Hypothesis about temperature (split from Physical mechanism how matter absorbs radiation.)

martillo · March 29

41 minutes ago, Mordred said:

Seems to me that you have chosen to completely ignore the fundamental definition of temperature or at the very least a good portion of the kinetic energy terms involved.

May be I need a new definition of temperature, I agree. I can perfectly define temperature based on the Stefan-Boltzmann Law Pot/A = σT⁴ which relates temperature with a radiation just considering this radiation as a radiation of photons.

9 minutes ago, Mordred said:

However I ask you the following if you cause vibrations an object to increase via any mechanism including sound do you agree that the average temperature of resonating nearby objects will increase ? or that you can heat up metal by hitting it with a hammer? Any time you increase an objects vibration you also increase the molecular and atomic vibrations.

That is the well known kinetic to heat energy conversion. The classic Joule's experiment. Where is the problem? I perfectly agree with it. Temperature increase just means more photons emitted.

Edited March 29 by martillo

Mordred · March 29

Try not to confuse how thermal energy is transferred until you understand why thermal energy is described via its mean average kinetic energy. There is a difference between the two both however are required.

I do have to ask why you would think the current understanding of temperature is incorrect in regards to frequencies/vibrations etc ? Particularly when we can definitively show our understanding via previous experiments and observations ? One example I can think of, offhand that clearly demonstrates our understanding is using lasers to supercool atoms and molecules to form a Bose-Einstein condensate. Using lasers to cool something is not something one would expect but in essence the lasers are used to reduce the internal motion of particles within the condensate.

Its not just any laser in that example its specific laser frequencies that vary depending on the condensate. Just another thing to keep in mind there is also a distinction between conductive heat transfer and radiative heat transfer in regards to Stefan-Boltzmann...

Edited March 29 by Mordred

martillo · March 30

1 hour ago, Mordred said:

I do have to ask why you would think the current understanding of temperature is incorrect in regards to frequencies/vibrations etc ? Particularly when we can definitively show our understanding via previous experiments and observations ?

I always thought in heat transferring as a flow of photons. If not, how do you think thermal energy is transferred from one body to another one? The sun, for instance, it warms earth surface radiating photons through empty space. This way I think in temperature as a magnitude related to the intensity of the radiation of photons. Black body radiation is a radiation of originally called "quanta" by Planck and after photons by Einstein I think. So it is natural for me to think in heat as a flux of photons and temperature a way to measure their intensity. The model I'm working matches with this viewpoint.

My approach focuses on how the energy is transferred, not in how it is contained. In the Kinetic Theory the energy is contained as vibrations of the atoms/molecules, I think it is not the case. I consider the theory of the electrons' levels of energy in the atomic electromagnetic structure well cover how the energy is contained by atoms. I mean the energy is stored in the electromagnetic fields of the atoms, not in mechanical vibrations.

Edited March 30 by martillo

Mordred · March 30

In the case of radiative heat transfer using photons is common as a mediator. However heat transfer is not the same thing as an objects temperature. In order to understand how photons can be used in thermal radiation one has to also understand the interaction with the molecules and atoms of a substance/state. So one also has to understand how this alters its temperature

martillo · March 30

37 minutes ago, Mordred said:

In order to understand how photons can be used in thermal radiation one has to also understand the interaction with the molecules and atoms of a substance/state.

Photons' absorption and emission. Electrons' energy levels in atoms. Photoelectric effect. Compton scattering. What else do you need?

37 minutes ago, Mordred said:

So one also has to understand how this alters its temperature

As I already said many times temperature is a magnitude related to the intensity of the radiation present. Is related to the quantity of photons passing through an area of space in relation to the interval of time and the area. The relation is given by the Stefan- Boltzmann Law Pot/A = σT⁴.

Edited March 30 by martillo

**swansont** · March 30

4 hours ago, martillo said:

consider "heat" as the energy flow of photons what is the same as a radiation of photons. As I said other time, there is empty space between atoms and molecules where the photons can pass through. The average velocity of these photons would not be c as there would be scattering dispersion with the atoms and also absorption and re-emission of them in their not linear way. Conductive heat transfer is precisely this phenomenon of photons travelling through dense materials or substances. The phenomenon could be described as the progressive diffusion of photons inside them.

But radiative heat transfer depends on the difference of T^4, while conductive heat transfer depends linearly on the temperature difference. A small vacuum gap between the solid and liquid has a huge change in behavior, but should make no difference if it’s radiation, since all of the photons would still be emitted from the solid.

