We all know it's possible to time travel into the future relative to everyone else. For example, say you went 75% the speed of light for an hour. The world around you relative to you would have aged thousands of years just from going at that speed for an hour.
The tricky situation is that once you travel into the future, there is no going back. You're stuck in the present and all your friends and family have already died.
Source for Relative "Time Traveling" into the future: (before crying about wiki, check the sources listed on the site) http://en.wikipedia.org/wiki/Time_dilation
Now the big question: How do you Travel BACKWARDS in time? Is it even possible?
Everything we know about physics so far points to no. There seems to be a system that protects itself from traveling backwards in time. We may just be looking in the wrong places or formulas. Now if you COULD travel backwards in time.....There are a few problems.
-Grand Father Paradox: If you traveled backwards in time and killed your grandfather, would it make you disappear from reality?
- What would happen if you ran into your past self?
Personally, I think if you travelled backwards in time, you would create simply another parallel universe in our already infinite amount of universes.(assuming string theory is true)
Fun Fact: If you travelled the speed of light, you would become infinitely massive and time would stop relative to you. I bet that would be fun.