The theory of relativity has been called the greatest triumph ever achieved by the disciplined imagination. When it was first proposed, in 1905, it shattered the traditional concepts of space-time, energy, and matter. Twelve years later its extended version challenged Newton's theory of gravity, replacing it with the concept of curved space. Its mathematical expressions disclosed some the nature's most intimate secrets. One of its equations became the backbone of the atomic age.
Physicists have a special respect for relativity because, unlike other theories that fade away with time, relativity has become more relevant today than in its early years. Black holes, expanding universe, the big-bang theory, all borrow heavily from relativity. .
Relativity's chief architect was Albert Einstein, a brilliant scientist, a concerned citizen, and a warm human being. He was good for nothing student who detested regimented wrote learning experiences of his youth. He sharpened his most powerful assets "concentration and mathematical ability "into the tools that needed to look into the mysteries of the nature. In his lifetime he was crowned as the prince of scientists and called the 'master-guru' of science and the father of the atomic age. Relativity is the property of almost every physical entity that exists in the universe. It is the most fascinating discovery ever been made by human being. Einstein is undoubtedly crowned for this marvelous discovery. Before Einstein, scientists were in confusion. Sometimes experiments proved that the earth is at rest but meanwhile some other experiment denied that fact. The truth was unknown. Einstein said that both the results are correct; it only depends on the fact that from which angle one sees the problem.
In 1905, Einstein put forward his 'Theory of Relativity'. Relativity is not one theory, but these are two theories i.e. "General Theory of Relativity (1916 AD)- and "Special Theory of Relativity (1905 AD)- He said that rest and motion are relative quantities and then he generalized it by saying, "Every physical quantity is relative to some other physical quantity".