Short answers, pulled from the story.
Jacob Moreno created the first sociogram in the 1930s by drawing lines connecting children who liked each other in a second-grade classroom. This visual map of human relationships laid the foundation for the field of social network analysis.
Ferdinand Tönnies distinguished between Gemeinschaft as community with personal and direct ties and Gesellschaft as society with impersonal and formal links. This distinction formed part of the intellectual lineage of social network analysis that began in the late 1890s.
Mark Granovetter published his groundbreaking paper on the strength of weak ties in 1973. The study showed that acquaintances bridging different social circles provide more value than close friends who share redundant information.
Stanley Milgram found an average of six degrees of separation in his 1960s experiment where participants mailed packages to a target person in Boston. The study demonstrated that social networks are self-organizing with globally coherent patterns emerging from local interactions.
The three dimensions of social capital are structural, relational, and cognitive. The structural dimension describes how partners interact, the relational dimension refers to trustworthiness and norms, and the cognitive dimension analyzes the extent to which organizations share common goals.