Depends on what you mean by “deterministic” (and “universe”).
1) Do you assume each interaction has only one outcome, or are multiple outcomes (in different Everett branches) possible?
2) Do you assume all universes started in the same state? Molecular interactions in an existing universe are a different topic than the “creation of the universe”.
If by deterministic you mean informationally, that is with complete information we have the possibility to predict any future states (barred complexity), then we most definitely know that molecular interactions are not deterministic. However, even hypothesizing a deterministic universe, you could have different starting conditions that would evolve to different universes, and while you are at it, why not postulates different deterministic laws?
If molecular interactions are deterministic, are all universes identical?
Depends on what you mean by “deterministic” (and “universe”).
1) Do you assume each interaction has only one outcome, or are multiple outcomes (in different Everett branches) possible?
2) Do you assume all universes started in the same state? Molecular interactions in an existing universe are a different topic than the “creation of the universe”.
In a universe where molecular interactions are deterministic, I don’t see any additional universes emerging.
If by deterministic you mean informationally, that is with complete information we have the possibility to predict any future states (barred complexity), then we most definitely know that molecular interactions are not deterministic.
However, even hypothesizing a deterministic universe, you could have different starting conditions that would evolve to different universes, and while you are at it, why not postulates different deterministic laws?