The bending of light by means of gravity is explained by Einstein's General Relativity. General relativity states that gravity is a force caused by the curvature of space time, similar in shape to a funnel, with the gravitational source at the centre, at the bottom. This curvature exists in a fourth spatial dimension. As light approaches this funnel, the curvature of its path increases, as the slope of space-time also increases. This is not easily observed on earth, due to it's relativistically small mass. Only in a gravity well approaching the vertical inclination of a black hole's event horizon, can the bending of light be noticed in a small distance.