Here's an article that has surfaced on the web in the last few days that seems to throw cold water on the possibility of time travel --- to the chagrin of all us science fiction buffs
:
http://www.technologyreview.com/blog/arxiv/23292/
Basically (very basically!
) some new theoretical advances/postulations in quantum theory cast doubt on the possibility of building something called an "Alcubierre Drive", which would, in effect, allow one to move at a perceived speed greater than the speed of light even though Einstein's limits are not breached.
It does this by moving space-time itself, as opposed to moving through space-time, by employing various quantum effects (wrap your head around that one!). You take your bubble of space-time with you. The sort of thing that a typical schlump in a Type II or Type III civilization might do for a Sunday drive through the galaxy.
My own quandary with this is this: What happens when you reach your destination and turn off your Alcubierre drive and your little bubble bursts? Are you in the future, present, or past? If you are in "the present", then time travel would not seem to have been affected; you've just arrived at your destination quicker, that's all. But, your space-time bubble
by definition is different from the space-time "around" you, so how could time travel not be affected, either past or future?
Anyway, the question seems to be moot, since these theoreticians say that quantum theory dictates that the Alcubierre Drive can't be done, even by a time-lord sort of guy.
A word of warning: My own ramblings may not have anything to do with anything --- I'm a confirmed lotus eater.
But it's fun to talk about!