[Fis] [External Email] Re: Fwd: Entropy, the Second Law, and Life
Pedro C. Marijuan
pcmarijuan.iacs at aragon.es
Thu Jan 21 13:45:04 CET 2021
Dear All,
Thanks to Arieh and Stan. I agree that given the sheer variety of cases
--or systems-- where physical entropy may be meaningfully considered,
and calculated, a common interpretation for all of them is problematic.
But thinking in the ordinary chemical reactions and molecules present in
life, my proposal of "freedom" or "dynamic freedoms of the system" has
the advantage that brings to light --and dovetails-- the other factor in
Gibbs free energy: the enthalpy, the energy change in bonds. So on the
one side we have the increased (or decreased) motions status (position &
momenta, also including vibrations & oscillations), thus the degrees of
freedoms. And on the other side the change in internal energy associated
to that "making and breaking of bonds". Freedoms versus bonds. Entropy
versus enthalpy. And depending on the respective signs they should be
added, rested, etc. At least it has the advantage of being clearly
expalinable to students without the usual mystical-mystery-tour.
What Stan says is OK, but it has implicit the proverbial (scientific?
informational?) observer. We have had plenty of discussions on that...
Joseph and Jerry made mention, if I don't remember it wrongly, to
Pauli´s exclusion principle as counteracting entropy. By opening the
possibility of bonding between heterogeneous atoms & molecules, there is
evident entropy decreases, but at the same time the heterogeneity of the
matter systems is remarkably increased, at least as "entropy of mixing."
It may be tricky depending on the initial/final conditions considered to
establish the entropy balance. Shu-Kun worked years ago on the paradoxes
associated to that entropy of mixing.
Best greetings to all!
--Pedro
it is El 18/01/2021 a las 21:28, Stanley N Salthe escribió:
> Pedro -- Regarding entropy definitions in respect to information, I
> have found it useful to consider that what in Information Theory
> is often/typically referred to as 'information' ought, instead, to be
> referred to as 'information carrying capacity', while a sample taken
> from this would then be 'information' neat. In other words, any system
> we encounter will have a capacity to deliver information upon
> investigation.
> STAN
>
> On Mon, Jan 18, 2021 at 6:32 AM Arieh Ben-Naim <ariehbennaim at gmail.com
> <mailto:ariehbennaim at gmail.com>> wrote:
>
> Dear Pedro,
> Sorry for the long delay in my answer.
> I will answer briefly since a long answer would take too much time
> and space.
> 1. I fully agree that entropy and SMI should be given different
> names. The fact that Shannon called his measure ( the SMI )
> entropy, was a grave mistake.
> This has caused great confusion in both thermodynamics and
> information theory. ( confusing entropy with SMI and SMI with
> “information” is very common)
> 2. I agree that in some specific processes the entropy change may
> be associated with increase in “freedom” or with “spreading.”
> This is also true for “disorder” however, none of these
> interpretations can be derived from the definition of entropy. So,
> in general, they are not correct interpretation of entropy.
> 3. Of course the Gibbs energy is the quantity which is more
> fundamental in a system at constant T and P. The formulation of
> the second law in terms of entropy is valid only for isolated systems.
> Best wishes
> Arieh
>
> On Wednesday, January 13, 2021, Pedro C. Marijuan
> <pcmarijuan.iacs at aragon.es <mailto:pcmarijuan.iacs at aragon.es>> wrote:
>
> Dear Arieh and FIS Colleagues,
>
> Again, regarding the interpretation of entropy as information
> or uncertainty (respect locations & momenta), my suggestion is
> that we should call "something else" to the extensive
> magnitude we are measuring. Otherwise, we easily give room to
> all those pseudo-interpretations you wonderfully describe and
> the general confusion with information. When I was teaching a
> bio-discipline for engineer students, I was using the term
> "freedom". You are measuring the degrees of freedom of the
> system, I was telling, how much they have changed either
> increasing or decreasing along the process. And that quantity
> of degrees of freedom when multiplied by the temperature gives
> the energy gained or lost via entropy change. So, the
> application of SMI to the system what tells us is about the
> degrees of freedom statistical measurement. In short: the new
> freedom status of the system. It may not be a terrific
> theoretical interpretation, but my students loved it (I
> confess that previously I was using Lambert's "dispersal",
> until I saw your criticisms in the web).
>
> All of this is well depicted in Gibbs' formula for the free
> energy of chemical reactions, with the part due to ENTHALPY
> change (basically internal energy), and the part due to
> ENTROPY change x Temp. Given than most biological --all!--
> occur to room temperature (or far lower), the resulting
> contribution of entropy is pretty moderate. Actually I was
> checking chemical tables of many biological reactions, and the
> contribution of entropy was generally an order of magnitude
> lower than enthalpy--around 10% or less. I wonder --following
> Howard's comment days ago-- all the obsession with entropy and
> the universal neglect of enthalpy. It is enthalpy (or internal
> energy, or free energy) the big concern of all biological
> systems, "the food of today", rather than the negentropy or
> low entropy you graciously comment.
