Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 exptools 1/6/84; site iham1.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!ihnp4!iham1!gjphw From: gjphw@iham1.UUCP Newsgroups: net.origins Subject: Re: Thermodynamics Message-ID: <214@iham1.UUCP> Date: Tue, 18-Sep-84 14:30:39 EDT Article-I.D.: iham1.214 Posted: Tue Sep 18 14:30:39 1984 Date-Received: Tue, 25-Sep-84 03:23:13 EDT References: <282@uwmacc.UUCP> Organization: AT&T Bell Labs, Naperville, IL Lines: 135 In a recent submission, N. Sharp posted a comment concerning an application of nonequilibrium thermodynamics. In reply, P. DuBois provided a quotation from a two part article that appeared in *Physics Today* (vol 25, Nov. and Dec. 1972) entitled *Thermodynamics of evolution* which was written by I. Prigogine et al. Also included was a second quotation (from *Impact of Science on Society*) that I have not checked. > ..."The point is that in a non-isolated system there exists a > possibility for formation of ordered, low-entropy structures > at sufficiently low temperatures. This ordering principle is > responsible for the appearance of ordered structures such as > crystals as well as for the phenomena of phase transitions. > > Unfortunately this principle cannot explain the formation of > biological structures. The probability that at ordinary > temperatures a macroscopic number of molecules is assembled > to give rise to the highly-ordered structures and to the > coordinated functions characterizing living organisms is > vanishingly small. The idea of spontaneous genesis of life > in its present form is therefore highly improbable, even on > the scale of the billions of years during which prebiotic > evolution occurred." > > Prigogine, Nicolis and Babloyantz, "Thermodynamics of Evolution." > Physics Today, 1972, v. 25. > > Speaking of dissipative structures and order through fluctuations, > Prigogine writes, > > "...let us have no illusions - our research would still leave us > quite unable to grasp the extreme complexity of the simplest > of organisms." > > Prigogine, "Can Thermodynamics Explain Biological Order?" Impact > of Science on Society, 1973, v. 23(3). > > (i) WRT the second quote: this is not to say that no progress > can be made in the direction of understanding such complexity. > I say this explicitly in the attempt to ward off the spate of > non-arguments such as were seen in the variable 'c' affair, in > which I was alleged to be arguing for a variable value of 'c'. > I didn't say 'c' varies there, and I don't say here that thermo > will never explain or describe biological complexity. > But perhaps one might reasonably express skepticism about the > place of evolution in producing that complexity? > > (ii) creationists are said to be "notorious" for quoting out > of context. If you think I'm doing so here, explain why, > please. With respect to the first of Mr. DuBois' comments (i), the recognition that the second quotation of Prigogine makes a cautionary statement concerning his research is indeed important. However, with respect to the first, and longer quotation, of Prigogine (ii), I intend to show that it has been taken out of context. Allow me to continue the text from the *Physics Today* article with the paragraph that follows the above quotation and which is used to finish the section dealing with equilibrium thermodynamics: The conclusion to be drawn from this analysis is that the apparent contradiction between biological order and the laws of physics - in particular the second law of thermodynamics - cannot be resolved as long as we try to understand living systems by the methods of the familiar equilibrium statistical mechanics and equally familiar thermodynamics. There is no dispute that the empirically discovered and idealized rules for equilibrium systems (i.e., the four laws of thermodynamics) are unable to explain any increase in order. Indeed, equilibrium thermodynamics (classical thermodynamics) does not permit any increase in order, or even the maintenance of locally ordered systems. What does cause a furor is the inappropriate and naive application of equilibrium thermodynamics (typified by uniform tempera- ture, pressure, mole fractions) to nonequilibrium conditions (systems with gradients or spatial and time variations in temperature, pressure, and chemi- cal concentrations). The out-of-context charge arises because we are led to believe from the ori- ginal quotation that Prigogine was referring to nonequilibrium thermodynamics. In fact, the quotation comes from the leading section of the article showing that while equilibrium thermodynamics does allow ordered systems at very low temperatures (interesting to me, though reasonable), it does not support the spontaneous formation of order at ordinary (e.g., room) temperatures. Systems are given one of three classifications in thermodynamics. The first is called isolated where no energy or matter can be exchanged. A second is called closed because while energy can be exchanged between the system and the outside environment, matter cannot be exchanged. The third category is called open, with both matter and energy being exchanged. Prigogine's reference to *nonisolated* was with respect to the closed system that he used to control the equilibrium temperature of the example system under discussion. It is due to the incorrect impression that the section quoted from the *Physics Today* article was in reference to nonequilibrium thermodynamics, rather than merely a closed system at equilibrium, that merits the out-of-context label. (Note also that the designation of the whole universe as closed is not the same as classifying a thermodynamic system as closed.) Allow me to continue on my soapbox. The studies of thermodynamics and sta- tistical mechanics cover three distinct regimes. The first is the familiar equilibrium thermodynamics, with its four laws (numbered 0 - 3). This occurs for systems having uniform temperatures, pressures, and chemical concentra- tions. The second is thermodynamics in the linear regime, also known as the thermodynamics of irreversible processes. Applied a posteriori, this occurs in systems of shallow or weak gradients. These gradients can only be linear, and spontaneous increases in order are not possible. (It was for his work on the thermodynamics of irreversible processes that Prigogine received his Nobel prize in physics.) A third regime is called nonequilibrium thermodynamics. Systems to which this applies, again a posteriori, have strong gradients which are not neces- sarily linear. Prigogine has already shown that in certain chemical systems, spontaneous increases in local order are possible in strongly nonequilibrium conditions (open systems). It is these nonequilibrium conditions which seem to apply to virtually all observed situations on Earth (at least within the biosphere) and appear to be most promising for further work. Prigogine et al are busily trying to discover the mathematical formulations that describe these systems that are far from equilibrium. Even in his technical writings and monographs, Prigogine has been making claims that his work in nonequilibrium thermodynamics can be used to explain all kinds of phenomena, especially living systems. These claims have all too often been difficult to substantiate or understand at this time. The *Physics Today* quotation struck me as out of character for Prigogine, so I explored it further. The *Impact* quotation is refreshingly cautious. -- Patrick Wyant AT&T Bell Laboratories (Naperville, IL) *!iham1!gjphw