“Ever since I was a kid, if I start to think about something hard, then all of my sensory systems turn off,” he says. “I can’t see or hear or anything. I’m using my brain to compute, not for incoming information.”

One of Musk’s favorite words—and concepts—was “hardcore.” He used it to describe the workplace culture he wanted when he founded Zip2, and he would use it almost thirty years later when he upended the nurturing culture at Twitter. As the Model S production line ramped up, he spelled out his creed in a quintessential email to employees, titled

Machine-learning systems generally need a goal or metric that guides them as they train themselves. Musk, who liked to manage by decreeing what metrics should be paramount, gave them their lodestar: the number of miles that cars with Tesla Full Self-Driving were able to travel without a human intervening. “I want the latest data on miles per

“I try to criticize the action, not the person. We all make mistakes. What matters is whether a person has a good feedback loop, can seek criticism from others, and can improve. Physics does not care about hurt feelings. It cares about whether you got the rocket right.”

Someday, Musk hoped, it would be able to take on even grander and more existential questions. It would be “a maximum truth-seeking AI. It would care about understanding the universe, and that would probably lead it to want to preserve humanity, because we are an interesting part of the universe.”

It’s that fighting to survive keeps you going for quite a while. When you are no longer in a survive-or-die mode, it’s not that easy to get motivated every day.

“I learned never to tell him no,” Mueller says. “Just say you’re going to try, then later explain why if it doesn’t work out.”

they showed him why they needed a second nail, and he nodded. It was part of the algorithm: if you don’t end up having to restore 10 percent of the parts you deleted, then you didn’t delete enough.

“Ever since I was a kid, if I start to think about something hard, then all of my sensory systems turn off,” he says. “I can’t see or hear or anything. I’m using my brain to compute, not for incoming information.”