GOOD ABSORBERS ARE GOOD EMITTERS

The gist of the Stefan-Boltzmann's Law was that a good emitter is a good absorber and vice versa.

In order for any matter to absorb a photon of given energy hf , it must have a pair of energy levels separated by that amount of energy hf. If a pair of electron energy levels is available for absorption of a photon, it is also available for emission of a photon, i.e. , radiation. If it is available for an upward jump, it is available for a downward jump.

But you must be wondering that what has it got to do with me??

Enquire yourself till i hv a glass of water.....