I think that Leonard Susskind does this derivation in one of his lectures on statistical mechanics that is available on youtube.
http://www.youtube.com/watch?v=H1Zbp6__uNw"
Is it as simple as
dQ\Big( \frac{1}{T_2} - \frac{1}{T_1}\Big)=dQ\Big( \frac{T_1-T_2}{T_1T_2}\Big)>0,
if dQ=dQ_1 - dQ_2 is the net-heat where positive direction is from B_1 to B_2 and dQ_1>dQ_2?
I am trying to understand the behavior of blackbodies in interaction with each other.
Conditions as follows.
1) There are two blackbodies, say B_1 and B_2, with corresponding temperature T_1 and T_2.
2) Initially T_1>T_2.
3) B_1 and B_2 have thermal contact only through radiation...