Laws of Thermodynamics and Biology

Matt Jones jonesmat at ohsu.edu
Mon Jul 17 12:00:55 EST 1995


In article <Pine.SUN.3.91.950713230414.5102R-100000 at noel.pd.org> Betty
Martini, betty at noel.pd.org writes:
>Evolution is religion, not science.  When you start making the second
law of >thermodynamics go in the wrong direction you have a problem!

These statements certainly reveal a problem. The problem, however, does
not lie with science, religion, evolution or the second law of
thermodynamics. 

In Principles of Physical Chemistry with Applications to the Biological
Sciences (Freifelder, D., 1985, Second Edition, Jones and Bartlett,
Boston), the first three laws of thermodynamics are given as follows:

First Law - "Energy can neither be created nor destroyed - the energy of
the universe is constant."

Second Law - "The ability of an isolated system to perform work
continually decreases, and it is never possible to utilize all of the
energy of a system to do work. In all real processes disorder increases." 

Third law - A perfect crystal (one in which all molecules are at their
correct positions in the crystal lattice) is considered to be perfectly
ordered with respect to position.

As I recall, there's also a 'zero-th' law which postulates that at
absolute zero (degrees Kelvin) the motion of molecules in a perfect
crystal is zero.

Biological processes do not violate these laws. The 'system' we are
considering in biology (the planet earth) is a very small subset of the
universe, and is by no means an isolated system. Due to the constant
input of energy from the sun and from thermal activity in the earth,
there is abundant energy to direct biological processes. Therefore, any
amount of ordering or evolution is permissible, given that we are not
using up the energy of the system to get this work done. The disorder of
the whole system (the universe) is increased by biological processes as
they re-radiate heat, *consistent with the second law*. This increase in
disorder is trivial on the scale of the universe.

As for statements about evolution being a religion and not a science,
perhaps some people's systems are more isolated than others...

My apologies to those who are irritated by all the banter about religion
and science in this newsgroup. Hopefully, thermodynamics and biological
systems are still fair game for discussion.

-Matt Jones



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