  Momentum production during the phase slip process in SNS Josephson junction
is discussed. It is caused by the spectral flow of bound states of fermions
localized within the junction. This effectively reduces the Magnus force acting
on vortices which provides an explanation for the experimental observation of
the negligible Magnus force in 2D Josephson junction arrays. The flow of the
fermionic levels is similar to that in sphalerons in particle physics, where it
gives rise to the baryogenesis.
