TABLE OF CONTENTS The true logic of this world is the calculus of probabilities.
J.Clerk Maxwell
Nothing is proverbially more uncertain than the span of an individual human life. Little is more certain than the financial stability of life insurance companies.
Attributed to Sir Arthur Eddington
In thermodynamics we are concerned with the macroscopic world. The dictionary definitions of macroscopic and microscopic are respectively visible and invisible (to the naked eye), but in statistical mechanics the usage is somewhat different, though analogous. Here, macroscopic means having a very large number of components, so that it would require an impossibly large amount of information to specify its state precisely. An object can be quite small on a human scale and still be macroscopic by our definition; for instance, a bubble of an ideal gas 1 m in diameter (the size of a small bacterium), at room temperature and pressure, contains ~10 7 molecules. The state of a macroscopic system, or macrosystem, is specified by a small number of parameters which can be measured (at least in principle) by ordinary mechanical or electromagnetic means; for example, the properties of our bubble of gas may be specified by its pressure and volume. A state defined by such properties is called a macrostate. The instantaneous positions and velocities of the individual molecules of which the macrosystem consists are beyond our ability to specify.
We use microscopic to mean on an atomic (or molecular) scale; a microscopic...
