Soft-matter and Colloid Physics

Colloids are microscopic particles so small that they move diffusively when dispersed in a fluid, exhibiting Brownian motion, controlled by the temperature of the system, like atoms. However, unlike atoms, colloids are big enough to see with light, so they can be probed with microscopes and laser light scattering. The interactions between atoms are fixed, dictated by quantum mechanics, but those in colloids can be very finely tuned.

Under normal conditions on earth, the separation between liquids and gases is usually a bit mundane: the level of water in a drinking glass simply falls as the liquid evaporates into a gas, since the liquid is denser. Two liquids of different densities, such as the oil and vinegar of salad dressing, are similarly unexciting; the oil just floats to the top after a period of time. However, when the effects of gravity are taken away, such as in the environment of the International Space Station (ISS), this separation creates far more interesting and complex patterns.