# HELP! Boltzmann law in terms of classical physics?

The Stefan-Boltzmann law is as follows: The energy radiated by a black body radiater per second per unit area is directly proportional to the fourth power of the absolute temperature.

Equation: I = σT^4

Is it possible to explain this law by means of classical physics only? If so, please explain.

## Answers and Replies

dextercioby
Science Advisor
Homework Helper
What's your answer to the question ? Yes or no ?

I would say no since the Stefan-Boltzmann law is derived from Planck's law of radiation which was found by Planck using a quantum hypothesis. Or really a bit psuedo-quantum, he didn't realise it himself at the time that he had more or less revolutionised physics.

dextercioby
Science Advisor
Homework Helper
Well, amazingly or not, the law bears the name of Ludwig Boltzmann, a renowned theoretician of CLASSICAL phyics. So it's pretty logic that the answer should be "yes", as confirmed by this very well written article

http://en.wikipedia.org/wiki/Stefan-Boltzmann_law

That's interesting, I was not aware that you could derive the Stefan-Boltzmann law classically, without the Planck law of radiation. Well then, the answer is as bigubau noted obivously yes to your question - the law can be derived classically.

However, it seems that a theoretical value of the Stefan-Boltzmann constant $$\sigma$$ can not be found without the aid of a quantum hypothesis (Planck's radiation law). It can only be measured.

Thanks guys