Scientists unlock the secrets of the Rubik's cube

Scientists unlock the secrets of the Rubik's cube

Remember the Rubik's Cube? That little box of multi-coloured squares that you could only complete by carefully steaming off all of the stickers and then re-sticking them in the right positions? 

A team of US scientists has used a powerful number-crunching supercomputer to work out that the minimum moves needed to complete a Rubik's Cube from any starting position, is 26, one less than the previous record.

In reaching this figure Daniel Kunkle and Gene Cooperman from Northeastern University in Boston developed algorithms that can be useful for all kinds of different applications from scheduling air flights to determining how proteins will fold.

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The Rubik's cube was a huge success in the 1980s - despite the frustration it caused

As a Rubik's Cube has approximately 43 billion billion (43,000,000,000,000,000,000) possible positions it would have taken too long for even the most powerful supercomputer to work through all of the different configurations.

So Kunkle and his advisor Gene Cooperman developed some clever mathematical and computational strategies to make the puzzle more manageable.

They programmed the supercomputer to arrive at one of 15,000 half-solved solutions. They knew they could fully solve any of these 15,000 cubes with a few extra moves.

The final results showed that any disordered cube could be fully solved in a maximum of 29 moves, but that most cubes could be completed in 26 moves.

Many mathematicians still believe that it should take only 20 moves to solve any Rubik's cube, but no one has been able to prove this theory yet.

Failing that, a steaming kettle and some deft fingerwork should do the trick.

At this year's Caltech 2007 competition American Rubik's Cube expert Dan Dzoan broke the world record for one-handed cube-solving by completing one in an incredible 17.9 seconds.