Entropy is perhaps the most arcane (but not occult) of thermodynamic concepts and in the top handful in all of physics? Pressure, Temperature, and Volume are roughly directly apprehensible with the likes of Energy, Work, Ergodicity, Equilibrium, Reversibility taking a little more thought, and Entropy, Enthalpy, and the wycked mother of them all the Partition Function (Z) really difficult to think about in their own terms.
Entropy blends macroscopic state functions with microscopic statistical behaviors. It resists single-intuition anchoring: it's about disorder, information, irreversibility, energy quality, and more.
Over decades, starting with a BS in Physics, I have been through the combinatorics of iso baric/choric/thermal (PVT)systems and all of their combinations, designed to implement the suite of common cycles (rankine, stirling, otto, diesel, etc) at different times and while that helped to carve out an intuition for the other more abstract quantities (like Entropy). I don't know I've ever been lead directly to those, instead having to absorb (much of?) the full suite of examples to begin to appreciate the arcane (albeit not quite occult) quantities?
Ruth and Bruce would have a few canned examples to work through which is sometimes a good way to get there, but sometimes there is nothing more satisfying than making up your own narratives and exploring their implications, providing your world-building is consistent and coherent. George is a very patient copilot in such adventures, if not always the perfect navigator?
I'm probably just stirring (increasing the entropy of this thread)? On 6/17/25 2:47 PM, Frank Wimberly wrote:
I supplied another prompt to Géminis which i thought would yield an illuminating response:What is isentropic expansion?Isentropic expansion is a thermodynamic process where a substance (usually a gas) expands without any change in its entropy. This is an idealized process, meaning it assumes two key conditions:* Adiabatic: No heat is transferred into or out of the system.* Reversible: There are no irreversible losses due to factors like friction, turbulence, or unrestrained expansion. Because entropy is a measure of disorder or randomness in a system, a constant entropy implies that the process is as efficient as possible, with no energy "lost" or converted into less useful forms.Key characteristics of isentropic expansion: * Constant entropy (\Delta S = 0): This is the defining characteristic. * No heat transfer (\text{Q} = 0): Since the process is adiabatic.* Decrease in temperature: As the substance expands and does work, its internal energy decreases, leading to a drop in temperature. This is in contrast to an isothermal expansion where heat would be added to maintain constant temperature. * Decrease in pressure: As the volume increases and temperature drops, the pressure of the substance also decreases.Why is it important?Isentropic expansion is a crucial concept in thermodynamics and engineering for several reasons: * Idealized model: It serves as a theoretical benchmark against which real-world processes can be compared. No real process is perfectly isentropic, but understanding this ideal helps engineers evaluate how efficiently actual systems operate. * Efficiency calculations: The concept of isentropic efficiency is used to measure how closely an actual expansion process (like in a turbine) approaches the ideal isentropic case. This helps in designing more efficient engines and power systems. * Design and analysis: It's fundamental to the design and analysis of various engineering systems, including: * Turbines: In gas and steam turbines, hot, high-pressure fluids expand to produce work. Isentropic expansion helps determine the maximum work output. * Nozzles: In applications like rocket propulsion and jet engines, nozzles are designed to accelerate fluids to high velocities through isentropic expansion. * Internal combustion engines: The expansion (power) stroke in these engines is often approximated as an isentropic process for analysis. * Refrigeration cycles: Isentropic expansion plays a role in these cycles as well. In essence, isentropic expansion represents the most efficient possible expansion of a fluid, and while it's an idealization, it provides a powerful tool for understanding, analyzing, and optimizing energy conversion systems.--- Frank C. Wimberly 140 Calle Ojo Feliz, Santa Fe, NM 87505 505 670-9918 Santa Fe, NM On Tue, Jun 17, 2025, 2:44 PM Santafe <[email protected]> wrote: Hi Nick, Yes; I can report how things appear to me. Feel free to growl that they are not correct. I will stay away from making claims about what things, or you, “are”. I have no access to that. What I see is you sort-of-demanding that the terms that happen to interest you will be the terms in which natural phenomena admit an understanding. So you give more and more elaborate descriptions of experiments and ask about outcomes, but you leave out 2/3 of the specification that an actual outcome would depend on, as somebody pointed out in this latest case about the tapping. This is why Marcus’s advocacy of putting things into an algorithm is so central. If a machine generates an algorithm, it might do so by simply making guesses about all the things you didn’t actually tell it, but at least, for the algorithm to exist, we will have an explicit record of what its assumptions were. Your comments about category errors upped the ante on that; I see them as a premise that the terms you choose going in, and the rules of argument you learned in parochial school, will grant you access through thinking to how nature really is. That’s why I called you a metaphysician before (and at which you growled). What I saw was people repeatedly telling you that, when the part of humanity that works in this area uses “the entropy” referring to equilibrium, they have the property of “being constructed to mean a state function” entailed in that term, and then you continued to make assertion-statements that entropy is not a function determinable by whatever one means by “a state”. One response to such a situation might be to ask “Hmm; I wonder what-all they mean when they say `a state’; they might not be