Albert Einstein (March 14, 1879 – April 18, 1955) was a German, Swiss and American physicist, of Jewish parents. In Physics, he published a research paper on the photoelectric effect, among three hundred other scientific papers of him in the equivalence of matter and energy, quantum mechanics, and others, and his proven conclusions led to the interpretation of many scientific phenomena that classical physics failed to prove. Einstein began with "special relativity" that contradicted Newton's theory of time and space to solve in particular the problems of the old theory regarding electromagnetic waves in general, and light in particular, and that was between (1902-1909) in Switzerland. As for "general relativity", he put it forward in 1915, in which he discussed gravity, and it represents the current description of gravity in modern physics. General relativity generalizes both special relativity and Newton's law of universal gravitation, by providing a unified description of gravity as a geometric property of space and time, or spacetime.