I’m not sure how to respond to this; the ability to compute it in a finite fashion for discrete universes seemed trivially obvious to me when I first pondered the problem. It would never have occurred to me to actually write it down as an insight because it seemed like something you’d figure out within five minutes regardless.
“Well, we know there are things that can’t happen because there are paradoxes, so just compute all the ones that can and pick one. It might even be possible to jig things such that the outcome is always well determined, but I’d have to think harder about that.”
That said, this may just be a difference in background. When I was young, I did a lot of thinking about Conway’s Life and in particular “garden of eve” states which have no precursor. Once you consider the possibility of garden of eve states and realize that some Life universes have a strict ‘start time’, you automatically start thinking about what other kinds of universes would be restricted. Adding a rule with time travel is just one step farther.
On the other hand, the space/time causal graph generalization is definitely something I didn’t think about and isn’t even something I’d heard vaguely mentioned. That one I’ll have to put some thought into.
I’m not sure how to respond to this; the ability to compute it in a finite fashion for discrete universes seemed trivially obvious to me when I first pondered the problem. It would never have occurred to me to actually write it down as an insight because it seemed like something you’d figure out within five minutes regardless.
“Well, we know there are things that can’t happen because there are paradoxes, so just compute all the ones that can and pick one. It might even be possible to jig things such that the outcome is always well determined, but I’d have to think harder about that.”
That said, this may just be a difference in background. When I was young, I did a lot of thinking about Conway’s Life and in particular “garden of eve” states which have no precursor. Once you consider the possibility of garden of eve states and realize that some Life universes have a strict ‘start time’, you automatically start thinking about what other kinds of universes would be restricted. Adding a rule with time travel is just one step farther.
On the other hand, the space/time causal graph generalization is definitely something I didn’t think about and isn’t even something I’d heard vaguely mentioned. That one I’ll have to put some thought into.