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Author | Topic: Thermodynamics and The Universe | |||||||||||||||||||||||||||
Percy Member Posts: 22499 From: New Hampshire Joined: Member Rating: 4.9 |
Ringo writes: Hoot Mon writes: If I placed a fresh deck of cards on the ground, and next to it I placed a shuffled deck, which of the two decks comprises (i.e., has) more entropy? The shuffled deck, of course. I'm not following that at all. Why would one arbitrary sequence of cards have "more entropy" than another? AbE: Let me quickly add a comment that I actually deleted before posting this. After seeing that Cavediver's message it's probably important to note that Hoot Mon seems to move back and forth freely in questionable ways between an information theoretic approach to entropy and a traditional thermodynamic approach. Good question. You're of course absolutely right that both orderings are arbitrary and equally unlikely. Hoot Mon's example does not state that the information about whether a deck is sorted or not is communicated to the person examining the decks. Without this information, both decks have equal entropy. If you change the example so that before examining a deck the person is told whether or not it is sorted, then he receives no information from actually examining the sorted deck because he already knows the order of the cards. All the necessary information was already communicated when he was told the deck was sorted. Once he was told it was sorted he already knew the order of the cards. Since he learns nothing from examining the order of cards in the sorted deck, in other words, no information is communicated, the entropy in the sorted deck is low. In information theory, low entropy is associated with communicating little information. On the other hand, in examining the shuffled deck the person examining it learns something new about the order of cards with every next card he examines. He is, of course, learning less and less information with each card. For example, the first card has 52 different possibilities, and so by examining the first card he learns a great deal. The last card has only one possibility, since by process of elimination there's only one card that could be left, so once 51 cards have been examined there is no point in actually examining the last card since it is a virtual certainty what it is. But the random deck has very high entropy since something is learned with every card but one. So if we change Hoot Mon's example to assume we're told which deck is sorted, then this is consistent with what Hoot Mon claimed. --Percy Edited by Percy, : Add brief clarification.
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Fosdick  Suspended Member (Idle past 5527 days) Posts: 1793 From: Upper Slobovia Joined: |
Percy wrote:
I want to make it clear that I am just a novice student of dissipative structures”only a isolated reader. I come to forums like this one to get my ass kicked into proper alignment and my head corrected for ignorance (and stupidity). If you have a better understanding of Prigogine than I then please educate me. I've tried my best to address all of your issues.
I don't think you have a clear understanding of what Prigogine means by a dissipative structure, and the ambiguity in your understanding is causing you to draw false conclusions. This is as untrue today as it was all the other times you said this. Manure is an open system. In an open field with the sun beating down on it, a recent cowpat that is full of microorganisms will likely have a negative dS, while a rock would have a positive dS. In other words, the rock would have greater dS. If a car burns one gallon of gas per hour to maintain a speed of 30 mph over a period of 48 hours, the rate of fuel burning and entropy production from hour to hour and day to day does not change. However, this was accomplished by burning 48 gallons of fuel, which amounts to a lot of irreversible entropy production over time: dS/dt 0. Prigogine states in the first chapter of his From Being to Becoming (1980):
quote:I hope I've cleared more than muddied the waters. For your part, can you provide something more than mere negation to force your points? I'd appreciate a few relevant quotes from experts to support your argument. ”HM
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JustinC Member (Idle past 4871 days) Posts: 624 From: Pittsburgh, PA, USA Joined: |
Just a question from the sideline...you write:
Thermodynamic equilibrium is not defined as dS=0, but rather is defined as a system in a state where dS cannot be anything but 0. is the "cannot" too strong? According to the probabalistic interpretation of entropy, isn't it just very likely that the system will remain in a state of maximum entropy (by definition)? There's still a chance (Vanishingly small as it may be) that entropy will decrease, right?
