The Science of Six Degrees of Separation
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The Science of Six Degrees of Separation


I have a friend named Sammy who back in the
early 2000s wrote some code for his MySpace page. And what the code did was anybody who
visited his page would have his picture and a tag line that said, “Sammy is my hero,”
copied over to their homepage. And that was a bit of fun for a while, but Sammy wanted
more. And so he tweaked his code so that no only the picture and the tag line were copied
over, but also the code itself. And now it exploded. In just nine hours he had reached
480 accounts. In 13 hours he was up to 8800. And in just over 18 hours he had hit a million
accounts, which was a full 1/35th of all the accounts on MySpace at the time. So in a panic,
he tried to delete his page. And when he was successful he actually took down the whole
of MySpace with it. He was arrested and convicted of computer hacking and ordered not to touch
a computer for the next three years. But I think what this story really tells us is just
how connected we all are. Imagine you have 44 friends and each one of
those friends has 44 friends who are not also your friends. And each of them has an additional
44 friends, each of whom has 44 friends who again has 44 friends and they have 44 more.
Then in a chain of just six steps you would be connected to 44 to the sixth or 7.26 billion
people, more than are alive on earth today. And we have contemplated how closely connected
we area since long before MySpace even existed. Back in 1929 a Hungarian author and poet named
Frigyes Karinthy wrote a short story called Chains. And in it, one of the characters challengers
the others to find another person on earth that he cannot connect himself to through
fewer than five intermediaries. This is the origin of six degrees of separation. If the theory is correct, it means that you
would be connected to the Queen or Tom Cruise in just six steps. But they may be the easy
ones. What about this shop owner or the Mongolian sheep herder? What the theory really means
is that any two people picked at random from anywhere on the earth would be connected by
just six steps. The idea remained just fiction until in the
1960s a Harvard psychologist, Stanley Milgram, attempted to test it. He called it the small
world experiment after that phenomenon where you are at a party, you meet a stranger and
you find out that you have a friend in common and you remark: Oh, it is such a small world.
What he did was he sent out 300 packages to people both in Boston and in Nebraska. Now
what he wanted those people to do was try to send their package to a target person in
Boston, but they weren’t allowed to send it directly to him. They had to send it to
someone they knew on a first name basis who they thought had a better chance of knowing
the target and they could forward it on in the same way. Now, as you might expect, most of the packages
never made it, but 64 did and the average pathway was 5.2. So now six degrees of separation
had experimental confirmation. Or did it? If you look more closely at Milgram’s sample,
you will find that of the 300 people, 100 were located in Boston, the actual city where
the target lived. Another 100 were stockbrokers, which was the same profession as the target.
So only 100 people lived in a different state and had a different job. And of them only
18 of their packages made it to the target. So we are talking about a sample size of 18
is all the evidence there was for six degrees of separation. So experimental evidence was tough to come
by. But a decade earlier, a mathematician named Paul Erdos had tried to work out the
theoretical properties of networks like these. But he didn’t have any information on the
structure of real social networks, so he decided to work on networks where the connections
between nodes were all completely random. And we can actually simulate a network like
this using buttons and thread where we just connect up the buttons at random.
What Erdos found is that when the number of links per node is small, the network is fragmented.
Pick up any button and few others will come with it. But once you exceed an average of
one connection per node, the behavior the network changes dramatically. They almost
all link up forming a giant cluster. Now if you pick up any button almost all of the rest
will come with it. This change happens rapidly and it resembles a phase transition in physics.
Now you could call this a small world network, since the path between any two buttons is
short. The thing about random networks is that they
are naturally small world networks, because you are just as likely to be connected to
someone here in Manila as you are to someone in your own town. But obviously a random network
doesn’t represent real life very well. So what do real world networks look like? Well,
for that, we need to go to the empirical data. In 1994 a couple of college kids invented
a game called six degrees of Kevin Bacon in which you try to connect any actor to Kevin
Bacon through just six steps through his costars. Now a couple of sociology researchers got
access to their database of a quarter million actors and they analyzed the network and what
they found was that it was a small world network, meaning between any two actors there were
only a very small number of steps. And that is very similar to a random network. But unlike
a random network, the actor network also showed a high degree of clustering, that is, they
often worked together in small groups. So how do you get both this grouping behavior,
a high degree of clustering, and the short number of steps between any two actors? Well,
to figure this out they looked at two different extremes. Imagine a circle of nodes. Now if
you connect them at random you get the same outcome as Erdos, short paths between any
two nodes, but little clustering. Now consider connecting up the nodes only with their nearest
two neighbors on each side. Now clustering is high, but path lengths are long for two
nodes picked at random. But what if you take this set up and rewire
just a small number of connections randomly. What you find is that the path length drops
rapidly, but clustering still remains high. So the key to modeling real social networks
is to have a lot of clustering behavior—that is, your friends are also friends with each
other—but also to have a few random acquaintances. And the importance of those acquaintances
can’t be overstated. There was a researcher named Granovetter in
the 1970s who published a paper called “The Strength of Weak Ties,” in which he points
out: You are much more likely to get a job through those random acquaintances than through
your close friends. And if you think about it, that makes sense, because you and your
close friends all know the same people and have the same information. It is through the
random acquaintances that you can get connections with people very far from your social circles.
So you can find new jobs, new places to live and you can be connected to the outside world. So, in fact, it is those random acquaintances
that make possible six degrees of separation. So when I want to…>>I am told the degrees have dropped in recent
years.>>Really>>…to like four degrees.>>Tell me about that. How do we know this?
>>I don’t know how they measure it, but I have tested it and I think it actually has
dropped based on how many people have friended one another on Facebook. The friendship circle
has grown, not that they are bosom buddies, but they are people you have access to. That
is the point.>>right.>>And it is… do you know this person who
then knows that so that I have access to these other people? So I am told that it has dropped.
As much as the six degrees, we are down to four, at most five.>>I think Neil DeGrasse Tyson might be right.
In 2011 Facebook analyzed their data and they found that 92 percent of their users were
connected through just five steps. And that number is decreasing over time.
The concept of six degrees of separation has fascinated people for nearly a century. And
I think that is not only because of how counter intuitive it is, but also how comforting it
is to know how closely we are all linked, not in some kind of abstract, ill defined
way, but through hard scientific data. Just six handshakes will connect you to anyone
else on the planet. Now I have a challenge for you. In the spirit
of six degrees of separation I want to try an experiment. I want you to try to get an
email to me. But you can’t send it directly to me unless you know me. So assuming you
don’t, I want you to send it to a friend of yours, someone you know on a first name
basis who you think has a better chance of getting that email to me. If your email eventually
gets to me through a chain of people, I will send you a postcard in the mail and I will
tally up if we were able to get that done in six links or not. So let’s try to do it and see if we can
connect. The instructions are in the description. This episode of Veritasium was inspired by
the Fine Brothers, Ben and Rafi Fine who are friends of mine. So we are connected through
just one degree of separation. Now they have a brand new TV series launching on TruTV.
It is called The Six Degrees of Everything and it is a fast paced comedic show that tries
to show us how six things that we don’t think are connected actually are. It involves
sketch comedy and songs and reality TV. I am really looking forward to seeing how they
are going to do this. So you can check it out Tuesdays at 9:30 or 8:30 central on TruTv.
I am so looking forward to it. And thank you to the Fine Brothers for sponsoring
this episode so I could check out the science of networks.

