Oh sure. You initiate a grandfather paradox variant and then expect others to clean it up for you?
"Excuse me... God? Your universe does not appear to be robust. Umm... Sorry."
I've always wondered -- with a nagging sort of fear -- whether the laws of physics as we know them only apply within the particular local section of space. That would just be scary -- to discover, for example, that the atoms comprising steel alloys are self-destructive in a different set of physics (if atoms even exist as atoms!). Bye bye, space shuttle.
You could have at least used time travel like everyone else.
Personally, I think the fourth dimension is like the first, second, and third dimensions -- you can stretch it or compress it, but you can't jump from one discrete value to another. Thus, Einstein's theory of relativity may hold true (I prefer to have faith that it doesn't (otherwise, mankind is forever doomed to the local star(s)), but I have no evidence supporting that belief), but time travel itself is entirely impossible, just as instantly winking into a new location is entirely impossible.
That's my theory, anyway.