"The development of full artificial intelligence could spell the end of the human race," Stephen Hawking told the BBC a few years ago. Elon Musk has delivered even more dire warnings, while Bill Gates recently suggested "we shouldn't panic" because potential problems are not imminent. Our sci-fi visions of the potential impact of artificial intelligence (AI) have always had a tinge of doomsday about them, but the truth is that we're a long way from Skynet-style sentience. Earlier this summer a Google Duplex demo showed off Google Assistant calling businesses to make appointments for people. It spoke in a natural, human-like way, as it made an appointment at a hair salon.