100 thoughts on “The Science of Six Degrees of Separation

  1. I know a guy who knows a lady who is good friends with Johnny Cash. I think that’s about 2 degrees away from me. I also have a family member who knows the guys on America Pickers. This is cool to think about

  2. Okay first i need a time machine to go to back in time to spring of 2015,
    so i can bring myself to the present and marry him

  3. 97% of comments: talking about how they have 44 less than 44 friends
    3% of comments: actually talking about the video

  4. i know im late to the party but bruh put your phone/wallet in different pockets or get looser pants

  5. I'm just as likely to be connected to anyone here in the comment section. Don't look down on this, one of the commentors could be your wife / hubby.

  6. I like how everyone in the background of these trafficked centers are just gawking at him as if he's the loudest person in the area.

  7. 7:42 I just started watching your videos. I've seen you at Greek corinthians columns per above and I've seen you under doric on another video, I bet there's and ionic column in the many remaining videos.

  8. Me > Aspen > The Glitch Mob > Riley Reid > Johnny Sins
    Me > Chris > Ted Cruz > Donald Trump > Kim Jong Un
    Me > Kwebbelkop > Afrojack > Hardwell > Darude Sandstorm
    Me > Tehnoobshow > Coppercab > Gavin McIness > Alex Jones
    Me > Logdotzip > Post Malone > Kanye
    Me > Skydoesminecraft > Susan Wojcicki > Zuckerberg
    I'm from a countryside village but my Internet friends gave me major clout.

  9. Now that I think about it…I have a good friend who has worked with Adam Savage. If I were to take on the 6-degree email challenge, I would probably go that route! (Just me hoping that all somewhat famous science people know each other)

  10. Does it struck only me, how this network definition resembles the neural structure of the brain? Think about it: multiple short links between closely located cells (to form a cluster) and one long connection. Right?

  11. I am a live example that the loosely connected acquaintances has more chances of lading you a job. Great analysis 👍

  12. Very interesting topic. The problem here is that "connected to" and "friends" aren't defined. As long as that's the case, "six degrees of separation" is a meaningless concept compared to 3, 4, 5, 7, 8, or 9 degrees of separation. I'm "connected to" anywhere between 3 and 3,000 people. Do relatives count? Ex girlfriends? Work colleagues? Contacts you had 20 years ago and can reach if you want to? The guy from Afghanistan at the checkout counter in the neighborhood convenience store? Case in point: Because of a coincidence, I had a chat with a famous actor, and in theory, I may be able to reach every actor in Hollywood via him, yet none of them would know who I am, and what are the odds that they would care, listen, or respond?

