Literature

Ever since it was realised that snowflakes can take "endless forms most beautiful", people have considered whether snowflake formation is in any way analogous to the products of evolutionary processes. For example, here is Mark Isaak on TalkOrigins:

"[. . .] order from disorder is common in nonliving systems, too. Snowflakes, sand dunes, tornadoes, stalactites, graded river beds, and lightning are just a few examples of order coming from disorder in nature; none require an intelligent program to achieve that order."

Snowflakes display a distinctive beauty

Another is David Bailey, writing for the National Center for Science Education, developing an argument around the improbability of getting a snowflake with a specific designated structure:

"[. . .] a snowflake is an exceedingly improbable structure, by any reckoning. In particular, it is extremely unlikely that a random roll-of-the-dice assemblage of water molecules would assemble a single snowflake with a specific designated structure. And yet this phenomenon is repeated trillions of times in a typical snowstorm.
[. . .] Snowflakes just happen - a homogeneous, undifferentiated mass of water molecules cools and becomes a sea of beautiful snowflakes with highly specific and differentiated structures. One could almost convince oneself that snowflakes constitute a demonstration of supernatural power."

With arguments like these, it is worth finding out just why snowflakes have such remarkable structures. A very helpful overview has appeared in Physics World. The author points out that the first problem to address is how crystals grow: "In fact, our understanding of crystal growth in general is remarkably primitive compared with our knowledge of crystal structure." The difficulty is that:

"crystal growth is a complex problem of molecular dynamics. The macroscopic development and morphology of a crystal - i.e. whether it forms facets or not, how fast it grows under different conditions and whether it develops into a single large crystal or many smaller ones - is governed by the precise way that the constituent atoms jostle into place as they solidify."

Scientists have been growing snow crystals in the lab, noting crystal shapes in relation to temperature and humidity. The key findings are illustrated in the graph below.

Snow-crystal morphology diagram (for larger image, click here. Credit: www.snowcrystals.com)

"Two features in this diagram immediately stand out. First, the crystals become more complex as the humidity increases: simple prisms arise when the humidity is low; while complex, branched forms appear when the humidity is high. Second, the overall morphology behaves peculiarly as a function of temperature, whereby it changes from plate-like to columnar and back again as the temperature is lowered. The latter behaviour has proven particularly difficult to explain, even at a qualitative level. Indeed, after 75 years we still cannot explain why snow crystals grow so differently when the temperature changes by just a few degrees."

Clearly, there are physical processes at work, operating at various levels, from the nano-scale upwards. This allows us to say to Isaak that the "order from disorder" is essentially the same order as any other case of crystallisation from the liquid to the solid state. It is an order that results from cooling, when interatomic forces become dominant over thermal energies. This should not be confused with order in living things, because that order is derived from information. Living things are best described as having "complex specified information", a term which Dembski has championed. Distinguishing "order" from CSI will greatly assist discussions of biological complexity.
Secondly, we can respond to Bailey's "exceedingly improbable structure" by pointing out that the temperature and snowclouds are not homogenous bodies in the sky. There are temperature gradients, humidity gradients, wind fluctuations and much more besides. Put all these together, and it becomes understandable that each snowflake emerges with a separate crystal growth history and a separate morphology. The extreme improbabilities then are inevitable. But how does this relate to evolutionary theory? Here again, CSI is the key. There is no evidence that biological information self-assembles, like snowflakes. So Law is not the explanation. Chance considerations yield numbers that have led some to think a multiverse is necessary to justify a naturalistic origin of life. The other option is Design - which requires a theistic metaphysic for science, but avoids the escapism from empiricism demonstrated by multiverse advocates.

The enigmatic snowflake
Kenneth Libbrecht
Physics World, 21(1), January 2008, 19-23.

Abstract: The beautiful symmetry of snowflakes masks the complex physics that governs how ice crystals grow and develop under different environmental conditions

See also:

Bailey, D.H. Evolution and Probability, Report of National Center for Science Education, vol. 20, no.4, 2001.

Isaak, M. Five Major Misconceptions about Evolution, October 1, 2003, The TalkOrigins Archive.

Quote: The concluding words of the first edition of Darwin's On the Origin of Species:
"There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one: and that whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved."