4.1 Special cases: Gibbs and Helmholtz free energies.
There are many versions of the second law, but they all have the same effect, which is to explain the phenomenon of irreversibility in nature. Entropy is a measure of how far along this evening-out process has progressed. In simple terms, the second law is an expression of the fact that over time, ignoring the effects of self-gravity, differences in temperature, pressure, and density tend to even out in a physical system that is isolated from the outside world. The second law traces its origin to French physicist Sadi Carnot's 1824 paper Reflections on the Motive Power of Fire, which presented the view that motive power (work) is due to the fall of caloric ( heat) from a hot to cold body ( working substance). 1, p. 267 (1988).The second law of thermodynamics is an expression of the universal law of increasing entropy, stating that the entropy of an isolated system which is not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium. Smith (eds.) Maximum-Entropy and Bayesian Methods in Science and Engineering vol.
The evolution of Carnot's principle, by E.T.
Stanford Encyclopedia of Philosophy: " Philosophy of Statistical Mechanics." by Lawrence Sklar.
Bristol Philadelphia : Institute of Physics, 2003
Maxwell's demon 2 : entropy, classical and quantum information, computing.
A gentle introduction, a bit less technical than this entry. Reflections on the Motive Power of Fire – and other Papers on the Second Law of Thermodynamics by E.
The economist Nicholas Georgescu-Roegen showed the significance of the Entropy Law in the field of economics (see his work The Entropy Law and the Economic Process (1971), Harvard University Press).
Flanders and Swann produced a setting of a statement of the Second Law of Thermodynamics to music, called "First and Second Law.
There are almost as many formulations of the second law as there have been discussions of it. Greg Hill and Kerry Thornley, Principia Discordia (1965) “ The tendency for entropy to increase in isolated systems is expressed in the second law of thermodynamics - perhaps the most pessimistic and amoral formulation in all human thought. Sir Arthur Stanley Eddington, The Nature of the Physical World (1927) “ But if your theory is found to be against the second law of thermodynamics I can give you no hope there is nothing for it but to collapse in deepest humiliation. If it is found to be contradicted by observation - well, these experimentalists do bungle things sometimes. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations - then so much the worse for Maxwell's equations. The law that entropy always increases, holds, I think, the supreme position among the laws of Nature. A heat engine is a mechanical device that provides useful work from the difference in temperature of two bodies. Pressure, density and temperature differences in an isolated system, all tend to equalize if given the opportunity density and pressure, but not temperature, are affected by gravity. In a general sense, the second law says that temperature differences between systems in contact with each other tend to even out and that work can be obtained from these non-equilibrium differences, but that loss of thermal energy occurs, when work is done and entropy increases.
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