Albert Einstein (1879-1955)
German-born American physicist and Nobel laureate, best known as the creator of the special and general theories of relativity
and for his bold hypothesis concerning the particle nature of light. He is perhaps the most well-known scientist of the 20th
Einstein was born in Ulm on March 14, 1879, and spent his youth in Munich, where his family owned a small shop that
manufactured electric machinery. He did not talk until the age of three, but even as a youth he showed a brilliant curiosity
about nature and an ability to understand difficult mathematical concepts. At the age of 12 he taught himself Euclidean
Einstein hated the dull regimentation and unimaginative spirit of school in Munich. When repeated business failure led the
family to leave Germany for Milan, Italy, Einstein, who was then 15 years old, used the opportunity to withdraw from the
school. He spent a year with his parents in Milan, and when it became clear that he would have to make his own way in the
world, he finished secondary school in Arrau, Switzerland, and entered the Swiss National Polytechnic in Zrich. Einstein
did not enjoy the methods of instruction there. He often cut classes and used the time to study physics on his own or to play
his beloved violin. He passed his examinations and graduated in 1900 by studying the notes of a classmate. His professors
did not think highly of him and would not recommend him for a university position.
For two years Einstein worked as a tutor and substitute teacher. In 1902 he secured a position as an examiner in the Swiss
patent office in Bern. In 1903 he married Mileva Mari, who had been his classmate at the polytechnic. They had two sons
but eventually divorced. Einstein later remarried.
Early Scientific Publications
In 1905 Einstein received his doctorate from the University of Zrich for a theoretical dissertation on the dimensions of
molecules, and he also published three theoretical papers of central importance to the development of 20th-century physics. In
the first of these papers, on Brownian motion, he made significant predictions about the motion of particles that are randomly
distributed in a fluid. These predictions were later confirmed by experiment. The second paper, on the photoelectric effect,
contained a revolutionary hypothesis concerning the nature of light. Einstein not only proposed that under certain
circumstances light can be considered as consisting of particles, but he also hypothesized that the energy carried by any light
particle, called a photon, is proportional to the frequency of the radiation. The formula for this is E = hu, where E is the
energy of the radiation, h is a universal constant known as Planck's constant, and u is the frequency of the radiation. This
proposal-that the energy contained within a light beam is transferred in individual units, or quanta-contradicted a
hundred-year-old tradition of considering light energy a manifestation of continuous processes. Virtually no one accepted
Einstein's proposal. In fact, when the American physicist Robert Andrews Millikan experimentally confirmed the theory
almost a decade later, he was surprised and somewhat disquieted by the outcome.
Einstein, whose prime concern was to understand the nature of electromagnetic radiation, subsequently urged the
development of a theory that would be a fusion of the wave and particle models for light. Again, very few physicists
understood or were sympathetic to these ideas.
Einstein's Special Theory of Relativity
Einstein's third major paper in 1905, "On the Electrodynamics of Moving Bodies", contained what became known as the
special theory of relativity. Since the time of the English mathematician and physicist Sir Isaac Newton, natural philosophers
(as physicists and chemists were known) had been trying to understand the nature of matter and radiation, and how they
interacted in some unified world picture. The position that mechanical laws are fundamental has become known as the
mechanical world view, and the position that electrical laws are fundamental has become known as the electromagnetic world
view. Neither approach, however, is capable of providing a consistent explanation for the way radiation (light, for example)
and matter interact when viewed from different inertial frames of reference, that is, an interaction viewed simultaneously by an
observer at rest and an observer moving at uniform speed.
In the spring of 1905, after considering these problems for ten years, Einstein realized that the crux of the problem lay not in a
theory of matter but in a theory of measurement. At the heart of his special theory of relativity was the realization that all
measurements of time and space depend on judgments as to whether two distant events occur simultaneously. This led him to
develop a theory based on two postulates: the principle of relativity, that physical laws are the same in all inertial reference
systems, and the principle of the invariance of the speed of light, that the speed of light in a vacuum is a universal constant.
He was thus able to provide a consistent and correct description of physical events in different inertial frames of reference
without making special assumptions about the nature of matter or radiation, or how they interact. Virtually no one understood
Early Reactions to Einstein
The difficulty that others had with Einstein's work was not because it was too mathematically complex or technically obscure;
the problem resulted, rather, from Einstein's beliefs about the nature of good theories and the relationship between experiment
and theory. Although he maintained that the only source of knowledge is experience, he also believed that scientific theories
are the free creations of a finely tuned physical intuition and that the premises on which theories are based cannot be connected
logically to experiment. A good theory, therefore, is one in which a minimum number of postulates is required to account for
the physical evidence. This sparseness of postulates, a feature of all Einstein's work, was what made his work so difficult for
colleagues to comprehend, let alone support. Einstein did have important supporters, however. His chief early patron was the
German physicist Max Planck. Einstein remained at the patent office for four years after his star began to rise within the
physics community. He then moved rapidly upward in the German-speaking academic world; his first academic appointment
was in 1909 at the University of Zrich. In 1911 he moved to the German-speaking university at Prague, and in 1912 he
returned to the Swiss National Polytechnic in Zrich. Finally, in 1913, he was appointed director of the Kaiser Wilhelm
Institute for Physics in Berlin.
