Albert Einstein was born on March 14, 1879, in Ulm in what is now West Germany. His father was a manufacturer of electrical equipment. Business failure led his father to move Einstein's family first to Munich and later to Milan. There were no early indications of Einstein's intellectual capabilities; in fact, there was even some concern on the part of his parents when he was a small child that he might be somewhat backward. During his school years he showed no special aptitude because of his dislike for rigid methods of instruction, and he was cited by school officials as being disruptive. Einstein was fascinated by mathematics and science, subjects that he studied on his own. He became a high-school dropout when he left school to join his family in Milan. Einstein had his German citizenship revoked in 1896 and became a Swiss citizen in 1901. He died as a naturalized citizen of the United States on April 18, 1955, in Princeton, New Jersey.
In 1896 he was able to enroll at the Swiss Federal Institute of Technology in Zurich after making up a number of subject deficiencies. At the institute the academic fare did not suit him either; he managed, however, to pass the required examinations for his degree. In the 2 years following his graduation in 1900, he subsisted on odd teaching jobs. By 1902 he had secured a position as patent examiner at the Swiss patent office in Bern, where he worked for the next 7 years.
The year 1905 was a momentous year for science, for without any academic connections, Einstein published, at the age of 26, four papers in the journal Annalen der Physik--papers that were to alter the course of twentieth-century physics. The first dealt with the random thermal motions of molecules in colloidal solutions, called Brownian motion, first noted in 1827 by the English botanist Robert Brown. Einstein's second paper reinforced the quantum theory of light developed by Max Planck in 1900. In it Einstein established the photon nature of light by accounting for the photoelectric phenomenon discovered in 1902. For this contribution, Einstein was awarded the Nobel Prize in physics in 1921. The third and most famous of Einstein's 1905 papers dealt with the special theory of relativity: "Zur Electrodynamik bewegter Korper" ("On the Electrodynamics of Moving Bodies"). And the final paper of that year introduced the now famous equivalence between mass and energy in the equation E = mc2. Because of this work, Einstein received his first academic post in 1908 at the University of Bern, which was followed by several others in Europe before he settled at the Institute for Advanced Study in Princeton in 1933.
Einstein's last years were spent searching for a unified field theory, for a universal force that would link gravitation with electromagnetic and subatomic forces, a problem on which no one to date has been entirely successful. Einstein was filled with reverence for the works of nature, and he noted that "The most incomprehensible thing about the world is that it is comprehensible." He thought of himself more as philosopher than as scientist, and in many ways he was from the same mold as the Greek natural philosophers, such as Plato and Aristotle, in trying to understand the natural world through mental concepts instead of experimentation. His success did draw on the insights of predecessors and the powerful analytical tools of mathematics, but most of all it was the result of an unerring cosmic intuition, the likes of which have been equaled by very few.