Will Dean's Ideas Factory: Six degrees of separation? Actually, it's 4.74, says Facebook

Facebook CEO Mark Zuckerberg (Getty Images)

When the Hungarian poet Frigyes Karinthy coined the immortal phrase "six degrees of separation" in his short story "Chains", he had no idea that the concept of any six people would not only outlive him and the rest of his work – but go on to be taken as accepted wisdom.

The phenomenon has been analysed by sociologists ever since – most famously in Stanley Milgram's paper "The Small World Problem", for which Milgram sent packages to random people who asked them to forward them on to someone else until they got to a final individual (see Malcolm Gladwell's The Tipping Point for more on this).

Anyway, a study conducted by Facebook and researchers at the University of Milan has narrowed the parameters of how much we know each other. Or at least other people with access to the internet and social networks (which rules out poorer countries and those without a free internet).

Facebook used the 721 million active Facebook users' friendships – all 69 billion of them and established that most people are connected by three degrees and 99.6 per cent are connected by five degrees. The overall average number of leaps is 4.74 degrees.

Though – as The New York Times points out – the definition of "friendship" on Facebook can be tenuous – this is still a vast number of people to analyse.

So how do we get the number even lower than 4.74? Easy – just send Kevin Bacon 721 million friend requests.

Read Facebook's report: ind.pn/facebookdegrees

Lighter than air... almost – a metal that is 99 per cent oxygen

A remarkable picture shows the world's lightest material sitting gently atop a dandelion. Developed by researchers from UC Irvine, HRL Laboratories and the California Institute of Technology, the team's new metal – with the snappy name of "metallic micro lattice"has a density of 0.9 mg/cc – making it about 100 times lighter than Styrofoam.

Not only is the stuff ultra light, but its design gives it elasticity. Dr Tobias Schaedler, the scientist from HRL who wrote up the group's findings in the journal Science, says: "The trick is to fabricate a lattice of interconnected hollow tubes with a wall thickness 1,000 times thinner than a human hair." Sounds easy...

It's this process, one of the scientists told the American website TPM, rather than the materials used that allowed them to create the ultra-light lattice that takes 10 seconds to float to the floor when dropped.

Having only produced coaster-sized samples so far, it's still unclear what any future uses for the product might be.

See the picture at: ind.pn/lightmat

A loud hum in the skies

The hummer and the aeroplane are not just the bêtes noire of Al Gore – now, reports Aviation Today's website, a carbon-gobbling hybrid is being planned for use by militaries.

Two giant US defence contractors, AAI and Lockheed Martin, are said to have "feasible designs" for a "flying Humvee" – a version of the giant military jeep that comes equipped with helicopter blades.

It's still a long way from reality, as you can tell from the graphic above – it depends on the availability of lightweight materials and other high-tech developments – but a prototype could be made by 2015.

Expect Arnold Schwarzenegger to be flying one across Los Angeles by the end of the decade.

Read more: ind.pn/flyhummer

Tick, tock... watching the numbers of the global clock

On one of many visits to Eureka! The National Children's Museum in Halifax as a child, I was frequently captivated by a pair of clocks on the museum's first floor featuring global birth and death counts – which, to a nine-year-old, ticked over with remorseless speed.

One website – Worldometers – does a similar job, live-updating not just births and deaths but other rolling stats from around the globe, including "books published today", "toxic chemicals released in the environment this year", "bicycles made this year" and dozens more. Most of the figures are sobering but it's fascinating to watch the tickers – which work on information taken from the United Nations, the World Health Organisation and the Food and Agriculture Organisation among dozens of others. The site's most famous cheerleader so far has been Bono – U2 ran Worldometers' data across a 360° screen during the band's last world tour.

And if the figures about death and pollution are too depressing, one can console oneself with the number of newspapers sold today: at the time of writing: 258,970,122. Sorry, 259,049,678. Actually....

Watch the stats: worldmeters.info

Send us your Ideas Factory fuel

The Ideas Factory is a weekly round-up of the best, weirdest and most interesting new discoveries, theories and experiments from around the world. If you have an idea you'd like to share, I'd love to hear from you. You can email me on w.dean@independent.co.uk or tweet me at @willydean.