Hi, I invite you to read and comment at this thread, where I exchange some ideas about the dual nature of light with exchemist:
Also, I'm copying your post and making some comments between paragraphs.
Original post (in black):
Aha! So that's where I'm going wrong and confused. I probably am. But exchemist, you don't offer me the explanation I seek.
You say "the photons are the wave coming off the antenna" . That needs explanation if I am to be corrected. I assume amplitude is the measure of energy in the wave. I am conceiving both amplitude of the carrier wave and the photon. You are saying this is false. I ask you: what is the wave made of? I believe it is photons. No?
Since the conceptualization of photons, early in the XX century and just when radio was rapidly creating a huge industry, differences between classical theory of electromagnetism based on waves started to clash with the spread of photonic theory of light, incorrectly proposed by Einstein's at his 1905 paper about the photoelectric effect. That shouldn't happen, and is a product of decades of miss-information by teachers and professors at high-school and college.
I suggest you to stick with Planck's definition of this "duality": "Light, in its broadest sense as electromagnetic radiation, propagates in the space as waves and is absorpted and emitted by matter in discrete quantities with e= h.f units of energy".
Then, by Planck's words (the man invented everything around the later called photons): Photons (a 1926 denomination of the discrete unit E=hf) don't travel in the physical space. An electromagnetic wave does. What is a photon, then? It's a reductionism of the discretness of EM waves when they interact with atoms and molecules, because it's SIMPLER to explain it in that way (photons emitted and absorpted).
If you read the whole thread I referenced, you'll understand that light, as an EM field disturbance, is expressed in FIVE DIMENSIONS (x,y,z,E,H).
There are no physical oscillations in the sub-space (x,y,z). Read Maxwell's definition of light in the referenced thread. Light travels as a massless point-like entity in the sub-space (x,y,z) and with time t. The oscillations exist in the sub-space (E,H), where the electrical field E and the magnetic field H oscillates in quadrature of phase, self-propagating along the space.
Any representation of light as a wave (at any book, publication, video) is a representation of how the components E, H or the composite value E2 changes with time. But nothing physical oscillates in light, only the values of E and H, or what's called AMPLITUDE A = (Epeak2 + Hpeak2)1/2.
So, talking about frequency of a "photon" or amplitude of the oscillations of a "photon" are meaningless terms. A photon is a point-like massless entity, which represent a SINGLE EM wave at the moment of its emission or absorption by atoms or molecules. STOP.
A visible light photon will oscillate in way that allows it to go through a 1mm hole in the mesh. But even if its amplitude is greater than the 1mm hole it may well pass through if it has a long wavelength and passes at a near perpendicular to the screen - or any angle that will allow it to pass through the hole. If the wavelength is has higher amplitude "and" short enough frequency that it will always be absorbed by the screen then you have the explanation to how the screen works. Imagine a tightly concertinaed rattle snake that can't straighten out - that is how I conceive each photon (or packet or lump of energy). I think you are saying that is a misconception.
That's the problem: a photon doesn't oscillate, nor have wavelength or frequency. It is the EM wave which oscillates, but not in a physical sub-space (x,y,z).
It oscillates in the sub-space (E,H), without any manifestation of spatial oscillations. If you could see a photon or an EM wave, you would see only a point-like entity (without any physical oscillations). What changes along space are the values of E and H components, for which there is a wavelength and a frequency, but you will never be able to observe this parameters unless your eyes can observe things in the subspace (E,H) besides your usual 3D visualization (x,y,z).
At the sub-atomic level, where "photons" exist (and only there), things HAVE TO be interpreted in THIS WAY:
1) Assume that you are a virtual observer, with a size of 1 Armstrong = 10-10 meters and you observe (in slow motion) that a beam of light is
incoming toward atoms that surround you. Assume that the energy of this beam of light is A and that the light beam is monochromatic with
2) What you'll observe is a shower of point-like particles (let's call them photons), in an amout N = A/(h.f) photons.
3) You'll observe how some photons "hit" electrons and are absorpted, while others pass through atoms or just kics electrons out of atoms,
if the energy of the photon is higher than 13.6 eV. If the photon is ultra-energetic (MeV or GeV), then other things happens, which are
explained within QFT.
This happens when you observe interactions at an atomic level.
But, in the macroworld, what happens has to be studied under classic electromagnetism. So, forget photons and think about EM waves and antennae. The interaction between EM waves and macro-matter is explained ONLY by classic electromagnetism and the simplification of antennae as single dipoles.
The absorption of an EM wave by a dipole is calculated by a mathematical expression which relates the VIRTUAL AREA OF CAPTURE of the dipole and the wavelength of the incoming EM wave.
