Fraunhofer, Joseph von
Fraunhofer, Joseph von, (1787-1826), German
optician and physicist, had born in Straubing. Fraunhofer instituted many improvements in
the manufacture of optical glass, the grinding and polishing of lenses, and the construction of telescopes and other optical instruments.
Fraunhofer also invented a number of scientific instruments. His name is associated with
the fixed, dark lines in the solar spectrum, called Fraunhofer lines, which he was the first to describe in detail. In 1823 Fraunhofer became a
member of the Academy of Science at Munich and served as its conservator of physics.
Albert Einstein
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. 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. 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. 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. 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. 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. 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. 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.
