Feedback to create order

Interference by itself is not a very complete model of reality and complexity. It doesn't account for the difference between "random" structures and the stable, highly complex entities that have emerged. The interference between two sound waves can easily lead to some random noise, without any musically appealing structure. The main difference between random emergence and complex, emergent entities, lies in the concept of feedback. Without some form of feedback the emergent patterns are semi-static: They might be random or might be highly repetitive.

Feedback is a term commonly found in the field of control systems engineering. It stands for the effect of using the current result of a system to control the future results of the system. In general this is as 'simple' as putting a sensor in the system, which measures the result and compares this result with the requested demand. If the result is not equal to the request, this difference (the error signal) can be used to steer the system to the required output. There are some well known examples of such systems, like the thermostat at home, car cruise control, but also our own sense of balance, allowing us to stand.

If an emergent entity would 'want' to have a longer existence (longer than just the random appearance due to interference) it needs to provide feedback to the separate entities that form it. In most complex structures in the world around us, this form of feedback is easily discernible:

• In evolutionary systems this feedback would be called the reward function. 
• In astronomy this feedback is provided in the form of gravity, in which the emergent system (stars, planets, rocks, etc) are formed by separate atoms, which through their own mass keep the emergent system stable.
• In social environments, this feedback is formed by social control, laws, norms, etc.

It is important to note (and this is a subject I'm still contemplating) that it is not clear yet why an emergent entity would 'need' or 'want' to exist. It seems there is some sort of 'existential urge' behind everything, as strong and fundamental as the laws of physics. (I tend towards believing that this urge is actually part of the laws of physics and/or is formed by it) More on this later:)