The Nature of Light: The nature of light has been debated by physicist for hundreds of years. Newton, in one of his famous works - Opticks, described mathematically observed light phenomena such as reflection and refraction, and thus constructed the bases of ray optics. Newton described light as a ray, or a particle, but by the beginning of the 19th century another view on the nature of light became the consensus - that light is a wave.   At the beginning of the 19th century Thomas Young, an English physicist, conducted many experiments that showed the wave nature of light. Probably his most famous experiment is the double-slit experiment; where you shine light through two small slits, and an interference pattern  is seen on far screen. This, and many other observations, led to the scientific acceptance of the wave nature of light in early 19th century. But all other waves observed by physicists before light propagated through a medium. Does this mean that light also propagates through some medium? Interference of  waves when passing through a double slit, as drawn by Thomas Young. This question, along with further developments of the nature of light led to the necessity of a propagation medium for light - the luminiferous aether.