COSMOGENESIS (Oxford University Press, 1990)
(Copyright © 2000 Piero Scaruffi | Legal restrictions - Termini d'uso )
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Inspired by cosmology, Layzer deals with the paradox of creation of order
by saying that,
if entropy in the environment increases more than the entropy of the system,
then the system becomes more ordered in that environment.
Entropy and order can both increase at the same time without violating
the second law of thermodynamics.
This phenomenon can be described as:
if the expansion of a set of systems is so quick that a number of states
which are occupied increases less rapidly than the number of states which
are available (i.e., the phase space gets bigger),
entropy and order can increase at the same time.
Unlike Prigogine, Layzer does not need to assume that an energy flow from the environment of a system can cause a local decrease in entropy within the system. Entropy and order increase together because the realization of structure lags behind the expansion of phase space. Drawing from Shannon's theory of communication, David Layzer defines information as the difference between potential entropy (the largest possible value that the entropy can assume under the specified conditions) and actual entropy. As actual information increases, actual entropy decreases (information is "negative" entropy in Shannon's theory). Potential entropy is also potential information: maximum entropy equals maximum information. In biological and astronomical systems the potential entropy may increase with time, thereby creating information if it increases faster than actual entropy. In particular, both contraction and expansion of the universe from an initial state of thermodynamic equilibrium would generate potential entropy. Genetic variation always generates entropy as information flows unidirectionally from the genotype to the phenotype: when it makes the distribution of genotypes more uniform in a genotype space, it generates entropy and destroys information; when it allows the population to populate previously uninhabited regions fo the genotype space, it generates potential entropy without necessarily generating entropy. Layzer then proves that several evolutionary processes (mutation, differential reproduction, gene duplication, differentiation and integration) generate biological information. Natural itself selection always increases the proportion of relatively fit variants in a population and decreases the proportion of relatively unfit variants, therefore natural selection always generates biological order. Layzer thinks that biological evolution is not driven by the growth of entropy (as a counterweight to the loss of order), it is not (directly or indirectly) driven by the second law of thermodynamics. That law presupposes certain initial and boundary conditions that are not present in biological systems. Influenced by Schmalhausen's theory that evolution is a process of hierarchical construction, Layzer thinks that there is a single universal law governing processes that dissipate order, but order is also generated by several hierarchically linked processes (including cosmic expansion and biological evolution). |
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