The black-body radiation law is very important to modern electronics. Most of the energy radiated is useless for vision and appears only as heat, since the black-body radiation spectrum is so broad. Black-body radiation, and the photoelectric effect were challenging the nice comfortable world of classical physics. Bose Einstein was looking at more than just solids, and in fact had a deep interest in the ionization of gasses. So, he began by re-examining the black-body radiation problem as an approach to assure that all of his readers would so to speak “be on the same page.” Max Planck worked with thermodynamics in developing the black-body radiation formula and was also a strong proponent of Boltzmann. Ehrenfest had developed a health problem similar to that of Boltzmann, which would lead to bouts of depression. In the 1880s, Boltzmann began to develop theoretically an idea on the emission using the statistical physics which he favored.