Seems like you would need time travel to know whether or not such "hinges" actually exist. The world may be so chaotically intertwined that changing anything ca

Seems like you would need time travel to know whether or not such "hinges" actually exist. The world may be so chaotically intertwined that changing anything causes timelines to wildly diverge. In fact, maybe someone could coin a term for such a measure: the ratio of historic divergence to supposed meaningfulness of a change in preceding cause-effect chain(s). Perhaps also a measure for the opposite: the resiliency (or inevitability) of events that are "fated" to happen, albeit in different ways, despite edits to cause-effect chains. This supposes that certain events are like the centers of funnels; you can edit where and with what velocities you roll a set of marbles on its curved surface, but within a specific set of parameters they're all fated to lead to the same outcome. I can imagine a sci-fi story in which a character tries to prevent WW2 first by assassinating Hitler, then by other means, but with each edit WW2 still happens, merely with different (and unpredictable) foundational cause-effect chains. (Likely there are already stories like this somewhere.)