Comment Re:From heat? (Score 1) 103
Because if something could absorb light of particular wavelength it can radiate light of particular wavelength.
So hotter body radiates more energy than it absorbs from colder body and energy flow from hotter body to colder one.
Second law of thermodynamics yeah.
There is quantum magic during absorption and conversion of photons to electric current but it did n't violate energy conserving.