QUANTIFYING the amount of information that exists in the world is hard. What is clear is that there is an awful lot of it, and it is growing at a terrific rate (a compound annual 60%) that is speeding up all the time. The flood of data from sensors, computers, research labs, cameras, phones and the like surpassed the capacity of storage technologies in 2007. Experiments at the Large Hadron Collider at CERN, Europe's particle-physics laboratory near Geneva, generate 40 terabytes every second—orders of magnitude more than can be stored or analysed. So scientists collect what they can and let the rest dissipate into the ether.

According to a 2008 study by International Data Corp (IDC), a market-research firm, around 1,200 exabytes of digital data will be generated this year. Other studies measure slightly different things. Hal Varian and the late Peter Lyman of the University of California in Berkeley, who pioneered the idea of counting the world's bits, came up with a far smaller amount, around 5 exabytes in 2002, because they counted only the stock of original content.

What about the information that is actually consumed? Researchers at the University of California in San Diego (UCSD) examined the flow of data to American households. They found that in 2008 such households were bombarded with 3.6 zettabytes of information (or 34 gigabytes per person per day). The biggest data hogs were video games and television. In terms of bytes, written words are insignificant, amounting to less than 0.1% of the total. However, the amount of reading people do, previously in decline because of television, has almost tripled since 1980, thanks to all that text on the internet. In the past information consumption was largely passive, leaving aside the telephone. Today half of all bytes are received interactively, according to the UCSD. Future studies will extend beyond American households to quantify consumption globally and include business use as well.

March of the machines

Significantly, “information created by machines and used by other machines will probably grow faster than anything else,” explains Roger Bohn of the UCSD, one of the authors of the study on American households. “This is primarily ‘database to database' information—people are only tangentially involved in most of it.”

Only 5% of the information that is created is “structured”, meaning it comes in a standard format of words or numbers that can be read by computers. The rest are things like photos and phone calls which are less easily retrievable and usable. But this is changing as content on the web is increasingly “tagged”, and facial-recognition and voice-recognition software can identify people and words in digital files.

“It is a very sad thing that nowadays there is so little useless information,” quipped Oscar Wilde in 1894. He did not know the half of it.