How is heat caused by photons?

[Cthugha]

Yes, that is my point. And I don't see why it really matters what the shape of an electron orbit is, only whether its path is closed or open and whether it is a satellite or fulcrum. The fact that it is relative light and a satellite of the nucleus means that it can transmit energy without disturbing the inertia of the nucleus, which allows for the transmission of electricity without heat up to a certain point, no?

Unfortunately, this intuitive approach taken in the beginning of qm does not work. One of the basic results of classical electromagnetism is that any charged particle which is accelerated somehow must necessarily give off radiation in order to conserve energy. So, if the electron was orbiting the nucleus it would continuously lose energy that way and finally crash into the nucleus. And no, conductivity does not depend on what the single electron does to a single nucleus.

So what you're basically saying is that the electron orbits of atoms oscillate at different frequencies and the combinatory frequency patters cause the atom to be prone to bonding in certain ways with certain other atoms, like the synchonization of gears so that they will couple? Still, it sounds like if you were able to capture in slow-motion the moment when the bonding actually occurs, you would see a pattern of electrons meshing with and then interlocking with another such pattern. And yet even though the interaction is governed by the two patterns, the patterns themselves can only be explained by the different oscillation speeds of the different electrons in the system, which I assume in turn is due to the relationship between each electron and its nucleus, no?

Well, they are not really orbiting as I mentioned above, but anyway: No, the electron resonances are not necessarily at different frequencies. Strong coupling works even better when they are at the same frequency. However, the combined system of two coupled resonances will have two different resonance frequencies. That is a rather general feature. It does not matter, whether you couple two springs that way or form molecules or couple light to excitons or whatever. Basically this whole approach can be applied to any strong coupling resonances (as long as they are similar to spring pendulums insofar as there is a restoring force). Of course the exact numbers where the final modes will lie are a result of the initial modes and the coupling strengths, but the general mechanism does not depend on that.

And once you have this broadening into bands of energy levels for many oscillators, conductivity becomes easy to explain. Usually the lowest of these bands will be filled and the next highest will be empty. To get conduction, you need to excite states with a well defined electron momentum, so you need to populate the next highest band (as every state of the lower bands is already populated the necessary states are not available there). Now the energy difference between the bands (analogous to the splitting of frequencies explained before) matters. If the energy is large, it costs a lot of energy to promote an electron to the higher band. This energy is not there and the material will not be a conductor. If there is no splitting, this excitation can happen easily and you will get a conductor. If you have a small splitting, the tempereture of your material might be high enough to promote electrons to higher bands. You get a semiconductor.

To get a basic understanding of these concepts, it is really not necessary to understand the exact nature and strengths of the forces involved. Those will only determine the exact energies where the resulting bands will lie. However, the occurrence of such bands is just a consequency of the large numbers of particles occurring. There is no analog to these band in single atoms and therefore one should not start from single atoms to explain conductivity.

I mean, if these properties were already imprinted in the single atoms, why would graphite and diamond - both pure carbon - have so very different properties in terms of heat conductivity, for example?

So you're saying the reason a photon interacts with an electron is because their oscillation strength/frequency matches up? It's not just because they orbit fast enough that the electron doesn't have time to get by them? After all, if electrons aren't slow enough to have their speed and position measured simultaneously, then doesn't that mean that they blur by as fast as the light that's hitting them?

Here I do absolutely not get what you mean. Orbiting photons? Electrons not slow enough to have speed and position measured simultaneously? Blurring electrons? You seem to have some strange misconceptions about photons and uncertainty

So what would happen if that nucleus/atom was relatively isolated in a vacuum when the photon encountered it?

You would get some discrete resonances. Only photons of well defined energies will interact with the atom.

 

[brainstorm]

Unfortunately, this intuitive approach taken in the beginning of qm does not work. One of the basic results of classical electromagnetism is that any charged particle which is accelerated somehow must necessarily give off radiation in order to conserve energy. So, if the electron was orbiting the nucleus it would continuously lose energy that way and finally crash into the nucleus. And no, conductivity does not depend on what the single electron does to a single nucleus.



Well, they are not really orbiting as I mentioned above, but anyway: No, the electron resonances are not necessarily at different frequencies. Strong coupling works even better when they are at the same frequency. However, the combined system of two coupled resonances will have two different resonance frequencies. That is a rather general feature. It does not matter, whether you couple two springs that way or form molecules or couple light to excitons or whatever. Basically this whole approach can be applied to any strong coupling resonances (as long as they are similar to spring pendulums insofar as there is a restoring force). Of course the exact numbers where the final modes will lie are a result of the initial modes and the coupling strengths, but the general mechanism does not depend on that.

