Historic references to Einstein’s A and B coefficients

Einstein’s famous 1917 paper did not only introduce the A and B coefficients, which can be regarded as the historic origin of the laser (“stimulated emission), but also considered light forces on atoms. He showed that the spontaneous light force is necessary to establish equilibrium between black body radiation and a gas of atoms.

Enjoy the reading:

2005 Physics Today column by Dan Kleppner download

1917 Paper by Einstein, as a special treat in both English and the German original