So Stephen Hawking says we'll need to get off-planet within 100 years. He may be right, or not. We may live on Mars or the moon, or not. Either way, space is physically tough on humans. Will we biologically evolve?
All we've got right now is a series of questions. So let's start with what we know.
Professor Stephen Hawking, a scientist who has taken in his dotage to making regular fear-inducing pronouncements on the future of human existence, says we have 100 years to leave Earth. That's if artificial intelligence doesn't get us first.
We face, says Hawking, serious and possibly insurmountable threats through climate change, potential asteroid strikes, overpopulation, and disease.
He has made a British television documentary in which he and a former student, Christophe Galford, travel our planet to discover how we could live "off-planet" - that is, on another planet in outer space.
Well, it's not going to be easy
Even if we find life - life that we recognize as humans - elsewhere in our solar system, it won't be a simple matter of "all aboard and see you later."
Don't get me wrong: Hawking is the astrophysicist, and I'm not. Respect where it's due. But we know humans have trouble surviving in space.
We are perfectly suited to Earth and it is perfectly suited to us, no matter how much we try to destroy it. Space, on the other hand, is no natural human habitat.