User:John courtneidge/Gibbs free energy

Gibbs Free Energy, Life Processes and 'Wealth' creation

Main article: Entropy and life

Standard information (no problems here)

The 1944 book What is Life? by Erwin Schrödinger, is the most referenced book in regards to free energy, entropy, negentropy, solar energy input, and evolution.

In this, Erwin Schrödinger’s 1944 postulate is that an organism keeps itself alive or aloof by feeding on negative entropy from its environment. From the famous chapter six “Order, Disorder and Entropy” in that book, Schrödinger asks: “what is the characteristic feature of life? and “when is a piece of matter said to be alive?” To answer these questions, Schrödinger turns to thermodynamics.

Life, according to Schrödinger, avoids a decay to maximum entropy, or thermodynamic equilibrium, which Schrödinger equates with death, by feeding on negative entropy. Specifically, according to Schrödinger, an organism avoids decay by eating, drinking, breathing, and in the case of plants assimilating, a process called metabolism.

In the past, Schrödinger states, this process would have been considered an exchange of matter or energy, such that organisms stay alive by exchanging energy. He uses the example of how caloric values are printed in certain menus in the United States or Germany, but states that these caloric energy exchange values are useless in trying to quantify life. He then asks “what then is that precious something contained in our food which keeps us from death?” The answer, according to Schrödinger, is that because according the second law of thermodynamics an organism continually produces “positive entropy” it must continually draw in “negative entropy” from its environment to stay alive. Or, specifically “the essential thing in metabolism is that the organism succeeds in freeing itself from all the entropy it cannot help producing while alive.”

These suppositions, because they were intended for a lay audience, however, met with great opposition in the physics community. In later editions of his book, Schrödinger attached a note to chapter six explaining his use of the term “negative entropy”. He states “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. It is the more familiar notion in this context. But this highly technical term seemed too linguistically near to energy for making the average reader alive to the contrast between the two things.”

Many others have contributed to this. The first was Herbert Spencer who, in his 1880 book First Principles, spoks in terms of ‘available energy’ and resources, dissipation, evolution, etc., but not necessarily free energy as it is in the article.

In 1922, Frederick Soddy applied steam engine theory to human life; he states: “life derives the whole of its physical energy or power not from anything self-contained in living matter, but solely from the inanimate world. It is dependent for all necessities of its physical continuance upon the principles of the steam engine. The principles of ethics of all human conventions must not run counter to those thermodynamics.”

In 1926, Vladimir Vernadsky,in his book The Biosphere, states: “Living matter, as a whole, is a unique system which accumulates chemical free energy G in the biosphere by the transformation of solar radiation.”

Another contribution is the 1998 book Thermodynamic Theory of the Evolution of Living Beings, by Russian physical chemist Georgi Gladyshev.

Additionally, the back cover notes of the book Information Theory and Evolution by theoretical physicist and chemist John Avery (published in 2003) suggests that the paradox between the complexity produced by living systems and the seeming contraction between the second law of thermodynamics has its resolution in the Gibbs free energy that enters the biosphere from outside sources.

Questionable material

By gathering together material from these and several other sources (See the reference list), the resolution of these matters, therefore, seems to be in recognizing that thermodynamic functions are additive: that is, for the case of Gibbs Free Energy, the global Free Energy change can be viewed as the sum of the change appropriate to ‘the system’ (ie that part of the universe under examination) and ‘the surroundings’ (ie all the rest):

G_global = G_system + G_surroundings

• Comment: what is your is your thermodynamic system in this example and what are the surroundings? --Sadi Carnot 15:43, 13 January 2007 (UTC)

This follows from the two conservation laws for matter and energy

• Comment: no, this follows from Hess' law and due to the fact that Gibbs free energy is an extensive property. --Sadi Carnot 15:43, 13 January 2007 (UTC)

(ie: ‘Matter is neither created nor destroyed during a chemical change: rather, it is distributed from one set of (atomic, and/or molecular) arrangements to another’ – likewise for the conservation of energy – both being cognizant of the Einstein matter/energy equivalence equation E=mc²).

For entropy, this becomes:

S_global = S_system + S_surroundings

So, the resolution becomes, :

Firstly, in this latter case, the Second Law of Thermodynamics indicates that, for any change, the overall entropy change for any process is positive (ie entropy increases in any change.

• Comment: no, increases only for processes within isolated systems. --Sadi Carnot 15:43, 13 January 2007 (UTC)

So, within the overall Gibbs free energy change for any process:

ΔG = ΔH - TΔS

A number of possibilities occur: given that, for the majority of processes,

• Comment: no, not for the majority of processes; some are spontaneous and some are non-spontaneous. --Sadi Carnot 15:43, 13 January 2007 (UTC)

$\Delta G$ is negative (a consequence of the fact that for most ‘forward’ processes – ie those that have positive equilibrium constants, K delta G has to be negative for the following equation to generta e a positive equilibrium constant K):

ΔG = -RTlnK

(where R is a constant – the Universal Gas Constant and lnK means ‘the natural logarithm of the equilibrium constant K – ie the ratio (roughly) of the amount of product divided by the amount of starting material left over at the end of the change)

And, secondly:

Living organisms are (fully) ‘open systems’ (though boundaried) – ie: in their cases, open to exchange of both energy and matter with their ('the organism’s') surroundings.

