"Maybe so, but that would be in the far far future, IMO. We'd have to either come up with a radical new method of propulsion or a new understanding of physics, or both, from what I understand about it."
I'm going to go a bit off-topic, since this is one of my favorite "relativistic hobby-horses".
Your statement would depend on:
a) your definition of "far, far future".
b) the effort that society as a whole is prepared to put into it.
For something like a star-wisp (microwave or laser powered sail), we almost have the required technology now. Same for an Orion-type (nuclear pulse propulsion) generation ship.
That probably wouldn't be worth the effort, though, since such vessels would almost surely be overtaken (in every sense of the word) by advances in technology.
A better bet, IMNSHO, would be a Valkyrie style vessel, much like the Venture Star from the movie Avatar. The main science/technology issue here is the production and storage of enough anti-matter to fill the tank. We're not at the point of being able to do that yet, but there's no immediate reasons why it would be impossible.
Another candidate is the ram-augmented interstellar rocket (RAIR), which makes use of interstellar hydrogen as fuel and reaction mass, thus neatly bypassing the pesky mass ratio limitations on conventional designs. For the RAIR as well, we're not quite there, technologically, but there's no immediate reason why we couldn't get there.
And the Venture Star of course brings us to the issue of time dilation. Interestingly, the Venture Star is (in the movie universe) cruising at 70% of light speed. This is an interesting "threshold" speed, because at 70% lightspeed, the time dilation factor is about 1,4, and it takes the ship about 1,4 years to travel a light year. So from the point of view of the crew, they are travelling almost exactly at lightspeed. Neat, huh? And manageable, from the point of view of timekeeping and communications. And, for a trip to Alpha Centauri C, that would keep the travel time (ship time) down to just under 6 years which would, again in my opinion, be within the limits of the practicable, even for a manned vessel.
And we haven't even started on things like wormholes or Alcubierre warp drives, mostly because these would require massive scientific and technological advances, some of which may for all practical purposes be impossible (e.g. creating negative mass and energy).
And last, but most certainly not least, the reason. Why would we (homo sapiens) make the effort? Sure, Terra can suck sometimes, but is it really bad enough that we need to leave? Well, yes, it is. For we are living on borrowed time, and the human race is doomed. We could be wiped out tomorrow, by the next extinction level event. Or in 20 years, in a thermonuclear WW III. Or in 5 billion years, when the Sun evolves into a red giant (at which point even Lunar or Martian colonies won't save us). So do we really have a choice?
Ahem. Thus endeth the rant. And now, back to our scheduled broadcast.
Regards & all,
Thomas L. Nielsen
PS: Would you like to know more? http://www.projectrho.com/public_html/rocket/slowerlight.php [/Starship Troopers]