While I am personally not going to hold my breath about the possibility of actual time travel, I must disagree with nortexoid about his bases. For one, much of the theory about light speed also has to do with theories regarding black holes and other space-time-bending phenomena. Despite what Stephen Hawking has 'discovered', even his theories are not complete and conclusive, and as history will show, many theories about light and its properties have been found to be in error, and I anticipate that the theory of light speed being unachievable by matter retaining mass will also be shown as inaccurate. Many like to think that there are no particles that move faster than light (which, in case some forget, is also made up of particles, while still being made up of waves - read yer physics books again ). This assumption may well be false. Why haven't we found proof that it is false? Well, how are you ever gonna 'sense' it? Something many have proposed is that the 'sixth sense' experienced by humans is related to particles faster than light or existing in an otherwise ethereal separate space from what we are accustomed to.
Basically, my point is that ruling out things light lightspeed travel and time travel cannot be disproven because the theories that the disputes are based on cannot all be proven. So have an open mind, for it's better to be pleasantly surprised than convincingly humiliated