telling me enough for me to follow them.” Or, one could conclude that they are making category errors, and that your rules of argument from parochial school tell you what those errors are. Choosing to do the latter, to me, is as close as one can get in real life, to the pupil for whom the master pours tea, and continues to pour after the cup is full. The student asks why do you keep pouring when the cup is full? etc. The standard story. It’s interesting: I would be the last one to criticize anybody for trying to understand something in other terms that occur to him, than those that a field conventionally uses. I very much like that mode of working, and it is mostly what I do — not through any greatness of soul; just because I can’t follow other people, so I grab on where I can from my own proclivities. Mostly I end up in a mess that way, too. So the difference is all in what you do when you hit a snag, and the people around you seem to be able to coordinate with each other enough to be getting something done. It’s evidence, to at least be reflected upon. Your statement "I’ve gone back to feeling that I don’t even know enough to ask a question.” struck me as a glimmering of the recognition that we don’t get to dictate to nature the terms in which phenomena become understandable. Those terms are something we have to figure out along the way, along with the rules of argument that apply to them. Glen has written in many posts (a burst of them a year or two ago) about the role of embedded practice in this “coming to terms”. Of course, we can always dictate. (We used to say “It’s a free country”; though that seems more awkward now.) But wherever that dictation gets you, it won’t be understanding. Anyway. DaveW can tell you that I don’t understand anything about Zen or about any contemplative tradition. (And if he can’t tell you that, I can find others who will. It is a *secret* in the closed hand!) But I hear these things that come out of the various literatures, and they often seem to me like delightful distillations of how people are; just the kind of things you would expect cultures to keep and to transmit over millennia, through innumerable hands, because they bring the world into better focus. EricOn Jun 18, 2025, at 1:01, Nicholas Thompson <[email protected]> wrote: I did not understand, and wanted to understand, your zen comment. I am reluctant to ask you to punch the tar baby again . You are, of course, under no obligation to cure my madness or buffer my aging. But given the coincidence between that comment and DaveW's, who often presses Zen on me, I thought you might be pointing at something there I should pay close attention to. It will be ok. You was born and bred in a briar patch. Nick ------------------------------------------------------------------------ *From:*Friam <[email protected]> on behalf of Santafe <[email protected]> *Sent:*Monday, June 16, 2025 11:30 PM *To:*The Friday Morning Applied Complexity Coffee Group <[email protected]> *Subject:*Re: [FRIAM] Entropy RE-redux Zen moment Nick:On Jun 17, 2025, at 12:00, Nicholas Thompson <[email protected]> wrote: I’ve gone back to feeling that I don’t even know enough to ask a question.Just there for an instant, the teacup dipped below full. btw.: this sentence is a wonderful encapsulation of the difference between the metaphysician and the scientist. Welcome back. Frank’s language below is good. It’s work to understand it, of course, but the crucial starting point is that it admits an understanding because there is a consistent thing being asserted. Eric You've probably done this. Nick. Yes, entropy (S) is a state variable in thermodynamics. Here's what that means: * Definition of a State Variable: A state variable (or state function) is a property of a thermodynamic system that depends only on the current state of the system, not on the path or process taken to reach that state. If a system is in a particular equilibrium state, its state variables will have specific, unique values. * Why Entropy is a State Variable: * Path Independence: The change in entropy between two states is the same regardless of the reversible or irreversible path taken to go from the initial state to the final state. * Unique Value for a Given State: For any given equilibrium state of a system (defined by other state variables like temperature, pressure, and volume), there is a unique value of entropy. * Mathematical Property: Mathematically, a quantity is a state variable if its differential is an exact differential, meaning that its integral over a closed path is zero. This is true for entropy. * Contrast with Path Variables: In contrast, quantities like heat (Q) and work (W) are not state variables. The amount of heat transferred or work done depends entirely on the specific path followed during a process. In summary, entropy is a fundamental property that characterizes the state of a thermodynamic system and is independent of its history. --- Frank C. Wimberly 140 Calle Ojo Feliz, <https://www.google.com/maps/search/140+Calle+Ojo+Feliz,+Santa+Fe,+NM+87505?entry=gmail&source=g> Santa Fe, NM 87505 <https://www.google.com/maps/search/140+Calle+Ojo+Feliz,+Santa+Fe,+NM+87505?entry=gmail&source=g> 505 670-9918 Santa Fe, NM On Sun, Jun 15, 2025, 9:27 AM Nicholas Thompson <[email protected]> wrote: Same setup as before. Cylinder with two plungers and a peggable slider at dead center. Lets fill our compartments with bbs of the same volume. Unpeg the divider. Now lets tap on the two opposite plungers with a series of blows of the same average magnitude but different but different positive skew in the distribution of magnitudes. Will the divider move? -- Nicholas S. Thompson Emeritus Professor of Psychology and Ethology Clark University [email protected] https://wordpress.clarku.edu/nthompson <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fwordpress.clarku.edu%2fnthompson&c=E,1,66C6e2iSekxSeQbiB_ZsTxOriBnqwKBTLqh8i1LVfbmh_RUPGnaMoA2X0XzGSNY1OSNIGVKq5JGhttJ4FEmJsNpv71mRlspOCeviAChun__2&typo=1> .- .-.. .-.. / ..-. --- --- - . .-. ... / .- .-. . / .-- .-. --- -. --. / ... --- -- . / .- .-. . / ..- ... . ..-. ..- .-.. 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