Mordred · March 30

49 minutes ago, martillo said:

Photons' absorption and emission. Electrons' energy levels in atoms. Photoelectric effect. What else do you need?

As I already said many times temperature is a magnitude related to the intensity of the radiation present. Is related to the quantity of photons passing through an area of space in relation to the interval of time and the area. The relation is given by the Stefan- Boltzmann Law Pot/A = σT⁴.

Swansont beat me to it. Once again there is a difference in thermal conduction of a material and thermal radiation. In solids you also have to factor in the conductivity of the material which will also involve density of states.

little side not there is a reason why photons aren't used in a crystal lattice. The reason has to do with momentum invariance within the lattice. There is only 1 vector in a lattice where the momentum is invariant and this doesn't represent the overall momentum of the entire lattice network. Instead they use a quasi-momentum and phonons as a quasi particle for the distinction.

example details here

https://www.ucl.ac.uk/~ucapahh/teaching/3C25/Lecture12p.pdf

phonons are used to represent lattice waves, while its common to use magnons for magnetic waves and keeping photons for EM waves. All three directly apply to thermodynamics of a solid or more accurately its conductivity

Edited March 30 by Mordred

martillo · March 30

59 minutes ago, swansont said:

But radiative heat transfer depends on the difference of T^4

No, heat transfer is governed by the laws of Thermodynamics whatever the origin of the heat through the linear, as you say, inter relations between Q, H, U, S and T. Heat transfer is always proportional to the difference in two temperatures. The value of each temperature is what is determined by the Stefan-Boltzmann Law.

59 minutes ago, swansont said:

A small vacuum gap between the solid and liquid has a huge change in behavior, but should make no difference if it’s radiation, since all of the photons would still be emitted from the solid.

I don't know about that case. Can you provide more details?

52 minutes ago, Mordred said:

little side not there is a reason why photons aren't used in a crystal lattice. The reason has to do with momentum invariance within the lattice. There is only 1 vector in a lattice where the momentum is invariant and this doesn't represent the overall momentum of the entire lattice network. Instead they use a quasi-momentum and phonons as a quasi particle for the distinction.

example details here

https://www.ucl.ac.uk/~ucapahh/teaching/3C25/Lecture12p.pdf

phonons are used to represent lattice waves, while its common to use magnons for magnetic waves and keeping photons for EM waves. All three directly apply to thermodynamics of a solid or more accurately its conductivity

As for now I have no idea of what you are talking about. May be in the future, who knows. That is the current interpretations of things. I'm beginning to work in a new approach now. You can't expect I would have already found the alternative explanation for everything at this time.

Edited March 30 by martillo

Mordred · March 30

1 hour ago, martillo said:

As for now I have no idea of what you are talking about. May be in the future, who knows.

That's why I'm adding links for reference. Thermal conductivity is governed by very different relations that it is in thermal radiation. I am describing thermal conduction specifically for the case of solids. None of the equations for thermal radiation such as Plancks radiation law, Bose-Einstein statistics, Stefan Boltzmann, etc apply as thermal conduction is distinct from radiation.

For solids the thermal conductivity of a material follows the Fourier Law of Heat conduction which for a 3d solid is

\[\vec{\hat{q}}=-k(\frac{\partial T }{\partial x}\vec{i}+\frac{\partial T}{\partial y}\vec{j}+\frac{\partial T}{\partial z}\vec{k})\]

most times you will see it as

\[\vec{q}=-k\vec{\nabla} T\]

such as this wiki link

https://en.wikipedia.org/wiki/Thermal_conduction

q is the heat capacity while k is a constant of proportionality for a materials conductivity.

One can use the above law to mathematically describe the scenario Swansont just gave. (Though that's typically one of the earliest lessons articles will give on Fouriers Law.) Lattice networks are typically the homogenous and isotropic scenario using the Fourier law in that link.

Quantum mechanically though the Fourier is represented by the quantum mechanical master equation for heat transfer lol just so you know I'm not blowing fluff on the name lol here is an example article on arxiv

https://arxiv.org/abs/0711.4599

very few ppl will understand the mathematics of this article

Edited March 30 by Mordred

**swansont** · March 30

7 hours ago, martillo said:

No, heat transfer is governed by the laws of Thermodynamics whatever the origin of the heat through the linear, as you say, inter relations between Q, H, U, S and T. Heat transfer is always proportional to the difference in two temperatures. The value of each temperature is what is determined by the Stefan-Boltzmann Law.

