20
2 Complexity Time Bomb
Understanding the emergence of new properties requires an interaction-oriented
perspective.
When many components of a complex dynamical system interact, they frequently
create new kinds of structures, properties or functions in a self-organized way. To
describe newly resulting characteristics of the system, the term “emergent phenomena” is often used. For example, water appears to be wet, extinguishes fire, and freezes
at a particular temperature, but we would not expect this based on the examination
of single water molecules.
Therefore, complex dynamical systems may show surprising behaviors. They
cannot be steered like a car. In the above traffic flow experiment, although the aim of
participants was to drive continuously at a reasonably high speed, a phantom traffic
jam occurred due to the interactions between cars. While it is straightforward to
control a car, it may be impossible for individual drivers to control the collective
dynamics of traffic flow, which is the result of the interactions of many cars.
2.4 Beware of Strongly Coupled Systems!
Instability is just one possible problem of complex dynamical systems. It occurs when
the characteristic parameters of a system cross certain critical thresholds. If a system
becomes unstable, small deviations from the normal behavior are amplified. Such
amplification is often based on feedback loops, which cause a mutual reinforcement.
If one amplification effect triggers others, a chain reaction may occur and a minor,
random variation may be enough to trigger an unstoppable domino effect. In case
of systemic instability, as I have demonstrated for the example of phantom traffic
jams, the system will inevitably get out of control sooner or later, no matter how hard
we try to prevent this. Consequently, we should identify and avoid conditions under
which systems behave in an unstable way.
In many cases, strongly coupled interactions are a recipe for disaster or other
undesirable outcomes.
7 While our intuition usually works well for problems that are
related to weakly coupled systems (in which the overall system can be understood as
being the sum of its parts and their properties), the behaviors of complex dynamical
systems can change dramatically, if the interactions among their components are
strong. In other words, these systems often behave in counter-intuitive ways, so
that conventional wisdom tends to be ineffective for managing them. Unintended
consequences or side effects are common.
What further differences do strong interactions make? First, they may cause larger
variability and faster changes, particularly if there are “positive feedbacks” that lead
to reinforcement and acceleration. Second, the behavior of the complex system can
be hard to predict, making it difficult to plan for the future. Third, strongly connected
systems tend to show strong correlations between the behaviors of (some of) its
components. Fourth, the possibilities to control the system from the outside or through
7 Helbing [6].
2 Complexity Time Bomb
Understanding the emergence of new properties requires an interaction-oriented
perspective.
When many components of a complex dynamical system interact, they frequently
create new kinds of structures, properties or functions in a self-organized way. To
describe newly resulting characteristics of the system, the term “emergent phenomena” is often used. For example, water appears to be wet, extinguishes fire, and freezes
at a particular temperature, but we would not expect this based on the examination
of single water molecules.
Therefore, complex dynamical systems may show surprising behaviors. They
cannot be steered like a car. In the above traffic flow experiment, although the aim of
participants was to drive continuously at a reasonably high speed, a phantom traffic
jam occurred due to the interactions between cars. While it is straightforward to
control a car, it may be impossible for individual drivers to control the collective
dynamics of traffic flow, which is the result of the interactions of many cars.
2.4 Beware of Strongly Coupled Systems!
Instability is just one possible problem of complex dynamical systems. It occurs when
the characteristic parameters of a system cross certain critical thresholds. If a system
becomes unstable, small deviations from the normal behavior are amplified. Such
amplification is often based on feedback loops, which cause a mutual reinforcement.
If one amplification effect triggers others, a chain reaction may occur and a minor,
random variation may be enough to trigger an unstoppable domino effect. In case
of systemic instability, as I have demonstrated for the example of phantom traffic
jams, the system will inevitably get out of control sooner or later, no matter how hard
we try to prevent this. Consequently, we should identify and avoid conditions under
which systems behave in an unstable way.
In many cases, strongly coupled interactions are a recipe for disaster or other
undesirable outcomes.
7 While our intuition usually works well for problems that are
related to weakly coupled systems (in which the overall system can be understood as
being the sum of its parts and their properties), the behaviors of complex dynamical
systems can change dramatically, if the interactions among their components are
strong. In other words, these systems often behave in counter-intuitive ways, so
that conventional wisdom tends to be ineffective for managing them. Unintended
consequences or side effects are common.
What further differences do strong interactions make? First, they may cause larger
variability and faster changes, particularly if there are “positive feedbacks” that lead
to reinforcement and acceleration. Second, the behavior of the complex system can
be hard to predict, making it difficult to plan for the future. Third, strongly connected
systems tend to show strong correlations between the behaviors of (some of) its
components. Fourth, the possibilities to control the system from the outside or through
7 Helbing [6].