Note to Chapter 6

Note to Chapter 6 (a)
Note to Chapter 6 (b)
Austrian physicist Erwin Schrodinger's 1944 Note to Chapter 6 which he had to append to his book chapter after taking heat from his fellow colleagues for his remarks on "negative entropy", in which he said he should have let the discussion turn to free energy. [1]
In famous publications, Note to Chapter 6 is an appended two-page section to chapter six “Order, Disorder, and Entropy” of Austrian physicist Erwin Schrodinger’s famous 1944 book What is Life?, wherein he responded to doubt and opposition from his physicist colleagues to his thermodynamics-based definition of life as something that “feeds on negative entropy”, in which he stated that had he been catering his lecture to them alone, he would have let the discussion turn on free energy, but that he judged the topic too difficult for a lay audience. The famous opening response statement is as follows: [1].

“The remarks on negative entropy have met with doubt and opposition from physicist colleagues. Let me say first, that if I had been catering for them alone I should have let the discussion turn on free energy instead.”

To upgrade this, as modern physical chemistry sees things, he should have let the discussion turn not simply on "free energy", which as many (such as Ilya Prigogine) have bantered on incorrectly about, could imply Helmholtz free energy, but correctly on Gibbs free energy, which is the correct thermodynamic potential for isothermal isobaric systems (which are the type of processes, animate or inanimate, seen going on about the surface of the earth). Schrodinger goes on to clarify:

“It is the more familiar notion in this context. But this highly technical term seemed linguistically too near to energy to make the reader alive to the contrast between the two things. He is likely to take free as more or less an epitheton ornans without much relevance, while actually the concept is a rather intricate one, whose relation to Boltzmann’s order-disorder principle is less easy to trace than for entropy and ‘entropy taken with a negative sign’, which by the way is not my invention. It happens to be precisely the thing on which Boltzmann's original argument turned.”

Schrodinger goes on, as shown adjacent, to mention the objections given by an "S. Simon" and also to mention van't Hoff's law.

Butler
English physical chemist and chemical thermodynamicist John Butler, in his 1946 article “Life and the Second Law of Thermodynamics”, gave his opinion that: [2]

[Schrodinger’s view that] “an organism feeds on negative entropy” [is a] “picturesque if somewhat inaccurate language”.

Butler, conversely, stated that: “a majority would probably be found in favor of the view that any local increase of ‘free’ energy is compensated by a greater amount of dissipation elsewhere.” This alternative statement (see also: local entropy decrease), however, has issues in its own right.

Pauling
In his 1989 memorial chapter “Schrodinger’s Contribution to Chemistry and Biology”, American chemical engineer Linus Pauling (1901-1994) probably gives one of the harshest critiques of Schrodinger’s overall ideas on the thermodynamics of life. Pauling, after telling how much respect he had for Schrodinger for his work in quantum mechanics (particularly for his Schrodinger equation), begins his rip into Schrodinger's What is Life? lecture with the following mock:

“In his discussion of ‘negative entropy’ in relation to life, he made a negative contribution.”

Pauling, then, after quoting Schrodinger’s two main excerpts about “keeping aloof” and “feeding on negative entropy”, continues:

“When I first read this book, over 40 years ago, I was disappointed. It was, and still is, my opinion that Schrodinger made no contribution to our understanding of life.

Several physicists and biologists with whom I have discussed this question have disagreed with me. When I asked what the contribution made by Schrodinger to our understanding of life is, each answered essentially by saying that Schrodinger showed that life is negative entropy, that living organisms utilize entropy in a way different from non-living matter.

I have not had the opportunity to discuss this matter with a physical chemist, a person with a good understanding of the great work by J. Willard Gibbs on chemical thermodynamics. I am sure that he or she would agree with me.

Schrodinger’s discussion of thermodynamics is vague and superficial to an extent that should not be tolerated even in a popular lecture. In the discussion of thermodynamic quantities it is important to define the system. When he is writing about a change in entropy of the system, Schrodinger never even defines the system. Sometimes he seems to consider that the system is a living organism with no interaction whatever with the environment; and sometimes it is a living organism in thermal equilibrium with the environment; and sometimes it is the living organism plus the environment, that is the universe as a whole.”

Pauling then goes on to discuss the Note to Chapter 6 and his views on spontaneous reactions. [3] All-in-all, this is a fairly excellent review by Pauling and in effect highlights the general ignorance in the modern-day science community that is only glimpsed by a rare few minds, such as Pauling, able to grasp not only all of modern science, but to have an acute awareness of what it means to have a "good understanding of the great work by J. Willard Gibbs", as Pauling put it.

Perutz
In 1987, Austrian-born English molecular biologist Max Perutz (1914-2002), in his memorial chapter (following Pauling), entitled “Erwin Schrödinger's What Is Life? and molecular biology”, also laid into Schrodinger. Perutz commented, in short, that: [4]

“We live on free energy and there [is] no [need] to postulate negative entropy.”

This, however, has issues with it as well; which can be attributed to the fact that Perutz had a less than rigorous background in the hard physical sciences (chemical thermodynamics in particular), as Pauling, a chemical engineer and and quantum chemist, did.

Thims
The final page of American electrochemical engineer Libb Thims' 824-page textbook Human Chemistry ends with a discussion of Schrodinger's Note to Chapter 6, and to summarize the bulk content of the previous 824-pages, states: [5]

"Herein, in Schrodinger's own words, we have let the discussion turn on free energy."

Dated added
The original public lecturing occurred in 1943. [6] Ecological economists Kozo Mayumi and Mario Giampietro seem to indicate that the note was added in either the 1945 edition or the combined reprint 1967 edition. [7]

References
1. Schrodinger, Erwin. (1944). What is Life? Note to Chapter 6, pgs. 74-75). Cambridge University Press.
2. Butler, John A.V. (1946). "Life and the Second Law of Thermodynamics" (abs), Nature, 158: 153-154.
3. Pauling, Linus. (1989). “Schrodinger’s Contribution to Chemistry and Biology”, in: Schrodinger: Centenary Celebration of a Polymath (§18, pgs. 225-). Cambridge University Press.
4. (a) Perutz, Max. (1987). “Erwin Schrödinger's What Is Life? and molecular biology”, pp. 234–251 in Schrödinger: Centenary Celebration of a Polymath, edited by C. W. Kilmister. Cambridge University Press, Cambridge.
(b) Max Perutz – Wikipedia.
5. (a) Thims, Libb. (2007). Human Chemistry (Volume One). Morrisville, NC: LuLu.
(b) Thims, Libb. (2007). Human Chemistry (Volume Two) (§What is Life?, pgs. 700-701). . Morrisville, NC: LuLu.
6. Schrödinger’s scripture "What is Life?" was based on a course of public lectures delivered under the auspices of the Dublin Institute for Advanced Studies at Trinity College, Dublin, in February 1943 and first published in 1944.
7. Mayumi, Kozo and Giampietro, Mario. (2004). “Entropy in Ecological Economics”, in: Modelling in Ecological Economics (pg. 83). Eds. John Proops and Paul Safonov. Edward Elgar Publishing.

Further reading
‚óŹ Dawkins, Richard. (2008). “Erwin Schrodinger from WHAT IS LIFE?”, in: The Oxford Book of Modern Science Writing (pgs. 249-54; §Note to Chapter 6, pg. 253-54). Oxford University Press.

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