Re: magnetic field

From: John (John_at_john.com)
Date: 09/27/04 

Date: Mon, 27 Sep 2004 04:23:13 GMT

>
> Take two electrons, separated in space, stationary relative to some
> observer. There's an electric field, obviously, but no magnetic field.
> Now take another observer moving perpendicularly to the line joining the
> electrons. This observe sees the electrons in motion. Electrons in
> motion are an electric current, and an electric current produces a
> magnetic field, so for that observer there is a magnetic field present.
>
> So one observer finds a magnetic field present where another observer
> finds none. The notion that a magnetic field has a concrete existence is
> clearly problematic. This paradox doesn't appear in the theory itself,
> because it simply tells you what will happen (or more exactly, what your
> measurements will show). It doesn't say anything about what is "really"
> there.
>
This is all a bit over my head, but presumably the first observer (the one
who doesn't see the magnetic field because it doesn't exist for him) sees
something else; whatever the second observer sees as a magnetic field
manifests itself somehow for the first observer? Don't conservation laws
say that elements might vary, but the total sum must be the same?
Probably not...

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