thing deeply hidden had to be behind things." After attending elementary and secondary schools in Munich and in Aarau, Switzerland, Einstein studied mathematics and physics at the Swiss Polytechnic Institute in Zurich. He graduated in 1900. From 1902 to 1909, Einstein worked as an examiner at the Swiss Patent Office in Bern. This job as patent examiner allowed him much free time, which he spent in scientific investigations. Einstein became a Swiss citizen in 1901. The papers of 1905. During this time, Einstein made three of his greatest contributions to scientific knowledge. The year 1905 was an epoch-making one in the history of physical science, because Einstein contributed three papers to Annalen der Physik (Annals of Physics), a German scientific periodical. Each of them became the basis of a new branch of physics. In one of the papers, Einstein suggested that light could be thought of as a stream of tiny particles. This idea forms an important part of the quantum theory (see Quantum mechanics). In 1900, the German physicist Max K. E. L. Planck had proposed that the radiation of light occurred in packets of energy, called quanta. Einstein extended this idea by arguing that light itself consisted of quanta, which were later called photons. Scientists before Einstein had discovered that a bright beam of light striking a metal caused the metal to release electrons, which could form an electric current. They called this phenomenon the photoelectric effect. But scientists could not explain the phenomenon as long as they assumed that light traveled only in waves. Using his theory of quanta, Einstein explained the photoelectric effect. He showed that when quanta of light energy strike atoms in a metal, the quanta force the atoms to release electrons. Einstein's paper established the theoretical basis for the photoelectric cell, or "electric eye." This device made possible sound motion pictures, television, and many other inventions (see El...
