  We want to explain non-observation of electromagnetic counterpart of
currently confirmed ten gravitational wave signals from the black hole mergers
assuming their existence in the hidden mirror universe. Mirror matter, which
interacts with our world only through gravity, is a candidate of dark matter
and its density can exceed ordinary matter density five times. Since mirror
world is considered to be colder, star formation there started earlier and
mirror black holes had more time to pick up the mass and to create more binary
systems within the LIGO reachable zone. Totally we estimate a factor 10
amplification of black holes merging rate in mirror world with respect to our
world, which is consistent with the LIGO observations.

General Relativity and Quantum Cosmology