Thermodynamic Systems

Abstract

Systems which are directly observable by human observers are solid, liquid or gaseous objects, in which case a more detailed observation shows that the inner level is a molecular one. On the macroscopic level — the object level — quantities like temperature and heat are definable. If one pays attention to the problem of the influence of temperature and/or heat, such a system is called a thermodynamic system. Thus, thermodynamic systems are elementary multi-component systems, where a microscopic level is given by the molecule system, and a macroscopic level is given by the mean value level, which is the more easily measurable object level. The quantities of the microscopic level are impulses and positions of the molecules, and macroscopic quantities are pressure, volume and temperature (in particular the absolute temperature). Derived quantities are quantities such as inner energy, free energy, entropy, etc.. Very often thermodynamic systems are equilibrium systems. Such systems I would like to consider in this chapter. However, it already has to be remarked that only systems far from thermodynamic equilibrium are able to produce more complicated patterns. Examples, which will be discussed later, are laser systems. If such systems are driven by pump energy, they produce relatively complicated electric field patterns, i. e. they reach a lasing state. The systems of the animated nature are also systems far from thermodynamic equilibrium, which becomes very obvious when the reader considers the many gradients which hold the human body active.