It seems that the play and film 'Six Degrees Of Separation' has led scientists to a whole new field of inquiry. To understand the article below, you should know that the title of the play and film has been associated with something called the 'small world experiment' by psychologist Stanley Milgram (although he did not make the association himself - unsurprisingly, since he died before the play came out). The association, in turn, led to a trivia game called 'Six Degrees Of Kevin Bacon', which 'requires a group of players to try to connect any film actor in history to Kevin Bacon as quickly as possible and in as few links as possible'.
Given that background, this article by the BBC on a forthcoming program is easier to understand.
Recreating a famous experiment done in the 1960s, 40 parcels were given to people randomly picked around the world, as part of a BBC programme testing the "six degrees" theory.
They then had to try and get the parcel to a scientist called Marc Vidal based in Boston, via someone they knew on a first-name basis.
Three of the parcels made it to Mr Vidal, and on average took six steps to get there.
Organisers of the experiment believe the other 37 chains broke because of the apathy of individuals who failed to send the parcel on.
One that made it started off in the remote village of Nyamware in Kenya, where Nyaloka Auma gave it to her aunt in Nairobi.
Margaret Owino then sent it to a friend in New York state who used to live in Nairobi, who in turn sent it to another friend in Boston. Eventually it arrived in the hands of the right person, through seven people in total.
Its success, and the fact that two other parcels also reached their destination within six links, proves that the theory can work, even if it does not always.
There have been many other attempts to test how "small" the world really is. Last year, Microsoft examined its instant-messenger network of 30 billion electronic conversations between 180 million people.
Its researchers concluded that any two people are on average apart by 6.6 degrees of separation, meaning that they could be linked by a string of seven or fewer acquaintances.
The six degrees theory has had a huge impact on other areas of science.
When mathematician Steven Strogatz and his PhD student Duncan Watts set out to investigate why some crickets chirp in unison the young Australian got inspired by his father's words in a phone call: "Did you know that you are only six handshakes from any person on Earth?" Watts thought this might explain why his crickets are such good synchronizers but he had no idea that this question would lead him to a major discovery in an emerging branch of research - network science.
If the phenomenon applies to cricket synchronisation, what are the consequences for the way disease spreads throughout a human population, or the dynamics of markets, he asked.
These sorts of questions seem to have something to do with networks. Teaming up with Strogatz, the two scientists used data from the online trivia game Six Degrees of Kevin Bacon to see if there was a mathematical basis for this complex set of relationships.
They discovered a formula for the invisible links that make the big world small, and another scientist Albert-Laszlo Barabasi examined the importance of hubs in how networks evolved.
A new discipline - network science - was established and other scientists gladly applied these universal laws to other kinds of networks, such as the world-wide web, the growth of cities, global travel, sexual relations between people, wealth and property distribution, and protein molecules in cells.
Professor Alex Vespignani, of Indiana University, says network theory is having a huge impact on predicting how swine flu will spread. His work is being used by the European Community and authorities in the US.
How people go from one place to another - what he calls mobility networks - is at the heart of his predictions, and involve long-range journeys (such as by plane), short-range commutes, and how we move around small spaces like the workplace or the home.
"We can identify the pathways along which the disease will spread and therefore the next places to observe the cases.
"That gives you time and where you can focus. With limited resources you need to make choices and focus on certain routes. Network theory can tell you and it's not just about looking at the obvious."
Marc Vidal, the "target" of the parcel experiment, is creating the first "roadmap" of the human cell - how proteins interact - in order to find the origin of disease.
"If I start with my favourite 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 whom."
Although scientists may disagree on how much emphasis they give network theory, it is now a well established principle.
And it's all down to Kevin Bacon.
There's more at the link.
Now that's fascinating! From a simple 'game theory' to a real-world scientific discipline, being applied across all sorts of different fields? In the words of the apocryphal sage, who'd a thunk it?
Peter
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