IT WAS hailed as the world’s first “sub-4”. On November 24th 2018, Yusheng Du, a Chinese Rubik’s Cube enthusiast, solved a standard 3x3x3 cube in an astonishing 3.47 seconds. The feat, now an official Guinness World Record, smashed the previous record by 0.75 seconds. Today, at the World Cube Association’s (WCA) World Championship in Melbourne, Australia, hundreds of eager “speedcubers” will try—and probably fail—to twist their way to a new record.
Speedcubing is a relatively new phenomenon. Erno Rubik, a Hungarian scientist, patented the original cube in 1974 (his first attempt at cracking it took several weeks). Made up of nine coloured squares on each of its six faces, the cube rotates around a central axis. By twisting the sides, the cube’s colours can be scrambled and unscrambled. When solved, each side of the cube is a solid colour.
After a global craze in the 1980s, the puzzle’s popularity gradually faded; it was propelled back from oblivion by the internet. Mass-circulated instructions, YouTube tutorials, and online clubs and forums all helped to re-popularise the cube. A World Championship was reintroduced in 2003, after a 19-year hiatus. Over the years, the record for solving the cube has been gradually whittled down to near-superhuman speeds. Beyond the classic competition, cubers also race to solve the puzzle one-handed, with their feet and while blindfolded (see chart).
The techniques to solving a Rubik’s Cube include the Corners-First method, The Petrus method and the CFOP method (the one used by Mr Yusheng). Although the classic 3x3x3 cube has a mind-boggling number of possible configurations (more than 43 quintillion), solving it never requires more than 20 moves; most configurations require just 18. But for speedcubers, there are other factors to consider. The WCA allows players to lubricate and sand their cubes’ twisting mechanisms to improve their times. But too much fiddling can be risky: damage or markings can result in disqualification. The arrival of magnetised cubes in 2016 has allowed for more accurate twisting, helping to shave off valuable milliseconds.
For some, a puzzle that was initially designed to stimulate complex mathematical calculations has become a fiercely competitive test of muscle memory, rote learning and luck (Mr Yusheng’s sub-4 benefited from a fortunate initial “scramble”). For others, speedcubing is more light-hearted. Last year a 13-year-old Chinese boy went viral after setting world records for solving three Rubik’s Cubes simultaneously while juggling them (5 minutes 6.61 seconds) or by using both hands and feet (1 minute 36.39 seconds).
Mr Yusheng, for his part, may have room for improvement. In 2016 a German-built robot solved the puzzle in a blur lasting 0.637 seconds. In March 2018 a robot built by two MIT engineering students, Ben Katz and Jared Di Carlo, did better still. The machine, which was outfitted with PlayStation Eye cameras and could execute a move in 15 milliseconds, solved the puzzle in just 0.38 seconds.