When asked if the 21st century would be the century of physics, Stephen Hawking replied: “I think the next century will be the century of complexity”. Then, if complexity is so important, what is it all about?
Complexity is a relatively new science, that studies complex systems. Nothing surprising so far. But again, what are complex systems? Answering this question is when things start to get… complicated. There is no precise definition of what complex systems are, but, of course, there is a leading idea. Many complexity scientists somewhat agree that complex systems are evolving systems with elements interacting with each other, in a nonlinear fashion, presenting emergent behavior, with no central control.
Ok, let’s brake this down. First “evolving systems with elements interacting with each other“. A system is a structure, an organization, a set of things as parts of a whole. These “things” are the elements of the system and they are not still. They are evolving as a whole, mainly because of the interactions among themselves. An easy example here is web pages (the elements) that link (interact) to other web pages in a constant adaptation and evolution creating the World Wide Web (the system).
Secondly, “in a nonlinear fashion“. Linear here means simple proportionality. If with five oranges you can make a glass of orange juice, with 10 you would make two glasses, 15 you’d make three glasses, and so on. Everything that you can imagine, different than that is nonlinear. Nonlinear means that such proportionality does not exist.
Next is “presenting emergent behavior“. An emergent behavior is something unexpected, when surprising phenomena occur. This happens also because of the interaction between the elements of the system. The example that I like to give here is the brain. The brain is a system formed by neurons, which are relatively simple cells. Despite of their simplicity if analyzed individually, when neurons interac together the result is incredible phenomena like thoughts, dreams, reasoning, commands.
Finally, “with no central control”. This one is simpler than the others. As you may have guessed, this means that complex systems don’t have something or someone to dictate the rules of the game. And by that I mean there is no unique entity controlling all the interactions among the elements of a system.
In another words, complex systems are composed by parts that interact among themselves. These interactions are not controlled by a single part of the system, they are very complicated, hard to explain and result in something surprising, unpredicted.
Complexity is a interdisciplinary science and people from several different backgrounds work together to face the challenging present and future problems. These scientists come from maths, physics, biology, sociology, computer science, chemistry, anthropology, engineering, architecture, geology, and the list goes on. As complex systems involve many disciplines, likely they also involve several theories and tools. Networks, game theory, information theory, cellular automata, genetic algorithms and chaos are only a few examples of what it takes to make this new thrilling area of science!