> As a resident thermodynamicist here, let me intervene quickly. You
are
> _both_ sort of right.
>
> Eduardo is right in that entropy and the 2nd Law are universal
concepts
> which are not invalidated in living systems. Glenn is right in that
the
> common ways people talk about them (for example, the idea that entropy
> always increases in a system) are not generally valid in these systems
> that are not isolated and also not at (and often not near)
equilibrium.
> Entropy and the 2nd law can still be useful concepts for these
systems,
> but (as Prigogine did) you have to do some things differently than
in the
> equilibrium thermodynamics most of us are used to.
>
Hi Allan,
I used to be a thermodynamicist myself but now my thermal science work
is mainly on Heat Transfer (that is, in non-equilibrium
thermodynamics). Thanks for your input. I was not being rigorous
with my terms anyway. Notice that I used "Entropic" equilibrium,
which is not engineering proper as far as I know. It was the quickest
way to confer the idea that the DNA sequences stay pretty much
structurally and functionally intact even in the mist of pretty high
thermal vibrations (kT energy). I mean, these sequences are being
"shaken". Of course, these are not loosly swimming but carefully and
thoughfully arrange in the nuclear matrix, which helps considerably.
Given, however, that is not just sitting there as a stainless steel
chain, but it is intead dynamic, its integrity is remarkable. A good
introductory essay on this is the work of the evolutionists and
east-mystic physicist Erwin Shrodinger (What is Life? Cambridge
University Press). This essay was written in 1944 and in it Erwin
predicts the site of the genetic mutations (the chromosomes) and the
size of the locus of the mutation (which in the 1950 was "discovered"
as the DNA).
The most important thing when doing a thermodynamic analysis is to
define the system, which in general easy terms it means that we need
to define the boundaries around a volume of interest. Once the
boundaries are "known", an energy balance and an entropy analysis is
pretty straight forward to do conceptually. Bearing this in mind, if
I define my system as a cell, it is pretty impressive to see the
conservation of the DNA structure an function given the energy flow
through the system (cell) and the many nonreversible processes that
occur inside the cell (system). The chances that something could go
wrong seem high but the occurrences are remarkably low. In fact, just
increasing the temperature of a cell (above the normal temp.) will
not cause DNA damage (protein denaturation is what happens). We can
give hundreds, if not thousands, of ionizing radiation equivalent
doses of thermal energy to the cell without DNA damage. On the other
hand, a single penetrating photon can easily cause a single strand
break, which is easily repaired by the cell BTW. The cell is then
remarkably able to withstand thermal insults (which are also
repairable by the cell) and is able to repair "localized" damage to
its DNA by ionizing radiation. How come? design? chance? evolution?
creation? We don't see the world as it really is, we see the world as
we see it. I see design.
Greetings
Ed,
==
EGM
"in ipso enim vivimus et movemur et sumus sicut"
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