And once you have this broadening into bands of energy levels for many oscillators, conductivity becomes easy to explain. Usually the lowest of these bands will be filled and the next highest will be empty. To get conduction, you need to excite states with a well defined electron momentum, so you need to populate the next highest band (as every state of the lower bands is already populated the necessary states are not available there). Now the energy difference between the bands (analogous to the splitting of frequencies explained before) matters. If the energy is large, it costs a lot of energy to promote an electron to the higher band. This energy is not there and the material will not be a conductor. If there is no splitting, this excitation can happen easily and you will get a conductor. If you have a small splitting, the tempereture of your material might be high enough to promote electrons to higher bands. You get a semiconductor.

To get a basic understanding of these concepts, it is really not necessary to understand the exact nature and strengths of the forces involved. Those will only determine the exact energies where the resulting bands will lie. However, the occurrence of such bands is just a consequency of the large numbers of particles occurring. There is no analog to these band in single atoms and therefore one should not start from single atoms to explain conductivity.

I mean, if these properties were already imprinted in the single atoms, why would graphite and diamond - both pure carbon - have so very different properties in terms of heat conductivity, for example?



Here I do absolutely not get what you mean. Orbiting photons? Electrons not slow enough to have speed and position measured simultaneously? Blurring electrons? You seem to have some strange misconceptions about photons and uncertainty



You would get some discrete resonances. Only photons of well defined energies will interact with the atom.

I typed a long response to your post and it got lost when I submitted it. I'm kind of discouraged to try to type it again. I believe I'm getting the oscillation frequency pattern-effects you're talking about but I still think you're unnecessarily avoiding including behavior of the individual oscillators in the model. Also, I don't see how "oscillation" is a different model from a planetary model such as Bohr's since planets are oscillators as well. I also pointed out in the post that I think it is possible for electrons to consistently lose energy through radiation and regain momentum from collisions. I think this would serve as a general mechanism for transferring heat from a system into radiation. Considering that all matter radiates black-body emissions, why wouldn't the cause of this be consistent evaporation of electron momentum into radiation?

 

[Cthugha]

Also, I don't see how "oscillation" is a different model from a planetary model such as Bohr's since planets are oscillators as well.

Not really. If you apply such a harmonic oscillator model, you have some energy oscillating back and forth between two types. You have kinetic energy and the energy for deforming the spring in a spring pendulum, you have photons and electronic transitions for Rabi oscillations or you have potential and kinetic energy for a string pendulum. In the ideal circular orbit case, a planet is just orbiting its sun at some equilibrium position. No energy is changing from one type to the other.

I also pointed out in the post that I think it is possible for electrons to consistently lose energy through radiation and regain momentum from collisions. I think this would serve as a general mechanism for transferring heat from a system into radiation.

Electrons are almost not involved at all in processes concerning heat. Most of the heat is "stored" in collective motion of the nuclei.

Considering that all matter radiates black-body emissions, why wouldn't the cause of this be consistent evaporation of electron momentum into radiation?

This applies only to matter to which a temperature can be assigned. This is a statistical concept that is only sensible for large numbers of particles. A single atom for example will not emit black-body emission.

 

[brainstorm]

Not really. If you apply such a harmonic oscillator model, you have some energy oscillating back and forth between two types. You have kinetic energy and the energy for deforming the spring in a spring pendulum, you have photons and electronic transitions for Rabi oscillations or you have potential and kinetic energy for a string pendulum. In the ideal circular orbit case, a planet is just orbiting its sun at some equilibrium position. No energy is changing from one type to the other.

So the term, "oscillator," refers to back-and-forth translation between two types of energy? So an electron orbit rising and falling with photon absorption/emissions is an oscillator but the same electron in an undisturbed consistent orbit would not be? So the oscillations you described that transmit electric current? What two states do the electrons oscillate between in that case?

Electrons are almost not involved at all in processes concerning heat. Most of the heat is "stored" in collective motion of the nuclei.

How would energy transfer between two nuclei except through contact between the electrons, since the protons are so far isolated from each other by the electrons?

This applies only to matter to which a temperature can be assigned. This is a statistical concept that is only sensible for large numbers of particles. A single atom for example will not emit black-body emission.

So electrons/atoms only emit radiation at certain moments and at other moments they emit absolutely none? I used to think that until someone who claimed to be a physicist told me that atoms are always emitting some level of radiation and that was called black-body radiation. I read about black-body radiation, and Max Planck's finding that radiation is absorbed and emitted in discreet "packets" determined by frequency and that it is not possible to radiate energy in partial amounts of such "packets." So what you're saying is that only certain atoms within a substance are actually emitting radiation at any given moment and the others are not? Does this mean that energy has to build up to a certain level in an atom before it will trigger a photon-emission? That is what I used to think before this person told me electrons are always emitting some level of radiation.

According to the planetary logic of the atom, the photon gets emitted when the electron "jumps" a level and then falls back to its original level. So if those levels are discreet, which makes sense considering that the radiation travels in discreet packets, then it would make sense that there would be a period of energy build-up before triggering the photon emission, much like a capacitor builds up so much charge before releasing it. So please confirm to me, then, that atoms do not emit radiation except intermittently according to their energy level.