umm... future time travel is not only possible, we have demonstrated it: Relativity defines it. The faster you go relative to an inertial reference frame (the Earth for instance), the slower your time passes compared to an observer in that frame. If you could approach the speed of light, you could easily travel forwards through time 100s and 1000s of years without hardly aging at all.
Even at the pitiful speeds airliners move at, they were fast enough to slow down an atomic clock and prove this aspect of Einstein's theory.
While I tend to believe the same thing that Voss does: all events have already happened/are coexistent and its our own perception that limits time to moment my moment observations, there is little evidence of such. It is still far more likely that time is merely a sequence of events that is non-repeatable.
Either the nuclear physics or astro physics people will hopefully find a way to resolve the unsolved issues between time, space, and gravity. The laws they discover will ultimately determine whether we will ever be able to travel to other planets beyond our solar system in any practical time frame, which will ultimately determine the fate of the human race if we don't kill ourselves off before we exhaust our local resources.
