BIG-BANG NUCLEOSYNTHESIS

In the first thousand seconds of its evolution the Universe was a prim ordial nuclear reactor synthesizing the light nuclides D, He-3, He-4 a nd Li-7. These messengers from the Big Bang provide a unique window in the early, hot, dense Universe, offering the opportunity fort tests o f the standard models of particle physics and of cosmology. A new, sta tistically coherent comparison of the primordial abundances of these n uclides inferred from increasingly accurate observational data with th ose predicted by standard models hints at a possible crisis. The case for this emerging crisis is presented and several paths towards amelio rating it are explored.