hua@cmu-cs-edu1.ARPA (Ernest Hua) (05/18/85)
______________________________________________________________________ > { from: miller@uiucdcsb.Uiuc.ARPA (A Ray Miller) } > > It has been suggested by some, that thermodynamics does not apply to > evolution. Indeed, one evolutionist on the net, after giving us the > entropy equation for heat flow, concluded: > > > In other words, people, the second law of thermodynamics, as the > > name implies, has to do with *thermodynamics*, and cannot be mean- > > ingfully applied to any other field. You probably misquoted him. I seriously doubt he means this literally. If he does, then he is seriously wrong. ______________________________________________________________________ Keebler { hua@cmu-cs-gandalf.arpa }
js2j@mhuxt.UUCP (sonntag) (05/20/85)
> ______________________________________________________________________ > > > { from: miller@uiucdcsb.Uiuc.ARPA (A Ray Miller) } > > > > It has been suggested by some, that thermodynamics does not apply to > > evolution. Indeed, one evolutionist on the net, after giving us the > > entropy equation for heat flow, concluded: It wasn't the entropy equation for heat flow, it was how the well-known textbook, University Physics, by (somebody), Zemanski and Young, *defines* entropy. > > > > > In other words, people, the second law of thermodynamics, as the > > > name implies, has to do with *thermodynamics*, and cannot be mean- > > > ingfully applied to any other field. > > You probably misquoted him. I seriously doubt he means this literally. > If he does, then he is seriously wrong. > All right then, please provide a rigorous definition of entropy along with your source, which allows the concept to be applied quantitatively to things like evolution (or any other non-thermodynamic process). > Keebler { hua@cmu-cs-gandalf.arpa } *** REPLACE THIS LINE WITH YOUR MESSAGE *** -- Jeff Sonntag ihnp4!mhuxt!js2j "Time has passed, and now it seems that everybody's having those dreams. Everybody sees himself walking around with no one else." - Dylan
mmt@dciem.UUCP (Martin Taylor) (05/23/85)
I haven't seen this newsgroup in more than a month, an the first time I look, I see a new idea! > All right then, please provide a rigorous definition of entropy >along with your source, which allows the concept to be applied quantitatively >to things like evolution (or any other non-thermodynamic process). >Jeff Sonntag How come evolution is not a thermodynamic process? Doesn't it conform to the laws of nature, then? Perhaps you mean non-equilibrium process, or non-isolated, but surely everything physical obeys the laws of thermodynamics insofar as they are correct descriptions of nature, just as everything obeys all the other laws of nature (except for those supernatural events so well known in this newsgroup). Maybe we have here the clue to the inconclusive nature of the creation-evolution argument: The creationists assure us that creationism is science, but to agree demands a great amount of faith; now an evolutionist argues that evolution is not science, but to agree demands a great suspension of faith. So -- let's have a coordinated creavolationist philosophy, in which you let the laws of nature run when you want them to, and suspend them when convenient. It would be so much easier to do research in this paradigm! Come to think of it, that's just creationism, isn't it. -- Martin Taylor {allegra,linus,ihnp4,floyd,ubc-vision}!utzoo!dciem!mmt {uw-beaver,qucis,watmath}!utcsri!dciem!mmt
js2j@mhuxt.UUCP (sonntag) (05/23/85)
Martin Taylor writes: > I haven't seen this newsgroup in more than a month, an the first time I > look, I see a new idea! > > > All right then, please provide a rigorous definition of entropy > >along with your source, which allows the concept to be applied quantitatively > >to things like evolution (or any other non-thermodynamic process). > >Jeff Sonntag > > How come evolution is not a thermodynamic process? Doesn't it conform > to the laws of nature, then? Of course it does. What I meant was that the definition of entropy which I posted (from "University Physics" by Sears, Zemansky and Young) is a quantitative formula involving the heat and temperature distribution within a system. Just how would you go about applying that to the concept of evolution? As long as we were using the fuzzy english language definition of entropy as 'disorder' it was easy enough for creationists to say that evolution violated the second law (always ignoring that little detail about 'in a closed system'.) When I say that evolution is a non-thermodynamic process, I don't mean that it is somehow exempt from thermodynamic laws. I just mean that *I* don't see any way to apply thermodynamics to study the process of evolution. *You* are welcome to try it, of course, but please use real, quantitative definitions of entropy, heat, temperature, etc, if you expect your results to have any validity. The second law is only a law when you use the real definitions of the terms it uses. While a closed system consisting of a pool player and table obeys the second law of thermodynamics, the second law would be useless to describe the motion of the balls (except to predict that at some indeterminate time in the future they would all be stopped.) Similarly, the second law can be applied to evolution only insofar as evolution can be described in terms of heat concentration and temperature distributions *or* if entropy can be defined somehow in terms which are more descriptive of biological systems. -- Jeff Sonntag ihnp4!mhuxt!js2j "Time has passed, and now it seems that everybody's having those dreams. Everybody sees himself walking around with no one else." - Dylan
rlp@cbosgd.UUCP (Bob Platt) (05/24/85)
