Chess fell to computers in 1997, but Go was supposed to be safe for years. The ancient board game has more possible positions than there are atoms in the observable universe, which makes the brute-force search that cracked chess useless. Experts guessed that a machine capable of beating a top human was a decade away. In early 2016, DeepMind's Nature paper reported that its program, AlphaGo, had already beaten the European champion Fan Hui five games to none, the first time a computer had defeated a professional on a full board.