In the Beginning was Information

work is theoretically impossible. This asymmetry is a primary result of thesecond law. In addition, the second law asserts that closed systems tendtowards a state where the usable energy is a minimum, and the entropybecomes a maximum. The change in the amount of entropy indicateswhether a process is reversible or not. The better a process can prevent anincrease in entropy, the more useful energy can be produced. Potential andkinetic energy, as well as electrical energy, can be arbitrarily convertedinto one another in such a way that the process is very nearly completelyreversible and can thus produce a maximum amount of useful work.On the other hand, heat energy can only be partially converted intomechanical work or into some other form of energy. It is impossible toconvert more than a certain fraction of the supplied heat energy, as givenby the formula Ë = (T 2 - T 1 )/T 2 for an ideal Carnot machine (a reversibleCarnot cycle; see also paragraph 2.5). This thermodynamically possibleamount of useful energy is known by a distinctive name, exergy. The factthat it is impossible to obtain more work from a heat engine than allowedby Ë C follows directly from the second law.Living organisms have a greater efficiency (= useful mechanical workobtained from a given energy input) than the maximum thermal efficiencyallowed by the second law. This does not contradict this natural law, butindicates that the Creator has endowed body muscles with the capacity toconvert chemical energy directly into mechanical work, and do so muchmore efficiently than ordinary heat engines can.Conclusion: The law of entropy precludes all events which might lead to adecrease in entropy, even while obeying the energy law. Entropy thusreveals itself to be one of the most important and most remarkable conceptsof physics.Entropy and disorder? In countless publications examples are givenwhich illustrate that when the entropy of a system increases, the amountof disorder also increases; in other words, the orderliness is diminished.This idea has unfortunately also been extended to biological systems. Thefollowing arguments refute such a view:– Biological processes take place in open systems, and are not closed. Thesecond law allows a decrease in entropy as long as there is a correspondingincrease in entropy in the environment. But what is completelyprecluded is that the overall amount of entropy could be diminished.– There can be no generally valid relationship between entropy and disorder,because entropy is a physical quantity which can be formulatedexactly, but there is no exact formulation for disorder. The presentauthor attempted a classification of the order concept in [G5], and differentkinds of order are depicted in Figure 43.225