ABSTRACT
The concept of specific heat is what bridges these two. This is in the sense that specific heats tell us how a certain amount of heat supplied to the system changes its temperature. Specific heats have played decisive roles in so many fundamental developments including that of thermodynamics itself. The Nernst-Planck postulate or the so called third law of thermodynamics precludes the attainment of absolute zero. In practical terms, this translates to the fact that the cooling powers of all cooling devices must vanish as absolute zero is approached. The specific heats play a somewhat subtle role. As noted, the Dulong-Petit law says that the molar specific heat of all solids must be 3R. This value is also what classical statistical mechanics gives. But the experimentally observed specific heats deviate from this value, and in fact the Dulong-Petit value is preferred only at high enough temperatures.
