There are multiple theories about time traveling. One is "proven": The time slows down according to your speed. The satellites in space are traveling faster than us, thus their clocks slows down a bit. So by traveling at the speed of light, you would travel without the time. So the time stops when you are traveling with the speed of light. Then you would travel forwards in time, because when you slow down, the time around you will have gone in the "regular" speed, while being still in your time.
Another completely "inverse" theory by Einstein is that extra dimension. The space time. So if you make a wormhole, you would be able to travel past the "bends" in the space time, thus traveling faster than the light. If you arrive before the light, then you would have traveled back in time.
I also want to point out that some physicists have managed to send messages back in time with the help of photons, even though we are only talking about microseconds. (I just saw an interview on Discovery Channel..)
Which of these (or both) is generally believed to be true, if any? And what about the paradoxes? Do you know any paradoxes regarding this? Maybe you are able to solve them? (One I've found is that if you travel into the future and grab a product that you start selling in the presence, the product will be in the future because you got it while time traveling. Who did make the product in the first place?
I'm mostly interested in the paradoxes created while time traveling.