Six degrees of separation: "There will be no more than five people between you and any stranger, that is, you can know any stranger through five people at most." According to this theory, there are only five people between you and anyone in the world, no matter which country, race or color. From 65438 to 0967, American social psychologist Meyer Glenn put forward the "six degrees of separation" theory. To put it simply, the theory holds that any two strangers can establish contact through "relatives and friends" under the background of interpersonal communication, and at most five friends can achieve the goal. This seemingly simple but mysterious theory has attracted the attention of mathematicians, physicists and computer scientists. Their research found that many other networks in the world also have a very similar "six degrees of separation" structure, such as the business connection network structure in economic activities, the food chain structure in the ecosystem, and even the human brain neuron structure and the molecular interaction network structure in cells. In 200 1 year, a research team from the sociology department of Columbia University started this experiment on the Internet. They set up an experimental website, and the destination is 65,438+08 people from different countries (including a writer in new york, an Australian policeman and a Parisian librarian). ), volunteers send emails to relatives and friends who are most likely to achieve the task through this website. Results 384 volunteers' emails reached their destination, and it only took five to seven steps for them to reach their destination. This activity continues.