Rattle Reflections

Rattle particles consist of a mobile core particle enclosed in a hollow shell. The core particle moves around due to thermal fluctuations. Applying an electric field will cause the particles to arrange on a lattice. When the particles arrange on a lattice and the distance between the particles is of the wavelength of light that hits the lattice, the result will be reflection of that light via Bragg's law. By tilting the crystal we change the distance between the particles that the light experiences. As such we can reflect different colors of light by tilting the crystal.

In this game you tilt the crystal (up and down arrow keys) in order to reflect the correct light. The light will only be reflected when the electric field is applied (spacebar). Notice that the strength of the field is lowered by extensive use of the spacebar! When the electric field strength is too low, the light can no longer be reflected. When the salt concentration gets to 100 mM, the particles become immobile and the game is over.