According to the legend, there's an Indian temple in Kashi Vishwanath which contains a large room with three time-worn posts in it, surrounded by 64 golden disks of different size. Brahmin priests, acting out the command of an ancient prophecy, have been moving these disks, in accordance with the immutable rules of the Brahma, since that time. When the last move of the puzzle will be completed, the world will end. The rules of the puzzle are: all discs are initially on the first post, biggest at bottom and smallest on top; only one disk can be moved at a time; each move consists of taking the upper disk from one of the stacks and placing it on top of another stack (i.e. a disk can only be moved if it is the uppermost disk on a stack); no disk may be placed on top of a smaller disk; the puzzle is solved when all the discs are on the third post, biggest at bottom and smallest on top. It can be easily proved that the smallest number of moves to solve a N-discs puzzle is 2^N-1 (two to the N-th power, minus one): for a 64-discs tower this number corresponds to 18446744073709551615 moves. If the priests were to perform one move per second, it would take roughly 585 billion years to finish, which is about 42 times the current age of the Universe or roughly 127 times the current age of our Sun. Will we be able to just count up to that number, without having to actually move anything, before the world ends?
