
1
The Beginnings
Like all sciences, the subject of thermodynamics too grew out of systematizing em-
pirical data. Needless to say, data has no meaning unless viewed within a reasonably
well-defined conceptual framework. The beginnings of such a framework is of course
in day-to-day sense perceptions and experiences. The notion of hotness and coldness
must have been around for a very long time. An important part of this experience is
also the recognition that upon contact, the hotter body grows colder and the colder
body grows hotter.
Another very important, though somewhat abstract, empirical notion is that of
equilibrium. Taking the example of mixing