Whatever changes to dS and dS<sub>R</sub> occur in the entropies of the sub-system and the surroundings individually, according to the Second Law the entropy S<sub>tot</sub> of the isolated total system must not decrease: | Whatever changes to dS and dS<sub>R</sub> occur in the entropies of the sub-system and the surroundings individually, according to the Second Law the entropy S<sub>tot</sub> of the isolated total system must not decrease: |