Sign in or 
- EasyEdit
- Edit tags
-
(what's this?What are these tools?
People just like you can add or edit the content on this site. If you want to try editing, but aren't ready to add to this site, try our demo area.
Read more about editing pages at Wetpaint Central.
) - Report page
Share this
Erwin Schrödinger
In life thermodynamics, Erwin Schrödinger (1887-1961) was an Austrian physicist notable for his famous 1944 book What is Life?, in which he postulated that “life feeds on negative entropy.” [1] In popular or colloquial use, this might be considered as one of the most oft-quoted passages culled from the publications of thermodynamics. In extrapolation to human life, this would imply that people, in some way, feed on negative entropy (or a negative value of entropy S). Schrodinger is also notable for having won the 1933 Nobel Prize for his development of the Schrodinger equation.In linguistic form, Schrödinger’s postulate is similar to Austrian physicist Ludwig von Boltzmann’s 1886 postulate that “the general struggle for existence of animate beings is … a struggle for entropy”. [2] In end-note commentary, however, Schrödinger added the note that had he been writing for the physicist rather than the lay audience that he would have let the discussion turn on free energy. Schrödinger also authored the 1946 book Statistical Thermodynamics. [3]
Negative entropy and order
In terms of entropy and order, in somewhat riddled form, Schrödinger reasoned that living organisms feed on negative entropy. To begin, he states that he will “try to sketch the bearing of the entropy principle (the second law of thermodynamics) on the large-scale behavior of a living organism”. Second, he equates thermodynamic equilibrium, or what he calls “maximum entropy”, as a state in which chemical potentials are equalized, wherein systems become dead, in which no observable changes occur. To avoid decay to this hypothetical death state, Schrödinger reasons that it is not energy that living beings feed on that keeps them at bay from decay but “negative entropy”. In rephrasing this statement, he says “the essential thing in metabolism is that the organism succeeds in freeing itself from all the entropy it cannot help producing while alive.” In making these ball-park statements, Schrödinger calls on the statistical concept of order and disorder, connections that were revealed, as he says, by the investigations of Boltzmann and Gibbs in statistical physics. On this basis, he situates the following definition:
Entropy = k log D
where k is the Boltzmann constant and D is a “quantitative measure of the atomistic disorder of the body in question”. Here, to note, he fails to mention that this expression is generally valid only for ideal gases. In any event, Schrödinger reasons that this statistical expression applies to living organisms. Moreover, to make his verbal argument mathematical, he states that “if D is a measure of disorder, its reciprocal, 1/D, can be regarded as a direct measure of order.” In addition, “since the logarithm of 1/D is just the minus of the logarithm of D, we can write can write Boltzmann’s equation thus:
- (entropy) = k log (1/D)
Hence, as Schrödinger states, “the awkward expression negative entropy can be replaced by a better one: entropy, taken with the negative sign, is itself a measure of order.” Thus, he concludes “the device by which an organism maintains itself stationary at a fairly high level of orderliness”, a state he equates with a low level of entropy, consists in “sucking orderliness from its environment”.
Difficulties on theory
The basic difficulty in Schrödinger’s negative entropy theory is that he equates sustenance (metabolism) with measures of entropy. In the correct sense, sustenance is a function of substrate interactions, as studied in the field of surface chemistry. In an appended note to his thermodynamics-life chapter, however, Schrödinger states that:
“The remarks on negative entropy have met with doubt and opposition from physicist colleagues. Let me say first, that if I had been law 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 linguistically too near to energy for making the average reader alive to the contrast between the two things.”
In other words, in terms of entropy as defined by Clausius, as the “amount of work the molecules of the system do on each other" (that cannot be compensated), this outline by Schrödinger makes little sense. If he had let the discussion turn on free energy, he would have been confronted with the various postulates of energy interactions between people, such as was done by Goethe in his 1809 Elective Affinities (see: Goethe's human chemistry); where before 1882, free energy was called "chemical affinity" or elective affinity.
In 1987 commentary on Schrödinger’s What is Life?, American chemical engineer Linus Pauling noted that Schrödinger was discussing a change in the entropy of the "system", he never defined the system. Pauling wrote, "Sometimes he seems to consider that the system is a living organism with no interaction whatever with the environment; 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 wrote that Schrödinger failed to recognize the most important question: "How biological specificity is achieved; that is, how the amino-acid residues are ordered into the well-defined sequence characteristic of the specific organism." [4] Similarly, Austrian-born English molecular biologist Max Perutz argued that we live on free energy and that there was no necessity to postulate negative entropy. [5]
References
1. (a) Schrödinger, Erwin. (1944). What is Life? (ch. 6 “Order, Disorder, and Entropy", pgs. 67-75). Cambridge: Cambridge University Press.
(b) What is Life? (1944 book in word doc download).
(c) 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 published in 1944.
2. Thims, Libb. (2007). Human Chemistry (Volume One), (preview), pg. 87. Morrisville, NC: LuLu.
3. (a) Schrödinger, E. (1946). Statistical Thermodynamics. New York: Dover
(b) based on a course of seminar lectures delivered in Jan-Mar 1944, at the School of Theoretical Physics, Dublin Institute For Advanced Studies.
4. Pauling, Linus. (1987). "Schrödinger's contribution to chemistry and biology", pp. 225–233 in Schrödinger: Centenary Celebration of a Polymath, edited by C. W. Kilmister. Cambridge University Press, Cambridge.
5. 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.
Sadi-Carnot |
Latest page update: made by Sadi-Carnot
, Jun 18 2009, 2:18 AM EDT
(about this update
About This Update
Edited by Sadi-Carnot
23 words added 3 words deleted view changes - complete history) |
|
More Info: links to this page
|
There are no threads for this page.
Be the first to start a new thread.
