Yesterday I went to a talk about the mathematics of relationships and why people congregate in cities. The speaker argued that the average probability of two people having a relationship (any sort of relationships: client, employer, lover, friend…) is inversely promotional to the number of people in their social sphere. His definition of a social sphere was the people that are located in the area which you can travel to in less time than the other person.
The main point that came out of the talk is that distance in terms of time is more important than real distance. The best cities are those with a good transport network which allow many opportunities for relationships.
The talk explained why over 50 million people migrate to cities each year. Cities offer so many more potential relationships than the surrounding population.
I’d like to look into this topic in closer detail but I’m on holiday at the moment.