The 'six degrees of separation' theory has actually been slashed to four, according to Facebook.

The theory, which was first detailed by Hungarian author Frigyes Karinthy in 1929 and later made popular by the John Guare play and film of the same name, says everyone on earth is connected to others in six or less steps, through 'friends of friends'. However, research by the social network has revealed that the gap has actually been closed slightly and now the majority of people are connected by only four degrees, or five or less steps.

"With the rise of modern computing, social networks are now being mapped in digital form, giving researchers the ability to study them on a much grander, even global, scale," Facebook said in a blog.

"We found that the degrees of separation between any two Facebook users is smaller than the commonly cited six degrees, and has been shrinking over the past three years as Facebook has grown."

The social network used "state-of-the-art algorithms" developed at the Laboratory for Web Algorithmics of the Università degli Studi di Milano, to come up with their estimates.

"While 99.6 percent of all pairs of users are connected by paths with five degrees (six hops), 92 percent are connected by only four degrees (five hops)," the blog added.

"As Facebook has grown over the years, representing an ever larger fraction of the global population, it has become steadily more connected. The average distance in 2008 was 5.28 hops, while now it is 4.74."

The social network added that when the analysis is limited to a single country, the world gets even smaller, and most people are only separated by three degrees (four hops).

Facebook's research also revealed members of the social network have an average of 190 friends and 84 percent of all connections are between users in the same country.

"This is what makes social networks somewhat unique: they are both well-connected in the sense that you can reach anyone from anyone else in a relatively short number of hops, but at the same time, they are very locally clustered, with the vast majority of connections spanning a short distance."