And S-B says radiated power depends on T^4

7 hours ago, martillo said:

I don't know about that case. Can you provide more details?

It’s as I described. An object in vacuum can only cool via radiative heat transfer. But all that radiation must hit the matter that surrounds the vacuum.

martillo · March 30

3 hours ago, swansont said:

And S-B says radiated power depends on T^4

But the energy transfer is always linear in the difference of the temperatures. dQ = CdT. The energy of a radiation at some place is given by S-B Law at a thermal equilibrium. Energy transfer involves difference in temperatures and so no thermal equilibrium. The energy transferred is directly proportional (linear) in the difference in temperature (assuming no loss in the transfer).

12 hours ago, swansont said:

A small vacuum gap between the solid and liquid has a huge change in behavior, but should make no difference if it’s radiation, since all of the photons would still be emitted from the solid.

The vacuum gap makes lot of difference in the conductance. In the gap there's no lattice so the emitted photons from one side don't follow the same diffusion pattern of the solids. They can just reflect while hitting the other solid surface, diffraction can happen etc. The conductance is lost.

Edited March 30 by martillo

sethoflagos · March 30

1 hour ago, martillo said:

But the energy transfer is always linear in the difference of the temperatures. dQ = CdT.

As @swansont infers: This is not true for heat transfer by thermal radiation where dQ is proportional to d(T⁴). ref (https://en.wikipedia.org/wiki/Thermal_radiation)

Quote

The net radiative heat transfer from one surface to another is the radiation leaving the first surface for the other minus that arriving from the second surface.

For black bodies, the rate of energy transfer from surface 1 to surface 2 is:

${\dot {Q}}_{1\rightarrow 2}=A_{1}E_{b1}F_{1\rightarrow 2}-A_{2}E_{b2}F_{2\rightarrow 1}$

where $A$ is surface area, $E_{b}$ is energy flux (the rate of emission per unit surface area) and $F_{1\rightarrow 2}$ is the view factor from surface 1 to surface 2. Applying both the reciprocity rule for view factors, $A_{1}F_{1\rightarrow 2}=A_{2}F_{2\rightarrow 1}$ , and the Stefan–Boltzmann law, $E_{b}=\sigma T^{4}$ , yields:

${\dot {Q}}_{1\rightarrow 2}=\sigma A_{1}F_{1\rightarrow 2}\left(T_{1}^{4}-T_{2}^{4}\right)\!$

where $\sigma$ is the Stefan–Boltzmann constant and $T$ is temperature.^[24] A negative value for ˙ ${\dot {Q}}$ indicates that net radiation heat transfer is from surface 2 to surface 1.

For two grey-body surfaces forming an enclosure, the heat transfer rate is:

${\dot {Q}}={\frac {\sigma \left(T_{1}^{4}-T_{2}^{4}\right)}{\displaystyle {\frac {1-\epsilon _{1}}{A_{1}\epsilon _{1}}}+{\frac {1}{A_{1}F_{1\rightarrow 2}}}+{\frac {1-\epsilon _{2}}{A_{2}\epsilon _{2}}}}}$

where $\epsilon _{1}$ and $\epsilon _{2}$ are the emissivities of the surfaces

This point has now been made to you several times and you have failed to address it properly.

1 hour ago, martillo said:

The energy of a radiation at some place is given by S-B Law at a thermal equilibrium. Energy transfer involves difference in temperatures and so no thermal equilibrium. The energy transferred is directly proportional (linear) in the difference in temperature (assuming no loss in the transfer).

There is no nett energy transfer at thermal equilibrium. Is that your defence? Under some very special circumstance 0 = 0 whichever way you calculate it?.

Not much of a defence is it, really?

Mordred · March 30

1 hour ago, martillo said:

The vacuum gap makes lot of difference in the conductance. In the gap there's no lattice so the emitted photons from one side don't follow the same diffusion pattern of the solids. They can just reflect while hitting the other solid surface, diffraction can happen etc. The conductance is lost.

heat transfer through a vacuum isn't conduction. Why do I get the impression You don't understand why and when you have conduction, convection and radiation ?

Stefan Boltzmann is a radiation law not a conduction law.

Just in case lets be absolutely clear. Both conduction and convection involve the medium containing atoms and molecules. In the former the atoms are stationary, in convection the atoms are moving (a fluid). In radiation there is zero atoms or molecules you simply have the EM field via photons for transference as the transfer occurs in a VACUUM not a medium.

