When de broglie postulated that material particles would show wave-like characteristics, expression(4), which relates the momentum to the wavelength, was taken to apply not only to photon but to matter waves also. However the matter has mass and the photon does not. This is the essential difference of the matter and the lightWhen de Broglie postulated that material particles would show wave-like characteristics, expression (4), which relates the momentum to the wavelength, was taken to apply not only to photon but to matter waves also. However, the matter has mass and the photon does not. This is the essential difference of the matter and the light