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How does the electron make a photon in an antenna?
Rick Law:
--- Quote from: T3sl4co1l on February 13, 2017, 05:06:31 am ---...
That is to say -- the universe is more than happy to allow conditions which, within the scope of a Fourier analysis, should count as a photon (say) with a frequency lower than the age of the universe -- that you consider it as such, is merely your fault of applying an analysis that can only resolve things in terms of frequency, and not in other, more suitable terms.
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--- Quote ---I am also unsure of your example Earth-Sun system analogy in reference to the very low energy discussion.
Do you scale Planck's constant with it?
--- End quote ---
Nope, as stock. Basically take the already-solved hydrogen atom equations, and plop in the correct potential (gravitational vs. Coulomb) and masses.
--- Quote ---The issue is not the absolute size of the quantum, rather, the issue is how close is it to Planck's constant. The closer to Planck's constant, the bigger the uncertainty. At the size of the solar system, uncertainty due to the uncertainty principle is not even in the scale of rounding errors. So even if you are talking about a single particle of graviton, you are talking a huge amount of energy far exceed the scale of uncertainly. There would be no chance of it hiding within the grey area covered by the uncertainty principle.
That said, much much much bigger "borrowing from uncertainty" came into play before - namely the big bang.
--- End quote ---
The nice thing about this example is, it illustrates the problem of limited analysis over a much more human time scale than the Big Bang. Since, as you say, the math doesn't care, you can simply plug in any number -- why not ask the same questions of an atom 2 A.U. across, or 100pm across? :)
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Tim
--- End quote ---
[This was going to be a quick reply, but to be clear I had to add more and more words. Hope I don't lose you half way.]
I see where we are out of sync. You are talking about adopting a different (in your word, "more appropriate") methodology of doing analysis.
Whereas, I am simply describing the inability of scaling math to the limit (not in the mathematical sense of limit but in the practical sense) and consider that as applicable to the physical world.
Let me ask you a question (and it is not a trick question, question just to discern your philosophy): This is similar to but is not the silly question. Let me dispatch with the silly question first so you know is not this: "if a tree falls in a forest and no one is around, does it make a sound." The forest is a known condition, the physical laws that govern are known. The tree will impact something and air molecule will vibrate. Such vibration is called sound so as a result, yes a sound will be made.
So however similar sound the question, this is a real non-silly question: If a particle is mathematically evaluated not to decade in 10E40 years, and I am not talking half-life, I am talking non-probabilistic hard number of 10E40 years. The question is: does it decade? Based on current rate of acceleration of expansion, in 10E30 years or so our universe is energy-dead. At 10E40 years, the particle has a life longer than the expected life of the universe. At 10E30 years, there would be no energy to use, no matter visible, no matter interaction since there is no matter left within reachable distance (rate of expansion>c)...
The universe in 10E40 years is an unknown condition. We don't know what physical laws will apply. We also know that the act of measurement itself affects what we are measuring...
I would not consider the question "does it decade" a question of physics but instead it is a philosophical question. In other words, it is outside the domain I think of as Physics since it is in a domain where I don't know if our physical laws apply.
We can hypothesize that our known physical laws still apply at the extremes, but we don't know. In fact, we don't know even today how our physical laws apply beyond near our own solar system. 96% of the universe is dark matter and dark energy. We don't even know what they are let alone form laws that may apply to that extend. So, I tend to think physics as what we can have a prayer of forming laws that we can describe and perhaps prove directly or indirectly.
So, bottom line (in my view), you can choose whatever way you choose to look at it, all we can say is "well, we think it does, but we really don't know for sure."
If you say the particle WILL decade in 10E40 years, I can accept that too. You have more faith in the robustness of our physical laws than I do.
John Heath:
Great thread guys , enjoying it. Especially the old Feynman flicks. Would like to add that there is an advantage to using the photon model vs EM wave model for RF energy leaving an antenna. With a photon you can model the exact energy and shape of each individual photon. For a 100 MHz transmitter the energy of each photon is E=hv or energy in joules = Planck's constant times frequency for each photon. Too small to measure as h = 6.2 * 10^-34 , ouch . However the diameter of the photon is also set by frequency making a 100 MHz RF photon a 3 foot beach ball. This is useful information as it tells one ahead of time the limit of resolution of a 100MHz photon in a intuitive way by just thinking of it as a 3 foot beach ball. You can tell if there is a building by bouncing it off it but the doors and windows would be hard to make out armed only with a 3 foot beach ball. 10 GHz on the other hand is a gulf ball photon so the windows and doors can be resolved. In short the photon is a nice way to think of RF as it paints an intuitive picture of how the RF will act when it reflects of objects.
RoGeorge:
--- Quote ---How does the electron make a photon in an antenna?
--- End quote ---
The question is misleading. First, because it suggest an answer, as in the electron being the one to be blamed for the produced photons.
AFAIK, an electron does not "make" or "release" photons. What we call a photon is, in fact, a pack of energy with some specific behaviors, or properties.
