Seis Graus de Separação (Documentário-2008)

[Music] [Applause] [Music] these people are part of a global study we're about to investigate the urban myth 6° of Separation the idea that in a world of more than 6 billion people Everyone is connected in just a few steps that's to say that you know someone who knows someone who knows someone who knows someone who knows me or anyone else on the planet when scientists began exploring 6° they made some profound discoveries Nature has a hidden blueprint a structure that connects us all the world is more highly more globally and more unexpected ly connected than

we ever thought testing an urban myth has led to an entirely new branch of science Network Theory and some believe it will change our lives networks are important because if we don't understand networks we can't understand how markets function how organizations solve problems or how societies change 6° has the potential to change the way we fight terrorism predict pandemics and combat disease it may prove to be one of the greatest scientific insights of recent times and for that there's one person to thank Hollywood actor Kevin [Applause] Baker Mark Vidal is a geneticist at the Danna

Farber Cancer Institute in Boston he's the target of our study to test 60 Degrees of Separation the claim that everyone on the planet can be connected to everyone else in just a few steps is it real or just an urban myth we'll find out we've chosen 40 people from around the world to see if they can get a package to Vidal our participants have never met him and they aren't allowed to look him up on the internet the rules are simple they must try and get the packages to Boston by passing it to family or

friends people they know on a firstname basis I have difficulty believing that they're going to be successful in delivering that package will any of the packages make it to Boston and how many steps will it take eight eight steps maybe one of our starters is college student Jessica Otto she lives in the German Town of Vil near dorf I've sent the package to K I thought because her boyfriend he studied in Boston and he has to do something with physics and I thought he would know a lot of professors and I'm pretty sure that one

of those knows Mark vid [Applause] testing 6° of separation is not a trivial matter a decade ago the idea began intriguing a small group of researchers trying to explain the world using mathematics it would eventually lead to the new science of [Music] networks one of the founders of the theory is mathematician Steve strarts his path to Discovery began with a broken love affair Romeo's love increases the more Julie is currently loving him so our DOT will be a the more that Romeo currently loves her the more that she recoils and wants to run away and

hide equation looks like this I I had a tumultuous relationship it was the first relationship of my life with a a girl in college and I couldn't understand what she was doing to me and uh whenever I seemed to get closer to her and try to to show her how much I loved her she would back away and then when I realized I better give up this isn't going anywhere then she was strangely attracted to me and this push and pull felt to me and probably this is why I had so much trouble with her

it felt to me like a mathematical equation and so I started to write equations for this given and take or push and pull between two people equations for the growth or decay of their love as a function of time this to me is a beautiful thing the unity of nature that something you can learn in physics has the same mathematical description as the the oscillations of A Love Affair the ups and downs of a of a romantic relationship the same [Music] formulas having explained romance with equations strarts turned his attention to other Mysteries nothing had

perplexed him more than the phenomenon known of synchronicity [Music] how can a population of dissimilar individuals suddenly synchronized how do fireflies Flash in unison across great distances or crickets chirp as one how does order emerge from chaos we're so used to thinking that if there's a group following acting in concert it's because there's a conductor for the orchestra but that's not necess neily so there's a 100 billion brain cells acting like a the most complicated thing in the universe and there's no cell that is the master conductor of the brain the brain does it as

a group the heart has 10,000 pacemaker cells that tell the rest of the heart went to beat who's in charge who's the pacemaker for the pacemaker nobody stro Arts was not alone in his passion for the simple Elegance of numbers Duncan Watts also wanted to make sense of the world with Maxs here we are sort of just kind of shambling through uh life try to make sure the wheel th come off but nothing like science and I started to think this is what I should be devoting my life to to try and bring something like

science to this this real world Watts had abandoned a promising career as Australia's top Naval graduate to study [Music] Physics and when he arrived at Cornell University Professor strogatz knew this was no ordinary student when I walked by his office I saw a picture of him hanging by his fingertips from uh a sheer cliff in Australia and I thought that's the kind of person that I could see myself working with on a a difficult problem strarts had found a worthy collaborator with whom he could attempt to tackle some of the deepest mysteries of nature we

