I have been reading alot of stuff on blackbody radiation and the ultraviolet catastrophe. Here is what I have so far. The ultraviolet catastrophe arises from the classical electrodynamics predicting an infinite amount of energy from a blackbody having any temperature. As far as I have understood, the way that people imagined how a blackbody absorbed and emitted radiation, were modeled by oscillators in the surface of the blackbody that could absorb (and emit) any incoming EM radiation. (I think today we would call these oscillators electrons?). Now, the result of this directly led to the ultraviolet catastrophe (the steps I have yet to fully understand). With Planck's introduction quantized energy, the problem was eventually solved. But here is where it breaks down in my head. As I understand it, the "real" quantization is caused by the fact that the EM radiation can only be absorbed/emitting in energy packets corresponding to the energy levels of the atoms/electrons. However, does this not clash with the definition of a blackbody, i.e. a body capable of absorbing/emitting all wavelengths?