When do we start panicking? DeepMind, an artificial intelligence company in London, just announced another breakthrough in machine intelligence. Starting from nothing but the rules of the ancient and sublime board game Go, the algorithm taught itself to play through trial and error. After playing four million games against itself, the software, called AlphaGo Zero, reached superhuman performance. And it did that in less than a month, compared with the decade or two of training it takes for a human to become a highly skilled Go master.

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