Here at the heath and experiment which, we have going
on in the space station which looks at how cubic particles,
actually particles that are halfway between cubes
and spheres, pack together to form crystals with the object
of understanding how geometry affects how you can
organize materials.
Superball particles are different from the spheres
because you can only imagine one crystal packing
for a spherical particle,
whereas cubes can take many different forms
when they crystallize.
One of the really interesting ways
of binding things together it turns out, is to use DNA,
which is not just the secret of life,
but also involves separate chains
which bind specifically together with one another.
And when you heat them up, they de-hybridize.
They come apart.
We're using tiny little particles
that are 200 times smaller than the width of a human hair,
and we try to make them smart.
We try to control their interaction, and by doing so,
we can sort of force them to form larger structures,
new materials, and, you know, an example is a colloidal crystal.
So this is something we do every day here on Earth,
but the forces that these particles experience here
on Earth are very often offset by the gravitational force.
The technique we're using
to crystallize these particles is called depletion.
On Earth, we always have the constant force
of gravity pulling the particles down, so crystals happen
in 2-D arrays-something that you could consider
like a checkerboard, a two-dimensional array of cubes.
We hope to see something that looks more
like a Rubik's Cube in space.
The most interesting thing which we found in previous experiments
in space, is theory isn't always right.
Theory is based on observations, and the observations
that you make from things
on the ground aren't always telling you the basic science,
the basic physics that's important
for understanding phenomena.
So for instance, when we did experiments
on the space shuttle, what we found is objects
which were supposed to grow as spheres with a radius
that just increases, that's what theory told us would happen,
in fact didn't do that.
In fact, they were like snowflakes.
They grew with arms, dendritic arms, we call them,
which grow out in an instability, okay,
which was masked by the fact that on Earth, in gravity,
these particles sedimented, in particular, in that case
for spherical particles.
If you're lucky you will see, you'll discover similar things
for our particles which are no longer spheres.
Spheres are the easiest thing that we want
to understand what happens for more complex shapes, okay,
and so we want to see whether similarly the ideas we have
from theory and from experiments from the ground hold
up when you get rid of sedimentation due to gravity
and you let these particles interact basically
by their shapes and the interactions that they have
with small particles around them
which supply the pressure to crystallize them.