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Percy Member Posts: 22499 From: New Hampshire Joined: Member Rating: 4.9 |
Hoot Mon writes: This is as untrue today as it was all the other times you said this. Manure is an open system. In an open field with the sun beating down on it, a recent cowpat that is full of microorganisms will likely have a negative dS, while a rock would have a positive dS. In other words, the rock would have greater dS. If a car burns one gallon of gas per hour to maintain a speed of 30 mph over a period of 48 hours, the rate of fuel burning and entropy production from hour to hour and day to day does not change. However, this was accomplished by burning 48 gallons of fuel, which amounts to a lot of irreversible entropy production over time: dS/dt 0. Your example is correct, but it's just an example of a different situation, not a counter example, and it isn't equivalent to the manure in your other example. In your car example you're considering the car as a closed system with no energy input (in the form of gasoline fillups). In your manure example, the manure is an open system, not closed, and what I originally said is that it is very difficult to know whether the entropy of the manure is increasing or decreasing. A recent cowpat in the hot sun is likely decreasing in entropy as the microorganisms transform the heat from the sun and the raw materials from the cowpat into methane and other chemicals as well as reproducing more of themselves. An old cowpat, perhaps at the bottom of a pile of old cowpats, with dying or diminishing populations of microorganisms is likely increasing in entropy. But my main point is that the determination of the direction of entropy changes in something as complex as life is often not a realistic possibility. You can draw broad trends in certain situations as I've tried to do, but there are so many factors involved that it is very difficult to be certain. That's why I keep telling you that you can't make definitive statements such as that manure gains entropy faster than rocks. First it depends upon a lot of factors, and second those factors aren't easy to analyze.
I hope I've cleared more than muddied the waters. For your part, can you provide something more than mere negation to force your points? I'd appreciate a few relevant quotes from experts to support your argument. I think the clarifications I've offered you about your manure versus rock example are far more than mere negation. I've explained the same thing a number of times and a number of different ways. I don't have quotes from any experts, just an understanding of thermodynamics that I learned at university, honed over the years through frequent discussions such as this one. I didn't learn thermodynamics by reading quotes from experts, and I don't think I could really name any experts. Your Prigogine excerpt is just a simple illustration and description of 2LOT, but it is fundamental to this discussion. Anything either of us says must obey 2LOT or it's wrong. But this isn't the tricky part of thermodynamics for this particular discussion. The tricky part is building an understanding of which types of processes tend to increase entropy versus which types decrease entropy. In general, heating that merely causes state changes increases entropy, but once the system heats up it will begin radiating as much heat as it absorbs and entropy will increase no longer. But heating that drives chemical reactions that store energy decrease entropy. In other words, the system has stored the potential to do work in the newly formed chemical bonds. I'd never heard of Prigogine until you mentioned him, and if his ideas about viewing life as dissipative structures are influential within biology then it is a rather quiet influence, as I hadn't heard of them before. I'm a little puzzled why you would focus on the ideas of Prigogine instead of just studying up on thermodynamics. I quick Google reveals that Prigogine is mentioned in some creationist source material, such as Duane Gish's book Creation Scientists Answer Their Critics, but only to dismiss his ideas. --Percy
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Percy Member Posts: 22499 From: New Hampshire Joined: Member Rating: 4.9 |
I can only guess that you're referring to thermodynamics origins with Boltzmann and his statistical approach. This is a kind of micro view of thermodynamics that I'm not that familiar with, I'm more familiar with a higher level view. Statistical approaches always have probabilistic error bars, but even at higher levels of abstraction we still have error bars, so even if we've measured some system to have maximal entropy, we could never be certain that was the case. Like absolute zero, maximal entropy is probably a state we'll never achieve in any practical terms.
--Percy
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JustinC Member (Idle past 4871 days) Posts: 624 From: Pittsburgh, PA, USA Joined: |
quote:I am referring to the Boltzmann view, I should have been more explicit. For example, take the simple case of a box with white gas molecules on one side and black on the other seperated by a partition. Once you remove the partition, the gas becomes homogenous. The statistical approach basically says "there are more ways to be disordered" so that is the most likely state the gas will be in. Or, to flip it around, the state that a system is most likely to be in is defined as "most disordered." The view also says that given enough time it is possible for the gas to once again separate since it's just more probable that is will be in a state of homogeneity. I'm positive you've heard this before, but that is the angle I was looking at your statement from.
