First, there is a general misunderstanding of time. Time is the change of position, it is motion itself. Time is how long it took object a to move from position a to position b. Their is no before time, because their was no motion, nothing moved. If you roll the hour hand back an hour on a clock did you go back in time, no. Did the little hand move, yep.
The idea that you physically can go back in time, besides this is also IMPOSSIBLE, not because of the paradox, but already proven LAWS OF PHYSICS. Matter and Energy can not be created or destroyed, it can only change state. To physically move you to a previous time, you will have to take the equal amount of energy and matter and transfer it to present time. There are a lot of paradox's that prevent this as well, including our favorite Cat in this game.
According to Einstein's Spacial Relativity. Going back in time from the point you current are is IMPOSSIBLE as well. As is not mathematically possible as time and space are bound to each other. Now, space can warp, and this is where going forward relatively is possible. If you hop on a space ship and travel near the speed of light, space warps around you, so when you return to earth. Earth relative to most other things will have moved as it normally does; however, you will have moved slower, so it will appear relative to you, that you have gone into the future, you also have no way back, that's a one way trip.
What about jumping to a 5th dimension, well then you don't know about multidimensional manifolds yet; however, it will exist outside of time itself, but that does not mean you can go to any point in time, it means, if you can detect time, that you see all motion at once, all TIME at once.
This can lead to some interesting ideas about black holes,multiverses, and entanglement. Anyone who kept up and understands everything above feel free to start going into those interesting ideas. For it maybe possible at a certain starting point once a device is setup, that we could get messages from the future or other universes.