Complex systems are systems (totalities of objects that are in a holistic context and are to be delimited from their surroundings by the interrelationships between them), which refuse to simplify and remain complex. In particular, this includes the complex adaptive systems that are able to adapt to their environment.
Their analysis is a matter of complexity theory (English complexity theory ) or systems theory , which is to be distinguished from complexity theory in the IT sense. The scientific description or investigation of complex systems is collectively referred to as complexity research .
- State space complexity
- Game tree size
- Decision Complexity
- Game tree complexity
- Computing effort
Complex systems show a number of properties (selection):
- Agent-based : Complex systems consist of individual parts that interact with one another (molecules, individuals, software agents, etc.).
- Nonlinearity : Small system disturbances or minimal differences in the initial conditions often lead to very different results ( butterfly effect , phase transitions ). The interrelationships of the system components are generally non-linear .
- Emergence : In contrast to merely complicated systems, complex systems show emergence . Contrary to a common simplification, emergence does not mean that the properties of the emerging system levels are completely independent of the levels below. However, emerging properties cannot be explained from the isolated analysis of the behavior of individual system components and can only be derived to a very limited extent.
- Interaction ( interaction ) : The interactions between the parts of the system (system components) are local, their effects are usually global.
- Open system : Complex systems are usually open systems . So they are in contact with their environment and are far from thermodynamic equilibrium . This means that they depend on a permanent flow of energy or matter.
- Self-organization : This enables the formation of generally stable structures (self-stabilization or homeostasis ), which in turn maintain the thermodynamic imbalance. You are able to process and learn information.
- Self-regulation : This allows you todevelopthe ability for internal harmonization . You are therefore ableto strengthenyour inner equilibrium and balance on thebasis of the information and its processing.
- Paths : Complex systems show path dependency : their behavior over time is not only dependent on the current state, but also on the previous history of the system.
- Attractors : Most complex systems have so-called attractors , which means that the system strives for certain states or sequences of states independently of its initial conditions, whereby these sequences of states can also be chaotic; these are the "strange attractors" of chaos research .
The human brain is an example of a complex system, as it is made up of multiple interlinked building blocks, the neurons, and other accompanying cells whose function is largely unknown. Consciousness is possibly an emergent phenomenon in the human brain. However, a distinction must be made here between consciousness itself (as a medium in the ontological sense) and consciousness content as information that manifests itself within the ontological medium 'consciousness'. Further, v. a. (Highly) complex systems known from everyday life are e.g. B. the Internet, financial markets, multinational corporations, but also the human nervous system, humans themselves, infrastructure networks and the like.
- Yaneer Bar-Yam
- Ludwig von Bertalanffy
- Fritjof Capra
- John L. Casti
- Jay Wright Forrester
- Brian Goodwin
- Murray Gell-Mann
- Hermann hook
- John H. Holland
- Stuart Kauffman
- Peter Kruse
- Christopher Langton
- Niklas Luhmann
- Fredmund Malik
- Bernhard von Mutius
- Stefan Thurner
- Frederic Vester
- Stephen Wolfram
Important institutes for research into complex systems
- New England Complex Systems Institute (NECSI) in Cambridge, Massachusetts.
- Institute for Scientific Interchange in Turin.
- Santa Fe Institute in New Mexico.
- Center for the Study of Complex Systems at the University of Michigan
Institutions in Germany
- Working group complex systems in Darmstadt
- Working group complex systems in Bremen
- Max Planck Institute for the Physics of Complex Systems in Dresden.
- Max Planck Institute for Dynamics of Complex Technical Systems in Magdeburg.
- Institute for Dynamics of Complex Systems in Göttingen.
Institutions in Austria
- Yaneer Bar-Yam: Dynamics of Complex Systems (Studies in Nonlinearity). Westwing Press, o. O. 2003, ISBN 0-8133-4121-3 (in English, see also web links )
- Hermann Haken , Günter Schiepek : Synergetics in Psychology. Understand and shape self-organization. Verlag Hogrefe, Göttingen 2006, ISBN 3-8017-1686-4 .
- Klaus Mainzer: Complex Systems and Nonlinear Dynamics in Nature and Society. Springer Verlag, 1999, ISBN 3-540-65329-5 .
- A. Korotayev , A. Malkov, D. Khaltourina: Introduction to Social Macrodynamics: Compact Macromodels of the World System Growth. Moscow, URSS, 2006, ISBN 5-484-00414-4 . (on-line)
- Roger Lewin: The Complexity Theory. Hoffmann & Campe, 1993. (History of the young branch of science written in a generally understandable manner)
- Bernhard von Mutius (ed.): The other intelligence. How we will think tomorrow. , Klett-Cotta, Stuttgart 2004, ISBN 3-608-94085-5 .
- M. Mitchell Waldrop: Islands in Chaos. Research into complex systems. Rowohlt Verlag, Reinbek near Hamburg 1996, ISBN 3-499-19990-4 .
- Hans Poser : Theory of Science. A philosophical introduction. 2nd Edition. Reclam, Stuttgart 2012, ISBN 978-3-15-018995-5 , pp. 291-311.
- Manfred Füllsack: Simultaneous non-simultaneities. An introduction to complexity research . VS-Verlag, Wiesbaden 2011, ISBN 978-3-531-17952-0 .
- Complex Systems . Complex Systems Publications, Inc., Champaign 1987-2017, 4 issues annually, ISSN 0891-2513.
- Significant Points in the Study of Complex Systems by Yaneer Bar-Yam , in English
- Dynamics of Complex Systems (Studies in Nonlinearity) by Yaneer Bar-Yam , in English, entry page from which the entire work can be downloaded in Portable Document Format (PDF)
- Three examples of complex systems and their application by Yaneer Bar-Yam (English): HIV infection , medical management , sport and complexity
- Modeling Complex Socio-Technical Systems using Morphological Analysis (PDF; 2.3 MB) From the Swedish Morphological Society (PDF file; 396 kB)
- Applied complexity research in the context of civic upbringing and education of the European Civic Education Foundation
- Complexity Explorer: Santa Fe Institute website with introductory courses on complexity research
- Gabler business lexicon on the keyword: dynamic complexity