Alex Honnold is an American rock climber best known for what’s called “free solo” ascents of intimidating rock faces which means that he climbs without any safety equipment. I’ve recently watched the awe-inspiring film Free Solo about his attempt to be the first person to climb the 3,000-foot south-west face of El Capitan in Yosemite National Park without ropes. (Spoiler alert : he did it!).