The other insight derives from the fact that digital media have provided us with a massive natural experiment that has allowed us to examine how and, more importantly, why our social world is as constrained as it is. The fact that our online social world is virtually identical to our offline social world tells us that the constraints are in our minds and not in the technology of how we communicate: it is the cognitive limits on our capacity to engage socially that limit the size of our social networks and, through the constraints imposed by time, their structure.
