My background educationally is physics and economics, and I grew up in sort of an engineering environment - my father is an electromechanical engineer. And so there were lots of engineery things around me.

I think it's important to reason from first principles rather than by analogy. The normal way we conduct our lives is we reason by analogy. [With analogy] we are doing this because it's like something else that was done, or it is like what other people are doing. [With first principles] you boil things down to the most fundamental truths…and then reason up from there.

You want to do things you’re passionate about but also are useful to other people.

I really do encourage other manufacturers to bring electric cars to market. It's a good thing, and they need to bring it to market and keep iterating and improving and make better and better electric cars, and that's what going to result in humanity achieving a sustainable transport future. I wish it was growing faster than it is.

Going from PayPal, I thought: 'Well, what are some of the other problems that are likely to most affect the future of humanity?' Not from the perspective, 'What's the best way to make money?'

I think it's very important to have a feedback loop, where you're constantly thinking about what you've done and how you could be doing it better.

You could warm Mars up, over time, with greenhouse gases.