He abundance
1.The theoretical and observational aspects for standard big bang nucleosynthesis (SBBN) model have been expounded. The latest progress in 1994 has been emphasized and discussed:as the primordial 4He abundance, which has been determined to three significant digits, might conflict with the primordial D+3He abundance deduced from the Milky Way observations and chemical evolution theory the SBB model may be confronted with severe test.


