061228 – Thursday – Emergent Properties

I’ve been frustrated for some time by thinking that I understand what an emergent property is – but having a hard time coming up with an easily grasped example when I’m trying to explain it.

Today, while I was reading The Revenge of Gaia: Earth’s Climate Crisis and the Fate of Humanity by James Lovelock over lunch, I came across an example he provided that I loved.

Remember, the basic idea with an emergent property is that simple units come together and combine and form an aggregate that is more than the obvious sum of their parts and this new property, itself, generally provides something of value which is, itself, then conserved.

Lovelock was talking about the governor James Watt created to control the speed of his steam engine.

…it consists of a vertical shaft driven by the engine on which is mounted two arms that carry metal balls at their ends. The arms are hinged to the shaft so that, as the shaft rotates, the balls swing out. The faster the engine runs, the higher the balls are lifted; a second pair of arms connected to those carrying the rotating balls simply lifts a level controlling the flow of the steam from the boiler of the engine. The faster the engine runs the more the steam valve is closed. It was obvious to me as a child, that the engine would settle down and run at a constant speed, and that simply by changing the setting of the connection to the steam valve the speed could be set as high or as low as one wished.

So, here we have a spinning shaft, some balls on arms and a linkage to the valve controlling the steam flow. When you put them all together, you have a brand new something which regulates the speed of the engine it is connected to. A new something which is would be impossible to predict the characteristics of by simply examining the component parts separately.

One Response to “061228 – Thursday – Emergent Properties”

  1. Bruce says:

    I like the example of flocks of birds. You look at them all flying together in those amazing patterns and you think it’s something really complex, but in fact it’s created by each bird following very simple rules about where to fly in relation to the other birds right next to it.