German-born American theoretical physicist whose theories of Special Relativity (1905) and General Relativity (1916) revolutionized modern thought on the nature of space and time and formed a theoretical base for the exploitation of atomic energy. He won the 1921 Nobel Prize for physics for his explanation of the photoelectric effect.
Biography: By around 1900, the increased precision of new measuring instruments had shown that the laws of motion and gravity established by Galileo and Newton were unable to explain certain phenomena. The observed orbit of Mercury, for example, differed slightly from that predicted by Newton, and laws describing the motion of electromagnetic waves left many electrical effects unexplained. In 1905, an unknown 26-year-old patent office clerk named Albert Einstein published four papers that not only solved these problems, but revolutionized physics. The first two presented his Special Theory of Relativity, which departed from the classical Newtonian concepts of space and time in its assertion that all reference frames (all coordinate systems) do not measure space and time equivalently. That is, space and time are not the same throughout the universe, but depend on the motion of the observer. But for Einstein, not everything was relative. Following the electromagnetic theory of Maxwell, Einstein argued that the speed of light is the same for all observers, and introduced a new concept of space-time to reconcile this with concepts of relative motion. He also introduced the famous equation expressing a direct relation between mass and energy, E = mc2, known as mass-energy equivalence. A third paper analyzed electromagnetic radiation such as light in terms of particles called photons, and explained how some substances, when exposed to such radiation, eject electrons in a quantum process called the photoelectric effect. A fourth paper explained the random movement of particles suspended in a fluid, now known as Brownian motion. In 1916, in his General Theory of Relativity, Einstein described gravity as a warping of space-time (as opposed to Newton's force) caused by the mere presence of objects possessing mass. Einstein's new conception of gravity correctly predicted Mercury's observed orbit, and his work on photons led to a more accurate description of electromagnetic radiation. In his later years, Einstein devoted himself to a search for a theory that would unify gravity with the other three fundamental forces in nature: the strong force, the electromagnetic force, and the weak force. This search is still ongoing.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
In 1939, a group of scientists, including Edward Teller, received evidence that Germany, then controlled by the Nazis, was planning to build an atomic bomb to use against the United States. These scientists persuaded Einstein to write to President Franklin D. Roosevelt and urge that the United States develop an atomic bomb first. (See Manhattan Project.)
Einstein believed strongly in the regularity of nature. He said, “God does not play dice with the universe,” and “God is subtle, but he is not malicious.”
It is important to distinguish between the theory of relativity, in which the laws of nature are the same for all observers anywhere in the universe, and the philosophical doctrine of relativism, which holds that there are no absolute truths. The similarity in their names has been a source of confusion.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.