Einstein's theory of radiation

Einstein’s theory of radiation explains how energy is transferred through electromagnetic waves, like light, via two key processes: emission and absorption. When atoms or molecules gain energy, they emit radiation; when they encounter energy, they absorb radiation. Einstein introduced coefficients to describe these probabilities, showing that emission and absorption are related and can occur spontaneously or due to existing radiation. This framework helps us understand phenomena such as blackbody radiation, the photoelectric effect, and the behavior of light in various systems, linking the quantum nature of atoms with classical electromagnetic theory in a consistent way.