[feral]

> If all the world is six degrees or less from everybody else, then we could perhaps say people have an average of 45 or so first degree connections to other people (45^6 == population of the world, approximately.) So at two degrees, there 45^2 = 2,025 people. That passes my sanity check.

45 is probably much too low.

Your model there doesn't take into account any clustering which is really important.

You want to think of a higher number of first degree connections (higher average node degree), but where there's a large overlap in the second degree connections each first degree connection provides (so you can't just do N^6).