Sam Altman is almost supine. He is leaning back in his chair, feet up, in his home library overlooking San Francisco’s Golden Gate Bridge. In washed jeans and a t-shirt, the 37-year-old entrepreneur looks about as laid-back as someone with a galloping mind ever could. Yet the ceo of OpenAi, a startup reportedly valued at nearly $20bn whose mission is to make artificial intelligence a force for good, is not one for light conversation. The only signs of playfulness are two pairs of pink-coloured high-tops sitting on a bookshelf, with logos representing his two favourite technologies, AI and nuclear fusion. Occasionally he drifts into nerd-speak. At one point, keen to convince your correspondent that AI will progress faster than people think, he says, sounding rather robotic himself: “I’m curious if that caused you to update your priors.”

Joe Lonsdale, 40, is nothing like Mr Altman. He’s sitting in the heart of Silicon Valley, dressed in linen with his hair slicked back. The tech investor and entrepreneur, who has helped create four unicorns plus Palantir, a data-analytics firm worth around $15bn that works with soldiers and spooks, talks fast—and interrupts frequently. By his pool is a giant throne, from the set of “Game of Thrones”. It fits with the grandeur of his worldview that the West, which he cherishes for its classical values of free thought and free speech, should be fighting an epic internal battle not to give in to self-loathing.