How far do you think our technology is from actual space colonies? We could use the earth as a natural resource for food and oxygen and other neighboring planets for ore. It seems this is more feasible than any significant space travel via jump to light speed in the near future, floating or submerged cities on or underwater. Due to gravity, as long as it's within an orbit, it seems likely and doable.
And the practicality of it all. What would we gain from a space colony other than the fact that we have one? I realize that experiments can be done along with research and experimentation, but it would seem more logical to simulate conditions here on Earth instead of another planet. Kind of like, creating a vacuum on Earth as opposed to riding into space or going to the Moon.