French theoretical physicist Louis de Broglie (1892 to 1987) furthered such research on the wave nature of particles by proving that there are particles (electrons, protons and neutrons) besides photons that have the properties of a wave. According to de Broglie, all particles traveling at speeds near that of light adopt the properties and wavelength of a wave in addition to the properties and momentum of a particle. He also derived the relationship "wavelength x momentum = Planck's constant."

From another perspective, one could say that the essence of the dual nature of light as both a particle and a wave could already be found in Planck's constant.

The evolution of this idea is contributing to diverse scientific and technological advances, including the development of electron microscopes.