Now teleportation, though extraordinary, is really just an extension of what we already do, all the time - move across distances, or space. As in walking across the street or taking a plane. Time travel, on the other hand, is something we never do. That is, we live forward in time, but never go backward, and never go forward any faster, certainly not instantly.
Which is what makes time travel such an immensely enjoyable vehicle for fiction. You can travel a day or a year into the future and see what you're doing then, and what's happening in the world. You can travel to the past and have a drink or a cup of tea with your great-great grandmother. (You can go back in the past and try to save Socrates...)
Except ... you'd need to make sure that if you did meet your great-great-grandmother, it wasn't before she met your great-great-grandfather. Because what if your meeting somehow distracted the two from ever meeting... Where you would be then?
Paradoxes like this are what make time-travel stories so much fun - and I think they're also what makes time travel impossible. Sure, you could come up with scientific possibilities, such as the creation of an alternative universe every time you travel into the past, which would allow you to change past A (your great-great-grandparents met and had children) into past B (they did not, because of your trip to the past), which would allow you (a product of A) to travel to the past and avoid the paradox of doing away with circumstances that allowed you to travel to the past (because the A that created you would still exist - all that would happen is a new B would be created) ... but, whew, creation of such alternative universes every time you travel seems even more farfetched than time travel!
And travel to the future has its own devastating problems. If I travelled even just a day into the future, and saw what you were wearing, would that mean you had no choice about what clothes you put on tomorrow? I don't know about you, but I'm rather sure that I have free will - at least, about what kind of shirt I wear. (Whether I exercise that will well or not is, of course, another story.)
So, in the end, I'm afraid that we'll never be able to travel in time, except in our minds and our fiction...
On the other hand, I just could be an agent from the future, doing my best to disguise my tracks...
Deja Well Worth Vu blog post review of 2006 Deja Vu movie
see elsewhere on Infinite Regress for reviews of Heroes and Lost episodes...
Time Travel in Fact and Fiction free 20-minute podcast
The Plot to Save Socrates
"a Da Vinci-esque thriller" - New York Daily News
"Sierra Waters is sexy as hell" - curled up with a good book