Snowflakes

[:Ace:]

How do "they" know that each one is different?

Do scientists run outside while it snows, catch one then quickly run back inside and look at it before it melts??

[WaldoMcFroog]

Yes.

[gen2]

You can do that but there is a slightly more comfortable way.  You go outside with a microscope slide that has been chilled below 0degC and catch a flake on it.  You also have a small bottle of prepared liquid in a dropping bottle which has also been chilled below 0degC.  I cannot remember what this liquid was called (it was 35 years ago) but it evaporated leaving an extremely thin coating on the snowflake.  The slide is then brought indoors where the flake is allowed to melt and evaporate leaving the coating in its original shape.  The mould of the snowflake can then be photographed or viewed down a microscope at leisure and in the comfort of a warm laboratory.

[jake-the-peg]

How do you "know" every person is different?

Seriously though there are a huge number of possible permutations so the chances of you finding two identical snowflakes are vanishingly small.

However with the huge number of snowflakes that do fall some somewhere are probably as close to identical as makes no odds.

http://tafkac.org/faq2k/science_51.html

More interestingly where does this belief come from? I have no idea but I'd love to know if anybody else knows where it originated from.

[secretsquiz]

my physics teacher at school told us to ignore the theory that they're all different as there have been an unimaginably large number of snowflakes and it's impossible to compare them all.

[Calvesy]

The number of snowflakes, and the number of their constituent ice molecules is not unimaginable. If each snowflake weighs 1/100 of a gram then it would contain about 300 billion trillion molecules. The number of ways they could organise themselves on crystallising would we 1x2x3x4x5........x (3x10^17) . Near as dammit infinite. But how many snowflakes have there been? You might guess that at any given moment there are a million cubic kilometres of falling snow at one flake per cubic metre for say 5 billion years

[Kingaroo]

Google "photo snowflake book" and you'll find a few beautiful examples of this art, including a children's book, Snowflake Bentley, about the Vermont farmer who first photographed them and came up with the uniqueness theory, and a book of modern photos done in a more high tech way (perhaps what gen2 described).  These sites will show you some of the photos -- lovely!