Romualdo Pastor-Satorras

Universitat Politècnica de Catalunya, Spain

Romualdo Pastor-Satorras (Barcelona, Spain, 1967) received a PhD in Condensed Matter Physics from the Universitat de Barcelona in 1995. He spent four years as postdoctoral researcher at the Massachusetts Institute of Technology (1996-1998) and The Abdus Salam International Centre for Theoretical Physics, ICTP (1998-2000). At present, he is Associate Professor of Applied Physics at the Universitat Politècnica de Catalunya since 2006. He has been visiting scientist at, among others, Yale University (USA), the University of Notre Dame (USA), the Kavli Institute for Theoretical Physics (USA), the Helsinky University of Technology TKK (Finland), Indiana University (USA) and the Institute for Scientific Interchange (ISI) Foundation (Italy). He has been awarded twice with the national “ICREA Academia Prize” by the Government of Catalonia. He has published more than 100 publications in peer-reviewed journals in the field of statistical physics, and is author of the book “Evolution and Structure of the Internet” (Cambridge University Press, 2007), together with Professor Alessandro Vespignani.

Effects of Social Influence on Collective Motion

Collective motion in animals is able to produce such stunning patterns as flocks of birds turning in unison or shoals of fish splitting and reforming while outmaneuvering a predator. The study of these phenomena is mainly based in simple models, a paradigmatic example being the one proposed by Vicsek and collaborators in the 90s. The main assumption of this and similar models is that individuals tend to orient their velocity parallel to the average velocity of their local neighborhood. The Vicsek model predicts a phase transition between an ordered phase, with individuals travelling in a common direction, and a disordered one, that has been recently the subject of a large interest in the statistical mechanics community. Here we will consider variations of the Vicsek model incorporating social interactions between individuals, represented in terms of a complex social network. The main result of the numerical study of this model is the observation that the heterogeneity of the social network can increase the resilience of the ordered state, making it immune to external perturbations. A related scalar version of the Vicsek model in networks allows for a mathematical treatment that lends support to the numerical observations, and allows for further generalizations.