  Building on the principles of quantum electrodynamics and special relativity,
we develop a semi-classical QED theory of gravitation. The experiment model for
theoretical analysis is the "hyperfine splitting" of the ground energy state of
hydrogen atoms. As the verification and validation by Newton's final
experiment, Newton's gravity constant G has been determined by this new
approach, G = 6.67221937(40)*10^(-11) N m2 /kg2. The result shows that, the
gravitational constant G is really a universal constant in free space, and can
be determined just by the more fundamental constants in physics.
