One must take into account all agents of entropy, and most evolutionists fail to account for the earthÃ¢â‚¬â„¢s thermal radiation (called Ã¢â‚¬Å“blackbodyÃ¢â‚¬Â radiation). The earth radiates energy back out into space. If subsurface and solar energy were the only means the surface exchanged energy with its surroundings, weÃ¢â‚¬â„¢d all be fried chicken! In fact, solar radiation alone increases entropy, it *must*!

I am not saying that the earthÃ¢â‚¬â„¢s surface is experiencing entropy gain, though it likely is. What I am saying is that evolutionistÃ¢â‚¬â„¢s oft claim that earth is experiencing entropy loss is unsubstantiated by facts and is merely an assumption.

Allow me to show, through the use of thermodynamics, that Earth's entropy certainly may decrease.

From our beloved (by some) sun the Earth absorbs sunlight on the illuminated side, i.e. it absorbs energy. Most of this energy comes in the form of visible light. Because there hasn't been any dramatic temperature increase over geological timescales (we're not as hot and nasty as Venus) the energy must, obviously, be radiating away at pretty much the same rate it's recieved. The energy radiated away by the Earth is, however, is mostly in the infrared part of the spectrum. To summarize, as a first approximation, we have:

energy from sun as visible radiation = energy out from earth as infrared radiation

Now, we approximate the radiation from both the sun and the Earth as blackbody radiation (as mentioned). We may now say that not only does the radiation have an energy density, but it also has an entropy density (i.e. entropy pr. volume). Furthermore, we have the general term for change in entropy

DS >= q/T

In words: the change in entropy is always larger than, or equal to, the energy input by heating divided by the temperature (i.e. this is a constant temperature process, but as we approximated, the average temperature of the Earth on geological timescales has remained the same). We can now express this in terms of the entropy from the incoming and outgoing radiation, so that

(entropy change on Earth) >= [(entropy in from the sun) - (entropy out from Earth)]

This doesn't tell us anything interesting, we need to know which of the terms on the right hand side dominates. Looking at the radiation from the sun and from Earth we know that the sun's surface temperature is approximately 6000 K, whereas Earth radiates at about 300 K. This is a difference by a factor of 20. Now, the energy of a typical blackbody photon is 2.7kT, where k is Boltzmann's constant, and T is temperature (for more information see source). Thus the energy of a typical infrared photon is only 1/20 that of a photon of the visible light. This means that for every photon arriving from the sun, the Earth will emit about 20 infrared photons. That's an increase in number that suggests higher multiplicity and thus higher entropy.

Now, I would just like to make a quick digression. As the observant reader noticed I used a word called "multiplicity". In thermodynamics entropy is DEFINED by multiplicity (mathematically: S = k*ln(M), where S is entropy, k Boltzmann's constant and M the multiplicity, usually denoted by capital omega). Without considering multiplicity, any "analysis" using entropy can quickly become meaningless. It therefore amazes me that I've never encountered the term multiplicity when reading creationist arguments involving thermodynamical entropy. Maybe it just slipped past me, but it ought to be such a major part of the argument, that it shouldn't slip past me. Now, this is, if nothing else, a serious image problem for people using thermodynamics as arguments against evolution. But that was a digression, back to the argument.

Furthermore we have that (see source for more details) the entropy pr. blackbody photon has a constant value of 3.60k (k again being Boltzmann's constant), independent of temperature. Because we have equal flow of energy in and out and because 20 photons leave for every that enters, this suggests that 20 times as much entropy leaves as arrives! Thus it ought to be clear that the dominant term in the above inequality is the last term: (entropy out from Earth), and so we have that

(entropy change on Earth) >= some negative value

That is the entropy change on earth can indeed be negative, i.e. we can indeed have a decrease in entropy here on Earth. Thus, from a thermodynamical point of view life is certainly permitted to arise and evolve.

Forgot my source there...My argument is from the book "Thermal Physics" by Ralph Baierlein, Cambridge University Press, ISBN 0-521-65838-1, p. 128-130.