[FRIAM] Entropy RE-redux

Frank Wimberly wimberly3 at gmail.com
Tue Jun 17 16:47:56 EDT 2025 

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 <desmith at santafe.edu> 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.
>
> Eric
>
>
>
> On Jun 18, 2025, at 1:01, Nicholas Thompson <thompnickson2 at gmail.com>
> 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 <friam-bounces at redfish.com> on behalf of Santafe <
> desmith at santafe.edu>
> *Sent:* Monday, June 16, 2025 11:30 PM
> *To:* The Friday Morning Applied Complexity Coffee Group <
> friam at redfish.com>
> *Subject:* Re: [FRIAM] Entropy RE-redux
>
> Zen moment Nick:
>
> On Jun 17, 2025, at 12:00, Nicholas Thompson <thompnickson2 at gmail.com>
> 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 <thompnickson2 at gmail.com>
> 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
> nthompson at clarku.edu
> https://wordpress.clarku.edu/nthompson
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