Every mode of transport that we use - whether it's planes, trains, automobiles, bikes, horses - is reusable, but not rockets. So we must solve this problem in order to become a space-faring civilization.

I'd like to dial it back 5% or 10% and try to have a vacation that's not just e-mail with a view.

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.

There's a real opportunity to have a vertical takeoff and landing electric supersonic jet.

Optimism, pessimism, f**k that; we're going to make it happen. As God is my bloody witness, I'm hell-bent on making it work.

Trying to read our DNA is like trying to understand software code - with only 90% of the code riddled with errors. It's very difficult in that case to understand and predict what that software code is going to do.

The key test for an acronym is to ask whether it helps or hurts communication.