Elon Musk, the billionaire South Africa-born entrepreneur whose business interests include the electric car company Tesla, the private rocket company SpaceX and the social media platform X (formerly Twitter), is the richest person in the world — and the subject of an expansive new biography by Walter Isaacson, whose earlier subjects famously include the Apple founder Steve Jobs. Our critic Jennifer Szalai discusses her review of the Musk biography.Szalai also discusses her recent Times Magazine profile of the writer and activist Naomi Klein, whose new book, “Doppelganger,” examines the “mirror world” of online conspiracy theories and paranoia and its effect on real-world politics.