Unified field theory Einstein's research after general relativity consisted primarily of a long series of attempts to generalize his theory of gravitation in order to unify and simplify the fundamental laws of physics, particularly gravitation and electromagnetism. In 1950, he described this effort, which he referred to as the "Unified Field Theory", in a Scientific American article entitled "On the Generalized Theory of Gravitation".
Although he continued to be lauded for his work in theoretical physics, Einstein became increasingly isolated in his research, and his attempts were ultimately unsuccessful. In his pursuit of a unification of the fundamental forces, he ignored mainstream developments in physics (and vice versa), most notably the strong and weak nuclear forces, which were not well understood until many years after Einstein's death. Einstein's goal of unifying the laws of physics under a single model survives in the current drive for the grand unification theory. http://en.wikipedia.org/wiki/Albert_Einstein บั้นปลายชีวิตไอน์สไตน์พยายามรวมทฤษฎีแรงโน้มถ่วง กับแม่เหล็กไฟฟ้า แต่ไม่สำเร็จ