Religion and Science is a bit deep for me SR,
(Yes I belive in god)
But I belive in the possibility of time travle. I mean why not. Man has made the impossible hapen time and again. But I do agre just by you going back you would change things. Just thrusting matter back in time would cause change. And if you moved anything or did anything, talked to anyone, I belive it would cause a fork in time. 2 time lines, call them demesions if you want. But I think it would be the same demession just one after the change and the one you lived.
Personaly I do not belive anyone should ever do it. Not to see if a person on trial realy did it, or even to just check things out, or to get rich. You never know what you could change.