I've read that in general for a modal formula P, a world w and a Kripke frame ⟨W,R⟩
w⊨□P if and only if for every u∈W, if wRu then u⊢P
In case of LTL, being a modal logic, I assumed that the worlds are different moments in time and the relation R is the chain of "arrows" between those moments. However, in this case the semantic of □ in LTL would not correspond to the definition above.
What did I misunderstood?