[FRIAM] Entropy Redux

Wed May 28 14:08:42 EDT 2025

Colleagues,

One thing that I want you all to know.  There is absolutely  no trickery
intended here.  I have been working with George for the last 8 months in an
attempt to arrive at an understanding of entropy that is robust.   I have
discovered that George's understanding is not robust.  I assume that the
reason is that there is an enormous amount of confusion out there in *Le
Monde* and that George's understanding arises ultimately from what *Le
Monde* thinks.

If I have a bias in all this, it is to try and make a severe distinction
between description, the presentation of a state of affairs to be
explained, and explanation, an account in other terms of how that state of
affairs has come to be.  The bridge between the two, is a description of
the future behavior of the slider, based on the explanation.  This the
explanation's heuristic (discovery) value.  My goal is to design a
minimalist model whose behavior can only be predicted on the basis of our
shared understanding of entropy.  My reasons for doing this is that the
distinction between an air temperature that is arrived at by compression
and the same air temperature that is arrived at through heating is crucial
to meteorology, about which I am trying to write.

The goal in solliciting your independent reactions to the prompt, is not to
catch anybody out but to discover all the various ways in which the prompt
can be misunderstood, so that I can write, insofar as possible, a robust
prompt.   On the basis of what I have learned from you-all this morning, I
have drafted a new prompt, which I will post under a new subject line in
the hope of getting some "naive" respondents.  It is hideously longer.
Please hold off, for the time being on any philosci commentary about the
attempt to eliminate ambiguity.  I know there is a lot to be said. Lord
knows, if any of you can come up with a slicker prompt that does not
presuppose any particular explanatory frame work, that would be GREAT!

Thanks again,

N

On Wed, May 28, 2025 at 8:38 AM Alexander Rasmus <alex.m.rasmus at gmail.com>
wrote:

> Pieter got all of this, but I’ll pile on. I think Nick is intending us to
> think that the initial fill is the same on both sides, but he definitely
> hasn’t said this. The answer to the problem as stated is that the barrier
> will move left, right, or not at all. I think Nick is intending that the
> fill be the same, and that the answer to be that the barrier move to the
> right. The pressure in the right cell is lower as the density is lower
> (unless the EOS is real weird).
>
> What’s air Nick? You also messed up your corrected version and set the
> second initial fill temp to be the post heating temperature
> Sent from my iPhone
>
> On May 28, 2025, at 3:02 AM, Pieter Steenekamp <pieters at randcontrols.co.za>
> wrote:
>
> 
> I'm not sure if you deliberately left out any mention of the initial
> pressures — perhaps as part of the “catch,” which is common in trick
> questions like this. As I mentioned in my initial answer, it’s common to
> assume the initial pressures are equal, in which case the slider would move
> to the tight.
> However, if the twist is that the right-hand cylinder was initially filled
> with high-pressure air, then of course the slider would move to the left.
>
> On Wed, 28 May 2025 at 07:14, Nicholas Thompson <thompnickson2 at gmail.com>
> wrote:
>
>> Thanks everybody.   Anybody else?   Remember, please no peeking.  Your
>> efforts have already helped me identify an ambiguity in how I stated the
>> problem.  Here is an edited version.  See if that clarification changes any
>> answers.
>> Remember, no peeking before you kick in your answers.  No herding
>> allowed.
>>
>> Side by side, butt-to-butt, two cylinders of air, of equal volume and
>> equal temperature, but different histories. They are separated by a
>> frictionless sliding divider which is now pegged.  Before compression or
>> heating, both started with air at 10 degrees C, and after compression or
>> heating, both arrive at 20 degrees C. The left one has arrived at its
>> present temperature and volume by being compressed, the right-hand one
>> by having its volume set to the same value as the left, BEFORE BEING FILLED
>> WITH AIR AT 20 DEGREES C, and ONLY  then having contents  heated.  All
>> compartments insulated, all manipulations quasi-static.  Now, remove the
>> peg, allowing the partition between the two parts to slide, one way or the
>> other.  Which way would it slide and why. What would your explanation
>> be?  Please don't read others' answers until you have submitted your own.
>> This is enormously helpful to me.
>>
>> On Tue, May 27, 2025 at 10:19 PM Pieter Steenekamp <
>> pieters at randcontrols.co.za> wrote:
>>
>>> Assuming the pressures were equal at the start, it will slide from the
>>> left (having been compressed) to the right.
>>> From the ideal gas law PV = nRT, both have equal nRT;s so the one with
>>> smaller V must have higher P and it would then push to the right.
>>>
>>> On Wed, 28 May 2025 at 04:59, Nicholas Thompson <thompnickson2 at gmail.com>
>>> wrote:
>>>
>>>> Side by side, butt-to-butt, two cylinders of air, of equal volume and
>>>> equal temperature, but different histories. They are separated by a
>>>> frictionless sliding divider which is now pegged.  Before compression
>>>> or heating, both started with air at 10 degrees C, and after compression or
>>>> heating, both arrive at 20 degrees C. The left one has arrived at its
>>>> present temperature and volume by being compressed, the right-hand one
>>>> by having its volume set to the same value as the left and then having
>>>> contents  heated.  All compartments insulated, all manipulations
>>>> quasi-static.  Now, remove the peg, allowing the partition between the two
>>>> parts to slide, one way or the other.  Which way would it slide and
>>>> why. What would your explanation be?  Please don't read others' answers
>>>> until you have submitted your own.
>>>> --
>>>> Nicholas S. Thompson
>>>> Emeritus Professor of Psychology and Ethology
>>>> Clark University
>>>> nthompson at clarku.edu
>>>> https://wordpress.clarku.edu/nthompson
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>>
>>
>> --
>> Nicholas S. Thompson
>> Emeritus Professor of Psychology and Ethology
>> Clark University
>> nthompson at clarku.edu
>> https://wordpress.clarku.edu/nthompson
>> .- .-.. .-.. / ..-. --- --- - . .-. ... / .- .-. . / .-- .-. --- -. --. /
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-- 
Nicholas S. Thompson
Emeritus Professor of Psychology and Ethology
Clark University
nthompson at clarku.edu
https://wordpress.clarku.edu/nthompson
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