Facebook has spread like an infectious disease but we are slowly becoming immune to its attractions, and the platform will be largely abandoned by 2017, say researchers at Princeton University (pdf).

The forecast of Facebook's impending doom was made by comparing the growth curve of epidemics to those of online social networks. Scientists argue that, like bubonic plague, Facebook will eventually die out.

The social network, which celebrates its 10th birthday on 4 February, has survived longer than rivals such as Myspace and Bebo, but the Princeton forecast says it will lose 80% of its peak user base within the next three years.

John Cannarella and Joshua Spechler, from the US university's mechanical and aerospace engineering department, have based their prediction on the number of times Facebook is typed into Google as a search term. The charts produced by the Google Trends service show Facebook searches peaked in December 2012 and have since begun to trail off.

"Ideas, like diseases, have been shown to spread infectiously between people before eventually dying out, and have been successfully described with epidemiological models," the authors claim in a paper entitled Epidemiological modelling of online social network dynamics.

"Ideas are spread through communicative contact between different people who share ideas with each other. Idea manifesters ultimately lose interest with the idea and no longer manifest the idea, which can be thought of as the gain of 'immunity' to the idea."

Facebook reported nearly 1.2 billion monthly active users in October, and is due to update investors on its traffic numbers at the end of the month. While desktop traffic to its websites has indeed been falling, this is at least in part due to the fact that many people now only access the network via their mobile phones.

For their study, Cannarella and Spechler used what is known as the SIR (susceptible, infected, recovered) model of disease, which creates equations to map the spread and recovery of epidemics.

They tested various equations against the lifespan of Myspace, before applying them to Facebook. Myspace was founded in 2003 and reached its peak in 2007 with 300 million registered users, before falling out of use by 2011. Purchased by Rupert Murdoch's News Corp for $580m, Myspace signed a $900m deal with Google in 2006 to sell its advertising space and was at one point valued at $12bn. It was eventually sold by News Corp for just $35m.

The 870 million people using Facebook via their smartphones each month could explain the drop in Google searches – those looking to log on are no longer doing so by typing the word Facebook into Google.

But Facebook's chief financial officer David Ebersman admitted on an earnings call with analysts that during the previous three months: "We did see a decrease in daily users, specifically among younger teens."

Investors do not appear to be heading for the exit just yet. Facebook's share price reached record highs this month, valuing founder Mark Zuckerberg's company at $142bn.

Facebook billionaire



When Facebook shares hit their peak in New York this week, it meant Sheryl Sandberg's personal fortune ticked over $1bn (£600m), making her one of the youngest female billionaires in the world.

According to Bloomberg, the 44-year-old chief operating officer of the social network owns about 12.3m shares in the company, which closed at $58.51 (£35) on Tuesday in New York, although they fell back below $58 on Wednesday. Her stake is valued at about $750m.

Her fortune has risen rapidly since last August, when she sold $91m of shares and was estimated to be worth $400m.

Sandberg has collected more than $300m from selling shares since the company's 2012 initial public offering, and owns about 4.7m stock options that began vesting last May.

"She was brought in to figure out how to make money," David Kirkpatrick, author of The Facebook Effect, a history of the company, told Bloomberg. "It's proving to be one of the greatest stories in business history."

Sandberg's rise in wealth mirrors her broadening role on the global stage. The Harvard University graduate and one-time chief of staff for former Treasury secretary Lawrence Summers is a donor to President Barack Obama, sits on the board of Walt Disney Co, and wrote the book Lean In. She will be discussing gender issues with IMF boss Christine Lagarde at Davos on Saturday.