What does it mean when black body radiation is "quantised"?

Can anyone explain these statements to me:



TThe behavior of black bodies was explained by Max Planck using his quantum theory.



-The electromagnetic radiation from the black body was emitted by atoms. (what does this mean?)



- These atoms could not vibrate at any frequency but rather their vibrations are quantised. (what does it mean that they are quantised?)



Any help would be greatly appreciated. Thanks!What does it mean when black body radiation is "quantised"?
In this case, quantized means discrete...ie indivisible distinct pieces.



You need to look up The unltraviolet catastrophe. Classical EM waves are consider continuous, but Plank solved this problem by assuming that EM waves in this case came in discrete packets; they are quantized. They can only exist in specific blocks.



This was crazy at the time and even Plank himself question this; I am pretty sure he just assumed this a special case problem as the assumption to solve the problem was almost ridiculous. His timidness left Einstein to claim the noble prize for his idea. Einstein used Plank's quantized blackbody EM waves idea to explain the photoelectric effect, which is completely trivial mathematics. It took Einstein, outside of academia, to have the balls to suggest that all EM is quantized. The establishment were not really willing to even think about such a thing even though it was staring them right in the face.What does it mean when black body radiation is "quantised"?
One of the sources of radiation is, as you may know, accelerating charged particles, as electrons. The atoms of the black body have electrons, and when of this electrons gets excited it changes its energy level, emitting radiation which energy corresponds precisely to the energy difference between the levels of energy.

This was Planck hypothesis, though he didn't have a clue about energy levels in the atoms, Bohr made this explanation later; but the mechanism of precisely defined energies, which corresponds to a discrete distribution of this energies, which means only certain values, was the hypothesis Planck used successfully to explain the black body radiation.