MATTER WAVES

Sections 7.1 and 7.2 established that electromagnetic radiation -- ordinarily understood as a wave -- also behaves like a stream of particles (photons) whenever it interacts with matter, most dramatically in the photoelectric effect. This section turns that discovery around. If radiation, normally a wave, can act like particles, could matter particles -- ordinarily understood as tiny, localized lumps -- likewise carry a wave character of their own? This is precisely the question Louis de Broglie asked in 1924, and the resulting idea of matter waves, developed a …