 These "energy quanta" later came to be called "photons", a term introduced by Gilbert N. Lewis in 1926.The idea that each photon had to consist of energy in terms of quanta was a remarkable achievement; it effectively solved the problem of black-body radiation attaining infinite energy, which occurred in theory if light were to be explained only in terms of waves.In 1913, Bohr explained the spectral lines of the hydrogen atom, again by using quantization, in his paper of July 1913 "On the Constitution of Atoms and Molecules".