The first scientist to try to answer this question was Stanley Milgram. He was a psychologist at Harvard University in the United States, and it was he who did that famous obedience to authority experiment.

In fact, Milgram had another famous experiment. He gave each of the participants in the experiment a parcel and asked them to send this parcel to a stranger by means of an acquaintance pass. The number of times this package was passed through this chain of acquaintances indicated what the distance between any two strangers was. Then calculate its average, which is a measure of the size of the world.

Before the results of the experiment came out, Milgram opened a handicap with his colleagues, asking them to guess how many times the package had passed through their hands.

The answers were varied: dozens, a hundred, and even more.

But the results were surprising. The shortest of these parcels that made it to their destinations used only one middleman, and the most changed hands with ten or so people. Overall then, the median number that went through a middleman was 5.2, which means that it was mailed after changing hands six times. That number is far lower than the initial guess. So Milgram famously exclaimed, "It's a small world!" This is the Small-World Phenomenon.

The Small-World Phenomenon is also known as the "six degree of separation". More than twenty years after the small-world experiment, the American playwright John Guare, who was the first to write about small worlds in the United States, wrote about the phenomenon. John Guare, an American playwright, wrote a play called "six degrees of separation" in 1990. One of the lines in the play goes like this: "It is said that in this world there are six people between any two people. So there are six degrees of separation between us and everyone else."

Upon hearing this, you may have noticed a small error in the playwright's understanding that if two people in the network are six steps apart, then there are five, not six, intermediaries in between. This is a distinction that you should keep in mind. Because in many discussions about the small world phenomenon and the six degrees of separation, people often get this confused, even including certain prominent scholars. And you will not have the same misunderstanding after listening to today's lesson.

From Six Degrees of Separation to Nineteen Degrees of Separation

So was the discovery of Six Degrees of Separation an accident? Can this number be verified over and over again?

In 2002, the sociologist Duncan Watts (1892-1945), who was a member of the National Association of Sociologists of the United States (NASA) and the National Association for the Advancement of Science and Technology (NAAST), published a paper on the subject. Duncan Watts, a sociologist, decided to repeat Milgram's experimental design. Because the Internet and email were available by this time, Watts replaced the packages in the original experiment with email, and, moreover, the size of the subjects was much larger.

He recruited 61,000 people around the world and asked them to use email as a medium to reach one of 18 randomly selected target candidates around the globe through a relay of friends. These people came in all shapes and sizes, including a professor at an Ivy League university in the U.S., an archivist in Estonia, a technology consultant in India, a police officer in Australia, and a veterinarian in the Norwegian army. Amazingly, despite the scaled-up experiment, the average distance for emails to reach the target person was still 6 steps. Again, you get the magic number of 6.

Moving into the age of big data, the scientists again tested the small-world phenomenon with data from MSN, with Twitter, with Facebook. It was found that although the distances had decreased, the conclusion still stood.

Twitter has 300 million users, and between any two users, the average distance is 4.67.

Facebook has 2 billion users, making it the largest social network in the world, but between any two users, the average distance is 4.74.

By far the largest man-made network is the World Wide Web, which has a trillion web pages. However, from any given web page, jumping to another given web page only takes an average of 19 clicks.

Do these two numbers surprise you? Intuitively, the larger the network and the greater the number of nodes, the greater the distance between points. But in reality, the number of nodes goes from thousands, to millions, to billions, even trillions, and the distance between nodes increases from just a few steps to a dozen.

And this is mathematically provable. In an article in Nature, sociologist Watts and his collaborators came up with a formula for calculating the average distance. According to this formula, assuming that the population of the entire United States is 300 million people, each of whom knows 30 acquaintances, the average distance of the network for that 300 million people is 5.7; assuming that the world's population is 6 billion people, each of whom still has 30 acquaintances, the average distance at that point is 6.6. You see, even though the size of the network has increased by a factor of 20, the average distance has increased by no more than 0.9.

That is to say that the number of nodes in a network, while the number of nodes grows exponentially, the average distance between nodes grows linearly. This is the math behind the small-world phenomenon.

1, access to the school network:

The first step is very simple, there are so many staff, there must be chatting, if you are unlucky, just be diligent. It's important to note that no one wants to chat with strangers, so there's a reasonable chance that you'll make friends while you're talking business.

2. Gathering information:

I was lucky enough to have another staff member show up when I was consulting with the front desk, and the two of them are BFFs. She was planning to spike the juicer and ran over to ask if she wanted to bring one for her so she could drink less milk tea and be healthier. I joined the chitchat, "It is not recommended to drink freshly squeezed juice, because there is a lot of free sugar, or directly eat fruit, locked in the pulp of the fructose digested slowly, the glycemic index is lower," and then we had a nice chat, and added each other as friends.

She was curious about what I was doing at school, and when I said I was doing a social experiment, she was even more curious. So I told her all about the small world theory and the goals of the challenge, and invited her to join the challenge and play together. She happily joined, providing tons of intel, relevant and irrelevant.

3. Connecting strong relationship nodes:

According to the information provided by my friend: there are so many teachers who usually have lunch with the principal, and one of them, Mr. Wang, has the same hobby as I do, and he's about to lead an open art class. This public lecture is very suitable for "chance encounters", for which I prepared some good questions, but unfortunately the public lecture did not set up a question and answer session. But it doesn't matter, I talked to the teacher after the show, and he asked me to make a suggestion, and my suggestion was that people often underestimate the importance of art, so I suggested that there should be more of these great classes in the future.

I also asked when the next class would be held, and I planned to bring a friend along. The teacher said that this is a trial, the next time to start the class is not yet decided. So we added each other's friends and kept in touch. After that, there are a lot of stories, such as attending the premiere of "To Love Van Gogh", most of which are centered around art, and it's easy to communicate when you have the same hobbies as ****.

4, naturally:

One day at lunchtime, I met Mr. Wang and the principal and his entourage, and this time it was a real chance encounter. I took the initiative to greet the principal, he was very surprised, I said "Mr. Wang always mentioned you, he envied you write a good hand", which solved his doubts. The principal invited me to dine with him, and pulled me to ask Mr. Wang, "Is this the XXX you always mention?"

When you are embedded in a network, you can provide your own unique value to the network, and do a good job of what you should be doing, when a reliable person, your information will be disseminated in the network, and naturally there will be a good result.

The above conversation has been simplified to retain only the general idea and omit a lot of details, so it feels a bit like patronizing, but please don't misunderstand. Socializing is based on the principle of value exchange, where competence determines value, sincerity is the lubricant, and equal dialogue is the basic gesture. In addition, people who are accustomed to being patronized by those around them are not worth socializing with.

Only restore this path to reach the goal, and the challenge involves the entire network, in addition to the above mentioned 4, the process also made a lot of friends. Recommended to try, some knowledge you taste sweet, will become your ability.