Emergent Complexity

Don't be scared away by the title - the idea of "emergent complexity" isn't itself complex. It is (to me) one of the most fascinating and awe-inspiring properties of our universe. The idea is that sets of small, simple rules can be combined to produce complex, intricate things. The complexity is called "emergent" because it isn't clear how the individual rules, simple and straightforward as they are, can produce things that are so complex. It is almost magical.


The idea is illustrated well by John Conway's Game of Life. The Game of Life isn't a game at all, but a simulation. In it, the world is represented by a two-dimensional grid of cells that are either "alive" or "dead" at any particular instant in time. At each iteration of the simulation, cells can be "born," they can "die," or remain in their current state (alive or dead). What they do at each iteration is based only on four simple rules (see the above link if you want to know what they are).

What makes the Game of Life interesting is that even though the rules are very simple, complex structures emerge when the simulation runs. Some configurations of cells evolve and at length disappear. Others settle on stable shapes like circles or pulsating masses. Still others travel across the screen like "gliders." It looks as if there is some kind of omniscient programming that is trying to bring order to the system. The truth, though, is that the individual rules operate independently and rather stupidly (if you will). It just happens that when they are combined, stable, complex structures happen to emerge. There is something deep and as yet undiscovered about how and why this happens.

At first glance, Conway's Game of Life might seem like irrelevant academic gas, but the philosophical and scientific ramifications are, I think, earth-shattering. The Game of Life demonstrates that ordered, complex things can emerge from unordered, simple things. It shows why evolution is reasonable, and it shows why the universe can continue to exist as we see it today.

In a sense, the universe is like a giant Game of Life. It is like the Game of Life with its four simple rules replaced by hundreds of thousands of more sophisticated ones. The stable structures that emerge in this giant Game of Life are... us, and everything around us. In a very real sense, everything we are and everything we know is the product of many simple rules operating mindlessly in the background.

This post is overlong. There are some specific examples I would like to explore that are absolutely fascinating, but they will have to wait for a future post.