COSMOLOGY AND UNSTABLE NUCLEI

Primordial nucleosynthesis has established itself as one of the three pillars of Big Bang cosmology. Many of the Big Bang Nucleosynthesis re actions involve unstable nuclei. Hence, there is a tight relationship between the subject of this conference and cosmology. The prime role o f unstable nuclei in cosmology is related to lithium synthesis and the lack of cosmological synthesis of Be and B. These nuclei will thus be focused upon. Nucleosynthesis involves comparing calculated abundance s with observed abundances. In general abundance determinations are do minated by systematic rather than statistical errors, and work on boun ding systematics is crucial. The quark-hadron inspired inhomogeneous c alculations now unanimously agree that only relatively small variation s in Omega(b) are possible vis-a-vis the homogeneous model; hence, the robustness of Omega(b) similar to 0.05 is now apparent. (These calcul ations depend critically on unstable nuclei.) The above argues that th e bulk of the baryons in the universe are not producing visible light. A comparison with the ROSAT cluster data is also shown to be consiste nt with the standard BBN model. Omega(b) similar to 1 seems to be defi nitely excluded, so, if Omega(TOTAL) = 1, as some recent observations may hint, then non-baryonic dark matter is required. The implications of the recently reported halo microlensing events are discussed. In su mmary, it is argued that the physics of unstable nuclei affects the fu ndamental dark matter argument.