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Chiroptera Inactive Member |
quote: Actually, the statistical approach says, "there are more ways for white molecules to be more or less evenly distributed throughout the box and for black molecules to be distributed throughout the box than for white molecules to be all on one side and for black molecules to be on the other side." The word disorder isn't really well defined, except that you say:
quote: That's about the best definition for "disordered" that I've seen. I would, though, say that the macroscopic state that is produced by the largest set of microscopic states is the most disordered. Actually, if their god makes better pancakes, I'm totally switching sides. -- Charley the Australopithecine
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Fosdick  Suspended Member (Idle past 5527 days) Posts: 1793 From: Upper Slobovia Joined: |
Percy wrote:
Ilya Prigogine won the 1977 Nobel Prize in chemistry for his advances in irreversible thermodynamics and his theory of dissipative structures. I have an article from Science (Procaccia & Ross, Nov. 18, 1977, pp. 716-17) describing Prigogine’s work. I’ll try to summarize it here with relevant excerpts:
I'd never heard of Prigogine until you mentioned him, and if his ideas about viewing life as dissipative structures are influential within biology then it is a rather quiet influence, as I hadn't heard of them before. I'm a little puzzled why you would focus on the ideas of Prigogine instead of just studying up on thermodynamics. quote:Lars Onsager had won the 1968 Nobel Prize in chemistry for proving that thermodynamic methods can be applied to nonequilibrium situations not too far from equilibrium. quote:From there, Prigogine developed his theory of dissipative structures to account for organization occurring in systems operating far from equilibrium. He went on to prove that entropy production is a Lyapounoff function (re: a math model of the stability of stationary states). quote: For a while, at least, back in the ”80s and ”90s, Prigogine was highly regarded for his fresh insight into biological processes, namely evolution.
quote:To me, a biologist pretending to understand evolution, Prigogine’s discoveries seem important. They would seem to answer Schodinger’s question: How does life manage to accomplish self-organization and not disobey the second law? Still, I am left asking, What has Prigogine done for me lately? ”HM
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Percy Member Posts: 22499 From: New Hampshire Joined: Member Rating: 4.9 |
Hoot Mon writes: To me, a biologist pretending to understand evolution, Prigogine’s discoveries seem important. They would seem to answer Schodinger’s question: How does life manage to accomplish self-organization and not disobey the second law? I'm not that familiar with the period when Schrodinger spoke in the 1940's, and Prigogine's work predates his Nobel prize in 1977 by quite a bit. You seem to be going pretty far back in time to find a mystery. I have no idea why Schrodinger chose to portray the cell's maintenance of organization as a puzzling thermodynamic mystery, but today his characterization seems both quaint and naive. Even when he said this back in the 1940's it might have sounded so, but I think such comments were just lead-in to his more serious speculations about cell organization, in some ways anticipating the discovery of the structure of DNA by Crick and Watson. If I were to translate his comments into modern terms, he was saying that a self-organizing/replicating molecule like DNA (in the sense of the way the nucleotides always choose the same partner) *had* to exist, even though at the time we had no idea what it was. Whether scientists really felt the cell's ability at maintaining organizational structure to be puzzling thermodynamically 50 years ago, I can't say, though I tend to doubt it. Today certainly there is no such puzzle. Open systems are free to gain and lose entropy, and loss of entropy is associated with increases in organization. --Percy
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JustinC Member (Idle past 4871 days) Posts: 624 From: Pittsburgh, PA, USA Joined: |
quote:Pedantry gratefully accepted.
