Lab Snapshots

by Marek Ples

Examples of self-organization in the non-living world

Self-organization is realized in the physics of non-equilibrium processes, and in chemical reactions, where it is often characterized as self-assembly. Self-organization relies on four basic ingredients:

strong dynamical non-linearity, often (though not necessarily) involving positive and negative feedback;
balance of exploitation and exploration;
multiple interactions among components;
availability of energy (to overcome the natural tendency toward entropy, or loss of free energy).

Chemical and physicochemical examples of self-organization include chemical oscillators and aggregation-diffusion processes (Fig.1).

Gallery:

Fig.1 A - Liesegang bands formed by cobalt compound in silica gel, B - Recreation of the classic Liesegang experiment - a ring formed by the reaction of silver and dichromates ions in gelatin, C - Multi-crystal silver dendrites, D - Multi-crystal copper dendrites, E - Dendritic crystals of pyrolusite in limestone

Silver dendrites in silica gel

A crystal dendrite is a crystal that develops with a typical multi-branching form. The name comes from the Greek word δενδρον (dendron) which means "tree", since the crystal's structure resembles that of a tree.

If we provide the appropriate conditions, we can achieve the growth of dendritic crystals of silver (Vid.1) and copper (Vid.2).

Vid.1

(English subtitles available)

Vid.2

(English subtitles available)

Maze solving using fatty acid

The Marangoni flow in a channel network can solve maze problems such as exploring and visualizing the shortest path and finding all possible solutions (Fig.2).

Fig.2

That's not all