- When do you think the first human will step foot on Mars? - I think it's a good chance in the 2030s that we will be on Mars. In fact, there's no physics reason why we can't do it. It's an engineering problem. It's a very difficult and dangerous engineering problem, but it is an engineering problem.

And in my book, "Future of Humanity," I even speculate beyond that, that by the end of the century, we'll probably have the first starships. The first starships will not look like the Enterprise at all. There'll probably be small computer chips that are fired by laser beams with parachutes. And like what Stephen Hawking advocated, the Breakthrough Starshot program could send ships, ships to the nearby stars, traveling at 20% the speed of light, reaching Alpha Centauri in about 20 years' time.

Beyond that, we should have fusion power. Fusion power is, in some sense, one of the ultimate sources of energy, but it's unstable. And we don't have fusion power today. Now, why is that? First of all, stars form almost for free. You get a bunch of gas large enough, it becomes a star.

I mean, you don't even have to do anything to it, and it becomes a star. Why is fusion so difficult to put on the Earth? Because in outer space, stars are monopoles. They are poles, single poles that are spherically symmetric. And it's very easy to get spherically symmetric configurations of gas to compress into a star.

It just happens naturally all by itself. The problem is magnetism is bipolar. You have a North Pole and a South Pole. And it's like trying to squeeze a long balloon. Take a long balloon and try to squeeze it. You squeeze one side, it bulges out the other side. Well, that's the problem with fusion machines.

We use magnetism with a North Pole and a South Pole to squeeze gas. And all sorts of anomalies and horrible configurations can take place because we're not squeezing something uniformly like in a star. Stars, in some sense, are for free. Fusion on the Earth is very difficult. But I think it's inevitable.

And it'll eventually give us unlimited power from seawater. So seawater will be the ultimate source of energy for the planet Earth. Why? What's the intuition there? Because we'll extract hydrogen from seawater, burn hydrogen in a fusion reactor to give us unlimited energy without the meltdown, without the nuclear waste.

Why do we have meltdowns? We have meltdowns because in the fission reactors, every time you split the uranium atom, you get nuclear waste. Tons of it. 30 tons of nuclear waste per reactor per year. And it's hot. It's hot for thousands, millions of years. That's why we have meltdowns.

But you see, the waste product of a fusion reactor is helium gas. Helium gas is actually commercially valuable. You can make money selling helium gas. And so the waste product of a fusion reactor is helium, not nuclear waste that we find in a commercial fission plant. And that controlling, mastering and controlling fusion allows us to convert this into a type one, I guess, civilization, right?

Yeah, probably the backbone of a type one civilization will be fusion power. We, by the way, are type zero. We don't even rate on this scale. We get our energy from dead plants, for God's sake, oil and coal. But we are about 100 years from being type one. Get a calculator.

In fact, Carl Sagan calculated that we are about 0.7, fairly close to a 1.0. For example, what is the internet? The internet is the beginning of the first type one technology to enter into our century. The first planetary technology is the internet. What is the language of type one?

On the internet already, English and Mandarin Chinese are the most dominant languages on the internet. And what about the culture? We're seeing a type one sports, soccer, the Olympics, type one music, youth culture, rock and roll, rap music, type one fashion, Gucci, Chanel, a type one economy, the European Union, NAFTA, what have you.

So we're beginning to see the beginnings of a type one culture and a type one civilization. And inevitably, it will spread beyond this planet. So you talked about sending at 20% the speed of light on a chip into Alpha Centauri. But in a slightly nearer term, what do you think about the idea when we still have to send biological, our biological bodies, the colonization of planets, colonization of Mars?

Do you see us becoming a two planet species ever or anytime soon? Well, just remember the dinosaurs did not have a space program. And that's why they're not here today. How come there are no dinosaurs in this room today? Because they didn't have a space program. We do have a space program, which means that we have an insurance policy.

Now, I don't think we should bankrupt the Earth or deplete the Earth to go to Mars. That's too expensive and not practical. But we need a settlement, a settlement on Mars in case something bad happens to the planet Earth. And that means we have to terraform Mars. Now, to terraform Mars, if we could raise the temperature of Mars by 6 degrees, 6 degrees, then the polar ice caps begin to melt, releasing water vapor.

Water vapor is the greenhouse gas. It causes even more melting of the ice caps. So it becomes a self-fulfilling prophecy. It feeds on itself. It becomes autocatalytic. And so once you hit 6 degrees, rising of the temperature on Mars by 6 degrees, it takes off. And we melt the polar ice caps.

And liquid water once again flows in the rivers, the canals, the channels, and the oceans of Mars. Mars once had an ocean, we think, about the size of the United States. And so that is a possibility. Now, how do we get there? How do we raise the temperature of Mars by 6 degrees?

Elon Musk would like to detonate hydrogen warheads on the polar ice caps. Yes. Well, I'm not sure about that, because we don't know that much about the effects of detonating hydrogen warheads to melt the polar ice caps. And who wants to glow in the dark at night reading the newspaper?

So I think there are other ways to do it with solar satellites. You can have satellites orbiting Mars that beam sunlight onto the polar ice caps, melting the polar ice caps. Mars has plenty of water. It's just frozen.