COSMOLOGY AND PARTICLE PHYSICS - A NEW SYNTHESIS

The best-understood links between cosmology and particle physics invol ve neutrinos and the cosmic background radiation which comes to us fro m the hot big bang. These links are explored in relation to the number of neutrino types and to the possibility that neutrinos of non-zero r est-mass constitute most of the dark matter in galaxies and in interga lactic space. This possibility forms the basis of a new speculative pr oposal that dark-matter neutrinos decay into radiation which ionizes m ost of the hydrogen in the Universe. This proposal, if correct, would have wide implications for astronomy, cosmology and elementary particl e physics.