The following table illustrates the difference between order and complexity.
| Structure | Alphabetical Arrangement |
Physical System |
Information | |
|---|---|---|---|---|
| Order | periodic | QBV QBV QBV | crystal | very little |
| Complexity | aperiodic | ADXOEVQW | polypeptide | a lot, but not useful |
| Specified Complexity |
aperiodic | THIS IS A CAT | DNA | a lot and useful |
Only man-made and biological systems have evolved to the level, in which the units are arranged in specified sequence and are capable of performing a certain function. The examples for specified complexity in the table either conveys a message by following a set of grammatical rules or produces a protein by following a recipe for translating three bases to an amino acid (an unit for the protein chain).
Another approach to define complexity is through the concept of energy flow per unit mass. Diagram (a) below shows the increment of complexity as the energy flow (per unit mass) into the various systems increases over the age of the universe. Diagram (b) depicts qualitatively the departure from equilibrium at each bifurcate point where the energy flow has reached a critical value and thus can promote more complexity in the system. The dotted curves indicate the options that have not been taken by the evolution.
