It seems I'm not the only skeptic: Professor Tom Murphy at UCSD also figures that near term visions of space colonization are implausible:
I want to caution against harboring illusions of space as the answer to our collision course of growth on a finite planet. We live at a special time. We have enjoyed spending our inheritance of fossil fuels, and are feeling rather heady about our technological prowess. For many generations now, we have ridden an exponential growth track, conditioning ourselves to believe that our upward trajectory is an eternal constant of our existence. We'll see. When we cross to the down-slope of fossil fuel availability--beginning with oil--we'll see how timeless the growth phase seems to be, and whether we can afford a continued presence in space. We should be mature enough to admit that we have no context in which to evaluate how successfully the human race will navigate this unprecedented transition.There's a lot more in his essay beside that — regular readers of this blog will find most of his arguments familiar from various blog posts of mine over the past 2-3 years — but it looks as if we've independently reached similar conclusions. And now he's been slashdotted, so his email inbox is probably full of stuff that is semantically indistinguishable from "WHY YOU SAY SANTA NOT EXIST?!?? YOU LIAR!! DO YOU WANT TO MAKE BABY JESUS CRY?!!11!!ELEVENTY!!"
What is it about the whole space colonization meme that causes its followers to personally identify with it so vehemently, despite the lack of scope for near-term actualization? (NB: this is a question about the cultural and sociological attachment aspects of space colonization as an idea, not about the idea itself.)