Let’s Begin with the Entropy

Abstract

When dealing with the concept of heat, the layman does not have particular problems: Heat is contained in hot bodies. The greater and the hotter a body, the more heat it contains. Heat goes or flows by itself from hot to cold, or from hot to less hot. Heat is produced within a flame, by mechanical friction or in the wire of a light bulb. It is strange, that physics has trouble with the concept of heat. Simple statements about the every-day concept of heat become incorrect, when interpreted in terms of the physical process quantity Q. They become correct, however, when the everyday heat concept is identified with the physical quantity “entropy” instead of Q. At the same time, one gets a simple intuition about entropy, otherwise infamous for its abstractness. A teaching sequence corresponding to the first five lessons of a thermodynamics course for beginners is presented, where entropy is introduced from the very beginning. In this short period of teaching time, not only the second and the third principle are introduced, but we also come to a physical description of basic processes of our everyday “thermal experience”. Entropy appears as a quantity no more difficult than length, time or mass.