On a table in front of you is a chessboard, its pieces frozen midway through a game. It’s white’s turn to play. How long would it take you to find white’s best move? Not a good move or even a great move, but white’s very best move.

Before you answer, consider what you’re up against. Five moves into a game, the number of possible board configurations already sits at more than 69 trillion. Mathematicians believe the total number of possible chess games exceeds the number of atoms in the known universe. Somewhere inside this cosmic haystack lies white’s best move.