The de broglie wavelength is h/p, where p is momentum, and hence mv, so wavelenght = h/ (mv). The mass is on the denominator, so a massive object, like a baseball, will have a small wavelength, beyond detection and we can ignore it. OK, so does the mass have to be moving to have a de broglie wavelength, because the denominator is mv. small particle can have 'detectable' wavelengths right? Do they need to be moving. What does the 'v' in the denominator mean? Do I have a de Broglie wavelenght only when I'm moving? I guess I'm a bit confused as to what happens with that v. What about really large particles moving really slowly?