(1879—1955) German-born American theoretical physicist
German-born physicist, a thinker of astounding insight, author of the special and general theories of relativity, and winner of the 1921 Nobel Prize for Physics for his work on the photoelectric effect.
The son of a manufacturer of electrical equipment, Einstein was educated at various schools in Germany and Italy, where he failed to shine as either an apt or particularly compliant pupil. At the age of fifteen, his prophetic dislike of all things German led him to persuade his father to allow him to renounce his German nationality. Consequently, after a period of statelessness the young Einstein, who was then studying at the Federal Institute of Technology in Zürich (from 1896), became a Swiss citizen (1901). As his academic prowess did not earn him the teaching job he sought, he began his career in the Swiss Patent Office in Bern (1902–08). His duties, neither onerous nor thought-provoking, allowed Einstein time to think about the physical problems that had puzzled him for many years and in 1905 he published four papers that revolutionized twentieth-century physics.
The third and most significant of these papers, ‘Zur Electrodynamik bewegter Körper’ (‘On the Electrodynamics of Moving Bodies’), contained Einstein's first statement of the special theory of relativity. The theory was special because it dealt only with bodies at rest or moving with uniform motion. Einstein proposed two simple principles: that the speed of light was constant irrespective of the velocity of the measurer or the source, and that the laws of nature are invariant in all frames of reference moving uniformly relative to each other. These principles enabled Einstein to predict that a body's mass increases with its velocity and the phenomenon of time dilation. The first 1905 paper developed a formula for the average displacement of particles subjected to the Brownian motion and had far-reaching effects in providing evidence for the atomic theory. The second paper, for which he won his Nobel prize, was a development of quantum theory to account for the phenomenon of the photoelectric effect. The last paper, a short two-page work titled with an innocent-sounding question, ‘Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig?’ (‘Does the Inertia of a Body Depend on its Energy Content?’, was perhaps the most inspired of all. Concluding that if a body emits energy E as radiation, it will lose mass E/ c2 (c is the speed of light), he came to the equation E = mc2, which was later to explain the devastating energy source behind the atom bomb, about which he later warned President Roosevelt.
Einstein's special theory of relativity was accepted with remarkable speed and in 1908 he was invited to join the faculty at the University of Bern. He did not, however, remain long in Bern and after brief periods in Zürich and Prague, returned (1914) to Germany to become director of the Kaiser Wilhelm Institute of Physics in Berlin. While in Berlin, Einstein began work on his general theory of relativity, undoubtedly his greatest achievement as a physicist. Published in 1916 as ‘Die Grundlagen der allgemeinen Relativitätstheorie’ (‘The Foundations of the General Theory of Relativity’), it extended the special theory to include accelerated motion, tackled the problem of gravity and inertia, and led to a number of very precise predictions. One prediction was that rays of light would be deflected by a strong gravitational field. In 1919 a solar eclipse provided an opportunity to test the theory. Sir Arthur Eddington headed an expedition to Principe in Africa and found that light rays did bend in the sun's gravitational field by just the amount predicted by Einstein. At this point Einstein's uniqueness as a thinker began to be recognized by the general public. He became a household name as well as a figure the world's press pursued and whose views they sought. He also became involved in political battles. As a Jew and a pacifist, Einstein inevitably came into conflict with the Nazis. They rejected his scientific work as worthless and he was dismissed from several scientific societies. When Hitler came to power in 1933 Einstein left Germany never to return and made his home in the USA at the Institute of Advanced Studies in Princeton. He became a US citizen in 1940.
Subjects: Science and technology