Charlie Stross is not optimistic about interstellar travel and colonization within our lifetime. He’s got an “essay” (it’s rather long to be an essay) on the matter over at his site.
He does a good job breaking down the fundamental flaws in space travel using modern technology. The main problem Charlie seems to have is a poor vision of future technology, in particular, advances in physics.
It takes about 20 years for the “next big thing” to pop out of the physics world. Relativity, quantum physics, superstring and quantum string theory– all of this stuff is really interesting and has let to advances in computers, understanding of microgravity, and a slew of other things. There’s even talk about “dark matter” and “dark energy”, and that we’ve recently been able to see the dark matter.
Quite frankly, there’s so much out in the universe we don’t understand, that it’s hard to simply cross our arms and say, “Nope. Can’t do it.” Space elevators are coming– people are invested in the idea because it will make space deployment of satellites cheap. In addition, once one space elevator is built, it will make the construction of other space elevators easier and cheaper. Having a conveyor of 4-6 space elevators transporting materials and personnel back and forth from orbit really blunts the costs of space travel.
The biggest blunt of all will be capitalism. I’m sure there are people out there that have looked up to Mars and thought, “Virgin territory for material construction!” Imagine the raw materials on Mars. Imagine the capabilities of building in a low-gravity orbit. Why continue to build objects for space travel on a full gravity world like Earth when you can get them to space easier by shooting them off of a lower-escape velocity platform like the top of Olympus Mons?
And if an outpost is build on Mars, then harvesting the nearby asteroid belt shouldn’t be too far away either. Raw iron & nickel is abundant, as well as other materials.
Of course, as Stross points out, it’s the time involved in transporting people to and from Mars. A trip could take 2-3 years one-way. Certainly there are ways to reduce the travel time?
And that’s where advances in theoretical physics come in. Einstein stated that time and space are connected. If that’s so, then it is possible to manipulate space, and I think this is where the research into dark matter and dark energy comes in. If space can be manipulated, such as in the teleportation experiments or some other form (space-folding ala Dune is an interesting thought) then distance shrinks as the problem no longer is a sheer velocity problem. And once that problem is solved, Proxima Centauri is just a hop, skip and a space-jump away.
So don’t be so down on the idea, Charlie. We may not see it in our lifetime (although medicine is working hard to keep us alive to experience it), but I think humans are closer to achieving that goal than you think.