  It is shown that, in the model of a flat 3D space, the time (i.e., the Hubble
or the gravitation constant) plays a role of a spatial property. Gravitation
field of spherical central mass does not lead to a lowering of symmetry of the
space and appearance of anisotropy. In particular, the relations that describe
the changes in the refractive indices of the space treated as an optical medium
near the massive spherical body under the influence of its gravitation field
have been derived.
