The Dynamic of Social Networks and Social Interactions

We have records, billions and billions of phone calls. And I have some colleagues at MIT who were able to get hold of all those records. So here's what you do with that. You say, I call Stuart, and then within six months just to take some arbitrary time, you call me back - we define that as a relationship. That's a social interaction not just you calling me, but there's a reciprocating. We count those in every city, and then we add them all up, and we plot that. And the prediction is that it should look just like that. The two different colours represent two different countries, Portugal and the United Kingdom. They lie on top of