You're right on, man. The whole theory has too many variables. The only thing that I can say halfway confidently is that if one were to go
back in time, change something, and return, everything would be different, because that action would change the course of events dramatically. Wait,
that sounds like something from TimeCop!
I'm not so sure...
Let's take the idea of existing parallel time lines...
Let's then say I go back and kill my grandfather before he has my dad. Ok, then I return to my own time. One of a few things could happen,
perhaps.
1. I cease to exist, as I also in effect killed my father before my birth.
2. I only cease to exist on THAT timeline's future. If I return to my own timeline, nothing has changed.
3. I don't cease to exist, I simply have different parents, maybe even a different name, race, etc. who knows?
or any other of a myriad of possibilities...
Most simply ASSUME that changing an event in the past would affect the future...we can't know that. We don't even know if we can theorize if we
would even be able to interact with that timeline at all.... We don't know enough about it to make even educated guesses. Quantum physics....ain't
it fun???