Summary

Computer simulations show that multi-agent systems obeying simple local rules can give rise to self-organisation that is very similar to that observed in the real world. The self-organisation is emergent behaviour because it is not apparent at the level of the individual agent nor is it dictated by the individual rules. That is, there are properties of the system which are not properties of the individual components. As in the last chapter, the examples here are of systems that are out-of equilibrium and furthermore, particularly in the case of boids and ants, the systems are able to adapt to changing circumstances. Although the simulations are valid examples of emergence, one must nevertheless be cautious in interpreting the results. Eventhough the results may be used to justify a simple model as one possible abstraction of a real system, this does not rule out other models, though again the simplest explanation is appealing. Finally, consider the Universe as a whole. It (and time itself) started at the Big Bang and expanded from an initial hot fireball into a cooler environment. The formation of galaxies, stars, planets and other regular structures that we see took place through the organising force of gravity. Thus we may say that universe itself is the largest system displaying self-organisation.