would try to do something intellectually dangerous to go to some place at the edge some place that um that people hadn't really thought about before possibly even a question that doesn't seem like uh a question you're allowed to think about I like those problems that are that are almost taboo because that's where there's a lot to be discovered whats and stroots began to investigate the mystery of synchronicity and for that they needed a real world example to study it occurred to us that actually here in Ithaca we have the world champion of synchronization called snowy

tree crickets on a warm summer evening thousands of them will all start chirping in unison if we could capture some of these crickets could we predict from an individual's Behavior how an enormous population of hundreds or thousands of crickets would behave as a group so we would find a tree and then I would clamber up in the tree with a flashlight on my head and a little glass vial and try and find these crits well the Hope was that each individual cricket was actually obeying little mathematical rules unconsciously that that each Cricket when responding to

the chirp of another Cricket just shifts its Rhythm by a certain amount that was very reproducible I would sit there for you know 3 hours waiting for the damn crickets to chirp and they wouldn't CH testing individual crickets would never work the answer seemed to lie elsewhere in their interaction as a group you have you know hundreds of these crickets and they're all sort of interacting with each other in some kind of complicated way and the question that came up in my mind over and over again was you know who is listening to whom and

so that got him thinking more generally about patterns of connections about networks and it was around that time that something his father said came into his mind do you know that you're only six handshakes from any person on Earth and I started to think maybe it's true that the that this Six Degrees of Separation phenomenon applies in the real world and what are the consequences if that's true for the synchronization of crickets for the the way that the disease spreads throughout uh a human population and it was almost a scary thought because we could see

when he when he suggested it to me that that we were on the rink if we could do anything sensible of a whole new science that didn't exist [Music] yet almost by accident they stumbled across a huge gap in our knowledge remarkably no one had paid much attention to networks [Music] before it was at that you know pivotal moment I really sort of forgot about the Crickets and started to think about Networks in our study to test the idea the packages are sent from locations all over the world each participant needs to try and get

it to Professor Mark Vidal in Boston in Paris dancer Nadia thomasova believes her letter has a good chance of making it I think somebody could send this to me because maybe as I traveled around the world it makes me very connected around the world yeah I'm sending it to my friend in Boston to Joseph she's a bad dancer I hope she will get it Nadia is part of an international network of dancers to her the Big World appears small is de as simple as [Music] that mathematically it's pretty easy to make small worlds if I

know 100 people and each of them knows 100 people then already within two steps of me two degrees of separation there's 100 times 100 and so if I do another step so now three degrees that's a million people and keep playing like that and you'll see that within five steps you've got more people than there are on the whole Earth but there's something terribly wrong with that calculation it may be true that I know 100 people and each of them knows 100 but a lot of those are the same people right it's not a 100

new people each time there's a lot of overlap in our Social Circles and so this is what makes the problem very [Applause] difficult in a Kenyon Village one of our participants is struggling with this problem [Music] [Music] NECA knows everyone in her Village of nare but nobody seems to know anyone who can get the package closer to Boston [Music] in nare the world seems very [Music] large but it's not a problem restricted to Kenyan villagers no matter where we live or what we do we all tend to know people very much like ourselves we're clustered

into closed circles locked within our own social networks this is the Paradox at the heart of the small world problem that the the world is simultaneously very small with everyone only a few steps from everyone else and yet very [Music] clustered there seem to be a contradiction how could the world be both small and large at the same time solving this Paradox was the key to understanding 6° and so we just started to play around it was pure mathematics fun and games where a network is thought of as points connected by lines and then asking

whether they would have the property of being a small world meaning that everyone is only a few uh hops away from everyone else in the network Watts began with a thought game a mathematical model imagine uh we we have a crowd in a soccer stadium and now imagine that you're trying to do the experiment of getting a message from this part of the stadium to the farthest remote part of the stadium and the only way that we can get a message is to talk to the person next to us right and then that person has

