PPT Slide
consider the case of thermal contact of two systems. The numbers of particles in system 1 is N1 and in system 2 is N2, the values of the energies in system 1 is U1 and in system 2 U2. The total energy U=U1+U2 is fixed.
(g(N,U) is the multiplicity function of system S, g1,2 for system 1,2 respectively.)
in thermal equilibrium the largest term in the above sum governs the properties of the total system!
we define a quantity ?, called entropy
In thermal equilibrium we have: