HISTORICAL INTRODUCTIONEinstein's first paper on the restricted 'Theory of Relativity', originally published in the 'Annalen der Physik' in l905. Translated from the original German Papers by Dr. Meghnad SahaLord Kelvin writing-in 1893, in his prefaceto the English edition of Hertz's Researches on Electric Waves, says" many workers and many thinkers have helped to build up the nineteenth century school of plenum, one ether for light, heat, electricity, magnetism; and the German and English volumes containing Hertz's electrical papers, given to the world in the last decade of the century, will be a permanent monument of the splendid consummation now realised."Ten years later, in 1905, we find Einstein declaring that " the ether will be proved to be superflous." At first sight the revolution in scientific thought brought about in the course of a single decade appears to be almost too violent. A more careful even though a rapid review of the subject will, however, show how the Theory of Relativity gradually became a historical necessity.Towards the beginning of the nineteenth century, the luminiferous ether came into prominence as a result of the brilliant successes of the wave theory in the hands of Young and Fresnel. In its stationary aspect the elastic solid ether was the outcome of the search for a medium in which the lightwaves may "undulate." This stationary ether, as shown by Young, also afforded a satisfactory explanation of astronomical aberration. But its very success gave rise to a host of new questionsall bearing on the central problem of relative motion of ether and matter.On the other hand, the negativeevidences in favour of the convection-coefficient had also multiplied. Mascart, Hoek, Maxwell and others sought for definite changesin different opticaleffects induced by the motion of the earth relative to the stationaryether. But all such attempts failed to reveal the slightesttrace of any optical disturbance due to the "absolute" velocityof the earthy, thus proving conclusivelythat all tne different optical effects shared in the general compensation arising out of the Fresnelian convection of the excess ether. It must be carefullynoted that the Fresnelian convection -coefficient implicitlasysumes the existence of a fixed ether (Fresnelo)r at least a wholly stagnant medium at sufficiently distant regions (Stokes), with reference to which alone a convection velocitycan have any significance.Thus the convection coefficient implying some type of a stationary or viscous, yet nevertheless "absolute" ether, succeeded in explaining satisfactorily known optical facts down to 1880.
About the Author: Albert Einstein (14 March 1879 - 18 April 1955) was a German-born theoretical physicist and philosopher of science. He developed the general theory of relativity, one of the two pillars of modern physics (alongside quantum mechanics). He is best known in popular culture for his mass-energy equivalence formula E = mc2 (which has been dubbed "the world's most famous equation"). He received the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect. The latter was pivotal in establishing quantum theory. Near the beginning of his career, Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field. This led to the development of his special theory of relativity. He realized, however, that the principle of relativity could also be extended to gravitational fields, and with his subsequent theory of gravitation in 1916, he published a paper on the general theory of relativity. He continued to deal with problems of statistical mechanics and quantum theory, which led to his explanations of particle theory and the motion of molecules. He also investigated the thermal properties of light which laid the foundation of the photon theory of light. In 1917, Einstein applied the general theory of relativity to model the large-scale structure of the universe. He was visiting the United States when Adolf Hitler came to power in 1933 and, being Jewish, did not go back to Germany, where he had been a professor at the Berlin Academy of Sciences. He settled in the U.S., becoming an American citizen in 1940. On the eve of World War II, he endorsed a letter to President Franklin D. Roosevelt alerting him to the potential development of "extremely powerful bombs of a new type" and recommending that the U.S. begin similar research. This eventually led to what would become the Manhattan Project. Einstein supported defending the Allied forces, but largely denounced the idea of using the newly discovered nuclear fission as a weapon. Later, with the British philosopher Bertrand Russell, Einstein signed the Russell-Einstein Manifesto, which highlighted the danger of nuclear weapons. Einstein was affiliated with the Institute for Advanced Study in Princeton, New Jersey, until his death in 1955.