One of the things everybody seems to have heard is
that no two snowflakes are alike.
But it turns out, that’s true in nature,
but not so much in the lab.
My name is Ken Libbrecht.
I am a professor of physics here at Caltech in Pasadena,
and I study snowflakes.
When I started studying the physics of snowflakes,
I really wanted to grow them in the lab under controlled conditions.
And so that’s what some of this equipment is,
you see behind me, are our growth chambers.
Part of it is to try to grow really beautiful
crystals that have never been seen before, and just
trying to understand the physics of how they grow.
Lately I’ve been interested in the artistic side,
and how to design the world’s most perfect snowflake,
or the world’s biggest snowflake.
I realized that if you grow two snowflakes very close to one another,
you could subject them to the same growth conditions at the same time,
and grow what I call “ identical twin ” snowflakes.
The overall six-fold symmetry of a snowflake really
comes from the ice crystal lattice, which
is how the molecules are lined up.
I was invited by Disney to be the
“ snowflake consultant ” for the movie Frozen.
So I went, and just told them all
about how snowflakes always have six sides.
They never have eight.
They never have seven.
And then the movie came out, and they were all six-sided.
It was just great.
That was my contribution to the movie Frozen.
标准的雪花被叫做恒星枝晶 它是星型 有着树枝一样的分枝：树枝晶
The standard holiday snowflake is called a “stellar dendrite.” It’s star-shaped, with branches like trees: Dendrites.
And most people think that snowflakes all look like that, but they don’t.
Some of them look like columns. Think hexagonal wooden pencils.
Sometimes you just get these long, straight columns growing.
I get this question a lot, you know,
why do you do this?
What’s it going to be good for?
And it’s not really meant to be good for anything right now.
I’m really trying to understand it just from basic research.
I’m really just trying to understand the molecular physics of how crystals grow.