The thing about time travel is that yes it is possible both backwards and forwards... there where ongoing theoretical experiments into blackholes and timetravel... and the idea is, if you focus enough light energy into a single point in space, you can cause the light, as a particle and a wave, to fold and warp space-time. allowing you to travel backwards, BUT... only as far as the time machine was activated... so in order to travel backwards a long time, you would have to find a highly advanced alien race that had a time machine active at the point you wanted to go to.
BUT... Quantum mechanics blows that right the fuck out the water... saying that by traveling through Space-time takes you to a Different space-time, meaning that by traveling back in time, you dont do anything to the current future, you just create another timeline, another universe if you will. only effecting that ONE. So nothing you did, would change the current space-time.
For example, the Grandfather Paradox, You go back in time and Kill your Grandfather before your father is born, thus making it so your never born, which means you never could have gone back in time, to have killed your grandfather... So your there, but you cant be there... and you cant Not be there.
This is into the PAST though, traveling into the future is easy... just Accelerate yourself to near-light speeds... Now, the problem behind this, is not only speeding up, but slowing down. It would be thought that while slowing, you again start to accelerate your aging, causing you to age many year's in just a few seconds. But that is just a thought.