Some ideas are:
- You branch off into another timeline and your actions make no difference to the previous timeline
- You’ve already taken said actions but just didn’t know about it so nothing changes
- Actions taken can have an effect (so you could suddenly erase yourself if you killed your parents)
- Only “nexus” or fixed events really matter, the timeline will sort itself out for minor changes
- something else entirely
Yeah, but I feel like if it were feasible to violate the condition we would have done it by now (besides the Casimir effect). That’s just an opinion of course, and I’m just an interested layperson, but I know physicists have been trying for at least a few decades.