No I don't think time travel is possible. Here is why I think this is so without getting to "scientific" about it. The fastest speed ever measured in the universe is that of the photon i.e. light particles. As far as we have been able to observe; nothing travels faster than the speed of light, not even gravity. Gravity is a unified particle influence i.e. the more gravitons you possess the higher your gravitational field. But the graviton influence never exceeds the speed of light.
Now that we have established this little fact let's go to the next step. Einstein in his theory of relativity States that space is time in a viewable form, he also states that light speed is the ultimate speed that can be reached in our universe; even in higher gravitational fields light never speeds up in direct relation to the intensity of that field. so there we have two observable immutable facts that everybody can observe for themselves with some simple experiments. Drop a steel ball the same size as a lighter rubber ball in a vacuum and they both hit the ground at the same time. Drop them from altitude in an atmosphere and they both attain the same speeds before they hit the ground; wind resistance will have an affect on the lighter object so this is just an acceleration model.Now I have stated that light will not exceed the speed of gravity and vise versa, why do I say this? When the existence of black holes was finally proven the idea that light could not escape their gravitational influence intrigued me. Was gravity traveling at greater the speed of light here? And therefore the light it emitted could not escape in order to become visible light? No. The gravity of a "black hole" is not traveling faster than the speed of light; it is traveling at the speed of light! So there for there is a canceling out effect here that renders the light emissions neutral and undefined.
So then why do we see the other parts of the universe? Because the incidents of graviton emissions from bodies of mass are weaker than in black holes and therefore not traveling at the speed of light; Einstein also postulated that gravity was not the same everywhere in the universe.I think that he was right.. that gravity is not related to the speed of light and that the speed of light is constant; therefore you cannot travel faster than the speed of light so therefore you cannot go back in time or forward in time because this means that the speed of time is directly related to the speed of light and not related to graviton influences. Are there parallel worlds?
I.E. worlds similar to ours but existing in the same space but at a different time?
No. time is directly relate to the speed of light and the speed of light is directly related to space. Period.