Close to zero as possible

Δx -> +0

1 eV = 1.6×10^{−19 J}

Electron = 9.1×10^{−31 kg}  = 511keV

Electron neutrino = 3.6×10⁻³⁶ kg = 2 eV

Plank constant h = 6.6×10^{−34　J・s}

^{Dirac constant h/2π = 1.0×10−34　J・s}