Here are some quotes that stood out for me
At the heart of most real-world examples of Complexity, is the situation in which a collection of objects are competing for some kind of limited resource – for example, food, space, energy, power, or wealth. In such situations, the emergence of a crowd can have very important practical consequences. For example, in a financial market, or the housing market, the spontaneous formation of a crowd of people who wish to sell – and hence are effectively competing for buyers – can lead to a market crash in which the price falls dramatically in a short time.
In all of these examples, the precise nature of the crowd-like phenomena which emerge will depend on how the individual objects interact and how interconnected they are. It
The formula: comprises a collection of objects (drivers) competing for a limited resource (road space).
Complexity can be summed up by the phrase
“Two’s company, three is a crowd”. In other words, Complexity Science can be seen as the study of the phenomena which emerge from a collection of interacting objects –
A complex system contains : Agents: Drivers, stock traders
**agents**.
**Interactions** between these agents may arise because the agents are physically close to each other, or because they are members of some sort of group, or because they share some kind of information.
These objects’ behavior is affected by memory or **“feedback”**. This means that something from the past affects something in the present, or that something going on at one location affects what is happening at another.
**The objects can adapt their strategies according to their history.** This simply means that an agent can adapt its behavior by itself, in the hope of improving its performance.
The system appears to be “alive”. The system evolves in a highly non-trivial and often complicated way, driven by an ecology of agents who interact and adapt under the influence of feedback. For example, financial analysts often talk as though the market were a living, breathing object, assigning it words such as pessimistic or bearish, and confident or bullish. The system exhibits emergent phenomena which are generally surprising, and may be extreme. In scientific terminology, the system is far from equilibrium. This basically means that anything can happen – and if you wait long enough, it generally will.
Complex Systems are able to move spontaneously back and forth between ordered behavior such as a traffic jam or a market crash, and the disorder typical of everyday operation, without any external help. In other words, a Complex System can move freely between disorder and order, and back again, and can therefore be said to exhibit “pockets of order”.The emergence of such pockets of order has very important implications in terms of being able to predict and control the system. Their appearance is also quite mysterious – after all, if a bag of unsorted socks were a Complex System (which it isn’t) it should therefore be capable of organizing itself into an ordered pile of pairs, ready for placing in the clothes cupboard. A wonderful idea but as we all know it doesn’t happen in something as simple as a collection of socks.
As we will see, feedback can arise in a given system in a variety of different ways. It can be built into the objects themselves – for example, humans have a memory of the past which can affect their decisions in the present. Or it can be information or influence fed into the system from the outside, as in the case of the balancing stick, or the announcement of news in a market. In the case of traffic, it can be the information that a driver obtains from looking at the cars around him, or listening to traffic reports on the radio. It doesn’t matter where it comes from, it is still feedback – and it is feedback which enables order to “kick in” in different ways and at different times. Feedback can create order in a disordered pile of files, and can order a tumbling ruler into its upright position. However it is typically very hard to see such feedback operate at the level of the individual objects in a particular Complex System – hence it can appear to an outside observer that the order appears out of thin air.
Modern Jazz involves a spontaneous interaction of a collection of objects (i.e. musicians). It exhibits surprising emergent phenomena in that it is improvised, and hence what emerges in a given solo is a product of the actual feedback which that soloist receives at that moment in time. It is also an open system in that its best performances arise in an environment with audience feedback. It even has the feature of extreme behavior when, for example, the whole ensemble begins to mimic the pattern being played by a particular soloist, and hence there is a crowd effect in which the whole group begins to synchronize its phrasing. Above all, it has no “invisible hand” such as an orchestral conductor or an existing piece of melody that all the players are simply repeating. Instead solos are built on the patterns, motifs or “licks” that a given player has in his memory, and which are then interwoven with original ideas in a truly complex way – all set against a loose backdrop of chord sequences.
Even art is a form of fractal, and the art that we tend to find most interesting is also in that middle-ground between complete order and complete disorder – in other words, between being completely boring and completely unintelligible.
So fractal shapes are a fairly ubiquitous feature of Complex Systems. In other words, they represent a fairly common emergent phenomenon from Complex Systems, in which the system behaves in time as though it is bouncing around in the middle-ground between complete order and disorder. In the same way, the shapes that a Complex System exhibits in space also appear to live in this middle-ground. However,
Memory is a form of feedback. It represents a feedback of information from an earlier point in time.
