Albert Einstein ( / ˈ æ l b ər t ˈ aɪ n s t aɪ n / ; German: [ˈalbɐt ˈaɪnʃtaɪn] ( listen ) ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist who developed the theory of general relativity , effecting a revolution in physics . For this achievement, Einstein is often regarded as the father of modern physics . [2] [3] While best known for his mass–energy equivalence formula E = mc 2 (which has been dubbed "the world's most famous equation"), [4] he received the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect ". [5] The latter was pivotal in establishing quantum theory within physics.