The central concept of the theory of relativity, developed by Albert Einstein, posits that the laws of physics are the same for all observers, and it introduces the interdependency of space and time. This theory consists of two parts: special relativity and general relativity. Special relativity emphasizes the constant speed of light and the relativity of simultaneity, while general relativity describes how gravity affects the curvature of spacetime, leading to gravitational effects. Overall, it revolutionized our understanding of physics and the universe.