A game involving sixty-five million participants has now come to an end, after mathematicians find the pursuit of primes too difficult to continue. The game has been in play for over a year, during which time mathematicians have sought to find prime pairs separated by values smaller than 70 million. This theory was first proposed by Yitang Zhang at the University of New Hampshire in Durham in May 2013, who suggested that there were an infinite amount of prime pairs, separated at most by 70 million. Zhang’s theory was the first major prime breakthrough in recent history and the first to put an upper limit on the gaps between pairs of primes. Since then, mathematicians have been competing in the online game to shrink this limit, though have now come to a halt after increasingly diminishing returns.

The theory behind the online game relates to a longstanding problem called the “twin prime conjecture.” While prime numbers are those that can only be divided by 1 and itself, twin primes are those just two numbers apart, such as 3 and 5, or 29 and 31. The twin prime conjecture was first proposed in 1849 and theorises that there are an infinite number of these pairings. However, little research had been devoted to proving or disproving this theory – until Zhang’s landmark 2013 breakthrough.

Mathematicians have since been collaborating through the Polymath Project, working together through the use of blogs and wikis to collaborate online.