Systems engineering: Challenging complexity
Systems engineering: Challenging complexity

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Systems engineering: Challenging complexity

1.6 Increasing complication, complexity and risk: mystery and mechanics

The winter of 1665/66 must have been exceptionally harrowing for the inhabitants of England. Along with the winter weather, the country suffered an outbreak of the plague. A minor effect of this was a decision by Trinity College Cambridge to close its doors. One of those affected by this decision was a young Fellow, Isaac Newton, who returned home to spend the winter in the Lincolnshire rectory in which he had been brought up.

Isolated in the bleak fens and without college high table and the conviviality of the other Fellows to distract him, he found himself at a loose end, so the 22-year-old Newton buckled down and during the next 12 months:

  • solved the binomial theorem

  • invented calculus

  • discovered the universal law of gravitation

  • developed a theory of colour.

Eventually the threat of the plague lessened and Newton returned to Trinity, where he was elected Lucasian Professor of Mathematics. The work that he did during the 1665/66 winter became the basis for Philosophiae Naturalis Principia Mathematica (The Mathematical Principles of Natural Philosophy), which was first published in 1687.

The importance of Newton's work cannot be overestimated, and it is no exaggeration to regard 1665/66 as the beginning of the modern world. The mysterious, magical world of the Middle Ages was replaced by one amenable to rational analysis. Explanation based on myth, magic or the unknowable will of a divinity gave way to observation, calculation and the operation of universal laws. This approach was so successful that 250 years later the French mathematician Henri Poincaré (1854–1912) stated:

If we know exactly the laws of nature and the situation of the universe at the initial moment, we would predict exactly the situation of that same universe at a succeeding moment.

(Poincaré, 1995 [1903])

The achievement of Newton, and others who built on his work, was to provide ways of understanding relationships and interactions in the physical, observable world. In doing so they reduced its complexity to mere complication at worst and simplicity at best.

As suggested earlier in this section, simplicity, complication and complexity are closely related to perception, understanding and the existing knowledge base. If we are faced with a problem that we do not fully understand or one that we cannot see how to solve, we label it ‘complex’. Effectively, we are saying that there is an unknown area that needs to be explored, and a way of dealing with it established. A close conceptual relation of complexity is complication.

The wristwatch that I habitually wear happens to have a glass back through which its mechanism can be viewed, as shown in Figure 10. It's an interesting world inside the watch case, with lots of tiny parts interacting with one another. It is complicated but not complex. There is no ‘unknown’ element in the nature of the outputs of the watch or how the mechanism achieves them. Although personally I couldn't construct a watch, there are plenty of people with the necessary skills. It's a ‘known problem’, albeit a complicated, tricky one.

Figure 10
Figure 10 The wristwatch mechanism

My watch is an illustration of the physical world of objects governed by Newtonian physics and for which, therefore, we have good explanatory models. There are, however, three other ‘worlds’ for which we do not, as yet, have models of equal stature.

Figure 11 shows our level of explanatory confidence as a function of three worlds – the ‘sub-physical’ world of quantum physics, the world of physical objects governed by Newtonian mechanics and a ‘supra-physical’ world of complex systems and which includes a fourth world of human activity systems. In both the sub- and supra-physical worlds there is considerably less success of explanation and therefore greater inherent complexity.

Figure 11
Figure 11 Explanatory confidence in three worlds

In 1927, the German particle physicist Walter Heisenberg (1901–1976) put forward the view that at a subatomic level it was possible to determine either the location of a particle or its vector, but not both. In order to study the behaviour of subatomic particles it is necessary to bounce other subatomic particles off them or to get them to collide with other subatomic particles. Either of these two actions destroys what was happening and so leaves it a mystery. Heisenberg's uncertainty principle states that what happens down in the depths of the subatomic world is unknowable.

In 1968, the German theoretical biologist Ludwig von Bertalanffy published General System Theory (von Bertalanffy, 1968). Although elements of this work had precursors, von Bertalanffy's work was essentially the basis of academic interest in ‘systems’ as a subject. The conceptual basis of systems is discussed in more detail later but one of its cornerstones – emergent properties – is relevant here. This concept states that the properties and behaviour of a system cannot be deduced from studying the properties or behaviours of its elements in isolation. At one level this principle hardly rises above the banal. Everything, be it a physical object or conceptual system, exhibits properties and behaviours that result from the interaction of its constituent elements and which, therefore, are not to be found in those elements in isolation. There are, I believe, no exceptions to this statement. This means that the possession of emergent properties cannot be regarded as a distinguishing feature of a system. However, it is often the case that systems, even simple ones, exhibit behaviours that are unexpected and which surprise their designers, users or observers. Sometimes these behaviours could have been foreseen, but through oversight or negligence were not considered during the design phase of the system. Of equal interest to these preventable emergent properties are those that could not have been foreseen and which are genuinely unexpected. There are external and internal reasons for the occurrence of these. This point will be examined in more detail in Section 3.

Externally caused emergence occurs when a system reacts to its environment in a way that could not have been predicted. There are two origins of unexpected externally caused emergence.

  1. The system has not been designed to be robust against variation in part of its environment. For example, part-way through the construction of the light-railway system serving London's Docklands area an announcement was made of the massive office development at Canary Wharf. On its own this project completely negated all the carefully calculated predictions of traffic for the new railway. To compound the problem the Canary Wharf announcement was made when the construction of the railway, its rolling stock and associated traffic management systems were all well advanced. It was thought that nothing could be done to accommodate the traffic that the Canary Wharf development was expected to generate but, in the event, the railway has coped remarkably well. Emergent properties do not always mean failure.

  2. The occurrence of a new element in the system's environment. The example of the Docklands Light Railway illustrated an unexpected variation in one of the important parameters used as the basis for the railway's design. Sometimes, however, a new factor will occur in the environment. The more complex the system, the longer (all other things being equal) the design, development and implementation processes take and therefore the more likely that unpredictable factors affecting the system will occur in the environment. The Iridium system was conceived as providing worldwide telecommunications through a network of geostationary satellites. Problems with the launch vehicles and the performance of the satellites themselves delayed the project, which was 12 years in development. In the meantime the interconnection of networks of terrestrial systems had overtaken the concept. Iridium declared itself bankrupt in August 1999 but may be resurrected as a system for specialist communication.

Internally generated emergence occurs when the elements of the system interact with each other in an unpredicted way. A potent source of this type of emergence is created by the behaviour of humans (most often, but other sentient creatures too) within the system. Once again, the Millennium Bridge provides an example of this. If only the people crossing the bridge had not perversely attempted to compensate for its lateral movement everything would have been fine and the ‘blade of light’ would have remained unsullied by dampers and struts. Emergence can also arise from the unforeseen interactions between the elements of the system and its environment.

Because we do not know everything which is salient when that knowledge is required, the often unexpected, unpredictable character of emergence means that it remains mysterious, adding to the difficulties of undertaking a complex systems engineering task.


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