OK. I should be asleep but I find myself pondering things. But my insomniac brain is working at 1/8 capacity. If that.
So I'll pose the puzzle to you guys and see if I get answers.
Roughly speaking, there are 7 billion people in the world. The way TheStarchDefenders and I figured it, we estimate about 4 trillion relationships (at least acquaintanceship, current or former with people who are still alive) in the world.
Assuming there is nobody who knows nobody, and everyone is connected by at least one "relationship chain" to everyone else. What is the maximum length of the minimum chain between two people? What would you estimate as the average length of the minimum chain between two people?
This is an open form puzzle. Kept a little ambiguous to allow for your own creativity in the actual definition of the puzzle. Feel free to define (or redefine) the puzzle as you deem fit. Just make sure the puzzle is still interesting once defined. My take on this is that it is a fun little "Fermi Problem" with some graph theory thrown in.