Born on March 14, 1879, in Ulm, Württemberg, Germany. His father was Hermann Einstein, a salesman who later ran an electrochemical works, and his mother was Pauline Koch. They were married in Bad Cannstatt, near Stuttgart. As an infant Albert Einstein was reported to have an excessively large had, which was a frightening observation to his parents. This is a trait often regarded as "benign macrocephaly" in large-headed individuals with no related disease or cognitive deficits. His parents also worried about his intellectual development as a child due to his initial language delay and his lack of fluency until the age of nine, though he was one of the top students in his elementary school.
Einstein attended the Luitpold High School (or in German: Gymnasium), where he received a very advanced education. In 1891, he taught himself Euclidean geometry from a school booklet and began to study calculus; Einstein realized the power of deductive reasoning from Euclid's Elements, which Einstein called the "holy little geometry book". At school, Einstein clashed with authority and resented the school regimen, believing that the spirit of learning and creative thought were lost in such endeavors as strict rote learning.
Einstein's first scientific work, called "The Investigation of the State of Aether in Magnetic Fields", was written contemporaneously for one of his uncles. That same year, at age 16, he performed a famous thought experiment by trying to visualize what it would be like to ride alongside a light beam. He realized that, according to Maxwell's equations, light waves would obey the principle of relativity: the speed of the light would always be constant, no matter what the velocity of the observer. This conclusion would later become one of the two postulates of special relativity.
In order to finish secondary school he was eventually sent to Aarau, Switzerland. While there, he studied Maxwell's electromagnetic theory and received his diploma in September 1896. Einstein subsequently enrolled at the Federal Polytechnic Institute in October and moved to Zurich. In 1900, Einstein was granted a teaching diploma by the Federal Polytechnic Institute. He obtained his doctorate under Alfred Kleiner at the University of Zurich after submitting his thesis "A new determination of molecular dimensions" ("Eine neue Bestimmung der Moleküldimensionen") in 1905.
In 1917, Einstein published an article in Physikalische Zeitschrift that proposed the possibility of stimulated emission, the physical process that makes possible the maser and the laser. This was the publication, which eventually paved the way for the development of the modern laser.
