Clas Blomberg - Physics of life-Elsevier Science (2007)

144 Part IV. Going further with thermodynamics
“q” and “u” are always together in English, “t” and “h” very often. “h” can start a sentence,
then followed by a vowel and it is otherwise normally together with “c”, “s” or “t”, seldom
or never together with other consonants. Such correlations appear in all languages and an
establishment of these is important for classifying a message as “probably a meaningful
writing in some language”. Concerning DNA sequences, there are many attempts to find
correlations. One purpose is to find ways to distinguish sequences (introns) that correspond
to genes, code for proteins and thus be meaningful, and those parts that do not seem to contain
any message (exons).
15D
The relation to the second law
There are different opinions about the analogies I have here. Some people like me think that
their opinions are relevant for clarifying important features of the second law while other
think they are misleading. Let me discuss more on this point.
Has the mixing of cards anything to do with this second law? I think so. It is useful to
clarify what is meant by “ordered”, “low-entropy” states, even what is meant by order. In the
card analogy, as for the monkey library, I think it is important to say that “order” is a high-level
concept, which to some extent is subjective. We may say that it is what we apprehend as
order. I don’t see that this would mean any restriction of the analysis. We can speak about the
“probability of some order”, where we have some kind of definition. This may be based on
some subjective conception, which, however, leads to a clear description. It is not necessary
to claim that the conception of order has any objective meaning, the important point is that
the observer, i.e. we, perceive certain situations as ordered. It is important for all real and
analogous situations that, if one starts with what is considered as an ordered state, and let it
develop uncontrolled, then system becomes more and more disordered, irrespective of what
definition one has. What is disordered remains disordered from any point of view and in all
these cases, when one starts from a disordered situation; the probability to get an ordered state
is very small, irrespective of the particular definition.
The definitions I have, red contra black cards for the card mixing, a meaningful English
text in the monkey library or some striking pattern formed by the single letters are in some
sense clear definitions of order, but they are also all subjective, all are decisions by an observer.
(The mention of an observer may lead to ideas of quantum mechanics, and I can see a certain
similarity. But, for the sake of clarity, do not confuse the issues at this point.)
One also has a metaphor of an untidy office. I have papers of different importance and
concerning different duties. As I normally have a limited time, I put my papers uncontrolled
in various stacks, and this leads to a considerable disorder. Again, this is the normal development
of the second law: an uncontrolled development leads to an increasing disorder,
whatever ideas one has about order.
When we speak about physical systems, about the thermodynamics of a cell, shouldn’t
there be an objective meaning of entropy of order and disorder? Clearly there is an order of
a solid, of the crystalline structure. The proteins of a cell have a structure, which is relevant
for the biological function, and there we have an order. There is also a flexibility, some kind
of disorder, also important for the function. But all the time, our concept of order shall refer to
the macroscopic view—the world as we see it. The world is in some sense subjective: it consists
of objects, which we apprehend as objects. I don’t think it is wrong to have a subjective