  Following many theories that predict the existence of the multiverse and by
conjecture that our space-time may have a generalized geometrical structure at
the fundamental level, we are interested in using a non-commutative geometry
(NCG) formalism to study a suggested two-layer space that contains our
4-dimensional (4-D) universe and a re-derived photon propagator. It can be
shown that the photon propagator and a cosmic microwave background (CMB)
angular correlation function are comparable, and if there exists such a
multiverse system, the distance between the two layers can be estimated to be
within the observable universe's radius. Furthermore, this study revealed that
our results are not limited to CMB but can be applied to many other types of
radiation, such as X-rays.
