jj:

A round about way of defining a "radio wave" is that it is just
any field function that satisfies a wave equation.

Period, end of story. No one really knows any more than that!

A wave equation is a partial differential equation of theoretical
physics which describes the dynamics of electrical and magnetic
fields. i.e. a wave equation is a simple derivation from Maxwell's
celebrated equations of electrodynamics.

In the beginning of electrodynamics there were only circuit-theoretic
concepts [Kirchoff, Ohm] which sufficed to explain many
electromagnetic phenomena.

Then later wave-theoretic concepts or wave electrodynamics [Maxwell,
Heaviside] were required to explain phenomena that circuit theory could
not explain satisfactorily [radiation, skin effect, proximity effect, etc.].
This is when the concept of radio waves as the solutions to partial
differential wave equations arose.

Then later quantum-theoretic concepts known as quantum
electrodynamics, or QED [Einstein, Dirac, Pauli, Feynman] were
required to explain phenomena that wave-theory could not explain
satisfactorily [photoelectric effect]. This is when the concept of radio
waves as a flow of particles [photons] arose.

QED is completely without intuitive analogic interperation by anything
closely related to regular human experience, like say waves. One just
has to "crank" the formulas [Feynman] and see what comes out.
Regardless, today in the first decade of the 21st century it seems that
the QED theory which is now approximately 60 years old and which
casts the "true" meaning of "radio waves" as a floww of discrete photons,
remains as the only theory that can quantitatively explain exactly all of
electromagnetic phenomena and the interaction of energy with matter.

An interesting high school level introduction and explanation of all of
this is available in the popular book on QED by one of the world's
great teaching physicists. The guy from CalTech who dipped a piece
of the Challenger rocket booster's O-ring in the glass of ice water at
the Challenger space shuttle disaster hearings.

cfr:

Richard Phillips Feynman, QED - The Strange Theory of Light and
Matter, Princeton University Press, Princeton, NJ 1985.
ISBN:0-691-02417-0 [QC793.5P422F48]

From the page 9 of the Introduction to "QED" Feynman says,
"You're not going to be able to understand it... You see my
Physics students don't understand it either. That is because
I don't understand it. Nobody does!"

Good luck with analogies to things we seem to "understand".

--
Peter K1PO
Indialantic By-the-Sea, FL.


"jj" wrote in message
om...
This may at first sound like a stupid question. But after some years
as a radio enthusiast, I don't know what a radio wave is - what it
really is. Supposedly, modern physics does not believe there is such
a thing as "action at a distance". In other words, if you launch a
radio wave and I intercept it, there must be a transfer of "stuff"
between you and me. You can't just say that if I wiggle an electron
at point A, I can cause a wiggle at the same wiggle rate at point B.
I mean you can say it, but it doesn't explain anything.

OK, so the latest science says that electromagnetic energy is really
particle-waves. I guess this means that when I transmit, my antenna
is firing particles in the form of low-energy photons (energy
packets), and that these photons do not really exist anywhere but
exist only as probability waves - until, of course, someone intercepts
the wave. Then, magically, the photons appear at the receiving
antenna, in which they manage to produce oscillating electrons.

So, the best I can ascertain is that radio waves are really
probability waves. I'm not sure that really helps with an intuitive
understanding. Does anyone have a good description for what a radio
wave really is?

- JJ