ABSTRACT
Before Einstein’s theory of relativity and the famous Michelson-Morley experiment, scientists used to believe that light propagates through a ‘medium,’ the so-called ether, as longitudinal waves just like sound waves. The transverse character of light was first comprehended in the experiments carried out by Fresnel and Young with birefringent materials. The origin of the hypothesis was based on the interference of polarized light conducted by Fresnel. It was observed that light waves polarized in mutually orthogonal directions cannot interfere. In order to explain this phenomenon, Young put forth his theory of transverse nature of light waves. Despite the fact that this contradicted earlier theories of longitudinal character of light, Fresnel used this successfully to derive many useful results, including the Fresnel formulas, which were discussed in Chapter 3. In this chapter we define the basic states of polarization and also discuss how they can be changed as light propagates through different kinds of media.
