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
What you described to me sounds exactly like what I’m referring to, so I’m not sure tbh. I’m referring to the many worlds interpretation of quantum mechanics.
I just looked it up, and it seems like my intuition aligns pretty well with MWI.
Anyway, the idea is that as you jump 100 years back, you enter a special timeline that isn’t exactly like the one you left. It’s mostly the same, but a time traveler visited at some point, which could radically alter the future of that timeline.
So if you become your own grandmother, there’s no real paradox, since you and your grandchild are not the same person. You are from different timelines, you are different branches of the same tree. Time traveling doesn’t cause branching, since every branch already exists.
A time machine can’t travel entirely freely to any branch, but since there are infinitely many branches you get the illusion of complete freedom. You can not jump to a timeline that doesn’t already have you jumping in it.
That makes sense, and I think it literally just is the Deustchian model at least according to this source. It’s been a long time since I read the original paper so I guess I misremembered it as a slightly different thing, though further reading suggests this might be a flawed explanation of his own theory, so I’m just thoroughly confused now haha.
I can think of a number of problems with how it would work, depending on the way you set it up it could result in something like “wormholes” to the future just randomly opening up constantly and everywhere just due to the way probability works. There are certainly a lot of interesting mathematical phenomena that arise from time travel like that.
If that model results in wormholes randomly opening up here and there, it doesn’t necessarily mean it’s going to violate our current observations. What if the probability of a wormhole event is incredibly unlikely. You know, like a tennis ball tunneling through a solid wall sort of unlikely. Even if the probability is a lot higher, those wormholes could open up anywhere in the universe, which just so happens to be incredibly vast. Or what if the wormholes are absolutely tiny, and last only a nanosecond? There are lots of ways it could still be compatible with observations.