When it comes to iconic items from the Eighties they don’t get more iconic than the humble Rubik’s Cube.
It may have caused many a gnashed tooth and uttered profanity, but there’s no denying that when someone wants a picture to illustrate the decade of the 1980s, they go straight for the cube. There are countless compilation albums and books featuring the cube on the cover, and a fair few websites too (hey, I’m as guilty as the rest of them!).
Whilst most of us would just fiddle and twiddle with the thing for hours, perhaps completing one side and then giving up, boffins around the world have been trying to work out what the maximum number of moves required to solve the cube is. This magic number, nick named a God Number, is a surprisingly low twenty – yep, a maximum of 20 moves is all that is required to solve any combination of the cube!
So how did they get to this number? Well, firstly the scientists took every single possible mixed up cube combination (a mere 43,252,003,274,489,856,000 possibilities!) and dissected this up into groups of similar types which would all be solved in the same way. These groups were further wittled down by taking symmetry into account, which left just 2.21 billion groups to solve!
A computer program was then devised to solve each combination in the most optimum manner. On a reasonably powered desktop PC this took around 20-30 seconds to solve a single combination. Not bad, but 2.21 billion groups would still take around 35 years of non-stop processing to complete!