Småverdensfenomenet

Småverdensfenomenet, often translated as the small-world phenomenon, describes a characteristic of many networks where individuals are surprisingly close to each other in terms of connections. This concept, popularized by sociologist Stanley Milgram's "six degrees of separation" experiment, suggests that any two people in the world can be connected through a surprisingly short chain of acquaintances.

In network theory, a small-world network exhibits high clustering and a short average path length. High clustering means that a person's friends are likely to be friends with each other. A short average path length indicates that the number of steps required to get from any one person to any other person in the network is relatively small. These seemingly contradictory properties can coexist.

The small-world phenomenon is not limited to social networks. It has been observed in various other complex systems, including the brain's neural networks, the internet, ecosystems, and collaborations between scientists. Understanding the small-world nature of these networks can provide insights into how information, diseases, or innovations spread, and how the systems are organized and resilient.

The mathematical framework for studying small-world networks was developed by Duncan Watts and Steven Strogatz in 1998. They showed that by introducing a small number of random connections into an otherwise regular lattice, a network could quickly transition from a highly clustered structure to one with short average path lengths, exhibiting small-world properties. This research has had a significant impact on fields ranging from sociology to physics.