The diffusion of the isotopes of hydrogen in nonmagnetic metals has been of interest for many years. Muon spin rotation (uSR) has permitted the study of the diffusion of the positive muon as a light isotope of hydrogen. This experimental technique has been applied successfully to the diffusion of positive muons in palladium. Classical diffusion theory does not seem to explain the experimental results. A quantum mechanical calculation which explains the results has not yet been made.