Doesn't the String theory support parallel universes. All of wich are stack on on e another?

Time travel.
This may sound a bit obsurd but hey.
They say you cannot reach the speed of light. In space there is no restriction or force against your mass. So having said that does it not seem possible that at some point we could device a device that would gradually work up to tremendous speed. Wich would make time slow down.
I think withvhe universe as big as it is that this is the only true means of time travel we can even ponder.