I'm pretty sure this a pretty good explanation of how time hopping to the past is possible.
If you found an Earth-Alpha Centauri wormhole, you could dive from Earth through it in the year 3000 and emerge at Alpha Centauri . But when? You might emerge not in year 3000 but perhaps in the year 2990 instead. If that happened, you could travel back to Earth at 99.5 percent the speed of light and arrive back at Earth 6 years before you left. You could wait on Earth for those 6 years and, so you could shake hands with yourself when you took off in the year 3000, You would have accomplished time travel to an event in you own past.
EDIT: Try following yourself through the wormhole (year 3000) and both of you will emerge at Alpha Centauri (hopefully year 2990). Now travel back to earth at 99.5 percent the speed of light. You will meet the "original" you and the you that shook hands, greet them and take a video of the three of you, and upload it to micetube.
ya, the multiple timelines (branes) have an affect(theoretically). it acts like a protection of travelling back in time, so what Mr. Einstein says about nothing going faster than light is true, so at S>C, teleportation occurs. the scientists at CERN accelerated a bunch of protons very fast and smashed them against a target that broke them into a bunch of subatomic particles, including neutrinos, which are very fast to begin with, and they accelerated to C, which sent it out of our brane, and made it re-appear in our brane a couple nanoseconds later. (~60 nanoseconds). so the neutrinos dissapeared, travelled at C through the bulk, and re-appeared in the brane, arriving at the lead target in italy 60 nanoseconds before a photon would. the concept of teleportation is to have particles at point A travel at C to point B.(not actually true) when something travels at C, time stands still for it, so to us, the travelling would be just almost instantaneous, cause it still occurs, and the particles gain almost no age. what happened at CERN is, (theoretically) the neutrinos travelled at C out of the bulk to arrive at Italy earlier than a photon travelling at C. the teleportation concept from earlier would not have occured because first of all, the concept states that particles would be travelling at C, which still takes up time to go places, so the particles would have to use the bulk as a travelling medium.
well i could go on for hours about time, space and relativity, but not today.