My book does not explain this and i cant rly find a simple explanation for this on google and my professor basically dodged my question: So the de Broglie wavelength formula basically says that matter creates waves with wavelength h/p, where p is the matter's momentum. However, when the velocity is zero, the denominator of the wavelength equation becomes infinite...by infinite wavelength im guessing this means that the wavelength is so long that it actually doesn't exist? So does that mean that a piece of matter only create a wave when it is moving? But that can't be right since motion is relative, so if something is not moving with respect to me, it is moving with respect to someone else, so that other person would be able to detect a matter wave but I wouldn't be able to...??