Obscure, generations-old theorems have been transformative in tech, and there are still plenty out there to be used
In 1998, a computer science PhD student called Larry Page submitted a patent for internet search based on an obscure piece of mathematics. The method, known today as PageRank, allowed the most relevant webpages to be found much more rapidly and accurately than ever before. The patent, initially owned by Stanford, was sold in 2005 for shares that are today worth more than $1bn. Page’s company, Google, has a net worth of well over $1tr.
It wasn’t Page, or Google’s cofounder Sergey Brin, who created the mathematics described in the patent. The equation they used is at least 100 years old, building on properties of matrices (mathematical structures akin to a spreadsheet of numbers). Similar methods were used by Chinese mathematicians more than two millennia ago. Page and Brin’s insight was to realise that by calculating what is known as the stationary distribution of a matrix describing connections on the world wide web, they could find the most popular sites more rapidly.
David Sumpter is professor of applied mathematics at the University of Uppsala, Sweden, and author of The Ten Equations that Rule the World: And How You Can Use Them Too
