The paper aims to elaborate General Relativity based on the principle of time dilation & length contraction happened between two relatively stationary reference frames in a gravitational field. The paper firstly, establishes a factor of General Relativity, for time dilation & length contraction; such factor is similar to the Lorentz factor, in Special Relativity. The strength of time dilation & length contraction in gravity field depends on the factor, and the radius distance from a point mass. This means the length of a ruler is shortened when it is moving radially away from a point mass; whereas the clock ticks faster if it is positioned radially away from the point mass. The equation of gravitational acceleration can then be derived with the help of the said factor, . With the derived equation, the graph of gravitational acceleration versus radius distance from a point mass can then be plotted. By aligning with the title of this paper, the author explained the Lorentz transformation of Special Relativity too by emphasizing physical insight. Thus, readers shall find the formulation of General Relativity lies within a same framework with Special Relativity and does not involve heavy mathematical tools, but is still rigorous and does not lose physical insight. After the formulation of General Relativity, the deflection of a light beam in a gravitational field can be explained by the increased of energy of the light beam occurred only at the radial component of momentum of the light beam that points towards the point mass, whereas the tangential component of momentum remains constant. Finally, the space-time invariant is explained and found to be valid in both Special Relativity & General Relativity
Keywords: Einstein, General Relativity, Gravity
