Albert Einstein (1879-1955), an American Scientist of German origin, is considered to be one of the greatest scientists, and definitely the greatest scientist of twentieth century.
Einstein is best known for formulating the theory of relativity which he first proposed when he was only 26 years old. This theory drastically modified the scientific view of many concepts such as time, space, mass, motion, and gravitation. He initially published a restricted version of theory of relativity in 1905. Later he expanded this theory and in 1915 expanded it to a general theory of relativity.
His famous equation e=mc^2 became the cornerstone for nuclear science. This equation establishes the relationship between mass of matter and energy. As per this equation the energy 'e' equivalent to a matter of mass 'm' is m times the square of speed of light.
On August 2, 1939, Einstein wrote a letter to President Roosevelt explaining the possibility of building an atomic bomb and urging him to provide government help to study the release of nuclear energy.
Albert Einstein developed the genera theory of relativity, one of them is physics such as quantum mechanics. He is also best known for his mass-energy equivalence formula E=mc^2 and his discovery of the law of the photoelectric effect.
1.mass energy equavalance
2.photo electric effect