidence for the consequent
>effects of this two-way coupling, its hard to understand why it
>meets such resistance. 

It's because we can't "touch" it.  Put 50kV through ones hand, and you
"feel" it.  Put 250,000 amps around a tin can, and crush it...  Give us a
"displacement current" and we can't even decide "how" it could possibly be
measured.  Measuring it with a pile of field theory equations is not quite
the same...

>
>At one time, Maxwell's displacement current was regarded as a basic
>hypothesis of EM theory, and was necessary in order for EM to account
>for observed phenomena.  Nowadays, with our much deeper understanding
>of EM in terms of quantum electrodynamics - the theory of charges and
>photons, we no longer need the hypothesis, instead the E and B fields,
>and the relationships between them - Maxwell's equations, emerge as a
>consequence of the bulk behaviour of vast numbers of virtual photons
>which constitute the underlying field that we measure as E and B.
>
>We now understand that E and B are really just two apparitions of a
>single field.   This is easily demonstrated by considering a charged
>object floating in space.  Park next to it, and you detect only an
>electric field.  Move past it at some speed, and you now see a mixture
>of electric and magnetic fields.  The charged object hasn't changed,
>nor has the field, its just that your relative motion has given you a
>different view of it.  So E and B are not intrinsic to the field.

Indeed.  But it is not as easy to comprehend...

>
>The connection goes much deeper, involving space and time.  For
>example, with a knowledge of just electrostatics and the properties
>of spacetime, you can predict the existance of magnetism and predict
>its laws, and vice versa.  Quantum electrodynamics is a strange
>theory that lays open before us a very odd universe underlying our
>familiar reality.  Needless to say, it's been tested to death and
>qualifies as the most accurate and well tested theory ever devised.
>It accounts for all known EM phenomena, plus quite a few things that
>EM doesn't account for.

I guess "I" missed the train on this.  Such knowledge and view, I do not
have :-(

>
>It's worth remembering when we're messing around with our coils and
>swapping ideas, that physics has moved on a long way in front of us,
>and most of our silly debates revolve around personal and popular
>misunderstandings.  We still seem to persist in raking through the
>remnants of 19th century arguments that have long since been cleared
>up.

"old" ideas have a lot of inertia.  Look at our 1/4 wavelength wire stuff.
Even Tesla know that was wrong, but a few writings in a private log... and
blammo!!!  100 years later...

>
>When it comes to Tesla coils, we never experience the magnetic
>consequences of displacement currents - the frequencies are far too
>low.  Instead, we see charge piling up on electrode A and an equal
>amount draining away from another electrode B.  We have a conduction
>current shifting the charge from B to A, and sometimes it is
>convenient to speak as if the charge returned from A back to B as a
>current, whereas in reality it is just piling up at A.

So Paul, tonight I find myself with a question...  "Do 'displacement
currents' produce a magnetic field that we can somehow measure?"

If displacement currents are just a mathematical link in the fabric of
theory, that is fine (but "i" would have to "chalk one up" for Richard in
that case ;-)).  But if trying to measure them in the physical world is
meaningless, we'll stop trying so hard ;-))  If displacement currents do
indeed have definite magnetic fields associated with them, I know just
where to look to see those effects ;-))

Cheers,

	Terry

>--
>Paul Nicholson
>--
>