How many people do you know around the planet? This is how the theory of the six degrees of separation works

Throughout a lifetime we have the chance to meet hundreds of people. The first friendships from school, the passage to higher studies, the coworkers or friendships arisen in various ways they are forming our nucleus of friendships during our life. Now, in this age interconnected with the Internet era relationships are even greater.

Regarding how many people we can meet in life, the Six Degree Theory establishes the possibility of contacting any of the more than 7.7 billion people around the world using up to five contacts. This theory is already more than 90 years old and was formulated by the writer of Hungarian origin Frigyes Karinthy in her story Chains.

Six Degree Theory

Is it possible to prove it? It is something that large entities such as Facebook and IBM, and some experts consider that, in this massively interconnected world, it is possible to reduce from the initial six degrees to four. The addressee, who would be the last link in the chain, also enters these six degrees.

Before the advent of the internet and social networks, the theory was that each person knows, on average, about 50 or 100 people (family, friends, acquaintances …). This figure, with the rise of new technologies, has grown. Continuing with the theory and taking from refer a total of 100 friends, each of them will have another 100: with just two degrees (friends and friends of friends) you can already contact 10,000 people.

The third degree represents a significant jump in the number of people to contact: the 10,000 previous contacts each know 100 people, resulting in one million. From there to 100 million in the fourth level, 10,000 million (exceeding the total of terrestrial inhabitants) in the fifth one billion people in the sixth and last level.

Theory shortcomings

But of course it also has some weak points. The first of these is the assumption that each person knows 100 different people from the rest of family and friends, something impossible to put into practice, because there are many that are common. But since a billion people are reached in total and there are not so many inhabitants on Earth, eliminating mutual friends could continue within the stipulated figure.

Another aspect to keep in mind is that most people have more than 100 contacts, and these relationships do not stay local, but reach a global level. Furthermore, it is possible that some member of the chain refuses to search for their contacts, so it would be impossible to implement.

The IBM and MIT attempt

The theory did not emerge until the 20th century, when began to globalize the world with the train, ships, airplanes or the telephone, which allowed the fact of being able to connect with people from the farthest corners of the planet. Before it would have been a utopia. Karinthy, in her story Chains make a bet with his friends: he could relate to any of the 1,500 million inhabitants of that time (1930) with just five contacts.

“I know a friend who is a tennis fan, who knows a person who plays tennis with the director of an international tournament who meets the King of Sweden, a tennis fan, and who also meets the last Nobel Prize in Literature, because he has given him the award. So I could contact the Nobel Prize for Literature, “he said.

Years later, in the 50s, the academic Ithiel de Sola Pool, from the Massachusetts Institute of Technology (MIT), and the mathematician Manfred Kochen, from IBM, they tried to demonstrate this theory using computers of their time. However, after several years in which the mathematical equations did not find a solution, they left it. The variables were many: an indeterminate number of people who do not have known, or have very few, populations that are isolated, or the influence that a person has to be more or less known.

Four degrees instead of six?

The increase in connectivity thanks to the internet has made many bet on four degrees instead of six. One of those who bet on this alternative is Facebook. Mark Zuckerberg’s social network tried to prove the theory in 2011 through his study Anatomy of Facebook. In it, I connect the friends of the 721 million users at that time (10% of the world’s population) to see how they connected with each other: 99.5% of them connected with just five degrees of separation.

Later, in 2016 and with a database of 1,600 million users, the degrees of connection dropped to 4.5. For its part, University of Milan carried out a similar study on other social networks: degrees of separation were 4.67 on Twitter and 3 on LinkedIn.

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How many people do you know around the planet? This is how the theory of the six degrees of separation works