The Whole Is Greater than the Sum of Its Parts: Entropy and the Second Law

  • Peter R. Bergethon


Besides the search for eternal youth, few other ideas are as attractive as the search for a system that will produce more energy or work than it consumes. Such machines are called perpetual-motion machines and are conceived in two varieties: perpetual-motion machines of the first and second kind. The first is a machine that produces more energy than it absorbs as work or heat from the surroundings and thus creates energy. This kind of device has never been found (though people attempt it every day), and its existence is forbidden by the first law of thermodynamics. The second type of perpetual-motion machine is permitted by the first law because it draws heat from the surroundings and converts that heat into work without changing the state of the surroundings. However, it turns out that there are substantial limitations on the construction of a machine or system that can take heat and convert it into directed energy or useful work. Were this not so, it would be possible to build a machine that:
  1. 1.

    Draws heat from the surroundings (there is an almost limitless supply of random thermal motion),

  2. 2.

    Converts the heat to useful work and,

  3. 3.

    In the course of using the directed energy to do work, returns the energy to the surroundings as dissipated or scattered energy (i.e., as random thermal fluctuations).



State Function Canonical Ensemble Heat Engine Joint System Boltzmann Statistic 
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Further Reading

Statistical Thermodynamics

  1. Hill T. L. (1986) An Introduction to Statistical Thermodynamics. Dover Publications, Inc., New York.Google Scholar
  2. McQuarrie D. A. (1973) Statistical Thermodynamics. University Science Books, Mill Valley, CA.Google Scholar
  3. For a derivation of the molecular partition functions see: Moore, W. J., Physical Chemistry, 4th ed. (1972) Prentice-Hall, New York. Chapter 14.Google Scholar
  4. Waldram, J. R. (1985) The Theory of Thermodynamics. Cambridge University Press, Cambridge.Google Scholar

Articles of Interest

  1. Bennett C. H. (1987) Demons, Engines and the Second Law. Scientific American, 257 (5): 108–112.CrossRefGoogle Scholar
  2. Mulero F. C. and Rubio P. (1994) The Perturbative Theories of Fluids as a Modern Version of van der Waals Theory, J. Chem. Ed., 71: 956–962. This article relates the ideas of intermolecular forces, gases, liquid properties, and the statistical mechanical tool of perturbation theory. A nice historical context is given to the development of the ideas.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1998

Authors and Affiliations

  • Peter R. Bergethon
    • 1
  1. 1.Department of BiochemistryBoston University School of MedicineBostonUSA

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