they are so connected that you may fully dissipate the electric energy into heat

   Dear Arbab,

   Your question is quite complex and no easy to give a simple answer too, but let me try to give you what I think is behind your question:

   1. Electromagnetism is vacuum is absolutely independent of the temperature. Thus Maxwell equations are not related with heat transport at vacuum.

   2. Phononic heat only exists in materials and its transformation in other kind of energies (e.g. electromagnetic) is against the second law of thermodynamics.

   3. The aplication of an electromagnetic field on a material has a physical response depending strongly of its characteristics: metal, semiconductor and insulator. For instance

   a- In one would metal you have electric conductivity and the Wiedemann-Franz law also gives you a good thermal conductivity. Due to the above law metals are not good thermoelectric, i.e. materials where the heat may be transformed in electricity.

   b- The good thermoelectrics are all semiconductors and unfortunately, although the figure of merit is quite higher than to the metals its maximum is close to 2 and this is quite low if no new materials are found.

   4. Finally, thermoelectricity is one transport (electronic and phononic) property through special materials able to have a high Seebeck coefficient and to reach a higher ratio as possible between the electric and thermal conductivities.

Dear Daniel,

Thank you very much for your very interesting answer to my questions. How does heat flow induce an electric current (voltage)? Heat drives electrons, and the driven  electrons induces electromagnetic energy that is transmitted along the conductor. Is that true? How the effect of temperature change is transmitted along the conductor, and with hat speed? Do electrons oscillate? It is easy to convert electric energy into heat, but is the reverse true, and under what conditions?

In Peltier effect the flow of electric energy can lower the temperature what happens to other thermodynamics quantities, like entropy? What is the mechanism behind this lowering?

Arbab

Heat is much easier to understand and predict if you view it at the quantum level.

In this model, heat is fundamentally a surplus of photons operating in the infra-red (and above) frequency band.

So for example, when you apply a flame to an iron rod, what you are actually doing is to provide a source of infra-red photons which interact with the electron cloud, moving the outer band electrons to a higher energy level.

At a random point these electrons shed the excess photon which may be captured by an adjacent atom's electron cloud (this is heat conduction) or may be emitted from the iron bar as photons (we call this radiant heat).

As you apply more and more photons from the flame then these two effects become more obvious. In particular the second effect (radiant heat) changes the colour of the iron. It starts to glow red and then white as the electrons release photons at a higher frequency, well into the visible band. This is a more efficient way to dissipate the excess photons and hence maximise entropy.

In the quantum energy model Maxwell's equations are fundamental to the explanation.

The Seebeck and Peltier effects are also simple to understand in the quantum model.

In the Seebeck effect, when heat is applied to a junction of dissimilar metals then the rate of photon / electron interaction differs between the metals. This sets up a voltage field which drives electric current around an applied circuit.

I will leave it as an exercise for you to explain the Peltier effect using the quantum model.

Regards

Ian

Dear Ian,

Thanks a lot for you elucidated exposition. 

Maybe the biggest difference between heat energy and electric potential energy: heat is a statistical quality (temperature is linearly related to the average kinetic energy of gas/fluid/solid molecules/atoms via Boltzmann's constant), where electric potential or electric field energy is defined also for a single particle.  A second difference: heat transfer is by means of longitudinal  waves (quantized in phonons), where electric power transfer is based on the transverse electromagnetic wave (quantized in photons).  Phonons seem to be restricted to material media, and are "forbidden" in vacuum. I wonder if modern physics outlaws 'something' quite natural in a most unnatural way, such as vacuum phonons and vacuum statistics beyond QED. The notorious renormalisation trick is based on gauge symmetry and 'c' as a speed limit, so vacuum phonons are forbidden, since luminal 'longitudinal' and 'time like' phonons in vacuum cancel each other.  Perhaps the simple Coulomb field is a statistical phenomenon of vacuum phonons, in stead of the QED virtual particle picture. The biggest reward of a better model of vacuum statistics, however, might be induced/controlled gravity.

Heat is not a kind of energy. Heat is a way of transmitting energy.

