Context

The birth of thermodynamics in the early twentieth century XIX ^e century, as an experimental science, was rapidly followed by its theoretical development as a phenomenological science. At the end of the XIX ^{n the} century, all the laws of thermodynamics had been developed; and with the XX ^{n the} century, the theoretical development of quantum mechanics (QM) began, with the rapprochement of thermodynamics leading to Planck's law, and the birth of quantum theory. Following Planck's ideas on black-body radiation, Einstein in 1905 proposed the quantization of the electromagnetic field