to to talk to the person next to them it's going to take a very long time for the message to get from there to there now if I give the person on the other side of the uh uh the soccer stadium a walkie-talkie and I have the other one we can communicate immediately clearly our path length has shrunk because now the person next to me can communicate with the person on the other side of the stadium simply by asking me to put a call all of a sudden a whole group of people in my local

neighborhood can connect to a whole group of people on the other side of the stadium in many many fewer steps than they could before this one link came into existence just a single random link has an enormous effect and add just a few more links and distance in the stadium has all but disappeared the world doesn't gradually get small it drops off a [Music] cliff here was a model that could make a big world [Music] [Applause] small in the Kenyan Village of Nimo neol loa's package has been going nowhere but as wats and stro arts

predict just a single link can make a big difference hey hey [Music] Lo's Aunt Margaret has come from Nairobi for a visit she's the link to the outside world like to meet Margaret welcome come in come to pick your package thank you I don't know anybody in Boston I don't even know this Markell but I know somebody in New York I know A lady called de H hello ma'am it's Express package from Kenya from Kenya oh it must be Margaret thank you so much all right thank you ma'am oh I'll have to open it I

was in Kenya uh last summer working with Margaret AO I don't know any scientists in Boston but I do know Le Men Mo who lives in Cambridge and she's an old friend and I thought her husband's some kind of scientist I thought maybe if I send it to lean she could she would also be able to somehow connect a key part of the 6° effect is that all of us know someone who has moved away and has now forged a link between us and and geographically distant communities that random connection is bringing the whole world

together and it's happening all across the world with everybody nice have a nice day y thank you thank [Applause] you wats and strog arts had a theory but now they needed to prove it by studying real networks the problem was no one had thought it worth mapping any except [Music] one for the scientists it was Hollywood that offered the first possibility to put their ideas to the test more than a million actors have worked in Hollywood on half a million films here was a huge network of connections [Music] in the mid90s some college students devised

a trivia game based around the idea of linking every actor to just one Stark Kevin Bacon Rodney Dangerfield was in Caddy Shack with Bill Murray and Bill Murray was in she's having a baby with Kevin Bacon then computer student Brett chayen thought it would be fun to turn the Kevin Bacon game into a website welcome to the Oracle of bacon at Virginia website S I wrote a program that would extract the path uh from every actor or actress to Kevin Bacon before I knew it uh a lot of people were visiting and a couple of

the uh websites picked up on it and made it their pick of the week or whatever and that brought in a tremendous number of visitors abbt and costell Brett shayen helped turn Kevin Bacon into a cult figure and the inspiration for a scientific breakr people kept saying to us when we would talk about 6° that oh yeah that's the Six Degrees of Kevin Bacon game that everyone was playing at that time but we thought well actually it's a scientifically serious thing so we wrote to to Brett and said look you know we're doing research on

networks and and you know we think that you have this really interesting data and would you mind if we had ited to their astonishment the Hollywood Network conformed precisely to the theory a few random links Shrunk the distance between a million actors the model worked almost perfectly that there was an incredibly high level of clustering but it was also the case that everyone could reach everyone uh through just a few steps hey I am the center of the universe Kevin Bacon great an actor as he is was not that special in the role that he

played in the network that is if you looked at any two actors the typical number of steps between them people you've never heard of was about somewhere between 3 and 4 hey can I write a check for this I just need to see some ID hold that thought Unice hi come okay so I was in a movie with an extra Unice whose hairdresser Wayne attended Sunday school with Father without even knowing it Kevin Bacon had inspired the first real evidence that small worlds existed so you see we're practically Brothers and when The two scientists began

looking small worlds began turning up everywhere tests have proven the great power system ready for transmission America's massive power grid was one network they could test it's been described as the world's largest machine so it was a kind of an organism that grew itself the grid is the result of thousands of random events as new generators and cables were added to meet the growing demands of America's industry and population we found that it too was a small world that even though it had 5,000 power plants over half a continent of area it only took a

