Statistical physics approach to social dynamics

 

Statistical physics has proven to be a fruitful framework to describe phenomena outside the realm of traditional physics. Recent years have witnessed an attempt by physicists to study collective phenomena emerging from the interactions of individuals as elementary units in social structures.

In social phenomena the basic constituents, individual agents, are incomparably more complicated than atoms or molecules and every individual typically interacts with a limited number of peers, usually negligible compared to the total number of agents in the system. In spite of that, human societies are characterized by global regularities. There are transitions from disorder to order, like the spontaneous formation of a common language/culture or the emergence of consensus about a specific issue. There are examples of scaling and universality. These macroscopic phenomena naturally call for a statistical physics approach to social behavior, i.e., the attempt to understand regularities at large scale as complex collective effects of the interaction among single individuals, considered as relatively simple entities.

In this lecture I will present an overview of recent results on the statistical physics approach to social phenomena. In particular I will focus on the topics of "opinion" and "cultural" dynamics, that describe the processes of formation of common opinions, cultures or languages starting from an initial disordered state. I will highlight the similarities and differences with phase-ordering phenomena in traditional condensed matter physics. Much emphasis will be put on the crucial role of the topology over which these types of dynamics take place: complex networks are in many cases the appropriate description of the pattern of interactions among individuals.