There will be no more than six people between you and any stranger, that is to say, you can know any stranger through six middlemen at most. This is the six-degree division theory, also known as the small world theory.

I. Meaning

Small-world phenomenon (also known as small-world effect), also known as six-degree space theory and six-degree separation theory (English: Six Degrees of Separation). Suppose that all people in the world who don't know each other only need a few middlemen to establish contact. Later, in 1967, Stanley milgram, a psychology professor at Harvard University, made a chain letter experiment based on this concept, trying to prove that it only takes five middlemen to contact any two Americans who don't know each other.

This phenomenon does not mean that anyone's contact with others has to go through six levels, but expresses an important concept: any two strangers can always have an inevitable connection or relationship in some way. Obviously, with the different contact methods and abilities, the opportunities to realize personal expectations will be obviously different.

Second, value.

The intimate combination of "six-degree segmentation" and the Internet has begun to show commercial value. In recent years, people pay more and more attention to the study of social networks, and many network softwares begin to support people to establish more mutual trust and close social ties. These softwares are collectively referred to as "social software".

Third, summary.

Although the six-degree division is a sociological theory, it is actually more like a mathematical theory. Many people say that the four-color problem has the same effect. Six-degree segmentation well expounds a network structure (our human society) and strengthens the connection and connection between different nodes. However, it is incomplete and not enough to guide our practice. However, this theory has made people have a profound understanding and exploration of human society in the information age to a great extent.