Is it possible to know everyone in the world? Is this theory really so amazing?

Audit expert: Chen Mingxin

National Level 2 Psychological Counselor, Senior Human Resources Manager

Imagine you are in a busy restaurant and you overhear two people talking about a faraway town you have never heard of. On impulse, you interject and discover that one of them has a mutual friend. This friend is the link between the two of you, magically connecting you two.

The connection between people is much closer and more magical than we think. All of this starts with the theory of "six degrees of separation".

Source: HackerEarth Blog

The "six degrees of separation" theory simply means that there are no more than six people between you and any stranger, which means that you can get to know any stranger in the world through at most six people. It sounds incredible, but there may really be less than six people between you and celebrities, scientists, and even ice cream makers around the world. So how did the "six degrees of separation" theory come about?

In the 1960s, Stanley Milgram, a psychology professor at Harvard University, designed an experiment of " letter delivery ". Milgram randomly sent letters to some residents living in cities across the United States. The letter contained the name of a Boston stockbroker and asked each recipient to send the letter to a friend who he thought was closer to the stockbroker . After receiving the letter, the friend sent the letter to a friend who he thought was closer to the stockbroker. In the end, some letters were sent to the stockbroker, and each letter was handled 6.2 times on average . Thus, Milgram proposed the famous "six degrees of separation" theory: it only takes six people at most to establish a connection between any two people in the world.

Source: pixabay

Later, for publicity purposes, the Facebook team studied the data of 1.59 billion registered users at the time. It was a huge challenge to calculate the number of people who could be connected to each other based on such a huge amount of data. On February 4, 2016, the research results titled Three and a half degrees of separation were published on the website FACEBOOK research. It was found that the "network diameter" of this magical number is 3.57, which means that each person is 3.57 people away from other people. If only American users are considered, this number will drop to an average of 3.46 people.

The "Six Degrees of Separation" theory is also like a treasure hunt game. Ideally, if you know 50 people or have 50 friends, and your 50 friends know another 50 people you don't know, and so on, you can calculate that in 6 steps you will establish connections with 50⁶ or 15.62 billion people . However, the key to success lies in whether you can find the six hidden channels connecting you and the stranger. If you look for people aimlessly, the answer is unknown.

However, this theory has some flaws and can only be realized under ideal conditions. Milgram was also controversial when he was doing the experiment. At first, the letter delivery rate was very low. Later, he found that the value of the letter or package in people's minds was an important factor affecting people's decision to continue to deliver it. After some adjustments, he successfully increased the delivery rate to 35%, and later it rose to 97%.