On some fundamental problems of the theory of gravitation

Cosmological observations indicate that the Einstein equation may not be entirely correct to describe gravity. However, numerous modifications of these equations usually do not affect foundations of the theory. In this paper two important issue that lead to a substantial revision of the theory are considered : 1. The significance of relativity of space-time geometry with respect to measuring instruments for theory of gravitation. 2. The gauge transformations of the field variables in correct theory of gravitation.