At the beginning of his career, Einstein realized that Newtonian mechanics could no longer unify the laws of classical mechanics with the laws of the electromagnetic field. From there he developed a special theory of relativity, with articles published in 1905. However, he realized that the principle of relativity could extend to the whole gravitational field, and this led to the creation of The theory of gravity in 1916, the year he published an article on general relativity.
He continued to study the problems of statistical mechanics and quantum theory, which gave explanations of particle theory and the motion of molecules. He also studied the thermal properties of light and laid the basis for the theory of quantum light. In 1917, Einstein used general relativity to describe the structural model of the entire universe. [6] Together with Satyendra Nath Bose, in 1924-1925 he predicted a new state of matter, the Bose-Einstein condensation of quantum systems in a state near absolute zero. Although also the father of quantum theory, he proved to be strict with this theory. This is reflected in his arguments with Niels Bohr and the EPR paradox on quantum theory.