very few hops to get from any one to any other we thought okay you know let's be ambitious here let's think about you know complet completely different kinds of networks so not networks that are social networks not networks that involve people at all something that comes from biology something that's totally different there's a certain worm called sea Elegance they've mapped every cell and they know how every cell in its nervous system is connected we were able to get a hold of the data and when we analyzed that it too was a small world we found

the same kind of result short path lengths High clustering it was like time to uncork the champagne for both of of us it was very very [Music] thrilling their Discovery seemed to solve the small world mystery but as it turned out it was just a beginning [Music] [Applause] [Music] Tokyo photographer Kenji myi is the second link in a chain he's received a package from Australia and paradoxically he plans to send it back in order to get it closer to Boston I don't think it would be easy but I decided to send it to my eldest

brother uh his name is nooshi he lives in Brisbane uh he's a scientist uh so I figured he'd know a lot more scientific people than I would and he's got a lot of contacts in the United States as well hey most of our packages are on their way in Germany Jessica is following the progress of her package online it's made it to Toronto in Paris the dancer Nadia is on vacation and her friend has found the package has come back from B Boston unopened this is not this letter it gets returns so I guess it

didn't make [Music] it from 40 original starting points 27 packages are still on their way even crossing paths as they pass through the giant sorting hubs of the courier companies and it's the significance of hubs that would be the next big Discovery in network Theory while strarts and Watts were pioneering small worlds another scientist would look at the problem from a different angle for Hungarian physicist llo barabasi understanding networks held the promise of predicting the [Music] future his inspiration came from a classic work of Science Fiction Isaac azimoff's Foundation I have said the Empire will

lie in Ruins within the next Century azimoff's foundation senters on a mathematician with the power of prediction but barabasi had identified a flaw in the story I started thinking what is that I could do to predict the future I realized that what is missing from us evolves thinking is the network the structure and the behavior of the network because events are never isolated they depend on each other they interact with each other so we need to understand how they interact to understand these interactions barashi needed a network that had been thoroughly mapped the major problem

was that the data was incredibly difficult to find but then then everything changed it was the early '90s and the worldwide web was exploding in [Applause] [Music] popularity here was a huge Network he could map by tracing the links between web pages no one directed the growth of the web anyone could put up a site and link to wherever they liked so the expectation was that the structure would be entirely random if the word wi to be a random Network then the distribution of the links follows a bell curve I would find something similar to

this in a bell curve there are a few extremes most web pages would be grouped in the middle having the same number of links but what he discovered was different the web links were not evenly spread most pages had very few links but there were some with a huge number of connections we found a few web pages that had thousands of links pointing to them and these were the hubs it was completely new completely unexpected first we did not know what to do with that this was no random World it seemed to have an organizing

principle based around hubs in these early days of the web long before the familiar super sites of today had emerged barashi study had glimpsed the future it predicted the potential for the existence of huge hubs like Amazon and Google and Yao turn out to be barabash she's hunch was the behind this pattern there may be a deeper truth lurking by coincidence wats had just published his paper on the small world of Hollywood actors barabasi wondered if there could be hubs there too I got an email from llo barabasi and he said would I mind sharing

some of the the data so we took the data set and we interpret it just like the worldwide weap as a map and we asked the question how many links each actor has we saw exactly the same pattern as we observed earlier on the worldwide map there were many many actors that had only a few links to other actors there were a few major hubs h however though it was right in front of them watts and strarts had missed a second great discovery the funny thing is we didn't really look and so we had all

this this data looking you know staring Us in the face and I never thought to actually plot the distribution finding hubs in Hollywood was a major break through it suggested that networks didn't just grow accidentally they evolved According to some pattern and if so hubs should be everywhere sure enough barabasi found Hub networks in transportation routes in computer chips and within the human cell I kept thinking how is it possible because they cannot be more different in the scope in the ma and their nature more I thought about it more I realized that there must

