文档介绍：Rereading Einstein
years of struggle, however Einstein
neous and stimulated emission are apparently had a slmmcrll;gdiscon-
917 paper on radiation, but his tent w~thhis understanding of ther-
s many other concepts-the ma1 radiation, for in July 1916. he
turned to the problem of how matter
and radiation can achleve thermal
equilibrium. One could argue that
Daniel Kleppner 1916 was too soon to deal with that
problem because there were serious
lbert Einstein had a genius for extracting revolution- conceptual obstacles to the creation of a consistent theory.
A ary theory from simple considerations: From the pos- Einstein, in his Olympian fashion, simply ignored them.
tulate of a universal velocity he created special relativity; In the next eight months, he wrote three papers on the
from the equivalence principle he created general relativ- subject, publishing the third, and best known, in 1917.
ity: from elementary arguments based on statistics he dis- In his theory of radiation, as the 1917 paper e
covered energy quanta. His 1905 paper on quantization of to be known,' Einstein introduced the concepts of sponta-
the radiation field (often referred to, urately, as the neous and stimulated emission, with rates characterized
photoelectric-effect paper) was built on simple statistical by theA and B coefficients. Einstein's A and B coefficient