We're running the most dangerous experiment in history right now, which is to see how much carbon dioxide the atmosphere can handle before there is an environmental catastrophe.

My opinion is it's a bridge too far to go to fully autonomous cars.

I tend to approach things from a physics framework. And physics teaches you to reason from first principles rather than by analogy.

If you get up in the morning and think the future is going to be better, it is a bright day. Otherwise, it’s not.

My vision is for a fully reusable rocket transport system between Earth and Mars that is able to re-fuel on Mars - this is very important - so you don't have to carry the return fuel when you go there.

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

Don't be afraid of new arenas.