The General Theory of Relativity
Even before he left the patent office in 1907, Einstein began work on extending and generalizing the theory of relativity to all
coordinate systems. He began by enunciating the principle of equivalence, a postulate that gravitational fields are equivalent to
accelerations of the frame of reference. For example, people in a moving elevator cannot, in principle, decide whether the
force that acts on them is caused by gravitation or by a constant acceleration of the elevator. The full general theory of
relativity was not published until 1916. In this theory the interactions of bodies, which heretofore had been ascribed to
gravitational forces, are explained as the influence of bodies on the geometry of space-time (four-dimensional space, a
mathematical abstraction, having the three dimensions from Euclidean space and time as the fourth dimension).
On the basis of the general theory of relativity, Einstein accounted for the previously unexplained variations in the orbital
motion of the planets and predicted the bending of starlight in the vicinity of a massive body such as the sun. The
confirmation of this latter phenomenon during an eclipse of the sun in 1919 became a media event, and Einstein's fame spread
For the rest of his life Einstein devoted considerable time to generalizing his theory even more. His last effort, the unified field
theory, which was not entirely successful, was an attempt to understand all physical interactions-including electromagnetic
interactions and weak and strong interactions-in terms of the modification of the geometry of space-time between interacting
Most of Einstein's colleagues felt that these efforts were misguided. Between 1915 and 1930 the mainstream of physics was
in developing a new conception of the fundamental character of matter, known as quantum theory. This theory contained the
feature of wave-particle duality (light exhibits the properties of a particle, as well as of a wave) that Einstein had earlier urged
as necessary, as well as the uncertainty principle, which states that precision in measuring processes is limited. Additionally,
it contained a novel rejection, at a fundamental level, of the notion of strict causality. Einstein, however, would not accept
such notions and remained a critic of these developments until the end of his life.
"God," Einstein once said, "does not play dice with the world."
After 1919, Einstein became internationally renowned. He accrued honors and awards, including the Nobel Prize in physics
in 1922, from various world scientific societies. His visit to any part of the world became a national event; photographers and
reporters followed him everywhere. While regretting his loss of privacy, Einstein capitalized on his fame to further his own
political and social views.
The two social movements that received his full support were pacifism and Zionism. During World War I he was one of a
handful of German academics willing to publicly decry Germany's involvement in the war. After the war his continued public
support of pacifist and Zionist goals made him the target of vicious attacks by anti-Semitic and right-wing elements in
Germany. Even his scientific theories were publicly ridiculed, especially the theory of relativity. When Hitler came to power,
Einstein immediately decided to leave Germany for the United States. He took a position at the Institute for Advanced Study at
Princeton, New Jersey. While continuing his efforts on behalf of world Zionism, Einstein renounced his former pacifist stand
in the face of the awesome threat to humankind posed by the Nazi regime in Germany.
In 1939 Einstein collaborated with several other physicists in writing a letter to President Franklin D. Roosevelt, pointing out
the possibility of making an atomic bomb and the likelihood that the German government was embarking on such a course.
The letter, which bore only Einstein's signature, helped lend urgency to efforts in the U.S. to build the atomic bomb, but
Einstein himself played no role in the work and knew nothing about it at the time.
After the war, Einstein was active in the cause of international disarmament and world government. He continued his active
support of Zionism but declined the offer made by leaders of the state of Israel to become president of that country. In the
U.S. during the late 1940s and early '50s he spoke out on the need for the nation's intellectuals to make any sacrifice
necessary to preserve political freedom. Einstein died in Princeton on April 18, 1955. Einstein's efforts in behalf of social
causes have sometimes been viewed as unrealistic. In fact, his proposals were always carefully thought out. Like his scientific
theories, they were motivated by sound intuition based on a shrewd and careful assessment of evidence and observation.
Although Einstein gave much of himself to political and social causes, science always came first, because, he often said, only
the discovery of the nature of the universe would have lasting meaning.
His writings include
Relativity: The Special and General Theory (1916);
About Zionism (1931);
Builders of the Universe (1932);
Why War? (1933), with Sigmund Freud;
The World as I See It (1934);
The Evolution of Physics (1938), with the Polish physicist Leopold Infeld;
Einstein's collected papers are being published in a multivolume work, beginning in 1987.
Text contributed by: Samuel Glasstone, "Einstein, Albert" Microsoftš Encarta. Copyright © 1994 Microsoft Corporation.
Copyright © 1994 Funk & Wagnall's Corporation.