  13. I tried this a while back with steam friends to see how far I connected with the highest level account. I believe the 6 degrees of separation rule to be true based off my testing with random users on steam alone. Along with the rest of all the research of course.

  14. like the Wikipedia game you get from one random word to another random word (extra hard if you don't allow scrolling)

  15. If the average number of connections per node is only just greater than 1, then surely that means that you'd just just have one button with two connections? How could that result in a network where nearly everything is connected via intermediaries?

  16. So basically that Myspace guy could've been connected to everybody on my space in the matter of days if he didnt delete his account… he probably would've been found out sooner or later either way

  17. How do I get a job working for or with Neil DeGrasse Tyson or Adam Savage? I have questions for both, and would love to learn from both. Does anyone have any ideas?

  18. Many e comments about the locals surprise, so you live at the top of the world and they are in the middle of nowhere, these guys after work connect to laptops like you lol.. it is just you are a follower of this guy and they are not, they just take a glance of a weird language sound coming from this guy like you when you hear "strange" language. be advanced. You are to me in the middle of no where too.. but we have 4 friends or 5 between us. Some people do not get it

  19. My brain: Don't comment about the guy in the EXO shirt. Don't comment about the guy in the EXO shirt. Don't comment about the guy in the EXO shirt. Don't comment about the guy in the EXO shirt.
    Me: So.. any of y'all see the guy with the EXO shirt @ 1:54?

  20. My meeting Kevin Bacon ten years ago was quite liberating. From then on I never had to worry about any degrees of separation with anyone or anything.

  21. I have an old friend who has met both David Cameron and Theresa May (both former UK prime ministers), so that means I'm two degrees from The Queen.
    Unfortunately, that means I am also only three degrees from Donald Trump. Now that I think about that, I am seriously conflicted.

  22. Sailing has a lot of clustering with people you are close friends and sail with but you meet and know a ton of people through sailing so I know and recognize many people that I see at regattas so that has a very small degree of separation through the sailing community

  23. For your information The French President MACRON said on television that it took 6 generations to reach the middle classes. This also implies 6 more generations to reach the upper classes. So 12! Like the apostles. Friendship, Stéph.Pour votre information Le Président Français MACRON a dit à la télévision, qu'il fallait 6 générations pour arriver aux classes moyennes. Ce qui suppose aussi encore 6 générations pour arriver aux classes supérieurs. Donc 12! Comme les apôtres. Amitié, Stéph.

  24. My dads boss is friends with Donald Trump and that connects me to Kim Jon un Putin, All the politicians and so many more lol

  25. 4:33. The moment that the guy in the blue Nike Kobe shirt figures out what the hell is going on with this weird guy in plaid gesturing and talking to nobody in the middle of the marketplace.. and then decides to step out of the shot 😀

  26. you random viewer!

    I know a guy
    who knows a guy
    who has a sister
    who knows a guy
    who married a woman
    who knows where you leave,
    so be aware

  27. There's these two swedish television personalities that made a show to try this concept. In one episode they started out in a small remote village with no water or electricity in the desert in Namibia, they choosed a old lady as the first person in the chain and managed to connect her with Michael Bolton in just 6 steps. They start by asking the first person if they know someone who might get them closer to the target (michael bolton in this case) and travel to that person and continue doing the same til they get to the target. The lady knew a guy that worked in the tourism industry, he knew someone in Isreal, and so on. In another episode they connected Gordon Ramsay with a old lady in a remote village in Nepal. Its amazin how this actually worked on several people in just 6 or7 steps. The show is called "Jorden runt på 6 steg" hosted by "Filip och Fredrik"

  28. Degrees of separation should get smaller due to the size of your network. Small equals smaller degrees. Does it make sense that the degrees of separation get smaller the longer certain folks are alive/live longer? Too many variables there Tyson.

  29. Nobody cares about network popularity. Itts already been proven that massive amounts of attention can be artificially generated by the creation and implementation of bots. I dont know why your opening statement to this concept involves anything on this heavily artificial platform of faux trends and bloated views. Im not even going to bother with this video. Just dumb

  30. How did a court of law convict Samy of hacking when his intention was to only delete his account, despite the payload attached to his code? The concept of deleting one's own account doesn't scream "bring down a site". This situation should have been based on intent, or a lack thereof. Perhaps it was Tom's fault for not building a secured-enough website. The court obviously didn't know what hacking really meant still, despite the fact that Hackers was released nearly a decade earlier. Samy's conviction should have been overturned and him given a settlement for the trouble he had to endure because of others' ignorance.

  31. There's a lot of comments but I don't think anyone pointed out he love tapped the girl in the beginning (or got super close)

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