HOW do radio waves form at the subatomic level?

[Dale]

My perspective and beliefs are very speculative right now. I can not at this moment describe my beliefs because I have not completed my education.
...
I hope I'm making myself clear. Try to think outside the box. Take the standard model to the next level. Do not feel limited to what the standard model seems to (in my case) lack in physical description. My current perspective on particle physics tells me that energy is not viewed in this manner. I'm telling you to look at it from a different view. A Quark? What does a quark look like in terms of energy? It exists doesn't it? Then what does it look like?!

I am glad that you recognize that you need to complete your education. I hope that as you do so you will be able to clarify your thoughts into something useful. The key goal of any scientific theory is to provide accurate predictions of experimental results. What something "looks like" is only a scientific question if you can describe what it means in terms of measurable experimental data. The "box" of science is always big enough for new ideas that improve on our ability to make accurate predictions.

In this discussion, I'm simply prodding the possible physical existence of energy in three or more dimensions (let me go on...). If energy found in photons or electrons is (at least) three dimensional, than one would naturally think it would have a "physical" form. This said, It would appear (not necessarily my belief) that everything we see around us exists as multi-dimensional manifestations of pure energy. Mass would appear to be the result of energy arranged in a particular fashion to produce what we perceive as 'mass' and we feel it as weight with the influence of gravity.

You may be interested in the concept of the energy-momentum four-vector. It is a four-dimensional quantity that unites the Newtonian concepts of energy and momentum into a unified relativistic framework. Energy is then recognized as the timelike component of a 4 dimensional vector. Mass is the norm of that vector, so it is related to energy, but also to momentum, and the disparate Newtonian concepts of conservation of energy, momentum, and mass are all combined into a single united conservation law. One of the most interesting things about relativity is how it unites seemingly separate concepts in this way.

In any case, I think that we are probably straying. Realistically, the generation of radio waves is a classical phenomenon which is described by Maxwell's equations. You can bring in all of the unwieldy mechanics of QED and write trillions of trillions of Feynman diagrams for all of the electrons in the antennas, but in such circumstances QED reduces to Maxwell's equations anyway, so it won't improve your results nor your understanding. Do you feel comfortable at this point with Maxwell's description, or do you need more details on it?

 

[sophiecentaur]

I am a bit disappointed with the apparent 'obsession', here, with the electron where EM radiation is concerned.
The first thing we are taught about the relationship between atoms and 'light' is the starter model of a Hydrogen atom. This catches the imagination because of the 'planetary' connotation and it seems to be where most people's appreciation stops. The Energy Levels, even in a H atom, are System energy levels. When a molecule alters its shape, you can get absorption or emission of EM - which particular electron do they want to be the one which shifts energy level?
It strikes me that too many people who post questions and answers on this topic, (of many) want concrete explanations and categorisations, with everything sewn up. I should have thought that even the first brush with Modern Physics (i.e. less than a hundred years recent) and the statements made by all the Greats would have shown that there isn't anything concrete about this aspect of our World.
Feynman diagrams, energy level diagrams, even the structural model of the H atom, are just MODELS, beyond which you can only stray if you have a better one - that means you have to be really smart. Anyone that smart will not be wanting or making concrete statements about 'what things really are'.

 

[Antiphon]

I won't take sides for or against the strongly held views here. However, I am an electrical engineer trained in the state of the art in antenna design. Maxwell's classical equations are good enough well into the Terahertz frequency range. We never need to refer to free charges unless a plasma is involved in the propagation of the radio wave or unless there is ionization near the antenna such ad reentry from orbit.

You can solve any antenna design problem without even referring to charges since such developments are almost universally done in the frequency domain and the equation of continuity replaces the expression for free charge with a divergence term of the electric field. In short, to design antennas you employ E (volts/meter), H(Amps/meter), J(electric current density Amps/cubic meter), and YES, M(magnetic current density Volts/cubic meter). Engineers know that there are no magnetic charges but we use magnetic currents to introduce full symmetry of the equations. It enables us to arrive at solutions to boundary value problems much more easily. Magnetic currents arise naturally and mathematically at a discontinuity on the electric field. We often introduce the discontinuity deliberately and then require the magnetic current in order to satisfy Maxwells equations together with all boundary conditions.

