The fact that you can’t think of a way to compute the behavior of such a universe is no reason to conclude that it can’t be done.
In particular, it’s easy enough to come up with simplistic billiard ball models where you can compute events without ‘backtracking’. Now such models are certainly weird in the sense that in order to compute what happens in the future one naturally relies on counterfactual claims about what one might have done.
However, Quantum Mechanics looks a great deal like this. The existence of objects like time turners creates the opportunity for multiple solutions to otherwise deterministic mechanics and if microscopic time turners were common one might develop a model of reality that looked like wave functions to represent the space of possible future paths that can interfere constructively/destructively via interaction from time turner type effects.
The fact that you can’t think of a way to compute the behavior of such a universe is no reason to conclude that it can’t be done.
In particular, it’s easy enough to come up with simplistic billiard ball models where you can compute events without ‘backtracking’. Now such models are certainly weird in the sense that in order to compute what happens in the future one naturally relies on counterfactual claims about what one might have done.
However, Quantum Mechanics looks a great deal like this. The existence of objects like time turners creates the opportunity for multiple solutions to otherwise deterministic mechanics and if microscopic time turners were common one might develop a model of reality that looked like wave functions to represent the space of possible future paths that can interfere constructively/destructively via interaction from time turner type effects.
That’s the transactional interpretation, right?