The universe is expanding agree? so if you are at the edge of the expansion you are in the future in relative position to the earth, if you were then to travel at the speed of light towards the center of the universe you would, in essence, be travelling back in time and vica versa. But keep in mind, that while you are travelling stars are born and destroyd, civilizations rise and fall with the rotation of their planets, comets/asteroids hit planets and extinguish life, sun's go supernova etc. and all these things are happening eveywhere in the universe simultaneously.
Since the expansion started all these things have been happening, so to say that you can, for instance, go back to the beginning of our planet's creation and change something, whatever that may be, is impossible as it has already happened.The earth is no longer in the position, relative to the universe expansion bubble, it was when it emerged as a planet.
There may be cycles of civilizations on a planet that repeat themselves, but everything that has happened, has happened, theres no way to literally go back in time and change anything.The earth ofcourse does not travel at the speed of light, so it will always stay in its relative position in the galaxy/universe untill influenced by cosmic events.
This is my opinion mind you, care to refute it?
The rolling film paradox Nice to see someone discuss it, and understand it!
However, that does not prevent travel as far as I can see, it simply does not change history. If I am reading it wrong, could I ask you to extrapolate please.
Here is some food for thought. What if one "time travels" to a point in the past where space does not exist yet. I wonder what we would encounter. Not before the big bang mind you, but say maybe 10 billions kilometers in fornt of the expansion border. I wonder what we might find?