Ponyless on 24 October 2013
I think if it was possible, i would imagine it like this:
You're in universe A and travel 20 years into the past. As soon as you do you immediately create a new Universe, such as Universe B that would be exactly the same as universe A but would start changing depending on what you did. It would be impossible to return to universe A and every time you time traveled, a new universe would be created. So if you went 5 years into the past of Universe B, you would create Universe C with the changes you made. Completely impossible to return back to the previous universe you traveled from.
