In fact, one could explain refraction without need of a special short-range force as proposed by Newton. He proposed a 'luminiferus ether', which is weightless and transparent, which permeates the entire universe. This is one reason for why shadow boundaries are more commonly diffuse. James Clerk Maxwell unified the scientific studies of electricity and magnetism in 1865 and showed that they were just two sides of a single force called electromagnetism. He proposed that electromagnetism is propagated by waves of varying frequency.
Light is simply electromagnetic waves of a certain range of frequencies.
Maxwell argued that the ether within the universe provides such an absolute framework. Speed of light is constant in that framework, but can vary in others which are moving at arbitrary constant velocities. The last problem which faced 19th Century science was then the nature of the 'luminiferous ether' needed to propagate electromagnetic waves and provide an 'absolute' reference frame. Lots of experiments were carried out, but no consensus was formed. Newtonian physics could not explain that.