About Complex Systems

What is a Complex System?

According to Wikipedia:
"Complex systems is a scientific field which studies the common properties of systems considered complex in nature, society and science."

Complexity is the richness in structure and behaviour often seen in large systems. The property that distinguishes complex systems from systems that are merely large but simple is the emergence of  global features from local interactions, as captured in the popular saying ’the whole is greater than the sum of its parts.’ For example, a flock of birds emerges when individual birds coordinate their behaviour with each other.
[quoted from Green, D.G. and Bransden, T.G. Complexity Theory, in McGraw-Hill Encyclopedia of Science and Technology. McGraw-Hill, New York, 2006. pp. 507-511].

Complex Systems (Wikipedia entry)

Complex Systems (Scholarpedia entry)


What is Complex Systems Science?

Complex systems science is an emerging discipline developing new ways of investigating large, highly intricate, dynamically changing systems across diverse areas such as biology, social networks and socio-technological systems, economics, ecology and the environment.

What do recombining genes have in common with air traffic control and with farmers irrigating their fields? The answer is that they are all activities involving agents interacting in networks, which result in systems that have very interesting, and often unexpected, properties. The common thread is that the agents act largely autonomously, and yet the system behaves in an apparently controlled manner.

  • Until recently, genomic research has focussed primarily on single genes that yield single products. However, many organic processes (for example, growth and development) involve large networks of interacting cells and genes. With maps of several genomes now available, biotechnologists have to understand these interactions and learn how to control them.
  • Air travel can be a highly efficient way of travelling from point A to point B. But with the continued growth in air travel, air traffic systems are increasingly coming close to overload. Small changes in traffic flow can lead to large delays further downstream, as the effects propagate through the air traffic network. Fog in Sydney, for example, can cause delays that ripple through the system, resulting in flights being in other parts of Australia, with all the resulting chaos and missed connections.
  • Farmers' use of water and fertiliser can have severe effects on conditions downstream if usage patterns of different farmers happen to combine in unintended ways. Major environmental problems with water quality, salinity and sedimentation have arisen in Australia's major river systems due to measures that have addressed local problems but have failed to take their system-wide impact into account.
  • The Australian National Electricity Market’s network of transmission lines is influenced both by physical-engineering constraints and market-control mechanisms. On a hot day in early 2001, a transmission line failed, causing a widespread cascade of blackouts and a separation of the energy supply in Victoria and NSW. Because operators lacked understanding of the complex relationships between the constraints and controls, they applied corrective measures that served only to increase the difficulty of restoring the network to full operation. They lacked the tools needed to visualise and control this dynamic network.

In all of these cases there is a need for better understanding of how high-level properties emerge  from largely independent system elements acting in networks.

"Complex systems research attempts to uncover and understand the deep commonalities that link artificial, human, and natural systems. By their very nature, these problems transcend any particular field, for example, if we understand the fundamental principles of organization, we will gain insight into the functioning of cells in biology, firms in economics, and magnets in physics. This research relies on theories and tools from across the sciences. Part of the rise of the complex systems research agenda can be tied to the use of theoretical computation as a new way to explore such systems."
[Quoted from the Santa Fe Institute website http://www.santafe.edu/about/FAQ.php]


General Resources

A quiet revolution – the science of complex systems

Nova. Science in the News. http://www.science.org.au/nova/094/094key.htm
An excellent and comprehensive topic published by the Australian Academy of Science and sponsored by the ARC Complex Open Systems Research Network. It also includes:

Complex...or just plain complicated?

Activity sheets for two modelling activities using NetLogo to explore the concepts of self-organisation (flocking birds), and emergence (termites). 
Developed for the University of Queensland's Open Day 2008.  See also the accompanying flyers: Flyer 1 and Flyer 2.

The science of complex systems

"An article in which Dr John Finnigan explains how scientists are probing the complex interactions that influence behaviour of topics as diverse as bushfires, cyclones, the stock market and even electricity prices". www.csiro.au/files/files/p83l.pdf (3 pages; 404KB; pdf)

Complex or just complicated: what is a complex system?

CSIRO fact sheet www.csiro.au/resources/About-Complex-Systems.html


Resources for educators

Diving into complexity: Developing probabilistic decentralized thinking through role-playing activities

Mitchel Resnick a; Uri Wilensky b
a MIT Media Laboratory. b Center for Connected Learning, Tufts University.
Journal of the Learning Sciences,7:2,153 — 172
Online Publication Date: 01 April 1998http://dx.doi.org/10.1207/s15327809jls0702_1 (may need to access via a university library)
"We present detailed descriptions and analyses of 2 role-playing activities...designed to help students explore (in a very participatory way) the behaviors of complex systems, helping them develop better intuitions on how complex phenomena can arise from simple interactions, and predictable patterns from random events."

Complex systems in education: Scientific and educational importance and implications for the learning sciences

Michael J. Jacobson a; Uri Wilensky b
a Learning Sciences Laboratory, National Institute of Education, Nanyang Technological University,
Singapore. b Departments of Learning Sciences and Computer Science, Center for Connected Learning and Computer-Based Modeling, Northwestern Institute on Complex Systems, Northwestern University.
The Journal of the Learning Sciences, 15(1), 11–34
Online Publication Date: 01 January 2006 http://dx.doi.org/10.1207/s15327809jls1501_4 (may need to access via a university library)

World-class basic and applied inter-disciplinary research on questions fundamental to understanding, designing and managing complex systems
© 2009 The ARC Centre for Complex Systems, Australia