The macroscopic picture of heat retained and heat emitted: Thermodynamics and its historical development

This introductory chapter provides the fundamentals needed to understand heat and its idealized, time-independent transfer, as a prelude to understanding heat flow, which is strongly time-dependent. The macroscopic nature depiction of light is introduced in this chapter. Because the equivalence of light and heat was demonstrated subsequent to the development of the first and second laws of thermodynamics, the classical physics depiction of light has not been adequately incorporated in basic discussions of heat and thermodynamics. This omission is evident in the 1800s focus on reversibility, and it impedes the realistic description of many large-scale processes. Some thermodynamic concepts and models that are important to natural sciences and engineering are based on incomplete or incorrect statements in the literature, and/or rely on the unrealistic ideal gas or nonexistent reversibility. This chapter attempts to address and manage those inconsistencies, in part by drawing attention to missed connections.