Why Study Thermodynamics?

In a nutshell, thermodynamics is the study of the internal motions of many-body systems. Virtually all physical entities that we encounter in everyday life are many-body systems of some type or other (e.g., solids, liquids, gases, and even electromagnetic radiation). Not surprisingly, therefore, thermodynamics is a discipline with an exceptionally wide range of applicability. Indeed, thermodynamics is one of the most extensively used subfields of physics outside physics departments. Prospective engineers, chemists, and material scientists generally do not study relativity or particle physics, but thermodynamics is an integral, and very important, part of their degree courses.

Many people are drawn to physics because they wish to understand why the world around us is like it is. For instance, why the sky is blue, why raindrops are spherical, why we do not fall through the floor, et cetera. It turns out that thermodynamics is a very powerful tool for accounting for the observed features of the physical world. For example, in this course, we shall explain why heat spontaneously flows from hot to cold bodies; why it is impossible to measure a temperature below -273$^\circ$ centigrade; why there is a maximum theoretical efficiency of a power generation unit that can never be exceeded, no matter what the design; why the Earth's atmosphere becomes thinner and colder at higher altitudes; why the Sun appears yellow, whereas colder stars appear red, and hotter stars appear bluish-white; and why high mass stars must ultimately collapse to form black-holes.