John Scales Avery on Information Theory and Evolution

Avery, John. “Statistical Mechanics and Information.” Information Theory and Evolution, World Scientific, 2012. Google Books, accessed 10 Dec. 2016, pp. 79-102. <https://books.google.com/books?id=pnS6CgAAQBAJ&lpg=PA79&dq=information%20theory%20bacteria&pg=PA79#v=onepage&q=information%20theory%20bacteria&f=false>

The quantum chemist John Scales Avery writes that the connection between life and information relates to the second law of thermodynamics: the universe has a tendency toward chaos and complexity, which is known as entropy (79). Information can be used to increase order and decrease entropy (82).

“The work of Maxwell, Boltzmann, Gibbs, Szilard, and Shannon . . . established the fact that free energy contains information, and that it can thus be seen as the source of the order and complexity of living systems” (Avery 79).

Avery describes a thought experiment by John Clerk Maxwell, who studied the second law of thermodynamics and determined that it is “a statistical law” (82). Using a thought experiment of a demon in a partitioned box, sorting particles by speed to either side, Maxwell shows that:

“entropy is thus seen to be a measure of disorder or lack of information. To decrease the entropy of a system, and to increase its order, Maxwell’s demon needs information. In the opposite process, the mixing process, where entropy increases and where disorder increases, information is lost” (Avery 82).

“All living organisms draw a supply of thermodynamic information from their environment, and they use it to ‘keep aloof’ from the disorder which constantly threatens them. In the case of animals, the information-containing free energy comes in the form of food. In the case of green plants, it comes primarily from sunlight. The thermodynamic information thus gained by living organisms is used by them to create configurations of matter which are so complex and orderly that the chance that they could have arisen in a random way is infinitesimally small” (Avery 95).

“Is a computer virus alive? . . . But a computer virus can use thermodynamic information (supplied by an electric current) to reproduce itself and it has a complicated structure . . .There are examples of bacterial spores existing in a dormant state for many millions of years, after which they have been revived into living bacteria. Is a dormant bacterial spore alive? Clearly there are many borderline cases between non-life and life . . . however, one theme seems to characterize life: It is able to convert the thermodynamic information contained in food or in sunlight into complex and statistically unlikely configurations of matter.  A flood of information-containing free energy reaches the earth’s biosphere in the form of sunlight. Passing through the metabolic pathways of living organisms, this information keeps the organisms far away from thermodynamic equilibrium (‘which is death’). As the thermodynamic information flows through the biosphere, much of it is degraded into heat, but part is converted into cybernetic information and preserved in the intricate structures which are characteristic of life . . . This is the process which we call evolution, or in the case of human society, progress.” (Avery 97).

The quantum chemist John Scales Avery writes that the connection between life and information relates to the second law of thermodynamics: the universe has a tendency toward chaos and complexity, which is known as entropy (79). Information can be used to increase order and decrease entropy (82). Avery writes, “free energy contains information . . . it can thus be seen as the source of the order and complexity of living systems” (Avery 79).

The sun’s energy carries “thermodynamic information” that allows organisms to stay alive by minimizing their entropy (Avery 95).  “As the thermodynamic information flows through the biosphere, much of it is degraded into heat, but part is converted into cybernetic information and preserved in the intricate structures which are characteristic of life . . . This is the process which we call evolution, or in the case of human society, progress.” (Avery 97). This information passes through the metabolisms of organisms in the food web, keeping them “far away from thermodynamic equilibrium (‘which is death’)” (Avery 97).

Avery describes the demon-in-the-box thought experiment by John Clerk Maxwell which : a demon stands in the doorway between two sides of a partitioned box, sorting fast particles to one side and slow particles to the other (82). Because this “demon” creates order by using information, this thought experiment shows that “to decrease the entropy of a system, and to increase its order, Maxwell’s demon needs information. In the opposite process, the mixing process, where entropy increases and where disorder increases, information is lost” (Avery 82). Thus, a theory of information can be understood by considering how the thermodynamic and genetic information powering an ecosystem creates a certain level of order against the universal tendency toward chaos.

Avery compares how thermodynamic information functions in biological systems to how it can function in computer systems in the form of an electric current (97).  “There are examples of bacterial spores existing in a dormant state for many millions of years, after which they have been revived into living bacteria. Is a dormant bacterial spore alive? Clearly there are many borderline cases between non-life and life” (Avery 97).