  We have examined the consequences of assuming the existence of a light scalar
boson, weakly coupled to neutrinos, and not coupled to any other light
fermions. For a range of parameters, we find that this hypothesis leads to the
development of neutrino clusters which form in the early Universe and which
provide gravitational fluctuations on scales small compared to a parsec (i.e.,
the scale of solar systems). The existence of such clustering produces an
effect which would appear as a negative mass squared for the electron neutrino
in Tritium beta decay, without conflicting with other experiments. The neutrino
masses arising in unified gauge theories would then be very much larger than
the masses extracted from experiments within the solar system.
