After taking several part-time positions, Einstein went to work as a junior official in the Swiss Patent Office in Berne.  The work appears to have left Einstein lots of time to think about theoretical physics.  In 1905, at the age of twenty-six, he published three articles, any one of which would have established him as one of the world's leading physicists.  The first proposed that light has a particle like, as well as a wavelike, nature and explained the photoelectric effect.  The second paper explained Brownian motion, the random erratic motion of very small particles suspended in a liquid, as being due to collisions with the rapidly moving molecules of the liquid.  The third showed that ideas of absolute space and time had to be replaced by the concept that space and time are relative to each other (the theory of relativity).  It was in this paper that Einstein derived the famous equation E = mc².

Einstein reached his revolutionary conclusions by means of rather simple but uncompromising logic based on experimental observations.  Remarkably, he did all this work without any contact with other important physicists of the time.

After the publication of these papers, the University of Zurich offered him a position, and Einstein quickly became an important figure in the world of theoretical physics.  In 1914 he was persuaded to move to Berlin as the head of the physics department of the world famous Kaiser-Wilhelm Institute.  Despite his prestigious position he was not entirely happy under the militaristic Prussian rulers of Germany.  Nevertheless, he continued to work in Germany throughout World War I and the difficult years that followed.  Ultimately, Hitler's repression of Jews forced Einstein to leave.  He arrived in New York in October 1933, and he stayed in the United States until his death in 1955.

Albert Einstein is universally recognized as the greatest physicist of our age.  Some say that if someone else had discovered the theory of relativity, Einstein's other work would have made him the second greatest physicist of his time.  His ideas radically changed our concepts of space and time.  From the 1905 publication of the theory of relativity until the end of his long life, he concentrated on one main task: the attempt to find a single unifying theory that would embrace both gravitation and electromagnetic phenomena, but this goal eluded him.  Thus far, it has eluded everyone else as well.