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Fosdick  Suspended Member (Idle past 5527 days) Posts: 1793 From: Upper Slobovia Joined: |
Percy wrote:
1. Nobel Prizes are not usually awarded right away; Watson & Crick didn’t get theirs until 1962. I'm not that familiar with the period when Schrodinger spoke in the 1940's, and Prigogine's work predates his Nobel prize in 1977 by quite a bit. You seem to be going pretty far back in time to find a mystery...Whether scientists really felt the cell's ability at maintaining organizational structure to be puzzling thermodynamically 50 years ago, I can't say, though I tend to doubt it. Today certainly there is no such puzzle. Open systems are free to gain and lose entropy, and loss of entropy is associated with increases in organization. 2. Have you considered the actual principles”the physicochemical ones”that enable biological self-organization? I believe Prigogine is the only scientist to demonstrate convincingly those principles that enable self-organization to occur far from equilibrium. Indeed that's what his theory of dissipative structures is all about. 3. Please keep in mind that I am older than most on this forum. I took my last exams in engineering with a slide rule. That was in 1970-71, three years before the HP-35 came out. If you will open your historical timeframe just a bit more, you could see how scientists back then struggled with how the self-organization of biological life flies, apparently, in the face of the Second Law and its disording principle. We all had copies of Schrdinger’s little orange book What Is Life & Mind And Matter (1958), and we liked the challenge he presented to physicists and chemists (pp. 3 & 4):
quote:He goes on to discuss order, disorder, and entropy in open systems with irreversible processes. Schrdinger could be credited for anticipating the principles of dissipative structures”he and Onsager. But Prigogine brought them around successfully enough to be awarded the 1977 Nodel Prize in chemistry. Mystery solved, I thought. At least now there are known thermodynamic principles that are friendly to biological life. And thus Prigogine became my hero. Sorry for belaboring the history lesson. Old farts will do that. ”HM
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Percy Member Posts: 22499 From: New Hampshire Joined: Member Rating: 4.9 |
You're missing my point. I wasn't trying to cast Prigogine's work in a negative light. I was saying it was a long time ago and doesn't seem to have any particular relevancy today. In Schrodinger and Priogine's day they didn't know what we know today about the chemistry within the cell and especially the nucleus. The puzzles about how life managed to obey thermodynamic laws have long since been answered.
As I said earlier, viewing life as dissipative structures does not appear to have had any particularly visible influence on modern biology. Neither Prigogine nor dissipative structures appear in the index of any of my four biology textbooks. You don't appear to have an accurate understanding of his views anyway, for example believing that being far from thermodynamic equilibrium indicates high entropy, and that's why I think your efforts would be better focused on understanding thermodynamics than on contemplating Prigogine.
3. Please keep in mind that I am older than most on this forum. Me too. So what. There's no excuse for becoming irrelevant while still able to think. If anything, I find greater experience provides an advantage. --Percy
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cavediver Member (Idle past 3671 days) Posts: 4129 From: UK Joined: |
for example believing that being far from thermodynamic equilibrium indicates high entropy I must admit I've never seen Prigogine's work before - or not that I can recall. However, at first glance he is possibly talking about local maxima of entropy, stable points in entropy space that are far away from the true maximum. Relative to the true maximum, they are low entropy but are trapped by surrounding lower entropy states. We do have the physics of local minima of energy, which give rise to solitons and related entities. It sounds like he tried to do something similar with biological entities. I have no idea how useful such as idea would be, and this ties in with some of the comments I have read concerning his science, which suggest that it was all well and good but had little to no useful nor predictive value...
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Hyroglyphx Inactive Member |
For a while, at least, back in the ”80s and ”90s, Prigogine was highly regarded for his fresh insight into biological processes, namely evolution.
quote: To me, a biologist pretending to understand evolution, Prigogine’s discoveries seem important. They would seem to answer Schodinger’s question: How does life manage to accomplish self-organization and not disobey the second law? Still, I am left asking, What has Prigogine done for me lately? We'd first have to ask whether or not 2LoT is even applicable to terrestrial, biological systems, such as evolution would be. Some creationists are apt to assign everything to 2LoT and some evolutionists are apt to dismiss by saying that earth is an open system, and therefore, does not qualify in practical terms. Both versions are extreme, so I generally take the middle ground on this one. Plus, there are two different meanings when either side employs 2LoT in trying to make a point. Often, when creo's are talking about it, they are talking about the inherent breakdown of any system because there is no such thing as perpetual motion. Any energy used at first dissipates with time unless new energy is introduced. So if we had an oscillating universe, they say that oscillation will eventually cease because their will not be as much useful energy as it had when it began oscillating. On the other hand, when evo's talk about 2LoT, they are often referring to things like heat and heat transfer. And so they often say that since earth has a constant source of energy, namely, the Sun, that 2LoT does not effect things like evolution. In a sense, both are right, but they are talking about two different kinds of entropy-- classical and logical-- which have been distinguished. The problem here, as you are relaying with Priogine and evolution, is that he's apt to simply ascribe everything in simple terms with the introduction of energy as almost this magical qualifier. Consider the worst example I've ever heard by Tim Berra. He once said:
[list]
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Hyroglyphx Inactive Member |
Double post
Edited by nemesis_juggernaut, : No reason given. "He has shown you, O man, what is good; And what does the Lord require of you but to do justly, to love mercy, and to walk humbly with your God. -Micah 6:8
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