Hmm, what if....

Ok so I was just watching the Terminator preview which has me wondering: Ok, say 1000 years in the future we finally figure out how to travel back in time. Well what if we try and travel back in time to now or even further to try and change it? And what's more, what if everyone is capable of making their own future? So say I disagree with my decision to tan so much because in the future I'm haggard looking and I'm in the year 3009 (because yes, I'm living to be 1021 years old), I could just come back and change it and make my own future. What if everyone could do it? What if we end up living forever because we can just go back and do over our mistakes? So, maybe time would forever be bouncing all over the place with whoever decides to change it? Which brings me to dimensions. What if the path we're on right now is just on way we could've gone? And there's an infinite number of dimensions continuing on as if I chose something different? Maybe in one I'm a celebrity, maybe in one I'm homeless, maybe in one I already have 10 kids... weird.