eng Science and Education Publishing International Journal of Physics 2333-4576 2020-08-25 8 3 90 104 10.12691/ijp-8-3-2 IJP2020832 article Hui Peng davidpeng1749@gmail.com A gauge theory of gravity with an internal symmetry U(1), denoted as Gravito-dynamics, is established, which is dual to the Electrodynamics and complies with Special Relativity. The Gravito-dynamics is quantized and renormalized, denoted as QGD. The Gravito-dynamics is unified with Electrodynamics at classical level, and QGD is unified with QED at quantum level, denoted as Electro-gravity interaction. Following the line of generalizing the U(1) Electrodynamics to Yang-Mills theory, we generalize the U(1) gravity to SU(2) gravity that indicates short-range gravity. Two thought-experiments are proposed to test the underlying physics of the U(1) gravity and to detect the particle nature of gravitational wave that leads to wave-particle duality of gravitational radiation. http://pubs.sciepub.com/ijp/8/3/2/ijp-8-3-2.pdf gravity WEP gauge theory quantization renormalization unification duality short-range gravity