Summary:applying thermodynamics to evolution > from Jeff Sonntag: > > ...the second law can be > applied to evolution only insofar as evolution can be described in terms of > heat concentration and temperature distributions *or* if entropy can be > defined somehow in terms which are more descriptive of biological systems. This has been attempted, although exactly how succesfully I can't say, as the mathematics are very complicated and beyond me. My source is "Structural Stability and Morphogenesis" by Rene Thom (Benjamin/Cummings 1975). I won't reproduce the specific mathematical details here, but the following quotes give the flavor of Thom's approach: "If two systems S1 and S2, with total energy c, are thermodynamically coupled, the equilibrium regime will occur at the value of t for which the total entropy S1(c-t) + S2(t) is maximum. If there is only one sufficiently sharp maximum, the joint system will evolve toward this state and stay there, neglecting fluctuations. "The importance of thermodynamical coupling comes from the fact that, if two dynamical systems over two contiguous open sets U1 and U2 are put into spatial contact, we can suppose (without any special hypothesis concerning the nature of the interaction) that the two systems are thermodynamically coupled." --- In the context of evolution, the "two systems" may be interacting species, such as wasps and orchids: "We must not forget that the essential object of study in biology is not the isolated individual but the continuous form in space-time joining parents to descendants; more precisely, when two or more species having some functional interaction between each other, such as predation or being an auxiliary in the fertilization process, it is necessary to consider the total figure in space-time, the union of all forms associated with each species. Then, for each adaptive process, we can probably find a function S of the local biological state expressing in some way the complexity of the state with respect to the process considered, and the configuration will evolve between two times t0 and t1 (e.g. parent at age A and offspring at same age) in such a way as to minimize the global complexity <integral from t0 to t1> of <magnitude of S> dt "In this way the minimum complexity and hence the most economical adaptation of the process will be realized. Natural selection is one factor in this evolution, but I myself think that internal mechanisms of Lamarckian character also act in the same direction." --- He of course realizes that this maximization of entropy occurs against a backdrop of negative entropy introduced by the sun: "The solar photons arriving in contact with the soil and seas are immediately stopped, and their energy abruptly degraded into heat; in this way the discontinuity of the earth and water surface is also a shock wave, a cliff down which the negentropy of the sun's rays falls. Now, life can be considered as a kind of underground erosion of this cliff, smoothing out the discontinuity; a plant for example is nothing but an upheaval of the earth toward the light, and the ramified structure of its stem and root is the same as that found when a stream of water erodes a cliff..." --- Thom's ideas are highly speculative, and has been criticized (rightly or wrongly) for couching his speculations in highly abstract terms understandable only to highly trained mathematicians. Nevertheless, he has presented a theory that specifies biological measures of entropy and information, makes predictions, and is falsifiable. Joe Knapp ATT-BL Columbus OH -- +----+ R. L. Platt /| /| AT&T Bell Laboratories +-|--+ | Columbus, Ohio | +--|-+ |/ |/ cbosgd!nscs!rlp +----+ (614) 860-4850 "Wherever you go, there you are"
friesen@psivax.UUCP (Stanley Friesen) (05/31/85)
In article <1200@cbosgd.UUCP> rlp@cbosgd.UUCP (Bob Platt) writes: >Summary:applying thermodynamics to evolution > >> from Jeff Sonntag: >> >> ...the second law can be >> applied to evolution only insofar as evolution can be described in terms of >> heat concentration and temperature distributions *or* if entropy can be >> defined somehow in terms which are more descriptive of biological systems. > > This has been attempted, although exactly how succesfully I can't >say, as the mathematics are very complicated and beyond me. My source >is "Structural Stability and Morphogenesis" by Rene Thom (Benjamin/Cummings >1975). I won't reproduce the specific mathematical details here, but the >following quotes give the flavor of Thom's approach: > >"If two systems S1 and S2, with total energy c, are thermodynamically > coupled, the equilibrium regime will occur at the value of t for which >the total entropy S1(c-t) + S2(t) is maximum. If there is only one >sufficiently sharp maximum, the joint system will evolve toward this state >and stay there, neglecting fluctuations. > "The importance of thermodynamical coupling comes from the fact >that, if two dynamical systems over two contiguous open sets U1 and U2 >are put into spatial contact, we can suppose (without any special >hypothesis concerning the nature of the interaction) that the two >systems are thermodynamically coupled." >--- >In the context of evolution, the "two systems" may be interacting >species, such as wasps and orchids: > > "We must not forget that the essential object of study in >biology is not the isolated individual but the continuous form in >space-time joining parents to descendants; more precisely, when two >or more species having some functional interaction between each other, >such as predation or being an auxiliary in the fertilization process, >it is necessary to consider the total figure in space-time, the union >of all forms associated with each species. >--- But this still does not address the other aspect of Jeff Sontag's objection, that is justifying treating a species as a thermodynamic system. Even the quotes only specify *how* one would treat a species as a thermodynamic system, not the reasons why doing so might be permissible. In short Dr Thom is here making a conceptual leap without adequate reasons(at least as far as the quoted excerpts are concerned). The problem with the treatment is that living things are *not* particles on the same sense as atoms in a gas(a typical thermodynamic system). One theoretically important difference is that particles of the same type in the physisist's sense are *indistinguishible* while conspecific organisms are fully distinguishable(that is they are not interchangeable without changing the state of the system). >Thom's ideas are highly speculative, and has been criticized (rightly >or wrongly) for couching his speculations in highly abstract terms >understandable only to highly trained mathematicians. Nevertheless, >he has presented a theory that specifies biological measures of entropy >and information, makes predictions, and is falsifiable. > And in my opinion also for inadequate justification of a major conceptual leap. -- Sarima (Stanley Friesen) {trwrb|allegra|cbosgd|hplabs|ihnp4|aero!uscvax!akgua}!sdcrdcf!psivax!friesen or {ttdica|quad1|bellcore|scgvaxd}!psivax!friesen