be a simple explanation for that because these are such a different systems that the only way they could be similar to each other is that there is one simple law that describe the structure of all of them and he discovered that simple equation that describes our complex interconnected World PK K to the minus GMA that is the formula barabash she's equation not only showed that hubs were inevitable it can also predict the number of hubs in any given Network here was the secret behind almost every Network the structure that nature uses to spin its webs

and once it could be seen it revealed networks have peculiar strengths and weaknesses with implications for all of us there are hundreds and thousands and potentially millions of errors in my cell and yet I don't even notice the internet can work even when hundreds of its routers are not functional if you remove the small nodes it does not matter the network will shrink but will not fall apart but there is a price you pay for this extreme robustness if you remove the hubs the system will fall apart [Applause] [Music] Society has its hubs too people

who are much more connected than the rest of us German lawyer Philip Thomas is one of them and it's made him the obvious Target for someone sending a package from [Music] Burma well the one who sent the package to to me is Michael N an old friend uh from Burma he's actually Australian Burmese Burma is a fairly isolated place so burmes unfortunately don't have too many contacts to the outside world Michael knows that um I have family spread in the US so um it must have been pretty obvious for Michael that I might be one

potential Link in that chain [Music] we live in a connected World networks dominate our economy our environment and our society our health depends on them and yet we barely notice their presence through random links or hubs the world is made small allowing everything to travel far and fast on on the network this can be good news or totally devastating it depends on what's spreading on the [Music] network in 2000 a virus the I love you bug took just hours to spread through the world's computer networks and penetrated the CIA the Pentagon and the houses of

Parliament one of of the scientists tracking the virus was physicist alesandro vespignani he was puzzled by its rapid spread and by its resilience even though software to kill the bug was released within a day it survived for months Japan came back from a weeklong holiday to find the Love Bug still lurking in many people's computers quicker is the disease at the beginning and the quicker it should die out from the system and actually this was not the case we were really puzzled by this fact that the H of virus was lingering in the wild like

many scientists best Pani assumed that viruses spread at random we were you know trying a few things and actually something at certain point I was truck by a paper it was barab bash's study showing the internet had a predictable structure when I saw that image of the internet I thought that that was the pattern that I had to include in the model in order to get a realistic description of what was happening with computer viruses the virus used Network structure to spread unstoppably through the hubs and hide in the far reaches on the net and

as vasani learned this had alarming implications far beyond the internet I got a question these results would apply to Human sexually transmit diseases well no way it was clearly not applicable in my mind because the internet is different from the web of sexual relation I was wrong wil Chamberlain nearly 7t tall even then Champion basketballer wil Chamberlain claimed he'd had sex with 20,000 women an average of 1.9 couplings per day over his adult life Wilt was almost Unstoppable even allowing for some exaggeration he was clearly a hub in the human sexual Network there are Hill

records left for Wilt to [Music] tilt a Swedish study of sexual behavior showed most people had only a few Partners but a handful had hundreds the web of sexual relations looked exactly like the internet it was dominated by a few hubs and just like I love you this meant that if a virus entered the network it would be almost impossible to remove so suddenly from one day to another what we were doing in the computer virus area was important for human diseases vespin yani's research helps us to understand the resilience of HIV despite two decades

and billions of dollars in prevention programs the virus is entering an explosive New Era of growth his findings also help explain the failure of early awareness campaigns to prevent the spread of the disease these were aimed at the general public long before the significance of hubs were recognized vasan's group is now modeling the intersection of Global Transport Network and disease they can predict the spread of a new flu virus Airline networks are dominated by a few major airports once an infected person passes through one of these hubs the virus will be [Music] unstoppable but vespin

yani's research also offers a solution to avoid a global catastrophe he believes Nations must share their stocks of precious antivirals what you find is that is beneficial to the entire world and to each country to share antivirus to be cooperative and not to be selfish we form a Global Network and whatever we do is going to reverberate across the network and have important implication at the at the global [Applause] level the first of our packages has made it to Boston reaching a colleague of the target Mark Vidal let me run inside and get that package

