# Evolution and Entropy

Tom Schneider toms at fcs260c2.ncifcrf.gov
Sun Jan 30 13:07:19 EST 1994

In article <PREP.94Jan29204725 at yarrow.wt.uwa.edu.au> prep at yarrow.wt.uwa.edu.au
(Paul Repacholi) writes:

| In article <hurd.759667755 at sfu.ca> hurd at fraser.sfu.ca (Peter L. Hurd) writes:
| >
| > jruspini at mail.sas.upenn.edu (Jason M Ruspini) writes:
| > >I'm wondering if someone can help me with a question concerning evolution and
| > >entropy.   I am arguing with someone on alt.christnet over whether evolution
| > >contradicts entropy.   I say that it does not because the internal physical
| > >order gained by a biological system is outweighed by the external chemical
| > >disorder it causes when it evolves.

| Non question. IE, the 'answers' "aren't even wrong".

No, it was a perfectly fine question, and it was answered by several posters
quite well.  The sun's energy is captured in plants and then dissipated and
radiated out to space.  The flux is quite sufficient to explain the existence
of life.

| LIFE contradicts entropy, as do rocks, clouds... But you will find that this
| requires large energy inputs, so the TD is fine.

Entropy is simply a measure of the state of a system:

S = - k \sum{p_i} p_i ln p_i

where k is Boltzmann's constant.  It is used in the Second Law of
Thermodynamics.  This was devised to explain many phenomena, and there are NO
KNOWN EXCEPTIONS.  There is no contradiction.  The "large energy inputs" are
dissipated, as expected by the second law.  A great book to read to learn about
this is:

@book{Atkins1984,
author = "P. W. Atkins",
title = "The Second Law",
publisher = "W. H. Freeman and Co.",
year = "1984"}

As the previous posters pointed out, the second law only says that IN A CLOSED
SYSTEM the TOTAL entropy will always increase (so long as the system is
macroscopic and it is for long periods of time, small atomic level fluctuations
are possible).  The earth is not a closed system.  Evolution does not violate
the second law because the decrease in entropy in living things is far
outweighted by the increase of entropy they produce by living.

Consider a far more puzzling case:  if one takes oil and mixes it with water,
they will separate (in a gravitational field it is quite fast).  This appears
to be a decrease in the entropy!  How could that be?

Further discussion can be held on bionet.info-theory.

Tom Schneider
National Cancer Institute
Laboratory of Mathematical Biology
Frederick, Maryland  21702-1201
toms at ncifcrf.gov