 Einstein, Albert
(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 century. 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 geometry. 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 Zürich.
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
Mariç, 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 Zürich 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
Einstein's argument. 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 Zürich. In 1911 he moved to the German-speaking university at Prague,
and in 1912 he returned to the Swiss National Polytechnic in Zürich.
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 worldwide. 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 entities. 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." World Citizen After 1919, Einstein became internationally
renowned. He accrued honors and awards, including the Nobel Prize in physics
in 1921, 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; and Out of My Later Years
(1950). Einstein's collected papers are being published in a multivolume
work, beginning in 1987.
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