Re-interpretation of the Two-World Background of Special Relativity as Four-World Background

The appropriate placements of the four-dimensional spacetimes of different universes make their coexistence possible, such that corresponding points in spacetimes within the universes are not separated in space or time. The corresponding points do not touch, because they are points in separate spacetimes. The different universes are described heuristically as existing in separate spacetime ‘compartments’. This new conception of many worlds (or universes) is therefore entitled compartment worlds (or universes) in this article. Compartment universes is a potential platform for many-world interpretations and uniform formulation of the natural laws. The two-world background of the special theory of relativity (SR) (involving two compartment universes), demonstrated elsewhere, is re-interpreted as four-world background (involving four compartment universes) in this article.