(c) Leo Patrizi

Marc Barthelemy and Vincent Verbavatz proposed a new equation to understand the distribution of urban populations in a country and their results are published in the journal Nature (online November 18, 2020)

This equation, constructed from data for several countries, accounts for the first time for the temporal variations of urban populations and their organization. This stochastic equation of a new type (with two multiplicative noises, one gaussian and the other of the Levy type) highlights the importance of “interurban migratory shocks”, rare but significant population movements, and makes it possible to understand the hierarchical structure of cities and statistical regularities such as Zipf's law. 

More information and the interview with Marc Barthélémy