  Growing neutrino quintessence solves the coincidence problem for dark energy
by a growing cosmological value of the neutrino mass which emerges from a
cosmon-neutrino interaction stronger than gravity. The cosmon-mediated
attraction between neutrinos induces the formation of large scale neutrino
lumps in a recent cosmological epoch. We argue that the non-linearities in the
cosmon field equations stop the further increase of the neutrino mass within
sufficiently dense and large lumps. As a result, we find the neutrino induced
gravitational potential to be substantially reduced when compared to linear
extrapolations. We furthermore demonstrate that inside a lump the possible time
variation of fundamental constants is much smaller than their cosmological
evolution. This feature may reconcile current geophysical bounds with claimed
cosmological variations of the fine structure constant.
