>> Well, I have had to think long and hard how I want to respond. I really
>> didn't want to get tied down as to the engineering of how one would
>> produce such a field. But I do get your point, something must produce
>> the field. If we were to take a bar magnet and rotate it at relativistic
>> speeds, obviously it would fly apart.
>No problem there! I wasn't concerned with practical issues, just the
>issue of what, exactly, was supposed to be rotating.
Ok, I think I miss understood what you were looking for. But all the same, that
problem is solved.
>So, a bar magnet it is.
>If we do it the easy way, so that you've got something like this:
|
| Spin Axis
|
-------------------------------
| |
| North South|
| |
-------------------------------
|
|
|
>then the answer's pretty obvious.
>Start with it stationary. With it stationary, you've got a field which,
>if the magnet's been there a long time, extends through all space.
>Now, start the magnet spinning. As I said, you can't spin a field! So,
>though one's mental model might be of the whole field spinning as a
>rigid body, that's not what happens. What happens is the information
>regarding the rotation propagates away from the magnet at C.
I'm still not convinced that you can't spin a field! You said before that we
can't grab a field, but we can in a way since fields do interact with each
other...
>If I've pictured this right (which I may not have!), the result, in
>short order, is going to be field lines twisted up in something like
>spirals, with the spiral pattern expanding away from the magnet at C. A
>stationary observer will see the peaks and troughs passing by at C, and
>will interpret it as an EM wave.
>In short, it radiates.
Yep, that is my conclusion as well. My argument is a little different, but I
think it amounts to the same. There is no symmetry of the E-field as it
rotates. I'm not sure this is the ONLY condition for EM radiation, but so far I
can't think of any exceptions.
>If you spin it about the long axis, it's a lot harder to understand what
>happens, for me, at least, because the distant field is rotationally
>symmetric about the long axis. In that case I don't think you get
>radiation, but I think you do get an E field which wasn't there while
>the magnet was stationary.
>(But I could be all wet on this, I'm no E&M expert...)
That is my conclusion as well, E-field, no radiation. And your the best expert
I have!
So, back to the original questions, does the magnetic field acquire inertial
mass? Are there time dilation effects? Are there changes in gravitational mass?
My conclusion is yes to all of the above. But I really would like your opinion.
Then I would like to develop this further. Where I'm going is to look at
delta-t as a field with direction and magnitude and relate it to both the E and
G fields as a result of relativistic effects. And here is were I wish I had the
math skills...
C. Michael Crosiar
