I realized that a methane-oxygen rocket engine could achieve a specific impulse greater than 380.

I think there are too many smart people pursuing internet stuff, finance, and law. That is part of the reason why we haven't seen as much innovation.

Don’t just follow the trend. You may have heard me say that it’s good to think in terms of the physics approach of first principles. Which is, rather than reasoning by analogy, you boil things down to the most fundamental truths you can imagine and you reason up from there.

When Henry Ford made cheap, reliable cars people said, 'Nah, what's wrong with a horse?' That was a huge bet he made, and it worked.

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.

Being an entrepreneur is like eating glass and staring into the abyss of death.

I think it matters whether someone has a good heart.