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.