An EM wave, using this math (which is the basis of radio-engineering) can be absorpted by the dipole only if the Virtual Area of Capture of the antenna has magnitudes similar to the wavelength of the EM wave. Anything else is NOT ABSORPTED by the antenna.
Now, what remains are phenomena of difraction, refraction and reflection (and there is NOTHING besides these three phenomena).
Difraction, refraction and reflection of any kind of light (EM visible OR NOT) are phenomena studied for centuries, long before Maxwell enlightened the world in 1865 with his theory of electromagnetism.
In the days of Newton, Huygens, Snell, Young, Biot, Kirchoff, etc. (which covers more than 150 years) there was a conviction that light was a wave which displaced by "mechanically" pushing and pulling the ether (luminuferous ether, as it was called for visible light).
The ancient scientist were clever (maybe 10X than the ones today) and they equated the behavior of a rope and sound to the one of light. Each one required a medium to oscillate (mechanical waves at the rope needed the rope, the sound needed the air "molecules" and the light needed the ether).
By using this interpretation of a PHYSICAL oscillation of light, and with the proverbial formula w = L.f (velocity = wavelength x frequency) PLUS the OLD wave equation (developed for mechanical oscillations of a rope, and later applied to sound and light), every single aspect of the behavior of light was understood and mathematically modelled. When Maxwell came along with his theory, it didn't change anything known, but opened new doors with electromagnetism. Consider that, by Newton's time, it was already known that white light was composed by primary colors and aditional mixes.
So, refraction, difraction and reflection were explained assuming that light displaced with physical oscillations in the (x,y,z) sub-space.
Now we know that this is not true, but the whole body of knowledge built around light survived because the formulae worked and still work.
Try to find any expression different than Fresnel equations, Snell equations, Huygens equations and else to be used today, and you'll fail.
Microscopy, telescopes and interferometry were developed by using these pre-Maxwell and pre-Planck theories, and are used today.
Now, if you want to know the REAL SCIENCE behind classical explanations for absorption, emission, refraction, difraction and reflection using
the REAL NATURE of EM waves, then you'll need to go to the atomic world and explain the interaction of electrical and magnetical fields with
matter, and also explain which is the effect of polarization of light in the atomic world.
In your analogy there are still zillions of photons all doing what? If your wave is made of photons then how do you describe their movement within a wavelength of 100m? Any of them that arrive at the hole will pass through at a carrier wave frequency of 100m.
I don't think it matters about my description of a carrier wave as a pulse. The antenna is charged and discharged at carrier wave frequency, giving off waves of emf spaced at that frequency. If you plot the emf of the wave you can rightly say it is continuous as it rises from low to high energy level. What is wrong with conceiving this as a pulse of energy just because its change is not instantaneous. That wave form that you see on an oscilloscope or a graph is just the power of zillions of photons rising and falling in number and individual energy level - yes? If not then what? What do you think the wave is made of? It must be photons - yes?
Most of it already explained.
Regarding how an antenna works, this is another phenomenom and it's caused by acceleration of free electrons under electrical fields of high energy present at the antenna. As Maxwell predicted, an accelerated charge emits EM radiation.
A dipole, for efficiency, is designed to be half the wavelength of the central carrier frequency, under AM, FM, CW or SSB modulations.
When radiating (transmitting) the antenna ELECTRICALLY RESONATES at the designed frequency, when a power amplifier inject current
into its terminations (two monopoles). For a transmission at 30 Mhz (10 meters wavelength) any point (infinitesimal one) at the antenna oscillates 30 million times per second.
This electrical oscillation generates an acceleration dE/dt, which forces electrons to radiate at such frequency (an average frequency).
At the receiver side, a dipole is HIT by an incoming wave of EM energy. If the energy is strong enough, it will cause the opposite effect: the electrons at each point of the antenna will oscillate, causing an electrical current to be detected, amplified and demodulated.
No photons involved here, as you can understand (I hope so).
In telecommunications, photons are used (for simplicity) in fiber optics communications. Light travels within the FO as a monochromatic wave, codified. When amplification is needed, optical amplifiers are used (tipically EDFA amplifiers). At the emitting and receiving side, diode lasers and photodiodes are used for electro-optical conversions (remember Planck).
So inside the rising wave (I still like pulse) of emf there are photons - yes? Zillions of photons represented at the peak of the plotted wave and very few (in my analogy zero) half way between the peaks. Have I got this completely wrong? Where?
exchemist, what is meant by "goldilocks frequency"? Can you explain how it penetrates where other frequencies fail? Are we still talking diffraction?
Hope this can help you.
Edited by rhertz, 06 June 2019 - 10:09 AM.