Second prediction from Big Bang Model: Abundance of the light elements
		� Big Bang Nucleosynthesis � T,  both high enough at start to fuse protons into heavier elements � T, � both dropping quickly so only have time enough to fuse a certain amount. � Simple models of expansion predict 25% abundance He � 25% is the amount of He observed � Abundance of 2H, 3He, 7Li depends on normal matter � Suggests normal matter is only 5% of critical � But we need to also consider �dark matter� and its gravity