okay thank you very much deliver it all right great great see you next time Mark and I serve on some committees together and I've advised him on a couple of uh legal matters over the years he's in the building right next door to me and I can deliver this package to him quite easily um did you see that Mark get this envelope please sure okay thank you very much so long thanks [Applause] [Music] bye Mark Vidal is a geneticist for him the six de study is part of a much greater project to understand the origins

of disease to do so he's creating the first road map of the human cell imagine if we try to understand traffic in a City without having any maps without having any idea of how interconnected the different roads are analogies are never perfect but it's one way that I can imagine how things occur in the [Applause] cell cells are the building blocks of life and hold the genes that determine our development those genetic instructions are carried out by thousands of different proteins the proteins are the little tools the parts of the cell they don't work in

isolation they interact with each other in Vidal's bustling cellular City proteins are like people constantly on the move and communicating with one another if I start from my favorite protein and I ask what does it interact with I'm now back to basically a problem of Six Degrees of Separation who is connected to home Vidal believes that if he could produce a map then potentially he could locate breakdowns in the system that cause disease diseases like cancer I devoted my life to to trying to understand the interconnectivity between genes the vast majority of biologists would have

thought that even if we had a good quality map of the wiring diagram of the cell not much really interesting would emerge out of it Vidal's Theory may have come to nothing had there not been another fortunate coincidence he stumbled upon the work of another scientist barab bash's paper describing a universal law in Networks and this really was an eyeopener what became immediately obvious to me when I opened that magazine it would be incredible if we could actually use it in the context of cellular networks and try to use similar models to explain human disease

seeing disease as a network means it's no longer just about biology it's become a math problem and this offers entirely new ways of dealing with disease that are so promising llo barabasi has joined forces with Vidal to explore the potential one day Lazo came to my office all excited saying what if we looked at all the connections at the same time for all diseases and all genes involved in diseases the result is the most remarkable Network map of all it shows connections between every known human disease and just as the Hollywood actors Network linked Stars

through their films we can now see how diseases are linked by the genes they have in common the network that came out of this analysis had absolutely incredible properties for one thing in many diseases we still don't know all the genes that are involved in those diseases breast cancer is one example of that we only know of four genes which cause the disease and these make up just 10% of all cases of breast cancer when we have a map like this one it seems to make a lot of sense to go for the Neighbors of

the known characters in the story if we didn't have a map like this we would go blindly basically we would have no way to guide the new research to try to fill those 90% of CAS where we still don't understand the molecular aspects of breast [Music] cancer another package has arrived at Mark Vidal's office hello another package for Mark Vidal is Mark in yes but while you're walking over there would you please sure pass that on to no problem let's see the story with this one all right see what you go here okay so this

package has traveled more than 10,000 km so this is a lady called Nala okay we went from a small town in Kenya all the way to Boston 2 3 four five six separation there you are perfect from Urban myth to Math's equation to a daring new approach to fighting disease this is the promise of network science a new way of seeing our world [Music] 6° is not just an urban myth after all a decade on Kevin Bacon has decided he might as well accept his cult status when I first heard about the Six Degrees of

Kevin Bacon game I was really kind of horrified I thought it was a joke at my expense and I was hoping that it would go the way of pet rocks and a track cassette tapes but it seems to be hanging on now he's put the Power of social networking to good use launching a charity website 6 de.org the site lets people introduce their friends and their friends friends to good causes like Mark fal's cancer research you take me out of the equation it's really sort of a beautiful notion the notion that we are all connected

in some kind of [Applause] way our packages have passed through 28 countries and 53 cities although only three Reach Mark Vidal they average just six steps to get there 6° has revealed a new view of Nature and a reminder that if the world is small then we're all in this together everything appears to be connected in ways that you know were absolutely not predictable just 10 years ago or even 5 years ago it's going to completely change the way we think about the world Network science is the foundation of the 21st century all the major

problems in science today depend on understanding networks the wobbly first steps of a newborn elk are the last of their worries secret forms of Yellowstone is next on BBC 2 oh [Music]