In 1923, at the Washington University in St. Louis, Arthur Holly Compton demonstrated an effect now known as Compton scattering. This effect is only explainable if light can behave as a stream of particles and it convinced the physics community of the existence of Einstein's light-particle. Lastly, in 1926, one year before the theory of quantum mechanics was published, Gilbert N. Lewis introduced the term " photon ", which soon became the name for Einstein's light particle. From there, the concept of messenger particles developed further, notably to massive force carriers (e.g. for the Yukawa potential).