BIG-BANG NUCLEOSYNTHESIS COMES OF AGE

The discovery of the Cosmic Background Radiation (CBR) revolutionized the study of Cosmology and extended our vision of the Universe to much earlier epochs. Primordial nucleosynthesis dramatically expands this view to the early Universe, providing a unique window on processes at high temperatures and densities. Big Bang Nucleosynthesis (BBN), the synthesis of the light elements during the first thousand seconds in the evolution of the Universe, offers a laboratory for testing models of elementary particle physics under conditions inaccessible to even the largest terrestrial accelerators. In the 25 years since the discovery of the CBR, the road to high energy physics via cosmology has been well travelled. However, in the absence of direct confirmation, many have remained sceptical of the value of this indirect approach. The very recent SLC and LEP results on the width of the Z0 now provide a validation of the BBN bound to the number of families of light neutrinos (N(v)) and a confirmation of the Cosmology/Particle Physics Connection. Since the BBN bound to N(v) is central to this connection, the history and evolution of this prediction is reviewed and its current status is explored along with a peek into the future. It is emphasized that accelerator and BBN bounds are complementary and that valuable insights into high energy physics may be gleaned from explorations of the Universe.