Edited March 30 by Mordred

**swansont** · March 30

1 hour ago, martillo said:

But the energy transfer is always linear in the difference of the temperatures. dQ = CdT. The energy of a radiation at some place is given by S-B Law at a thermal equilibrium. Energy transfer involves difference in temperatures and so no thermal equilibrium. The energy transferred is directly proportional (linear) in the difference in temperature (assuming no loss in the transfer).

No, this is patently untrue.

S-B gives the radiated power. It does not require thermal equilibrium.

1 hour ago, martillo said:

The vacuum gap makes lot of difference in the conductance. In the gap there's no lattice so the emitted photons from one side don't follow the same diffusion pattern of the solids. They can just reflect while hitting the other solid surface, diffraction can happen etc. The conductance is lost.

Once there’s a gap there is no conduction. It’s why a dewar flask works so well; radiative heat transfer is fairly small for low temperatures, but becomes important owing to the T^4 behavior

Being unaware of facts does not make them untrue. It gets to be frustrating to be told that they aren’t simply because you don’t know much about physics.

martillo · March 30

3 hours ago, sethoflagos said:

As @swansont infers: This is not true for heat transfer by thermal radiation where dQ is proportional to d(T⁴). ref (https://en.wikipedia.org/wiki/Thermal_radiation)

This point has now been made to you several times and you have failed to address it properly.

There is no nett energy transfer at thermal equilibrium. Is that your defence? Under some very special circumstance 0 = 0 whichever way you calculate it?.

Not much of a defence is it, really?

3 hours ago, Mordred said:

heat transfer through a vacuum isn't conduction. Why do I get the impression You don't understand why and when you have conduction, convection and radiation ?

Stefan Boltzmann is a radiation law not a conduction law.

Just in case lets be absolutely clear. Both conduction and convection involve the medium containing atoms and molecules. In the former the atoms are stationary, in convection the atoms are moving (a fluid). In radiation there is zero atoms or molecules you simply have the EM field via photons for transference as the transfer occurs in a VACUUM not a medium.

2 hours ago, swansont said:

No, this is patently untrue.

S-B gives the radiated power. It does not require thermal equilibrium.

2 hours ago, swansont said:

Once there’s a gap there is no conduction. It’s why a dewar flask works so well; radiative heat transfer is fairly small for low temperatures, but becomes important owing to the T^4 behavior

OK, I have made a serious mistake, I admit.

I was badly wrong when I said:

15 hours ago, martillo said:

Heat transfer is always proportional to the difference in two temperatures.

I must have a good answer, based in my new approach, to the case of why a vacuum gap acts as a so good thermal insulator, of course. The thing became something very interesting for me. I should also have to explain why and how heat is so well transferred in the conductance of metals.

2 hours ago, swansont said:

Being unaware of facts does not make them untrue. It gets to be frustrating to be told that they aren’t simply because you don’t know much about physics.

You don't need to answer so ironically to that mistake. While true I graduated in Electrical Engineering and not in Physics, I'm in the Physics' area since lot of years ago although in an auto didactic way, that's true. You are ironic because I'm proposing a new approach and think this is something not right. For you there's no errors at all in all the already developed modern Physics. I'm strongly interested in the problem you presented now. I don't have a proper answer at this time but I'm thinking about. The case is a new challenging problem for me now. I hope I could arrive to the right answer not taking too long.

Wait, a good idea to work on has just knocked my mind. Let me some time to present it properly.

Edited March 30 by martillo

Mordred · March 30

Glad to see you understand where your errors were coming about. GL in your studies on the 3 scenarios.

martillo · March 30

I think I already got it in the right way in my approach. Let me try to explain it now.

I have said that diffusion of photons, travelling inside a lattice structure would be the process of the conductance but I think now this was not the right thing. Bad tentative I admit.

First scenario: thermal radiation:

I consider this currently perfectly described by the Planck and the Stefan-Boltzmann laws applied to black body radiation with the necessary adjustments when applied to real bodies in practice. Radiation would be far not good in transmitting heat as the metals conductance is.

