sci.physics.electromag

"Timo A. Nieminen" wrote in message
news:Pine.WNT.4.64.0803161053490.1404@serene.st...
> On Sat, 15 Mar 2008, Bill Miller wrote:
>
>> The title of the post pretty much says it all.
>>
>> The participants of this list seem to have fairly clear agreement
>> that the
>> primary *cause* of magnetic fields is the motion of charges.
>>
>> With a few hold-outs, most folks seem to (finally) understand that an
>> E
>> field does not *cause* an H field. (Those that disagree: p-l-e-a-s-e
>> read
>> Jefimenko's "Causality" before jumping in to dispute this statement.)
>>
>> OK. So far, so good.
>>
>> A permanent magnet has associated with it a magnetic field whose
>> characteristics seem to be indistinguishable from those of a magnetic
>> field
>> that is caused by the motion of charges.
>>
>> Where the H--- does the H come from? How do we know?
>
> This is a nice little mystery in (classical) physics! Sure, we can say
> there is an "Amperian equivalent current" around the magnet, but ???

Bound current in a magnet happens because there is a boundary edge.

> But I think it comes down to: experimentally/observationally, we find
> that there is no magnetic (monopole) charge to be found, but many
> materials have a non-zero magnetic dipole moment. Even diving into
> quantum mechanics, all we get is the magnetic dipole moment as some
> magic physical quantity tacked onto "electron".

I am sure that atomic magnetic moments have been measured and that is
mainly the source for the H field in permanent magnets. In the
viewpoint of the quantum "vacuum" (QV) as a relativistic medium, there
is not much "magical" about an electron's magnetic moment. ;-) Keep in
mind that in the QV medium picture, virtual fermionic pairs interact
directly with a fermion such as an electron constantly. It takes a bit
of different thinking to visualize it as most people are so used to
interactions as pictured in Feynman diagrams.

Best,

Fred Diether
Co-moderator sci.physics.foundations