Elon musk, perhaps the world’s most famous entrepreneur, is sometimes referred to as “the Trump of technology”—not for political reasons, but because of his habit of making, at short notice, spectacular pronouncements that stretch the bounds of credibility. On July 16th he was at it again, unveiling a new type of brain-machine interface (bmi). If human beings do not enter a symbiosis with artificial intelligence (ai), he declared, they are sure to be left behind. And he, the announcement implied, was going to be the man who stopped that happening.