God's Number is up (or down)

Back in May I blogged about Rubik’s cube being solved in under 11 seconds. Since then more work has been done on solving it – but this time in determining what the smallest number of moves to “solve any disordered Rubik’s cube” aka “God’s Number” because only God would know the shortest, most efficient way to solve the cube. I’m not sure if this is an inference that God is a Russian. But back to the number … which is not 42 (which could have been fun) but 26. Fittingly, the answer was not deduced by mere mortals – rather it took a supercomputer 63 hours to produce the proof (or would that be evidence). The researchers, Mr Dunkle and Mr Cooperman announced their findings at the International Symposium on Symbolic and Algebraic Computation in Waterloo in August.