Pathica is based on the theory of "Six Degrees Of Separation", which is the idea that any two people on the planet can be connected through five or fewer individuals. As a result, a chain of "friend of a friend" statements can be made to connect any two people in a maximum of six steps.
I don't quite understand the point of this app, if I'm being honest. Considering the number of connections on Instagram that exist due to lifestyle pages, brands, or meme pages, how meaningful are the "degrees of separation" even going to be? The app claims you can "start talking to famous people." Is John Stamos going to start talking to me because we both follow IKEA on Instagram?