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In the following paper Professor Pierre-Marie Robitaille has argued that thermal emission is due to vibrations of nuclei within the lattice of a material, and hence also of a blackbody: Robitaille, P.M. On the validity of Kirchhoff’s Law of thermal emission. IEEE Trans. Plasma Sci., 2003, v. 31, no. 6, 1263–1267.


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These answers are way too complicated. It's not rocket science. When a charged particle moves it creates electromagnetic radiation. Matter is made of charged particles. Since everything not at absolute zero is moving around and everything is made of charged particles you're gonna get a spectrum of EM radiation coming off matter. If the thing is ...


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Unit problems can be tricky, especially if you start with SI definitions of unadorned fundamental constants. My technique is the think in energies and lengths whenever possible: \begin{align} [\hbar c] &= \rm eV\,nm \\ [\lambda] &= \rm nm \\ [k_B T] &= \rm eV \end{align} So the argument of the exponential, ${hc}/{\lambda kT}$, is dimensionless ...


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A travelling wave in the direction of the picture(or whatever direction) can have two polarizations, each perpendicular to its direction of propagation. Now, in the black body radiation derivation, we usually use a box as a black body and inside the box standing waves are formed. But standing waves are nothing more(mathematically as well as physically) ...


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Everything not at absolute zero gives off infrared radiation, we are taught. If by "everything" you qualify with "composed of atoms and molecules" yes; not only infrared of course, but matter at some average temperature will be giving off electromagnetic radiation because of collisions in gases, and vibrational and rotational transitions in liquids and ...


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Your hydrogen cloud can be considered a very dilute gas when observed over long enough time and distance scales. In a gas, the collisions between atoms/molecules are the microscopic mechanism for thermal radiation. Generally, all it takes for thermal radiation is charged particles and thermal motion.


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A black body is a figment of the imagination. It is something which is a perfect emitter and a perfect absorber of radiation. The concept is introduced to predict the continuous spectrum of the radiation emitted from such a body at a given temperature. These predictions can then be compared with the spectrum of real bodies and an estimate of the temperature ...


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The definition of a blackbody is not just that it should absorb light perfectly at all wavelengths; it should also be in thermal equilibrium at some temperature. If this is the case, then at equilibrium, all absorption processes must be balanced by emission processes. If that were not the case then the populations of energy levels would change, or the ...


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I think a black body radiating in a certain range of spectrum would cause some serious problems, since we wouldn't be able to explain why it preferred that particular range. Therefore, a black body must radiate in all frequencies, because one interval is not physically preferable than the other.


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First at all, really black bodies do not exist. We simulate them, making a hole in a cavity with thick walls and painting the walls black. As you know, colour surfaces emit the radiation they get from the surrounding space, in a narrow range. Black surfaces absorb the incoming electromagnetic radiation and this of course has to heat them up. Otherwise a ...


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Absorption necessitates emission (and vice-versa). If you can absorb some energy (say by absorbing a photon) then you can also emit that energy (by emitting a photon with the same frequency). Therefore if a black body can absorb all frequencies, it must also be able to emit all frequencies. Edit: Thanks to @Bort! Absorption and emission necessitate each ...


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For the electromagnetic waves, the electric field parallel to the wall must go to zero if the wall is a perfect conductor. An Electromagnetic wave , which is a self propagating transverse waves of oscillating electric and magnetic fields. In case of a metal wall, the metal has electrons free to move through the entire solid. This is why metals can ...


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These responses do not really answer the question. Planck's distribution was explicitly provided by Planck to represent the distribution of energy for what are now referred to as a boson. The proposition of Bose, 24 years later, was a quite terse reiteration of the same geometric expansion, and to recommend it as a more general principle for thermal ...



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