You cannot change time, as you going back to change something actually would create the future in which you exist, because time fits together like a jigsaw and cannot be changed.
I believe the notion of creating paradoxes cannot happen because anything you do in the past would not change the future in anyway, because the past has happened, and your arrival would have already happened, in the time you aimed for, and any changes you could have made would have made the world you were born into, and thus you cannot go back and change it, because anything you would do would be cause of the events now.
Also, the notion of time travel in itself is unfeasible for the future, as we would be constantly be visited, through history, by people, and this has not happened, so i can deduce that time travel is not possible.