A different view: if we live in a universe that branches into multiple universe at every $PLANCK_TIME, then free will could be our consciousness choosing the branch it follows without actually interacting with the universe.
Of course, there is branching in the quantum sense, but alas, no evidence that we can choose which "world" we end up in. Run the Schrodinger's Cat experiment a million times, and if you get something far from a 50-50 distribution, then maybe this definition is useful.
Love this! As if God designed universe timeline to be immutable. The question is, by making choice B you get universe B unique to that branch you chose, but is it a new branch per person per choice? Or do multiple people get “switched” to that branch?
If you were to view people as a composition of their choices, then in the current branch every individual chose said branch. Every person who did not chose the current branch, is now a different individual.
If the universe is considered a set of individuals or object, then it's unclear whether a multiple paths could lead to equivalent universes or the same. It all depends on the category theory (is the composition of choices associative, etc).
That being said, I really don't like multiple/branching universes theories.