sci.physics.electromag

On Sat, 8 Mar 2008, Benj wrote:

> On Mar 7, 7:17 pm, "Timo A. Nieminen" wrote:
>
>> Part the Second
>> ===============
>> The retardation of electromagnetic effects presents a direct challenge to
>> the view of electromagnetism as solely an interaction between charges and
>> currents, with fields merely as a mathematical auxiliary. This is
>> especially the case for radiation.
>
> This is exactly correct! This is what Jefimenko has done in his
> approach and has taken quite a bit of flack for. One problem is that
> a huge amount of problems have been solved using Maxwells equations
> NOT taking retardation into account.

No. If you use the Maxwell equations, you are taking retardation into
account. Notice that you can extract the wave equation from the Maxwell
equations.

>> While fields introduce some problems into physics, I believe they resolve
>> more than they introduce. The mathematical convenience is immense. Whether
>> they are "real" or not, they are certainly useful. The only stance that is
>> certain to be properly aligned with reality is agnosticism wrt the reality
>> of fields or otherwise. However, I'd say that, on balance, it's reasonable
>> to assume that fields exist. This opinion may well be coloured by the
>> practical engineering usefulness of assuming that they exist.
>
> Wow. Major exposition!
>
> Do you see what you've just said here? You've said in essence that
> it's OK to assume fields exist because that mathematics gives me lots
> of practical answers to questions I have and the answers seem
> reasonably close to what I'm measuring!

Ah, I see! You want to completely ignore the discussion of the problems
with AAAD electromagnetic theories, the problems with field theories,
radiation, and conservation laws, and focus instead on the last sentence.
You could try addressing what was actually said instead of trying your
usual cheap debating tricks. (Btw, didn't you claim to have kill-filed me,
or was that another cheap debating trick?)

> You are saying that physics
> (science) is a religion where the important thing is how you feel
> rather than what is true. If believing in fields gives you comfort
> then, who is to say that you shouldn't do it? Well, I say that
> philosophers say you shouldn't do it. They say that one has to be
> careful in your definitions of what is reality and what is merely a
> model mimicking reality. And to them that difference is fundamental.
> In religion the difference doesn't matter. But science is supposed to
> be tested constantly against observation and if you don't do that then
> it ain't science anymore.

No, _you_ are saying that physics is a religion. I don't see how a
reasonable person could interpret a statement that the only definitely
correct stance is agnosticism as "religion".

Physics isn't about "truth", because we don't know, and perhaps can't
know, what is "true". Physics is about what works, and fields work very
well. While your last sentence is OTT (there's no need for "constantly" in
practice), field theories of electromagnetism are pretty much tested
constantly against observation. And they work, and work well. Where they
fail (entering the quantum domain) is well-known.

--
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