  Modern multimessenger astronomy delivers unique opportunity for performing
crucial observations that allow for testing the physics of the gravitational
interaction. These tests include detection of gravitational waves by advanced
LIGO-Virgo antennas, Event Horizon Telescope observations of central
relativistic compact objects (RCO) in active galactic nuclei (AGN), X-ray
spectroscopic observations of Fe K line in AGN, Galactic X-ray sources
measurement of masses and radiuses of neutron stars, quark stars, and other
RCO. A very important task of observational cosmology is to perform large
surveys of galactic distances independent on cosmological redshifts for testing
the nature of the Hubble law and peculiar velocities. Forthcoming
multimessenger astronomy, using such facilities as advanced LIGO-Virgo, Event
Horizon Telescope (EHT), ALMA, WALLABY, JWST, EUCLID, and THESEUS, can
elucidate the relation between Einstein's geometrical and Feynman's
quantum-field approaches to gravity physics and deliver a new possibilities for
unification of gravitation with other fundamental quantum physical
interactions.
