If you mean 'is time travel theoretically possible'? Then, yes, according to physics theory it is possible. In fact at the quantum physics level it supposedly is possible for a single quantum particle to be in two places at once and supposedly in time as well. THEORETICALLY. It is not, however, ACTUALLY possible as yet at multi-particle levels.
Yes. Stephen Hawking, for example, subscribes to the one-way theory: if you can increase an object's velocity enough, perhaps by sling-shotting around a black hole, it can go forward in time. There is however no current practical theory about traveling backward in time.