Er, I guess I didn't do that well. I think the view is NOT that things are "revisable" by travelling back and forth in time, but rather that all things exist "statically" at all times. So like the Bradbury story "Sound of Thunder" where people travel to the past and change it is impossible. "Back to the Future" also out (a shame though, classic flick)
It's more like in EVERY instantiation of 2005, there's this note from the aliens. If it's here in ANY instantiation of 2005, then it was there for all versions.
That's why "circular causality" is legal (I think). Because all "times" "exist" "at the same time" analagous to the spatial dimensions. Clearly we don't have the proper language to explicate this, and I'm not smart enough to find inventive ways to use better terms.