ABSTRACT
When we deal with systems containing many particles, it soon becomes essential to adopt statistical methods of analysis. To a large extent, statistical mechanics has been developed with a view to studying condensed matter systems, such as solids and fluids, upon which controlled laboratory experiments can be performed. In some cases, the quantum-mechanical properties of the constituent particles are crucial. This is true, for example, when we study the properties of electrons in metals or semiconductors, or of superfluid helium. In other cases, it is sufficient to treat the constituent particles according to classical mechanics, although it may still be necessary to determine their properties, such as the forces which act between them, from the underlying quantum theory. The properties of most normal fluids and many magnetic properties of solid materials, for example, can be adequately and conveniently treated by classical methods.
