In an interview with Alex Springer, Bezos shares his thoughts about why humanity must leave Earth. Basically humanity will one day run out of power or outgrow our power supply. There’s more power in space and we will have to harness that power to move forward and survive.

Let me give you just a couple of numbers. If you take your body—your metabolic rate as a human it’s just an animal, you eat food, that’s your metabolism—you burn about a 100 Watts. Your power, your body is the same as a 100-Watt lightbulb. We’re incredibly efficient. Your brain is about 60 Watts of that. Amazing. But if you extrapolate in developed countries where we use a lot of energy, on average in developed countries our civilizational metabolic rate is 11,000 Watts. So, in a natural state, where we’re animals, we’re only using a 100 Watts. In our actual developed-world state, we’re using 11,000 Watts. And it’s growing. For a century or more, it’s been compounding at a few percent a year—our energy usage as a civilization.

Now if you take baseline energy usage globally across the whole world and compound it at just a few percent a year for just a few hundred years, you have to cover the entire surface of the Earth in solar cells. That’s the real energy crisis. And it’s happening soon. And by soon, I mean within just a few hundred years. We don’t actually have that much time. So what can you do? Well, you can have a life of stasis, where you cap how much energy we get to use. You have to work only on efficiency. By the way, we’ve always been working on energy efficiency, and still we grow our energy usage. It’s not like we have been squandering energy. We have been getting better at using it with every passing decade. So, stasis would be very bad, I think.

Now take the scenario, where you move out into the Solar System. The Solar System can easily support a trillion humans. And if we had a trillion humans, we would have a thousand Einsteins and a thousand Mozarts and unlimited (for all practical purposes) resources and solar power unlimited for all practical purposes. That’s the world that I want my great-grandchildren’s great-grandchildren to live in.