Observational Imprints of Our Lost Twin Anti-Universe

We consider observational consequences of the entanglement between our universe and a hypothetical twin anti-universe in the third quantization scheme of the canonical quantum gravity. Based on our previous investigations we select some special form of the interuniversal interaction which allows the entanglement entropy of the pair of universes to diverge at some critical points of their classical evolution. We find that the modification of the cosmic microwave background (CMB) power spectrum due to the entanglement with our twin anti-universe is enlarged for small modes $k$ and small multipole numbers $l$ with the Planck constraint onto the interaction coupling constant $\lambda_o\lesssim\mathcal{O}(10^{-56})$. Some other coupling functions which allow more critical points are also briefly commented on in the context of their observational effect on CMB and other observations.