Second scenario: thermal conductance:

The situation is, we would have a "source" of heat emitting photons in direct contact to the crystalline lattice of a metal conductor connected by direct contact to a target "sink" of heat at its end. I'm considering now that the atoms of the lattice can absorb and re-emit photons quite instantaneously to the next atom of a linear path (not necessarily straight, it could be curved) in the lattice. This way the photons in one end can quite instantaneously be transmitted to the other end of the conductor. The capacity of conduction of the lattice would depend on the capacity of the atoms to absorb and re-emit photons to their other side which would be high in metal lattices. This the explanation for the excellent conductance of metals.

Third scenario: Vacuum gap between two conductive materials as an insulator:

A vacuum gap involves the surfaces at the end of the lattices' structures of two conductive materials. The point is that the atoms at those surfaces have no next atom to re transmit their absorbed photons on the other side. This way the conductance is lost. They could only radiate photons but this is the case of the first scenario which have much less capacity of heat transfer than the second scenario. This explains the insulation capacity of a vacuum gap.

I hope this explanations could work for you at least as just a possibility to be taken into account.

Edited March 30 by martillo

Mordred · March 30

Do you recall me mentioning phonons under the conduction case ? I do recall providing a gauge invariance requirement with a link detailing where this requirement becomes an issue with a lattice. Now I'm not saying its incorrect to use photons in this case however you must also factor in the conductivity of the material. If you look at the article the same equation for the quanta of phonons are identical to the equation for photons. We use the phonons simply to make the distinction between the conductive case to the radiative case. This also frees up certain key conservation laws with particle to particle scatterings. Those include conservation of charge, color, flavor, energy momentum, spin etc. Using phonons as a quasi particle we can avoid these issues.

Edited March 30 by Mordred

martillo · March 30

12 minutes ago, Mordred said:

Do you recall me mentioning phonons under the conduction case ? I do recall providing a gauge invariance requirement with a link detailing where this requirement becomes an issue with a lattice.

Ok so, do I have the equivalent of conductance with phonons with this my photons approach?

Mordred · March 30

8 minutes ago, martillo said:

Ok so, do I have the equivalent of conductance with phonons with this my photons approach?

I wouldn't say equivalent when you further consider photons scatterings such as with say Thompson scatterings.

You can see the issue via this link.

https://en.wikipedia.org/wiki/Thomson_scattering

however that's not an issue with phonons defined as

Phonon (lattice vibration, cause of thermal conduction in electric insulators, and participant in energy conversion involving kinetic energy of solids).

as opposed to photons

Photon (has the largest range of energy, carriers its energy even through vacuum, and interacts with electric and magnetic entities in energy conversion).

Now consider a solid is held together by an EM field.

Edited March 30 by Mordred

martillo · March 30

6 minutes ago, Mordred said:

I wouldn't say equivalent when you further consider photons scatterings such as with say Thompson scatterings.

You can see the issue via this link.

https://en.wikipedia.org/wiki/Thomson_scattering

Thanks for the comment. At least I'm moving forward I think.

Mordred · March 30

see the edit above we cross posted on edit.

martillo · March 30

18 minutes ago, Mordred said:

Photon (has the largest range of energy, carriers its energy even through vacuum, and interacts with electric and magnetic entities in energy conversion).

Now consider a solid is held together by an EM field.

I think I can handle that. Where do you think I should focus the attention now?

**swansont** · March 30

1 hour ago, martillo said:

A vacuum gap involves the surfaces at the end of the lattices' structures of two conductive materials. The point is that the atoms at those surfaces have no next atom to re transmit their absorbed photons on the other side. This way the conductance is lost.

They could have a next atom, but it would be some distance away. But the shouldn’t matter much to photons. And an atom doesn’t “know” where the photon it absorbs came from.

Mordred · March 30

1 hour ago, martillo said:

I think I can handle that. Where do you think I should focus the attention now?

truthfully put aside any concern on what the mediator particle is. It really doesn't matter as they can be used offshell being a mediator boson. Reduce the problem to 2 forms of energy. Potential energy and kinetic energy. Study the linear equations first via studying the mathematics of a classical spring. A graph of its momentum over time is dipolar just as the case with the EM field. This will further equate to the harmonic oscillations as well as the wave equations of QM/QFT. Make sure you have a good understanding of the energy/work/power/momentum relations involved. (all included in any decent book on thermodynamics thus far.).

study each case separately conduction, convection and radiation. You should note the relationship between the potential energy terms and the kinetic energy terms an objects conductivity can be described via the spring and those energy terms.

After that for a field treatment for temperature use a scalar field this is also included in any decent book on the topic.

you will need to understand wave equation treatments if you plan on applying QM/QFT.

Edited March 30 by Mordred

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