Abstract : In these papers, physicists will find the latest mathematical analysis of the results of the Michelson-Morley experiment, which was the source of all papers for Fitzgerald, Lorentz, Poincare, Minkowski and Einstein. This analyzes are the result of a study of the elastic collision theory, and are quite different from those of early physicists who have paved the way for the emergence of relativity theory. This work will discuss Fitzgerald-Lorentz's explanations and prove that they are not correct.