At one o'clock in the afternoon local time, a digital Google creation will challenge one of the world's top players at the game of Go, the ancient Eastern pastime that's often compared to chess—though it's exponentially more complex. This Google machine is called AlphaGo, and to win, it must mimic not just the analytical skills of a human, but at least a bit of human intuition.

Over the years, machines have topped the best humans as checkers, chess, Othello, Scrabble, Jeopardy!, and so many other contests of human intellect. But they haven't beat the very best at Go. As Google likes to point out, there are more possible positions on a Go board than atoms in the universe—more than even the most powerful computers can contemplate. The scope of the game is so enormous that top human players must rely on more than careful analysis to succeed. They play based on what the board looks like, how it feels. To beat these humans, a machine must, in some way, reproduce this magic.