  About 40 years ago, the neutrino was ruled out as the dark matter particle
based on several arguments. Here I use the well-established concept of quantum
uncertainties of position and momentum to describe the decoupling of neutrinos
from the primordial plasma, which took place about half a second after the Big
Bang. In this way I show that the main arguments against the neutrino are
either wrong or have loopholes, and conclude that the neutrino urgently needs
to be reconsidered, not as a 'hot', but as the 'cold' dark matter particle.
