The lessons of history would suggest that civilisations move in cycles. You can track that back quite far - the Babylonians, the Sumerians, followed by the Egyptians, the Romans, China. We're obviously in a very upward cycle right now, and hopefully that remains the case. But it may not.

The revolutionary breakthrough will come with rockets that are fully and rapidly reusable. We will never conquer Mars unless we do that. It'll be too expensive. The American colonies would never have been pioneered if the ships that crossed the ocean hadn't been reusable.

It's important that we attempt to extend life beyond Earth now. It is the first time in the four billion-year history of Earth that it's been possible, and that window could be open for a long time - hopefully it is - or it could be open for a short time. We should err on the side of caution and do something now.

I think the high-tech industry is used to developing new things very quickly. It's the Silicon Valley way of doing business: You either move very quickly and you work hard to improve your product technology, or you get destroyed by some other company.

If you think back to the beginning of cell phones, laptops or really any new technology, it's always expensive.

An asteroid or a supervolcano could certainly destroy us, but we also face risks the dinosaurs never saw: An engineered virus, nuclear war, inadvertent creation of a micro black hole, or some as-yet-unknown technology could spell the end of us.

It is definitely true that the fundamental enabling technology for electric cars is lithium-ion as a cell chemistry technology. In the absence of that, I don't think it's possible to make an electric car that is competitive with a gasoline car.

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.

If you look at our current technology level, something strange has to happen to civilisations, and I mean strange in a bad way. And it could be that there are a whole lot of dead, one-planet civilisations.

SpaceX is only 12 years old now. Between now and 2040, the company's lifespan will have tripled. If we have linear improvement in technology, as opposed to logarithmic, then we should have a significant base on Mars, perhaps with thousands or tens of thousands of people.

Silicon Valley has some of the smartest engineers and technology business people in the world.

There are really two things that have to occur in order for a new technology to be affordable to the mass market. One is you need economies of scale. The other is you need to iterate on the design. You need to go through a few versions.

Over time I think we will probably see a closer merger of biological intelligence and digital intelligence.

Brand is just a perception, and perception will match reality over time. Sometimes it will be ahead, other times it will be behind. But brand is simply a collective impression some have about a product.

It would take six months to get to Mars if you go there slowly, with optimal energy cost. Then it would take eighteen months for the planets to realign. Then it would take six months to get back, though I can see getting the travel time down to three months pretty quickly if America has the will.

I think a lot of the American people feel more than a little disappointed that the high-water mark for human exploration was 1969. The dream of human space travel has almost died for a lot of people.

To make an embarrassing admission, I like video games. That's what got me into software engineering when I was a kid. I wanted to make money so I could buy a better computer to play better video games - nothing like saving the world.

In order to have your voice be heard in Washington, you have to make some little contribution.

I think it matters whether someone has a good heart.

America is the spirit of human exploration distilled.

Patience is a virtue, and I'm learning patience. It's a tough lesson.

If we're going to have any chance of sending stuff to other star systems, we need to be laser-focused on becoming a multi-planet civilisation.

Any product that needs a manual to work is broken.

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 we are at the dawn of a new era in commercial space exploration.

The space shuttle was often used as an example of why you shouldn't even attempt to make something reusable. But one failed experiment does not invalidate the greater goal. If that was the case, we'd never have had the light bulb.

It is theoretically possible to warp spacetime itself, so you're not actually moving faster than the speed of light, but it's actually space that's moving.

Land on Mars, a round-trip ticket - half a million dollars. It can be done.

So we originally expected to make about 35 gigawatt hours at the cell level and about 50 gigawatt hours at the module or pack level. Now we are expecting to do about 150 gigawatt hours in the same volumetric space as the original design.

If we drive down the cost of transportation in space, we can do great things.

What I'm trying to do is, is to make a significant difference in space flight. And help make space flight accessible to almost anyone.

If anyone has a vested interest in space solar power, it would have to be me.

If you look at space companies, they've failed either because they've had a technical solution where success was not a possible outcome, they were unable to attract a critical mass of talent, or they just ran out of money. The finish line is usually a lot further away than you think.

Nobody wants to buy a $60,000 electric Civic. But people will pay $90,000 for an electric sports car.

Selling an electric sports car creates an opportunity to fundamentally change the way America drives.

Biofuels such as ethanol require enormous amounts of cropland and end up displacing either food crops or natural wilderness, neither of which is good.

I'm anti-tax, but I'm pro-carbon tax.

As you heat the planet up, it's just like boiling a pot.

Life is too short for long-term grudges.

Boeing just took $20 billion and 10 years to improve the efficiency of their planes by 10 percent. That's pretty lame. I have a design in mind for a vertical liftoff supersonic jet that would be a really big improvement.

It is impossible to preserve my friendship with people who are allegedly leaders when they are attacking their own people, shooting at them, using tanks and other forms of heavy weaponry.

Islam is a religion. It is not an ideology. For a Muslim, there is no such thing as to be against modernity. Why should a Muslim not be a modern person? I, as a Muslim, fulfill all the requirements of my religion, and I live in a democratic, social state.

Before anything else, I'm a Muslim. As a Muslim, I try to comply with the requirements of my religion. I have a responsibility to God, who created me, and I try to fulfill that responsibility. But I try now very much to keep this away from my political life, to keep it private.

A political party cannot have a religion. Only individuals can. Otherwise, you'd be exploiting religion, and religion is so supreme that it cannot be exploited or taken advantage of.

As a politician who cherishes religious conviction in his personal sphere, but regards politics as a domain belonging outside religion, I believe that this view is seriously flawed.

Jerusalem is holy to three religions. You have to respect that.

My nation wants the death penalty. That is the decision of the Grand National Assembly of Turkey.

Your targets can only be realized on the basis of dreams.

My legal bond with the A.K.P. may have ended the day I took the presidential oath of office, but my bonds of love have never ended and never will.

I consider skateboarding an art form, a lifestyle and a sport. 'Action sport' would be the least offensive categorization.