The Eclipse to Confirm the General Theory of Relativity

Abstract

One of the milestones of the science of light commemorated during this International Year of Light and Light-based Technologies is “the embedding of light in cosmology through general relativity in 1915,” that is, the celebration of the centenary of Albert Einstein’s general theory of relativity. As Adolfo de Azcárraga, president of the Spanish Royal Physics Society (RSEF), points out in his book titled Albert Einstein, His Science and His Time, Einstein’s theory contained a spectacular prediction: “light also possessed ‘weight’, i.e., it should be attracted and deflected by celestial bodies.” Since the equivalence between acceleration and gravity extends to electromagnetic phenomena and light is an electromagnetic wave, light rays should bend in the presence of a gravitational field. Einstein had already realized that the only way to experimentally verify this theoretical prediction was for a total solar eclipse to take place since this would make it possible to photograph a star near the Sun when observed from Earth without the presence of strong sunlight. Well, on May 29, 1919 there would be a solar eclipse, which would be total on some parts of the Earth’s surface and would make it possible to verify that light rays are bent by gravity.