Here's a description taken from Alyssa M. Adams' blog (http://www.curiosityspaces.com/computation/):

> Droplets bouncing around on a surface is apparently a great way to think about quantum mechanics, or at least some system with a wave encoding information about a discrete object. Here's a nice video showing how a bouncing particle on a liquid surface has a chaotic trajectory. The probability distribution of that particle's position ends up being something like the most unstable mode of the boundaries for the particle. But this paper shows that the droplet's trajectory can be totally reversed, even though the trajectory is chaotic. This is because the droplet's trajectory is completely encoded in the resonating wave it's riding. In other words, the system totally remembers what the droplet is doing and that memory can be accessed and then totally reversed. A great physical (well, MORE physical than usual) example of what memory is.