• Comment: living systems can be both open or closed depending upon the system boundary, e.g. the earth, according to many definitions, is a "closed" living system. --Sadi Carnot 15:43, 13 January 2007 (UTC)

Thus, for example, a tree draws in (during the process of photosynthesis) carbon dioxide and water from the surrounding environment (along with smaller amounts of other elements in the form of other, mostly inorganic, mineral plant nutrients), and returns some of the ingested (metabolized) oxygen to the surrounding atmosphere, while at the same time absorbing (and storing as chemical energy) the photo-energy of sun-light.

Thus, plant photosynthesis is an, over-all, endothermic process:

Carbon dioxide + water + energy (from sun-light) --> cellulose (mostly) + oxygen

More-over, this life-process is one that creates order, locally (ie as the system - called ‘the tree’ - which has a lower entropy – is ‘more organized’ - than its constituent materials) and, so, for the global process, the ‘freed’ gaseous oxygen must add to the positive entropy of the products.

– I am not sure of an experimental confirmation of this .

• Comment: yes, you are missing a number of elements and energetic relations in this approximation to be able to make such assignments. --Sadi Carnot 15:43, 13 January 2007 (UTC)

For animal metabolism (and this is particularly true of warmer-than-ambient, ‘warm-blooded’ animals – including human beings), the creation and life forms are also endothermic (energy requiring – strictly enthalpy requiring) processes – again these life forms are fully energy- and material-exchanging (boundaried) open systems which, create, locally, a reduction of entropy (‘order out of chaos’), by creating a compensating greater amount of entropy (‘disorder’) in the surroundings.

Animal + water + energy (from food) --> maintained/growing animal + excreted materials and energy

• Comment: using the order out of chaos approach isn't going to work in the long run. --Sadi Carnot 15:43, 13 January 2007 (UTC)

Taken as a global, planetary, whole, when these life processes occur in a sustainable way, the overall absorption of energy (sun-light) by planet earth is matched by the sum of energy released to the surrounding universe (less that stored in the litho-, aqua-, and bio-spheres). This homeostasis (ie: ‘over-all no net change’) principle is called the Gaia hypothesis, while an excess (or deficiency) of energy absorption (or loss) by the atmosphere is called global warming or climate change.

Original research?

These ‘natural life processes’ (as contrasted to human-created proceses) can be described by the the following word equation:

Raw Materials + Energy --> Wealth + Pollution

So, for the example of photosynthesis, the raw materials are – largely - carbon dioxide and water, the ‘wealth’ is the well-being of the (usually, both, high energy and low entropy) life–form (of, say, a tree or a grain of wheat), and the ‘pollution’ is, in this example, the released - high entropy - oxygen.

• Comment: this whole bottom section needs so much work, it's hard to even comment. Firstly, the terms "wealth" and "pollution" are non-existent in nature. They are entirely anthropomorphic. In nature, what is one entities' polution is another's wealth. If you want to explain human life, via wealth and pollution terms, you will need to rephrase these in terms of stability, i.e. wealth (stability) and pollution (instability) and thermo-molecular dynamics, i.e. molecular systems tend to reconfigure towards stability and away from instability. --Sadi Carnot 15:43, 13 January 2007 (UTC)

So that, during the early development of oxygen-releasing – photosynthetic – life-forms, the released oxygen was, for the majority of anaerobic life-forms, an atmospheric pollutant.

Thus, according to this generalization, ‘non-natural’ wealth creation (ie human-directed processes) create local systems of lowered entropy (‘order from chaos’) and/or locally endothermic (raised local enthalpy – ie: locally ‘concentrated energy’), but always with an overall (global) increase in entropy. For globally-sustainable wealth creation, this implies a requirement for reduced levels of human-directed activity (‘wealth creation’), along with a longer-lived component to that human-generated wealth (since, both, the formation and decay/aging of the products of those human-created objects all contribute to global production of pollution (ie: higher entropy materials and atmospherically-retained thermal energy).

References

• ‘Introduction to Physical Chemistry’ G I Brown, Second (SI) edition, 1972, Longman, London, England;

• ‘Wealth, Virtual Wealth and Debt: The Solution of the Economic Paradox’ Frederick Soddy, [nd – 1926?], George Allen and Unwin, London, England;

• ‘The Entropy Law and the Economic Process’ Nicholas Georgescu-Roegen, 1971, Harvard University Press, Cambridge, Mass, USA and London, England;

• ‘Entropy: Into the Greenhouse World’ Jeremy Rifkin (with Ted Howard), 1980 (revised edition 1989), with Afterword by Nicholas Georgescu-Roegen, 1980.

• Comment: why do you have these references here, you don't even use them (i.e. "refer" to them) in your article? --Sadi Carnot 15:43, 13 January 2007 (UTC)