Let's try to visualize a photon:
- There are fields and particles.
- What we call a particle is just a ripple, a perturbation in a field. A photon would be a ripple in the electromagnetic field.
To picture this, imagine the surface of a still lake. The surface of the lake is "The Field". Now, let's make "A Particle". That would be to make some ripples, or waves, on that perfect mirror of the still lake.
See that group of ripples moving away from the central drop? That whole group of ripples is a pack of energy. Let's call it a Riplon:
Can a drop of water make a Riplon? Apparently it can. Look, it's a fact:
But it's the drop of water who's making the Riplon? Or it's the rain?
Can an insect make a Riplon? Yes, it can:
Now, who's making the Riplon? It's the insect, or it is the surface tension of the water, or it is just the gravity? Causality seems to be an empirical concept and a rabbit whole, so it's hard to say "who's fault" is this or that. I guess the safest one can say is that some energy was transferred to the surface of the lake in the form of a Riplon. We will end here our analogy between photons and water waves. Analogies might help to "visualize" abstract concepts, but this can be dangerous in the long run. A mathematical representation serves better.
In conclusion, electrons "jumping from one energy state to another" (whatever the hell that could mean) it's not the only way to "produce" photons. Ripples in the electromagnetic field (AKA photons) can be made in many ways, and causality (AKA who's making the photons in an antenna) is more of a philosophical concept, because in a mathematical equation, there is no such thing as "variable x is the cause of variable y". It's just an equality, where the x and y terms can be rearranged upon wish, as long as we don't brake the math.
So, who's making a photon in an antenna? One electron jumping from a higher to a lower energy state? No.
I'd rather say it's the "dance of a gazillion of electrons", all moving in the rhythm of the variable electric potential produced by the radio transmitter. That dance produces ripples in the electromagnetic field, and those ripples are what we like to call photons.
John Heath:
--- Quote from: RoGeorge on February 13, 2017, 08:27:01 am ---
--- Quote ---How does the electron make a photon in an antenna?
--- End quote ---
The question is misleading. First, because it suggest an answer, as in the electron being the one to be blamed for the produced photons.
AFAIK, an electron does not "make" or "release" photons. What we call a photon is, in fact, a pack of energy with some specific behaviors, or properties.
Let's try to visualize a photon:
- There are fields and particles.
- What we call a particle is just a ripple, a perturbation in a field. A photon would be a ripple in the electromagnetic field.
To picture this, imagine the surface of a still lake. The surface of the lake is "The Field". Now, let's make "A Particle". That would be to make some ripples, or waves, on that perfect mirror of the still lake.
See that group of ripples moving away from the central drop? That whole group of ripples is a pack of energy. Let's call it a Riplon:
Can a drop of water make a Riplon? Apparently it can. Look, it's a fact:
But it's the drop of water who's making the Riplon? Or it's the rain?
Can an insect make a Riplon? Yes, it can:
Now, who's making the Riplon? It's the insect, or it is the surface tension of the water, or it is just the gravity? Causality seems to be an empirical concept and a rabbit whole, so it's hard to say "who's fault" is this or that. I guess the safest one can say is that some energy was transferred to the surface of the lake in the form of a Riplon. We will end here our analogy between photons and water waves. Analogies might help to "visualize" abstract concepts, but this can be dangerous in the long run. A mathematical representation serves better.
In conclusion, electrons "jumping from one energy state to another" (whatever the hell that could mean) it's not the only way to "produce" photons. Ripples in the electromagnetic field (AKA photons) can be made in many ways, and causality (AKA who's making the photons in an antenna) is more of a philosophical concept, because in a mathematical equation, there is no such thing as "variable x is the cause of variable y". It's just an equality, where the x and y terms can be rearranged upon wish, as long as we don't brake the math.
So, who's making a photon in an antenna? One electron jumping from a higher to a lower energy state? No.
I'd rather say it's the "dance of a gazillion of electrons", all moving in the rhythm of the variable electric potential produced by the radio transmitter. That dance produces ripples in the electromagnetic field, and those ripples are what we like to call photons.
--- End quote ---
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The second picture with blue water shows the drop moving up not down. This is a nice way to demonstrate Heavyside's reflection caused by the degree of impedance difference between falling through air and falling through water. The drop of water experience an impedance difference leading to a reflection as seen with a portion of the water drop being reflected back up. In a RF coaxes cable it is only 1 dimension however with the water drop the reflective action can be seen in full 3 dimensions. A full 3 dimensional demonstration of the dynamics of a sudden change in impedance. That is cool.
I would add that waves leaving of the surface of the water outward become smaller and smaller through distance but photons do not as seen in the photoelectric effect. Green light will force an electron off metal but red light no matter how strong will not. The waves are quantified into energy packets of E=hv for reasons unknown.
RoGeorge:
--- Quote from: John Heath on February 13, 2017, 03:57:11 pm ---...A full 3 dimensional demonstration of the dynamics of a sudden change in impedance. That is cool.
--- End quote ---
You, Sir, have made my day! :-+
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