Entropy def12/15/2023 ![]() Rather, entropy is a measure of disorder. Yet, much like the commonplace misinterpretation of Darwin's theory of natural selection as 'survival of the fittest', entropy is not 'a progression from order to disorder or chaos'. A common misinterpretation of the concept of entropy, that all systems progress towards more disorder, has been leveraged by those challenging evolutionary science and the teaching of evolution in schools by asserting that thermodynamics falsifies evolution (for example, Morris 2000, Ross 2004, Yahya 2005 ()). As with the concept of entropy, the theory of evolution by natural selection was originally proposed and has been refined primarily during the preceding two centuries (Figure 1). Although not immediately obvious, the inaccurate characterization of entropy weighs heavily in current events involving education, especially in national and international debates involving the teaching of evolution. It is perhaps apropos that the concept of entropy has continuously picked up misunderstandings and misinterpretations that have left the concept bloodied, beaten, and unrecognizable. Clarification of the interactions between entropy, the second law of thermodynamics, and evolution has the potential for immediate benefit to both students and teachers. Finally, we discuss the association of these traditionally physics-related concepts to evolution. ![]() We provide teachable examples of (correctly defined) entropy that are appropriate for high school or introductory college level courses in biology and evolution. Herein, we review the history of the concept of entropy from its conception by Clausius in 1867 to its more recent application to macroevolutionary theory. Entropy is a metric, a measure of the number of different ways that a set of objects can be arranged. Entropy is not disorder or chaos or complexity or progress towards those states. We write \(S^o_A\left(T\right)\) to indicate the absolute entropy of substance \(A\) in its standard state at temperature \(T\).Misinterpretations of entropy and conflation with additional misunderstandings of the second law of thermodynamics are ubiquitous among scientists and non-scientists alike and have been used by creationists as the basis of unfounded arguments against evolutionary theory. It is usually included in compilations of thermodynamic data for chemical substances. The standard entropy is usually given the symbol \(S^o\). ![]() When the entropy value is calculated for one mole of the substance in its standard state, the resulting absolute entropy is called the standard entropy. Where the substance undergoes phase changes, the contribution that the phase change makes to the entropy of the substance is equal to the enthalpy change for the phase change divided by the temperature at which it occurs.Īt any given temperature, the entropy value that is obtained in this way is called the substance’s absolute entropy or its third-law entropy. ![]() Phase changes are isothermal and reversible. In temperature ranges where experimental heat capacity data are available, the entropy change is obtained by integration using these data. \), using Debye’s theoretical relationship, \(C_P=AT^3\) \(A\) is obtained from the value of \(C_P\) at the lowest temperature for which an experimental value of \(C_P\) is available. ![]()
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