[FRIAM] Entropy RE-redux

[Frank Wimberly]

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,
Santa Fe, NM 87505

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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