The problem of "Infinite Domains"

Everything has to be inside something else. In a model where time is the fourth dimension and the whole space-time could be thought of like a sphere in a 3d world, what would that 3d world be in the fourth dimension world? So that would need another domain/universe, which need to have a beginning and end and that could be thought of another sphere in 5 dimension; so on and so forth.

Questions on truth, proof & reality

Is truth cumulative? Is it monotonous? Something that once happened can it be ever proved that it never happened? How is proof different than reality?