Game Development Reference
In-Depth Information
weather system at the moment, but there is considerable debate about whether it is
a permanent change or part of a very long cycle.)
FIGURe 3.1
Four categories of
behavior of complex
systems
Emergent systems are less ordered and more chaotic than periodic systems. Emergent
systems often display stable patterns of behavior, but the system might switch from
one pattern to another suddenly and unpredictably. The weather system is a good
example. Although the cycle of seasons has overall norms in a particular area, pre-
dicting the weather for a particular year is difficult. The date of the next hard frost
or the amount of snow in winter is nearly impossible to predict accurately because
of the complex interactions of pressure systems, ocean temperature, and air temper-
ature. It is still possible to make assumptions and create rules of thumb based upon
statistical norms, such as “plant peas on Good Friday,” but these will not be reliable
in every year.
experiencinG emerGence in a simple experiment
You can experience the four categories of complex behavior through a simple experi-
ment. all you need is a water tap (although this experiment works better with some
taps than with others). When you open a water tap very gently, at one point it will start
dripping drops of water at a slow, regular pace. sometimes it is easier to reach this
state by opening the tap and then gently closing it. a closed tap is an easily predictable,
ordered behavior: no water flows. a dripping tap is in a periodic state. now, when you
gently open the tap further, it will start dripping faster and faster. however, at a certain
point, not very long before you get a full stream of water, the pattern of water flow will
become irregular. at this stage, you are moving the system quickly toward a chaotic state.
somewhere in between the chaos and periodic dripping you might be able to get more
complicated periodic patterns, such as two quick successive drips followed by a longer
pause. sometimes the tap will alternate between fast drips and a slow, irregular trickle.
Opening the tap further will quickly push the tap state back to a steady, ordered flow
of water.
