JMS had it right: Mary Ann Cramer: I have to ask you the same question people back home are asking about space these days. Is it worth it? Should we just pull back? Forget the whole thing as a bad idea, and take care of our own problems at home? Sinclair: No. We have to stay here. And there's a simple reason why. Ask ten different scientists about the environment, population control, genetics, and you'll get ten diff…
I don't think it's accurate thinking about space as a physical place out there you can simply go. It's more like jumping from one gravity well to another and what you have to think about is what part of the system you're aboard can do that by means of conservation of momentum. And that's the main reason why I don't think we have the technology nor the energy budget to think about feasible interstellar trips. It's a bit like telling techno fairy tales to children, only it's adults and we have a lot of other adult problems.