Could any “useless” natural object composed of simple materials exceed the beauty of a snow crystal?  As you wish for a white Christmas, think about two snowflake designers: one who makes them in a lab, and one who makes them in clouds.

Kepler’s snowflakes:  Six-sided snowflake crystals have been known by everyone with sharp eyes living where snow falls – the Chinese who wrote about them in the 2nd century, Albert Magnus who described them in the 13th century.  But the first to really discuss their structure and origins in a scientific way was Johannes Kepler.  Philip Ball wrote about this in Nature this week (Vol. 480, 22 December 2011, p. 455, doi:10.1038/480455a).  The sight of a snowflake on his lapel provoked the great German astronomer to ponder their construction.  His short 1611 booklet, De nive sexangula (On the Six-Cornered Snowflake) “seeded the notion from which all of crystallography blossomed: that the geometric shapes of crystals can be explained in terms of the packing of their constituent particles.”  Kepler imagined that a snowflake was composed of constituent particles (“not explicitly atoms, but as good as,” Ball remarks) whose packing led to the emergent geometric structure.  Elegant as this beginning of a theory was, Kepler was unable to explain the plate-like shape and hexagonal ornamentation:

Kepler instead fell back on Neoplatonic occult forces. God, he suggests, hasimbued the water vapour with a “formative faculty” that guides its form. There is no apparent purpose to the flake’s shape, he observes: the “formative reason” must be purely aesthetic or frivolous, nature being “in the habit of playing with the passing moment”. That delightful image, which touches on the late Renaissance debate about nature’s autonomy, remains resonant today in questions about the adaptive value (or not) of some complex patterns and forms in biological growth.

Ball does not discount the genius of the otherwise influential Kepler, “for not until the 1980s was this seen to be a consequence of branching growth instabilities biased by the hexagonal crystal symmetry of ice.”  In fact, Kepler’s tentative foray into crystallographic principles proved a good heuristic for researchers who followed him.

Libbrecht’s snowflakes:  The modern master of snowflake photography today is Kenneth Libbrecht of Caltech.  His collection is not only vast (10,000 and growing), but stunningly beautiful (see his SnowCrystals.com Caltech website for a tour).  As a physicist, Libbrecht brings the quest for scientific explanation to his famous hobby.  Yes, he does believe that no two snowflakes are alike.  Though much has been explained in his lab experiments, where he can grow snowflake-like crystals under controlled conditions, he admits much remains to be learned.   Jascha Hoffman interviewed him for Nature (Vol. 480, 22 December 2011, pp. 453–454, doi:10.1038/480453a).  He asked why Libbrecht studies snowflakes….

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