The properties were controllable through the addition of other types of atoms called doping in semiconductors which led to the invention of the transistor. Then the whole science of solid state electronics evolved, which now dominates our communications and computer technology. Einstein proposed that the transition of an atom from its excited state to its lower state would be enhanced if it were struck by a photon of the same energy and it would lead to the appearance of two quanta of a certain energy where there had only been one before. This can lead to chain reaction stimulated by photons striking a large population of atoms in the excited state, giving rise to a big burst of radiation of the same frequency and wavelength. Based on this principle, LASER (which stands for Light Amplification by Stimulated Emission of Radiation), a beam of light of very high intensity and very small angular divergence was invented by Theodore Maiman in 1927.