What is complexity?

New scientific paradigm

Complexity is a new scientific paradigm whose aim is to identify the laws governing the global behavior of systems made up of a large number of interacting units. Such systems are encountered in many situations of great concern, both fundamental and technological.

Research on complex systems is therefore a markedly interdisciplinary enterprise, focusing on the analysis of typical phenomena observed in very different contexts. In this sense it may be regarded as a basic analytic instrument for approaching a host of problems concerning Exo/Astrobiology from a unifying angle. In particular, the origin and evolution of extraterrestrial life is closely related to the issue of self-organization, a key concept of complexity theory.

Complexity has also a high training value owing to the development of flexible, polyvalent methodologies applicable to a wide range of problems and to the bridge it builds between mathematical, physical, applied, biological and human sciences.

Over the last ten years the research on complex systems has considerably modified the scientific landscape by the creation of new scientific journals and new divisions of the main scientific societies, as well as by the emergence of specially designed university departments, chairs and research institutes. One of the reasons for this success is the discovery of universal laws common to many non-linear complex systems. Another reason is the development of minimal models whose implementation on computer allows studying generic forms of complex behaviors from fundamental physics and chemistry to atmospheric sciences, life sciences and sociology.

Belgium as one of the founders of complexity

Belgium is considered as one of the founders of modern Complexity research. "Exploring Complexity", one of the very first treaties on Complexity published in 1989, is authored by G. Nicolis and I. Prigogine. In parallel, innovative research on the related fields of non-linear science and statistical mechanics has been conducted in the Université Libre de Bruxelles, the Katholieke Universiteit Leuven and other academic institutions as well as in the Royal Meteorological Institute. The principal signature of the contribution of Belgian scientists in this effort is a multilevel approach based on:

• The development and use of advanced techniques of non-linear dynamics, thermodynamics, statistical physics, multifractal data analysis and numerical simulation.
• Mathematical and computer modeling based on these techniques and covering a wide range of problems.

The identification and exploration of links between macroscopic, nano and microscopic scales; deterministic and probabilistic views; the integration of the issue of evolution and prediction in the traditional description of physical systems thereby paving the way to fruitful associations with researchers involved in life, environmental and space sciences, at the heart of the field of exo/astrobiology.