Albert Einstein

Albert Einstein's Early Life

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.

The 1905 Papers

In the first of three seminal papers that were published in 1905, Einstein examined the phenomenon discovered by Max Planck, according to which electromagnetic energy seemed to be emitted from radiating objects in quantities that were ultimately discrete. The energy of these emitted quantities, the so-called light-quanta, was directly proportional to the frequency of the radiation. This circumstance was perplexing because classical electromagnetic theory, based on Maxwell's equations and the laws of thermodynamics, had assumed that electromagnetic energy consisted of waves propagating in a hypothetical, all-pervasive medium called the luminiferous ether, and that the waves could contain any amount of energy no matter how small. Einstein used Planck's quantum hypothesis to describe visible electromagnetic radiation, or light. According to Einstein's heuristic viewpoint, light could be imagined to consist of discrete bundles of radiation. Einstein used this interpretation to explain the photoelectric effect, by which certain metals emit electrons when illuminated by light with a given frequency. Einstein's theory, and his subsequent elaboration of it, formed the basis for much of quantum mechanics.

General Theory of Relativity

After 1905, Einstein continued working in all three of his works in the 1905 papers. He made important contributions to the quantum theory, but increasingly he sought to extend the special theory of relativity to phenomena involving acceleration. The key to an elaboration emerged in 1907 with the principle of equivalence, in which gravitational acceleration was held a priori indistinguishable from acceleration caused by mechanical forces; gravitational mass was therefore identical with inertial mass. Einstein elevated this identity, which is implicit in the work of Isaac Newton, to a guiding principle in his attempts to explain both electromagnetic and gravitational acceleration according to one set of physical laws. In 1907 he proposed that if mass were equivalent to energy, then the principle of equivalence required that gravitational mass would interact with the apparent mass of electromagnetic radiation, which includes light. By 1911, Einstein was able to make preliminary predictions about how a ray of light from a distant star, passing near the Sun, would appear to be attracted, or bent slightly, in the direction of the Sun's mass. At the same time, light radiated from the Sun would interact with the Sun's mass, resulting in a slight change toward the infrared end of the Sun's optical spectrum. At this juncture Einstein also knew that any new theory of gravitation would have to account for a small but persistent anomaly in the perihelion motion of the planet Mercury.

About 1912, Einstein began a new phase of his gravitational research, with the help of his mathematician friend Marcel Grossmann, by phrasing his work in terms of the tensor calculus of Tullio Levi-Civita and Gregorio Ricci-Curbastro. The tensor calculus greatly facilitated calculations in four-dimensional space-time, a notion that Einstein had obtained from Hermann Minkowski's 1907 mathematical elaboration of Einstein's own special theory of relativity. Einstein called his new work the general theory of relativity. After a number of false starts, he published the definitive form of the general theory in late 1915. In it the gravitational field equations were covariant; that is, similar to Maxwell's equations, the field equations took the same form in all equivalent frames of reference. To their advantage from the beginning, the covariant field equations gave the observed perihelion motion of the planet Mercury. In its original form, Einstein's general relativity has been verified numerous times in the past 60 years, especially during solar-eclipse expeditions when Einstein's light-deflection prediction could be tested.

Later Life

When British eclipse expeditions in 1919 confirmed his predictions about the general theory of relativity, Einstein was bombarded by the popular press. Einstein's personal ethics also fired public imagination. Einstein, who after returning to Germany in 1914 did not reapply for German citizenship, was one of only a handful of German professors who remained a pacifist and did not support Germany's war aims. After the war, when the victorious allies sought to exclude German scientists from international