  We explore the new physics phenomena of gravidynamics governed by the
inhomogeneous spin gauge symmetry based on the gravitational quantum field
theory. Such a gravidynamics enables us to derive the generalized Einstein
equation and an equation beyond it. To simplify the analyses, we linearize the
dynamic equations of gravitational interaction by keeping terms up to the
leading order in the dual gravigauge field. We then apply the linearized
dynamic equations into two particular gravitational phenomena. First, we
consider the linearized equations in the absence of source fields, which is
shown to have five physical propagating polarizations as gravitational waves,
i.e., two tensor modes, two vector modes, and one scalar, instead of two tensor
polarizations in the general relativity. Second, we examine the Newtonian limit
in which the gravitational fields and the matter source distribution are weak
and static. By deriving the associated Poisson equation, we obtain the exact
relation of the fundamental interaction coupling in the gravidynamics with the
experimentally measured Newtonian constant. We also make use of nonrelativistic
objects and relativistic photons to probe the Newtonian field configurations.
In particular, the experiments from the gravitational deflection of light rays
and the Shapiro time delay can place stringent constraints on the linearized
gravidynamics in the gravitational quantum field theory.
