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  • Print publication year: 2015
  • Online publication date: April 2015

3 - Energy and how the microscopic world works


Quantum theory

To conceptualize the molecular origins of thermodynamic equilibrium, one must first understand the elemental ways by which molecules interact. How does the world really work? What are the most fundamental principles that form the basis of reality as we know it?

Currently our understanding of reality rests upon two principal concepts in physics: quantum theory and relativity. Both of these have been subjected to stringent experimental tests over the past century, and their combination has in part led to a deep understanding of elementary particles. There still remain some incompatibilities between the two, namely in understanding the nature of gravity, and there have been intense efforts to find new fundamental physical explanations. However, for the purposes of our discussion, we will focus solely on quantum theory since for nearly all of the models and systems that we will discuss one can safely avoid considerations of relativistic effects.

Quantum mechanics describes the complete time evolution of a system in a quantum sense, in a manner analogous to what Newtonian mechanics does for classical systems. It is most easily described in terms of a system of fundamental particles, such as electrons and protons.

Further Reading
Hill, T. L., An Introduction to Statistical Thermodynamics. Reading, MA: Addison-Wesley (1960); New York: Dover (1986).
Hill, T. L., Statistical Mechanics: Principles and Selected Applications. New York: McGraw-Hill (1956); New York: Dover (1987).
Israelachvili, J., Intermolecular and Surface Forces, 3rd edn. Burlington, MA: Academic Press (2011).
Jackson, E. A., Equilibrium Statistical Mechanics. Mineola, NY: Dover (1968).
Kittel, C. and Kroemer, H., Thermal Physics. New York: W. H. Freeman (1980).
McQuarrie, D. A., Statistical Mechanics. Sausalito, CA: University Science Books (2000).
McQuarrie, D. A., Quantum Chemistry. Mill Valley, CA: University Science Books (1983).
Ruelle, D., Statistical Mechanics: Rigorous Results. River Edge, NJ: World Scientific (1999); London: Imperial College Press (1999).
Tolman, R. C., The Principles of Statistical Mechanics. New York: Dover (1979).