Einstein was born in Ulm, Germany on Mar. 14, 1879. Einstein's parents, who were non observant Jews, moved from Ulm to Munich when Einstein was an infant. The family business was the manufacture of electrical parts. When the business failed, in 1894, the family moved to Milan, Italy. At this time Einstein decided officially to relinquish his German citizenship. Within a year, still without having completed secondary school, Einstein failed an examination that would have allowed him to pursue a course of study leading to a diploma as an electrical engineer at the Swiss Federal Institute of Technology. He spent the next year in nearby Aarau at the cantonal secondary school, where he enjoyed excellent teachers and first-rate facilities in physics. Einstein returned in 1896 to the Swiss Federal Institute of Technology, where he graduated, in 1900 as a secondary school teacher of mathematics and physics.
After two years he obtained a post at the Swiss patent office in Bern. The patent-office work required Einstein's careful attention, but while employed (1902-09) there, he completed an astonishing range of publications in theoretical physics. For the most part these texts were written in his spare time and without the benefit of close contact with either the scientific literature or theoretician colleagues. Einstein submitted one of his scientific papers to the University of Zurich to obtain a Ph.D. degree in 1905. In 1908 he sent a second paper to the University of Bern and became a lecturer there. The next year Einstein received a regular appointment as associate professor of physics at the University of Zurich.
By 1909, Einstein was recognized throughout German-speaking Europe as a leading scientific thinker. In quick succession he held professorships at the German University of Prague and at the Swiss Federal Institute of Technology. In 1914 he advanced to the most prestigious and best-paying post that a theoretical physicist could hold in central Europe, professor at the Kaiser-Wilhelm Gesellschaft in Berlin.
1905年3月發表《關於光的產生和轉化的一個啟發性觀點》(On a Heuristic Viewpoint Concerning the Production and Transformation of Light),認為光是由分離的粒子所組成。愛因斯坦解釋光也是由小的能量粒子(量子)組成的,並且量子可以像單個的粒子那樣運動。「光量子」理論把1900年普朗克創立的量子論大大推進一步,對早已成為定論的光的波動理論提出有力挑戰,揭示了微觀世界的基本特徵:波動—粒子二元性。
1905年4月:根據在咖啡館裡關於茶的討論,愛因斯坦寫出一篇論文,論證可以根據糖在液體中的擴散速度來計算糖分子的大小。這一篇《根據分子運動論研究靜止液體中懸浮微粒的運動》(On the Motion Required by the Molecular Kinetic Theory of Heat of Small Particles Suspended in a Stationary Liquid)的論文。
1905年6月30日,德國《物理學年鑑》(Annalen der Physik)發表〈關於運動物體的電動力學〉(On the Electrodynamics of Moving Bodies)一文。首次提出了狹義相對論基本原理,論文中提出了兩個原理:「光速不變」,以及「相對性原理」。
1905年9月27日,德國《物理學報》刊出〈物體的慣性與其所含能量有關嗎?〉(Does the Inertia of a Body Depend Upon Its Energy Content?),認為「物體的質量可以度量其能量」,隨後導出了E = mc²的公式。