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 ???
>
> 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".
>
> Well, we see that the universe is stranger than we expected! Sorry to not
> be of more help.

That's OK! An honest "I don't know" is kinda refreshing on this list!

Bill

>
> --
> Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
> E-prints: http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html
> Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
>