Kevin Bacon, Covid-19, & Social Networks (Part 1)

Let me start by noting that I am not suggesting that Kevin Bacon has Covid-19 or is spreading the virus. To the best of my knowledge, the guy isn’t even infected. So why bring him up? Do you remember that game Six Degrees of Kevin Bacon? There is a good lesson to learn about Covid-19 from that game.

Although there are approximately 7.8 billion people in the world, on average, any two people on the planet are separated by about six people. That means, for you, the person reading this post, there are about six people between you and the very first person to be infected by the Covid-19 virus. Hard to believe, isn’t it? As amazing as this may seem, if you do the math it makes sense.

Let’s approach this from a different angle. How many people would the average person have to know for this to be true? We know that the population of the world, as of this writing, is roughly 7.8 billion people. To calculate how many people the average person would need to know for there to be only six degrees of separation, we would use the equation: 7,800,000,000 = X6. Therefore, X would need to equal 44.5 acquaintances. Is it reasonable to believe that the average person knows around 44 or 45 people on a first-name basis? Of course, some of us know many more people while some know far fewer, but this seems a relatively reasonable average.

More than numbers there have been multiple studies that have shown this to be true. In 2008, when Microsoft performed an analysis of 30 billion online conversations of 180 million people in various countries, they discovered that any two strangers were separated on average by 6.6 people.

Of course, when we talk about messaging and on-line social networks this interconnectivity between people is not surprising. We become friends with people who are friends of friends or may just share the same interest. However, this level of connectivity between people has existed long before the Internet. In 1967, Stanley Milgram conducted The Small World Experiment. In this experiment, he sent packages to 160 random people in Omaha, Nebraska. He asked that the recipient to send the package to a person they knew, either a friend or acquaintance, that would bring the package closer to a specific recipient who was a stockbroker in Boston, Massachusetts. The only rules were that you had to know the person to whom you were sending the package on a first name basis. The person to whom they sent the package was to do the same. The package reached the target, the stockbroker in Boston, in four days with only two intermediary acquaintances. Think about it. This was in 1967, well before email and social media.

I guess Kevin Bacon isn’t all that special after all. Well, except for his acting. We need to give him credit for being a really good actor.

Let’s look at how these numbers relate to the spread of Covid-19 in the United States. Currently, the population of the United States is approximately 328,200,000. All we would need is to know between 26 and 27 other Americans to have six degrees of separation between ourselves and any other American. However, if we use the same number of acquaintances that we used above, 45, any two random United States residents are separated by just five other people. This means that on average you are just five people away from each of the 8.7 million people in the United States that has been infected with Covid-19. With just five unguarded interactions, you can be infected.

I don’t say this to invoke fear. I am not suggesting that we should hide in hermetically sealed bunkers to protect ourselves. There are simple nonobtrusive steps we can take to minimize the spread. We all know what those are: wearing masks, frequent hand washing, and social distancing.

There are things we can do on a larger scale, as a society. This interconnectivity between people, these interactions and relationships, form a network, a social network. As we examine the spread of the Covid-19 through these social networks we will be able to better predict the behavior of the virus enabling us to take appropriate corrective action. This network analysis is the subject of part two of this article.

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