A Small World or Not?

Academia often seems like a small world where everyone knows everyone else. But http://www.linkedin.com/profile/edit?trk=hb_tab_pro_top">my experiences on LinkedIn suggest the opposite. Most of the people I am connected to on LinkedIn are only connected to perhaps 1-2 people that I am already connected to and when I browse their lists of connections there are normally only 1-2 other people that I