WHERE ARE THE SNOWS OF YESTERYEAR?
-Francois Villon, c. 1461
By Edwin D. Reilly, Jr.
The Sunday Gazette
write a week
before Christmas day. As I adorn our tree with its last ornament, an
but otherwise realistic white snowflake, I look out at our lawn, as
green as it
was in June. And the forecast seven days out says that unless the
Irving Berlin and Bing Crosby intervene, rain is much more likely than
unlikely that the first Christmas was white. Christ was born in about 4
mere 2,010 years ago, so its climate has not changed over such a short
we do not know that He was born in the winter, much less in a
such as December. One can view the dynamic seasonal advance and retreat
snow ridge from the North Pole southward and back again at http://en.wikipedia.org/wiki/Snow.
front of maximal probable advance never reaches as far as the heart of
Middle East, so certainly not as far south as
hexagonal symmetry of individual snowflakes. They form miles above the
so soft and feathery that they take hours to flutter down to earth.
fall in the company of similar but rarely identical flakes,
excessive numbers of poor little water droplets that never got promoted
ethereal splendor of ice crystals, they share the magic power to cover
urban landscape with a soft velvety white blanket that hides its every
sadness, too. I thought of leading with a quote from James Russell
“The First Snowfall,” a childhood favorite that I can still recite. But
would be too painful, akin to listening to Judy Garland sing “Have
Merry Little Christmas” in a way that makes the listener believe that
wish is unlikely to come true for whomever she is singing to: “Through
years we all will be together, if the fates allow.” I
tear up every time.
the following from a novel in which Smilla, the protagonist, a native
Greenlander who emigrated to
eight-year-old Isaiah, who jumped off the snow-covered roof of a seven-story building, was being chased. Early in the book, Smilla as narrator says:
“For the first time I look at his coffin, hexagonal in form, like ice crystals. Now they are lowering him into the ground. The coffin, made of dark wood, looks so small, and there is already a layer of snow on it. The flakes are the size of tiny feathers, and that’s the way snow is; it isn’t necessarily cold. What is happening at this moment is that the heavens are weeping for Isaiah, and the tears are turning into frosty down that is covering him up. In this way the universe is covering him up, pulling a comforter over him, so that he will never be cold again.”
only thing on
my Christmas list is a new book whose large cover features a glorious
the most perfect imaginable snowflake (see above). The photo
is credited to Patricia Rasmussen, but the book’s author is Cal-Tech
Kenneth Libbrecht, who has a cottage industry going in the production
snowflake books (see Amazon.com
and search for “snowflakes.”) An earlier snowflake
pictorial book was published in 2000 by Wilson A. Bentley. See http://snowflakebentley.com
for a portrait of this renowned “Snowflake Man” and some of his work.
with snowflakes is that of a scientist interested in art, just as an
interested in science would be—and there are many of both types. Surely
hexagonally symmetric pattern of a snowflake with its whorls and
is an artistically pleasing architectural edifice, even if only a few
millimeters in diameter.
that each of a snowflake’s six arms is in a whorl of its own, but
true because what one arm does as it grows through transition of
water vapor to solid crystal, so do the other five, in lockstep. That,
is the crux of my scientific interest in snowflakes. As one arm
extend an outstretched limb of a certain length at a certain angle
say, seven millimeters away from the previously formed extension, how
other five arms “know” to do exactly the same thing?
possibility, the one I like best as a computer scientist, is that a
functions as a tiny cellular automaton. Information as to what a tiny
(non-biological) “cell” of an arm does at any one point depends on the
characteristic values of adjacent small cells, areas of identical
of equilateral triangles, perhaps, for a two-dimensional simulation—or
of identical shape, regular tetrahedrons most likely, for a
simulation. So if the flake grows from a hexagonal seed, hexagonal
maintained until the flake reaches maturity.
tried to make such models work, but with only limited success. To
of flakes of acceptable fidelity this way, one must deduce the
“rules” that cause an initially empty cell adjacent to a partially
to remain water vapor or to crystallize.
space eluded me, but I also wanted to tell you about “ice nine” as
my favorite philosopher, Kurt Vonnegut. The substance is fictional, but
book “Cat’s Cradle” that describes it lies open to the right page at
Kurt’s brother Bernard and his friend Vince Schaefer knew how to make it snow; how I wish they could help us on the 25th. But the fates didn’t allow it, so dreaming will have to do.
Edwin D. Reilly, Jr. lives in