rlp@cbosgd.UUCP (Bob Platt) (06/09/85)
>>> from Jeff Sonntag: >>> >>> ...the second law can be >>> applied to evolution only insofar as evolution can be described in terms of >>> heat concentration and temperature distributions *or* if entropy can be >>> defined somehow in terms which are more descriptive of biological systems. >> >> This has been attempted [in] "Structural Stability and Morphogenesis" >> by Rene Thom (Benjamin/Cummings 1975). >> ... > from Stanley Friesen: > > But this still does not address the other aspect of Jeff >Sonntag's objection, that is justifying treating a species as a >thermodynamic system. Even the quotes only specify *how* one would >treat a species as a thermodynamic system, not the reasons why doing >so might be permissible. In short Dr Thom is here making a conceptual >leap without adequate reasons... Well, I pretty much agree that the treatment is far from rigorous. Let me expand the context of the first quote though, as you may have been misled a bit by what appeared to be the opening salvo from a creationist: "If there is only one sufficiently sharp maximum [of entropy], the joint system will evolve toward that state and stay there, neglecting fluctuations. [He continues] On the other hand, if there are several maxima or if the maximum is very flat, we cannot say anything a priori about the evolution of the system, for it could take on one of these maxima, or fluctuate without a well-determined limit." So although the trend is toward a local maximum, an opening is there for an increase in complexity. Rupert Sheldrake in "A New Science of Life" (Houghton 1981), makes the point very well: "In living cells, the physico-chemical systems ... include many potentially indeterminate phase transitions and non-equi- librium thermodynamic processes. In the protoplasm there are crystalline, liquid and lipid phases in dynamic inter-relation; then there are numerous types of macromolecule which can come together in crystalline or quasi-crystalline aggregates; lipid membranes, which as 'liquid crystals' hover on the borderline between liquid and solid states, as do the colloidal sols and gels; electrical potentials across membranes which fluctuate unpredictably; and 'compartments', containing different concentrations of inorganic ions and other substances, separated by membranes across which these substances move probabilistically. With such complexity, the number of energetically possible patterns of change must be enormous, and there is thus a vast scope for the operation of morphogenetic fields through the imposition of patterns on these probabilistic processes." So the problem remains of how to reconcile some intuitive notion of complexity (of the form) with entropy. As you have maintained, it turns out that this is not straightforward. Complexity depends on context. A good example is that of trying to estimate the complexity of the light reaching an organism. A plant extracts merely (but very efficiently) the raw energy of the stream of photons; a mammal extracts information from the patterns of the light waves, facilitating its quest for energy (Thom 1975). We also have to realize that our idea of complexity may not be synonomous (in principle) with entropy, re the following thought experiment: Suppose there is a salt solution at room temperature which is placed into a low-temperature system which is then closed. As the solution cools the salt crystallizes. Intuitively, at least, there seems to have been an increase in morphological complexity in this non-living closed system, although there has clearly been an increase in entropy. In addition, thermodynamics is powerless to explain the spatial distribution of the crystal(s). (Sheldrake 1981) But don't just throw your hands up in mock-despair of ever reconciling these difficulties. You may be afraid that attempts at injecting the principles of thermodynamics into biology are usually a net loss for science due to misuse by ideologues. But don't let that close your mind to every application. And there is some concrete justification for this one. For example, although the form and flow of a river system resists strict thermodynamical treatment, there is no reason to doubt that its morphogenesis is subject to those principles. Thom's insight has been to note the similar morphogenesis of many of earth's forms (e.g. river networks, plant branching, human nervous system development) and to give mathematical justification to many of those observations. The model presupposes a space of external parameters which imposes a certain topology on the way that the form evolves. While the dimension of this space may be very large in principle, often a local model can be constructed that depends on only a few parameters (and observables) and in these cases, the topology of the space can be analyzed, and the "structurally stable" patterns of morphogenesis classified. Entropy (and other measures) plays a role in determining this structure. Since it seems that non-living and living systems do show similar patterns, I believe that the "conceptual leap" if not justified, is definitely worth pursuing. It's refreshing to see the problem of the birth of form tackled head on, not swept it under the rug with the promise that the biochemists will eventually figure it out. Joe Knapp cbosgd!nscs!jmk "I used to be a member of the reptile family, but I'm NOT anymore!" Leonard Zelig