At some point in the past few years, humanity collided with a new kind of intelligence. And things are getting strange. People are being accused of crimes by algorithms; falling in love with digital beings; pioneering new ways to fight old diseases; turning to machines for comfort in their worst moments, and using artificial intelligence to commit - and hide from - terrible crimes. The Guardian’s Michael Safi investigates the story of a technology so complex that its own creators have no idea what it is thinking, and captures a snapshot of the era when people first made contact with AI