   Dear Arbab,

   I'm sorry that I didn't see your post till now. Well, your questions are quite interesting but not simple to answer. Notice that thermoelectricity is not at all a general effect that every material have the possibility of exhibiting. In fact there are few materials that can be called thermoelectrics.

   The basic idea is that when you get a gradient of temperature between a cold and a hot focus within a material, you can get a difference of electric potential V which is directly related with the increment of temperature because the number of charges is different in both focus (the chemical potential is very different). The relation of such physical magnitudes is given by a coefficient (Seebeck coefficient) which only depends of the material characteristics, as higher is this coefficient as higher is the transformation of thermal energy in electric one (both are coupled), i.e.

                      V=ST

   where V stands for the increment of electric potential, S Seebeck coefficient and T by increment of temperature.

. This coefficient is the main parameter for the transformation of thermal energy in electric one, because it enters as its square in the figure of merit. Obviously the electric conductivity of the material also plays one role, because it allows to transport much electric charge proportionatally to it and the thermal conductivity is inverse proportionally because it avoids to mantain the (against the zero principle of thermodynamics) the gradient of temperature.

@Malinowski,  it is easy to confuse the notions of 'heat' and  'internal energy' of a volume/body; basically you are right. Btw, infrared radiation is also called 'heat'. I wonder if the vacuum has more 'statistical' properties than just TEM wave medium and passing electric or magnetic fields, see for instance https://www.youtube.com/watch?v=hByJBdQXjXU

https://www.youtube.com/watch?v=hByJBdQXjXU

Dear Prof. Arbab,

                                 We can give you an Econophysics anaswer which is based on the Third Law of Thermodynamics in which we have shown that when orderly particles are quantum transported or communicated through AGN Networks by using our developed Functor Algebra Calculus the integral of energy in the system subject to Planck scale (the Lie Algebra non-commutativity and "jump quantum" transitivity) at near earth temperature and pressure (Riemannisability))(Mallick, Hamburger, Mallick (2016)) allows the quantum coherence between heat energy, electrical energy, light energy with String Duality and Higgs mechanism at an Archimedean point in history at least where zero is a solution (primordial) or may be within the box by Nobel potential calculations (Mallick (1993, 2014, 2015)). We don't think the system can ever attain Entropy = 0 in one form of energy because of String Duality and order of coherence. However for approximate Management-Engineering cybernetic systems approximate zero is equilibrium over spacextime flow.

Soumitra K Mallick

for Soumitra K Mallick, Nick Hamburger, Sandipan Mallick

Dear Arbab: Let me refer first to Black Body one important aspect of the heat. In the study of the black body Planck has used the statistical approach of a physical phenomenon introduced by Boltzmann. As a result he was able to propose a satisfactory fit of the experimental data concerning the distribution of the energy. Using statistics of the gas in the study of the light energy he was introducing the hypothesis of countable particles. There is a difficulty of our physics which is not always clearly realized. Indeed in our scale we have the notion of the continuum that is of measurements taking all possible values along a segment, of energy for example. But the number of the possible values along a segment is much larger than that of the integer numbers, they can always make a discrete series of points along a given segment. As a result the use of atomic statistics in the study of the black body makes the light a phenomenon bound to the atomic scale, thus to the countable. With this remark it is more or less easy to see that the heat is transmitted by exchange with choc. You can find in my work “The Black Body and the Dulong and Petit Law” a study of the heat flows, the same with “Specific heat of Solids at low temperature”

Dear Arbab: Now concerning the electricity, there are different difficulties. First the hypothesis of the free electrons is not correct. The first difficulty was the absence of heat capacity for the conduction electrons. In fact in the study of the “Specific heat of Solids…” I show that there is a very small number of conduction electrons. In fact the valence electrons are localized, my work “conductivity and superconductivity confirms this approach. I have not study the Seebeck and Peltier effects but according to my remark for the Black Body we have probably to use statistical exchanges of energy.

Dear Anil and Arbab, Thank for you recommendations. I think it important that people realize the statistical aspect of the heat

Xavier