>
> I had also a comment regarding Joseph's and Jerry's on Pauli
> Exclusion Principle, but better for another day.
>
> Best wishes to all--Pedro
>
> El 08/01/2021 a las 19:22, Arieh Ben-Naim escribió:
>> Dear Pedro and everyone else interested.
>>
>> I will briefly answer your questions, as I have discussed
>> these in more details in my previews publications.
>> Regarding the interpretation of entropy as a measure of
>> information and as uncertainty.
>> In my view these are the only valid interpretations of
>> entropy, provided that one specifies information about what,
>> and uncertainty with respect to what. Both of these are
>> discussed in my book on “Information Theory” and in “Entropy:
>> the Greatest Blunder in the History of Science.”
>>
>> Regarding the question of dimensions for entropy, I have also
>> discussed that in my book on “Farewell to Entropy.”
>> In my view this is a result of historical “accident” that
>> temperature was given a special dimensions that were not used
>> before in physics:”degrees”
>> If temperature was given the dimensions of energy, then
>> entropy would become dimensionless. This would ease the
>> acceptance of the only correct interpretation of entropy
>> either as a measure of information or a measure of
>> uncertainty (in both cases the information and uncertainty
>> with respect to the distribution of locations and momenta of
>> all particles of the system at equilibrium)
>>
>> In my recent book I have criticized both Shermer’s and
>> Pinker’s misuses of the concept of entropy in their books.
>>
>> I hope I have answered your questions, though very briefly.
>> Best regards
>> Arieh
>>
>> On Fri, Jan 8, 2021 at 15:40 Pedro C. Marijuan
>> <pcmarijuan.iacs at aragon.es
>> <mailto:pcmarijuan.iacs at aragon.es>> wrote:
>>
>> Dear Arieh & FISers,
>>
>> My appreciation for your elegant and lively contribution.
>> Reading about
>> labeling the food on their "negentropy content" or
>> advising on low
>> entropy food (icy water!) was a most humorous way to
>> criticize all the
>> nonsense and "mystical mystery tours" around entropy.
>> Particularly,
>> Atkins (& Dawkins) quasi-religious views have always been
>> unswallowable
>> for me. Anyhow, two further aspects I would like to hear
>> from you.
>>
>> First, to put it most briefly, what basic, visual image
>> would you convey
>> for an intuitive understanding of entropy beyond the
>> technicality of
>> SMI? Uncertainty, chaos, disorder, diffusion,
>> dispersal... some many
>> terms around! I could see years ago some heated
>> exchanges you had with
>> Frank Lambert, the champion of entropy as energy
>> dispersal. There is
>> also a longish comment on how Steven Pinker approaches
>> entropy-information-evolution-cognition as the four
>> fundamental concepts
>> in our scientific understanding of the world. He is wrong
>> (IMO) in all
>> of them! Although it he is an extraordinary social
>> psychologist the
>> basic sci. background he proposes is tainted. If we could
>> give a more
>> sound "tetrad" even with those same concepts, it would be
>> a great
>> outcome. Clarifying entropy in all aspects we could
>> advance would a
>> terrific step.
>>
>> And second (maybe to be discussed later on) do you accept
>> "dimensions"
>> for entropy? The units of jules/degreeK aren't they
>> derived from having
>> entered the Boltzmann's constant? Why do we need at all
>> separate units
>> for temperature and energy?
>>
>> Thanks for all the exchanges so far!
>>
>> Best--Pedro
>>
>> --
>> -------------------------------------------------
>> Pedro C. Marijuán
>> Grupo de Bioinformación / Bioinformation Group
>>
>> pcmarijuan.iacs at aragon.es <mailto:pcmarijuan.iacs at aragon.es>
>> http://sites.google.com/site/pedrocmarijuan/
>> -------------------------------------------------
>>
>>
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>> --
>> Prof. Arieh Ben-Naim
>> Department of Physical Chemistry
>> The Hebrew University of Jerusalem
>> Jerusalem, 91904
>> Israel
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>
> --
> -------------------------------------------------
> Pedro C. Marijuán
> Grupo de Bioinformación / Bioinformation Group
>
> pcmarijuan.iacs at aragon.es <mailto:pcmarijuan.iacs at aragon.es>
> http://sites.google.com/site/pedrocmarijuan/
> -------------------------------------------------
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> --
> Prof. Arieh Ben-Naim
> Department of Physical Chemistry
> The Hebrew University of Jerusalem
> Jerusalem, 91904
> Israel
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--
-------------------------------------------------
Pedro C. Marijuán
Grupo de Bioinformación / Bioinformation Group
pcmarijuan.iacs at aragon.es
http://sites.google.com/site/pedrocmarijuan/
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