 

[map19]

Haven't read all the posts, but here's my take on this.
radio waves are produced in an antenna by the transmitter feeding in RF energy at a set frequency. This causes the loose electrons in the antenna metal lattice structure to slosh back and forward at the chosen frequency.
Accelerating and decelerating electrons produce a varying electric field around the antenna. This field in turn produces the magnetic 'other half' of the electromagnetic wave.
The speed of propagation is set by the permeability and permittivity of the medium (air, or vacuum)
The length of the antenna is not too important except that it needs to be 'tuned' to the frequency so that the load is seen by the transmitter as resistive. This prevents power being reflected back and overheating the transmitter.

 

[jeblack3]

But unlike an atom, the energy difference between each possible level is the same: \hbar \nu.

Sorry, that should be h \nu, or \hbar \omega.

 

[taylaron]

Do you feel comfortable at this point with Maxwell's description, or do you need more details on it?

This discussion has clarified my understanding of Maxwells equations. However, it seems obvious to me that my understanding is limited until I can comprehend the mathematics associated with them.

Accelerating and decelerating electrons produce a varying electric field around the antenna. This field in turn produces the magnetic 'other half' of the electromagnetic wave.

Haha, now we're getting into the particle-wave duality phenomenon. Your statement above seems completely logical and easy to understand in terms of fields, but some (all?) EMR's ability to behave like particles provokes more debate on what EMR actually is.
I don't know where I'm going with particle-wave duality, but it bothers me that EMR can be easily explained as a wave (above), but not so easily as a particle.
Any thoughts?

 

[map19]

The photon is the quantum of electromagnetic energy.
It contains energy E = hf. So its energy is proportional to frequency.
It is a mathematical construct to explain how a quantum can be seen as a particle.
The electromagnetic waves are propagated in space at C (or close to it in air ) and can easily be measured and shown on an oscilloscope.
Some experiments rely on the packet nature of the quantum to 'count' photons.
They have no existence outside the electromagnetic wave field.

This is easily seen where isotropic propagation over a long distance calculates to one photon per sq m or even per sq km. Where is it exactly ? But the waves, at very low amplitude are still all over the area.

 

[Dale]

it bothers me that EMR can be easily explained as a wave (above), but not so easily as a particle.
Any thoughts?

Again, being easy to explain or easy to visualize is not a requirement for a scientific theory. The only requirement is that it accurately predict the results of experiments. The particle model (QED) predicts the results of certain specific experiments better than the wave model (Maxwell's eqts), but those specific experiments are not relevant to generating typical radio waves in an antenna.

That said, the best non-technical explanation of QED that I have found is a series of three or four lectures by Feynman at the university of Auckland sponsored by the Vega foundation. But to really understand any theory, Maxwell or QED, requires learning the math.

 

[sophiecentaur]

Haha, now we're getting into the particle-wave duality phenomenon. Your statement above seems completely logical and easy to understand in terms of fields, but some (all?) EMR's ability to behave like particles provokes more debate on what EMR actually is.
I don't know where I'm going with particle-wave duality, but it bothers me that EMR can be easily explained as a wave (above), but not so easily as a particle.
Any thoughts?

I think the problem is with the way the word 'particle' was chosen, in the first place. It goes, of course, way back to Corpuscular Theory and seems to have latched on. It implies the notion of a little bullet and carries all those connotations.

For people concerned with short wavelength phenomena, like light, there seems to be less of a problem because photons appear to be fairly localised and it doesn't seem necessary to delve too closely into their 'size'. With RF wavelengths, it gets more awkward to assign a particular extent for the photon. 'Size' is not really a relevant concept for an entity which is traveling at c so I just don't see why we have to have little (or big) bullets. Let's just keep photons as quanta of energy, let them be associated with a wave and stop trying to picture them in a spatial form.

 

[GT1]

Here's a more interesting question: fluorescent molecules are ~10 nm in size, yet the radiation they emit is 50 times that size. Similarly, radio antennas are a small fraction of the wavelength of emitted light. How can this be? How does the photon 'fit' inside the emitter?

So how can we explain it?

 

[f95toli]

Single photons do not have a "size" as such so there is nothing to "fit". Again, for the full explanation you really need QED; there is no simple, classical explanation for how this works,